CN116285502B - Preparation method of ink for reducing melting point of metal nanowire, optical invisible pattern electrode and electrode - Google Patents

Abstract

The application relates to the technical field of electrode materials, firstly, providing an ink for reducing the melting point of metal nanowires, which specifically comprises 0.1-1 part of molten compound and 95.2-99.7 parts of polar solvent in parts by weight; the melting compound is selected from any two or more of metal halide, iodonium salt, nitrate, iodate, metal oxide, brine and monoacid, and the ink can obviously reduce the melting temperature of the metal nanowire, thereby reducing the heating cost and the processing difficulty. The application further provides a preparation method of the optically invisible pattern electrode, which has the advantages of simple process, high processing precision and strong practicability, can effectively enhance the photoelectric performance of the metal nanowire pattern electrode, and is suitable for large-scale production and application. The application further provides the optical invisible pattern electrode prepared by the method, which has the advantages of high transmittance, low scattering and the like, and has excellent overall optical performance.

Description

An ink for lowering the melting point of metal nanowires, optically invisible patterned electrodes Electrode preparation method and electrode

Technical field

The present invention relates to the technical field of electrode materials, and more specifically, to an ink for reducing the melting point of metal nanowires, a method for preparing an optically invisible pattern electrode, and an electrode.

Background technique

At present, the global flexible electronics market is in a rapid growth trend. The types of flexible electronic products such as flexible screen mobile terminals, wearable smart devices, implantable electronic medical devices, and soft robots are constantly increasing, and their application fields are constantly expanding. The market demand for flexible transparent electrodes continues rise. The current mainstream flexible transparent electrode material is mainly indium tin oxide (ITO), which has the advantages of high transparency and good conductivity. However, ITO films will produce a large number of cracks under low strain (2-3%), which greatly affects the durability of flexible electronic devices. At the same time, there are disadvantages such as harsh high-temperature deposition conditions during preparation, high device energy consumption, and expensive metal indium.

Metal nanowires include silver nanowires, copper nanowires, iron nanowires, etc. The prepared transparent electrode has excellent conductivity, transmittance, and flexibility, among which silver nanowires have the most outstanding comprehensive properties. Metal nanowires can be synthesized using chemical methods and can be dispersed in polar solutions. They have the advantages of simple synthesis methods, high cost performance, and simple film formation processes. They can be easily deposited on large-area flexible substrates in a roll-to-roll manner through solution processes such as doctor blade coating, spray coating, and screen printing. The deposited film has the advantages of high light transmittance, good conductivity, excellent flexibility, and low cost, and is considered an ideal substitute for ITO electrodes. However, the application of metal nanowire flexible transparent electrodes in the field of optoelectronics, especially displays, still has the problem of optical visibility of patterned electrodes. Different from thin film materials, metal nanowires have a significant scattering effect on visible light, resulting in significant optical differences between the conductive and non-conductive areas of the metal nanowire electrode, allowing the human eye to observe traces of the electrode pattern. Pattern visibility will deteriorate the performance of transparent optoelectronic devices, such as the display quality of display devices. Currently, metal nanowire networks can achieve electrode patterning through two technical routes: top-down and bottom-up methods. Commonly used top-down methods include photolithography and laser ablation, while bottom-up methods mainly include inkjet printing, screen printing, and transfer printing. Regardless of the process, there are no metal nanowires in the insulating area of the metal nanowire patterned electrode. The resulting differences in refractive index and scattering inevitably lead to optical differences in the electrode pattern, that is, visibility.

At present, some literature has reported the technology of metal nanowire pattern elimination, which can be roughly divided into two strategies: (1) retaining traces of nanowires in the insulating area to eliminate pattern traces. There are mainly two methods: photolithography semi-etching and laser fusing. Take patent CN 103258596 B as an example. In this patent, the electrode area and the non-electrode area are first divided, a photoresist protective film is used to protect the electrode area, and the non-electrode area is etched by a semi-etching method to make it non-conductive. Maintain traces of silver nanowires to achieve elimination of conductive films; for another example, Myeongkyu Lee and others used nanosecond pulse lasers to selectively fuse the silver nanowire network, retaining nanowire segments in the insulating area to achieve conductivity patterning [The Journal of Physical Chemistry C 2016,120,20471-20477]. (2) Change the surface of the metal nanowires or the surrounding medium to reduce or even out the scattering of the electrodes, thereby achieving the purpose of patterning and elimination. For example, patent CN 105960298 B prepares a transparent conductive film by using colored compounds as dyes to adsorb on metal nanowires to prevent the black floating phenomenon; patent CN 108399977 B uses transparent conductive films between the substrate and nanosilver wires. A functional layer is set between the layers. The functional layer contains metal nanoparticles with strong diffuse reflection. By adjusting the thickness of the functional layer, the difference between the haze and the conductive layer can be less than 0.2, thereby achieving pattern elimination. However, the methods reported in the above literature and patents have the disadvantages of complicated processes, expensive equipment, poor practicability, or deterioration of the photoelectric performance of the electrodes. Therefore, to address the visibility problem of metal nanowire patterns, it is very necessary and challenging to develop a patterning technology that is simple in process, highly practical, has high processing precision and can enhance its optoelectronic performance. Among them, surface modification of metal nanowires or other special treatments to change their physical and chemical properties such as melting point so that the metal nanowires meet the preparation requirements of optically invisible patterned electrodes are the key points to be overcome to achieve the aforementioned goals. Therefore, the development Inks that meet the requirements and can be used to decorate metal nanowires are particularly critical.

Contents of the invention

In response to the above-mentioned problems, one of the purposes of the present invention is to provide an ink for reducing the melting point of metal nanowires, specifically including 0.1 to 1 part of a molten compound and 95.2 to 99.7 parts of a polar solvent; wherein, the The molten compound is selected from any two or more types of metal halides, iodonium salts, nitrates, iodates, metal oxides, brine, and monobasic acids.

Further, the molten compound is selected from diphenyl iodine nitrate, silver nitrate composition or acetic acid, nitric acid, iron oxide composition or diphenyl iodine triflate, iodine water composition or diphenyl iodine nitrate, Silver nitrate composition or silver iodide, potassium iodide, silver nitrate composition or silver iodate, silver nitrate, silver iodide composition;

And/or, the polar solvent is selected from one or more of water, acetone, monohydric alcohol, and polyhydric alcohol.

In some embodiments, the ink used to reduce the melting point of metal nanowires further includes 0.1 to 0.8 parts of metal nanowires in parts by weight.

Further, the metal nanowires are one or more of silver nanowires, copper nanowires, and iron nanowires;

And/or, the diameter of the metal nanowire is less than 200 nm.

In some embodiments, the ink used to reduce the melting point of metal nanowires further includes 0.1 part to 1 part by weight of a dispersant.

Further, the dispersant is selected from fluorine-containing nonionic surfactants, sodium dodecylbenzene sulfonate, sodium 3-mercapto-1-propanesulfonate, 4-(1,1,3,3-tetramethyl Butyl)phenyl-polyethylene glycol, hydroxypropyl methylcellulose, polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, polyethyleneimine, polyvinylpyrrolidone, polyethylene glycol, shell Polysaccharide and other polymers, polyether defoaming agents, polysiloxane defoaming agents, silicone defoaming agents, silicone oil defoaming agents, acrylic acids, acetylenic diols, silicones, fluorocarbons one or more compounds.

The mechanism for the molten compound to reduce the fusing temperature in the present invention is as follows: the molten compound is in contact with the metal nanowires and mixed, and the molten compound directly interacts with the metal nanowires to promote the diffusion behavior of atoms on the surface of the metal nanowires at low temperatures, and then at low temperatures Rayleigh instability is induced to break the nanowire network, which macroscopically manifests itself as a reduction in the melting point of metal nanowires.

Another object of the present invention is to provide a method for preparing an optically invisible pattern electrode,

In some embodiments, a method of preparing an optically invisible patterned electrode includes the following steps:

S1. Deposit a metal nanowire network on the substrate and dry it for later use;

S2. Selectively deposit the ink used to reduce the melting point of metal nanowires on the substrate obtained in step S1. In a preferred embodiment, the ink does not contain metal nanowires, and the metal deposited with the ink The nanowires form a low melting point site, and the metal nanowires where the ink is not deposited form a high melting point site;

S3. Heating the metal nanonetwork obtained in step S2 to melt the metal nanowires at the low melting point location, obtaining an insulating area where the metal nanowires are melted at the low melting point location, and obtaining a complete conductive area of the metal nanowires at the high melting point location. , forming an optically invisible pattern electrode, wherein the preferred heating temperature is 50°C-300°C, and more preferably 50°C-200°C.

In some embodiments, a method for preparing an optically invisible pattern electrode includes the following steps:

S01. Deposit the ink used to reduce the melting point of metal nanowires on the substrate, the ink contains metal nanowires, and dry;

S02. Implement patterning on the substrate obtained in step S01: Place a mask plate above the substrate. The mask plate is provided with an exposure area that allows light to pass through and a light-shielding area that blocks the light; use a light source to irradiate the mask. Membrane plate, the exposed area forms a high melting point metal nanowire network, and the light shielding area forms a low melting point metal nanowire network;

In specific embodiments, the patterning method described in step S2 and step S02 can adopt a bottom-up method or a top-down method, wherein the bottom-up method includes inkjet printing, transfer printing, and screen printing. The bottom-up method includes photolithography, laser radiation method and other methods, and inkjet printing, screen printing, PDMS soft seal and other methods are preferred to achieve electrode patterning.

S03. Heating the substrate obtained in step S02, the low-melting-point metal nanowire network is fused, and the high-melting-point metal nanowire network remains intact, thereby forming an optically invisible pattern electrode, wherein the preferred heating temperature is 50°C-300°C ℃, more preferably 50℃-200℃.

In some specific embodiments, in order to further reduce the reflectivity of the electrode, the process of preparing the optically invisible pattern electrode, before performing step S1 or step S01, further includes the following steps: coating an anti-reflection layer on the substrate, preferably Preferably, the anti-reflection layer is a polymer film layer or a two-dimensional material coating.

Another object of the present invention is to provide an optically invisible pattern electrode, which is prepared by using the preparation method of the optically invisible pattern electrode.

The preparation process of the optically invisible pattern electrode in the present invention utilizes the principle of Rayleigh instability, in which the ink used to reduce the melting point of the metal nanowires changes the heat resistance of the metal nanowires, and is irradiated above the mask plate. Ultraviolet rays cause the decomposable compounds in the irradiated area to decompose, thereby losing the melting point-lowering effect on the metal nanowires, and serve as a preset conductive area; forming a thermal stability difference with the low-melting-point metal nanowires in the unirradiated area, which is the preset insulating area. Thereafter, the heating temperature is adjusted so that it is higher than the melting point of the metal nanowires in the preset insulating area and lower than the melting point of the metal nanowires in the preset conductive area. After heating, the metal nanowires in the insulating area melt and lose their conductive effect, while the metal nanowires in the conductive area are not affected, thus forming the required optically invisible pattern electrode. The refractive index difference between the two areas of the optically invisible pattern electrode produced by the invention is less than 0.2, and the haze difference does not exceed 2%.

Compared with the prior art, the beneficial effects of the present invention are:

(1) After using the ink of the present application for reducing the melting point of metal nanowires to treat metal nanowires, the fusing temperature of metal nanowires can be significantly reduced, thereby reducing the heating cost during fusing;

(2) The ink used to reduce the melting point of metal nanowires of the present invention is obtained by uniquely compounding different molten compounds. Compared with the ink of a single molten compound, the compounded ink can reduce the total amount of molten compounds added and can also Demonstrates a better effect of reducing the melting temperature of metal nanowires;

(3) The preparation method of optically invisible pattern electrodes of the present invention can reduce optical differences and reduce reflectivity. In addition, by adding an anti-reflection layer composed of two-dimensional materials or polymers between the substrate and the metal nanowire network, Further reduce optical differences in optically invisible pattern electrodes;

(4) The preparation method of the optically invisible pattern electrode of the present invention can also significantly reduce the sheet resistance of the conductive area, improve the transmittance, and reduce scattering;

(5) The preparation method of the optically invisible pattern electrode of the present invention has simple process, high processing precision and strong practicability, can effectively enhance the photoelectric performance of the metal nanowire pattern electrode, and is suitable for large-scale production applications;

(6) The optically invisible pattern electrode prepared by the present invention has a small difference in refractive index and haze between the insulating region and the conductive region, effectively improves transmittance, reduces scattering, and has superior overall optical performance.

Description of the drawings

Figure 1 is a schematic diagram of a substrate after ultraviolet irradiation in Embodiment 1 of the present invention.

Figure 2 is a schematic diagram of the substrate after heating in Embodiment 1 of the present invention.

Figure 3 is a scanning electron microscope image of the substrate after heating in Embodiment 1 of the present invention.

Figure 4 is a schematic diagram of the silver nanowire grid after heating the substrate in Embodiment 2 of the present invention.

Figure 5 is a picture of the substrate after heating in Embodiment 3 of the present invention.

Figure 6 is a schematic diagram of the ratio of the sheet resistance of the sample after heating different samples to the initial sheet resistance of the sample in Example 6 of the present invention.

Reference signs: In Example 1, the silver nanowire network area where ink is not deposited forms a high melting point area 01, in Example 1 the silver nanowire network area where ink is deposited forms a low melting point area 02, Example 1 conductive area 1, Example 1Insulated area2.

Detailed ways

The drawings of the present invention are only for illustrative purposes and should not be construed as limitations of the present invention. In order to better explain the following embodiments, some components in the drawings will be omitted, enlarged or reduced, which does not represent the size of the actual product; for those skilled in the art, some well-known structures and their descriptions in the drawings may be omitted. Understandable.

Example 1

1.1 Ink preparation

In parts by weight, the ink formula used to reduce the melting point of metal nanowires is as follows:

Molten compound: 0.25 parts of diphenyl iodine nitrate, 0.3 parts of AgNO ₃ ;

Polar solvent: 25.9 parts of deionized water, 3.2 parts of acetone, 69.35 parts of absolute ethanol;

Dispersing agent: 1 part chitosan.

Wherein, the AgNO ₃ is a standard silver nitrate solution.

1.2 Use the ink used to reduce the melting point of metal nanowires in 1.1 to prepare an invisible pattern electrode. The preparation method is as follows,

(1) Preparation of silver nanowire network: Spin-coat 30nm silver nanowire liquid on a polyethylene naphthalate (PEN) substrate to form a silver nanowire network.

(2) Modifying metal nanowires through ink patterning: Use screen printing to pattern-print the ink used to reduce the melting point of metal nanowires on a polyethylene naphthalate substrate, and leave it to dry; The portion of the silver nanowire network where ink is not deposited forms a high melting point region; the portion of the silver nanowire network where ink is deposited forms a low melting point region.

(3) Heating the substrate to form a patterned electrode: heating the substrate, when the low melting point area is heated, the silver nanowires on it are destroyed and fused, forming an insulating area; the silver nanowires in the upper high melting point area do not change significantly. , forming a conductive area, thereby obtaining the required optically invisible pattern electrode. In this embodiment, the refractive index difference between the low melting point area and the high melting point area of the optically invisible pattern electrode is less than 0.2, and the haze difference does not exceed 0.2%.

1.3 Among them, the schematic diagram of the substrate obtained after screen printing in this embodiment is shown in Figure 1, in which the shaded part is the area where ink is not deposited and retains a high melting point, which is the high melting point area 01, and the blank part is where the ink is deposited The silver nanowire network area with ink has a lower melting point and is a low melting point area 02.

In this embodiment, the heating stage temperature is set to 110°C during heating. After preheating is completed, the substrate is placed on the heating stage. After heating for 2 minutes, the substrate shown in Figure 2 is obtained. It can be measured that the blank part shown in Figure 2 loses conductivity, that is, the low melting point area 02 in Figure 1 forms an insulating area 2, and the resistance tends to be infinite; the shaded part in the figure retains conductivity, that is, the high melting point area in Figure 1 01 forms conductive area 1.

Figure 3 is an electron microscope scan of the substrate after heating in this embodiment. The dotted line is the dividing line. The right side is an electron microscope scan of the insulating area, and the left side is an electron microscope scan of the conductive area. The electron microscope scanning image in Figure 3 shows that the silver nanowire structure in the insulating area is damaged and broken, but the silver nanowire structure in the conductive area is not damaged.

Example 2

2.1 Ink preparation

In parts by weight, the ink formula used to reduce the melting point of metal nanowires is as follows:

Molten compound: 0.2 parts of acetic acid, 0.2 parts of nitric acid, 0.2 parts of iron oxide;

Polar solvent: 79.18 parts of deionized water, 20 parts of propylene glycol.

2.2 Use the ink used to reduce the melting point of metal nanowires in 2.1 to prepare an invisible pattern electrode. The preparation method is as follows,

(1) Deposit a silver nanowire network on a clean glass substrate and dry it at low temperature;

(2) Transfer the required non-conductive area pattern to the inkjet printing electronic software;

(3) The ink used in 2.1 to reduce the melting point of metal nanowires is selectively deposited on the silver nanowire network through inkjet printing to form a silver nanowire film patterned and modified with ink, wherein the silver nanowire network is The part where ink is deposited is a low melting point region, and the part where ink is not deposited on the silver nanowire network is a high melting point region.

(4) Heating the substrate to form pattern electrodes: Adjust the temperature of the heating stage to 120°C for preheating. After preheating is completed, place the substrate in the center of the heating stage for heating.

The silver nanowire network after heating in this embodiment is shown in Figure 4.

After heating at 120°C, the silver nanowires in the low melting point area were destroyed by Rayleigh instability and melted, forming an insulating area; the silver nanowires in the high melting point area did not change significantly, thus producing an optically invisible patterned electrode. .

In step (3) of the preparation process of the optically invisible patterned electrode in this implementation, the method of selectively depositing the ink on the metal nanowire network can be top-down printing, including but not limited to photolithography patterning, laser ablation, The adhesion difference method can also use bottom-up printing methods, including but not limited to screen printing, gravure printing, hydrophobic self-assembly, template-assisted printing methods, etc., to achieve the ink used to reduce the melting point of metal nanowires. Patterning on metallic nanowire networks.

Example 3

3.1 Ink preparation

In parts by weight, the ink formula used to reduce the melting point of metal nanowires is as follows:

Molten compound: 0.27 parts of diphenyltriflate iodine, 0.43 parts of iodine water;

Polar solvent: 25.01 parts of deionized water, 3.43 parts of acetone, and 70.62 parts of absolute ethanol.

3.2 Use the ink used in 3.1 to reduce the melting point of metal nanowires to prepare an optically invisible pattern electrode. The preparation method is as follows,

(1) Deposit a metallic silver nanowire network on the PEN substrate and dry it at low temperature;

(2) Transmit the preset non-conductive area pattern to the inkjet printing electronic software;

(3) Selectively print the ink used in 3.1 to reduce the melting point of metal nanowires on the metal nanowire network through inkjet to form a metal nanowire film patterned and modified with ink; wherein, on the metal nanowire network The part where ink is deposited is a low melting point region, and the part where ink is not deposited on the metal nanowire network is a high melting point region.

(4) Heating the substrate to form pattern electrodes: Adjust the temperature of the heating stage to 120°C for preheating. After preheating is completed, place the substrate in the center of the heating stage for heating.

After heating at 120°C, the metal nanowires in the low melting point area were destroyed by Rayleigh instability and melted, forming an insulating area; the metal nanowires in the high melting point area did not change significantly and formed a conductive area, thus making the optically instable Visual pattern electrode.

Optionally, in step (3) of this embodiment 3.2, the way in which the ink is selectively deposited on the metal nanowire network can be a bottom-up method or a top-down method, wherein the bottom-up method is preferred. Inkjet printing, transfer printing, screen printing methods, and bottom-up methods are preferably photolithography and laser radiation methods.

The substrate obtained after heating in this embodiment is shown in Figure 5.

Example 4

4.1 Ink preparation

In parts by weight, the ink formula used to reduce the melting point of metal nanowires is as follows:

Molten compound: 0.26 parts of diphenyl iodine nitrate, 0.33 parts of AgNO ₃ ;

Polar solvent: 26 parts of deionized water, 3.5 parts of acetone, 69.69 parts of absolute ethanol;

Metal nanowires: 0.22 parts of 30nm silver nanowires;

Wherein, the AgNO ₃ is a standard silver nitrate solution.

The optically invisible pattern electrode is prepared as follows:

(1) SU-8 preparation mold: Drop a certain amount of SU-8 photoresist on a clean glass substrate, put it into a glue spreader to spread the photoresist evenly on the substrate, and seal the edge of the substrate Excess photoresist is removed. Slowly increase the temperature of the substrate and heat it at a constant temperature for 20 minutes when the temperature is 90°C. A mask plate is placed above the substrate, and the mask plate is provided with a patterned area that allows light to pass through. Illumination was performed for 30 seconds above the mask. Remove the mask and slowly raise the temperature to 80°C to heat the substrate. The heating time is determined according to the required seal depth. Coat propylene glycol methyl ether acetate (PEN) on the substrate so that the photoresist completely displays the pattern of the above mask. Put the SU-8 photoresist after the above treatment into isopropyl alcohol until complete reaction.

(2) PDMS copy template to form PDMS soft seal: Mix PDMS prepolymer (Sylgard 184elastomer) and curing agent in a ratio of 10:1, and stir the mixture thoroughly with a glass rod. Put the above mixture into a vacuum machine to vacuum and let it sit for 30 minutes. Pour the bubble-free transparent mixture onto the above SU-8 mold and allow the mixture to level naturally. Preheat the heating stage to 70°C and heat the above mold to solidify the PMDS. The PDMS soft seal is obtained by peeling off the cured PMDS.

(3) Put the clean PEN substrate into the air plasma machine and perform hydrophilic treatment.

(4) Spin-coat 30nm silver nanowire liquid on the PEN substrate obtained in step (3) to form a metal nanowire network.

(5) Put the PDMS soft seal prepared in step (2) into a plasma machine for hydrophilic treatment.

(6) Soak the PDMS soft stamp obtained in step (5) in the ink used to reduce the melting point of metal nanowires as described in 4.1.

(7) Paste the ink-loaded PDMS soft stamp obtained in step (6) onto the target substrate PEN. By raising the temperature and heating, the patterned array can be transferred to the target substrate, where the metal nanowire network forms a low melting point area in the parts pasted by the soft seal, and the metal nanowire network in the parts not pasted by the soft seal. A network of wires forms a high melting point area.

(8) The substrate is heated at 120°C, and the metal nanowires in the low melting point area are melted to form an insulating area, while the metal nanowires in the high melting point area remain intact to form a conductive area, thereby obtaining the required patterned electrode.

Use steps (1) to (7) of this embodiment to prepare multiple optically invisible pattern electrodes. The transmittance at 550nm after being irradiated with light is as follows:

Sample serial number Transmittance of soft seal pasting area Transmittance of area not pasted by soft seal 1 91.70% 90.50% 2 92.10% 90.90% 3 91.10% 90.30% 4 89.40% 88.90% 5 91.80% 89.90% 6 92.40% 90.70% 7 92.00% 91.40% 8 91.50% 91.00% 9 91.90% 90.80%

The reflectivity comparison at 550nm between the exposed area and the non-exposed area of the sample prepared in steps (1)-(7) of this embodiment is as shown in the following table:

Sample serial number Reflectivity of soft seal pasting area Reflectivity of areas not pasted by soft seal 1 5.40% 6.50% 2 5.10% 5.90% 3 5.40% 6.20% 4 6.60% 6.60% 5 5.40% 6.60% 6 5.50% 6.30% 7 5.50% 5.10% 8 5.60% 6.20% 9 5.50% 6.70%

The difference in transmittance and reflectance at 550 nm between the low melting point region and the high melting point region of the sample patterned invisible electrode obtained in this example does not exceed 2%.

The sheet resistance changes of the samples in this example are shown in the table below.

Example 5

5.1 Ink preparation

In parts by weight, the ink formula used to reduce the melting point of metal nanowires is as follows:

Molten compound: 0.16 parts of silver iodide, 0.1 parts of potassium iodide, 0.33 parts of AgNO ₃ ;

Polar solvent: 26 parts of deionized water, 3.5 parts of acetone, 69.56 parts of absolute ethanol;

Metal nanowires: 0.22 parts of 30nm silver nanowires;

Dispersant: HPMC 0.13 parts;

The AgNO ₃ is a standard silver nitrate solution.

Prepare MXene/PET substrate: Take several clean PET substrates, put them into an air plasma machine for hydrophilic treatment, spin-coat an MXene solution with a concentration of 0.5mg/mL on the PET substrate, and leave it to dry. A PET substrate with a two-dimensional antireflection layer of MXene is formed.

The optically invisible pattern electrode is prepared as follows:

(1) Suspension-coat the ink that reduces the melting point of metal nanowires as described in 5.1 on the MXene/PET substrate, and leave it to dry;

(2) Place a mask plate above the substrate obtained in step (1), and the mask plate is provided with an exposure area that allows light to pass through and a light-shielding area that prevents light from passing through;

(3) Use a light source to illuminate the substrate above the mask;

(4) Using molten compound and illumination, the silver nanowire network corresponding to the exposure area on the substrate remains intact, maintaining the original melting point, and is a high melting point area; at the same time, the silver nanowire network corresponding to the light-shielding area on the substrate Melting occurs, forming a low melting point area; when the substrate is heated at 135 degrees Celsius, the silver nanowires in the low melting point material area are destroyed, forming a non-conductive insulating area, while the silver nanowires in the high melting point material area remain intact, forming a conductive area, thus making Obtain optically invisible patterned electrodes.

Use the method of this example to prepare several samples, and measure the reflectance at 550 nm in different areas. The results are as shown in the table below.

Sample serial number Sample conductive area reflectance Sample insulation area reflectance 1 5.00% 6.30% 2 5.50% 6.30% 3 5.00% 6.00% 4 5.90% 6.40% 5 5.10% 6.50% 6 5.30% 6.30% 7 5.50% 6.20% 8 5.60% 6.20% 9 5.50% 6.60%

Compared with Example 4, in this implementation, an anti-reflection layer is added to the original substrate, and the experimental sample produced has lower reflectivity and superior optical performance.

The above method for preparing invisible pattern electrodes is suitable for a variety of flexible materials, including polydimethylsiloxane, polyethylene terephthalate, polyethersulfone resin, polyethylene, polyimide, and polycarbonate. ester, polyurethane, polyethylene naphthalate, etc.

Comparative example 1

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this comparative example are as follows: molten compound: AgNO ₃ 0.1 part

Polar solvent deionized water: 99.9 parts.

Referring to Example 3, the above ink was deposited on the metal nanowire substrate.

The experiment found that after 10 minutes of post-baking at 200°C, the areas where ink was not deposited were still conductive, while the areas where ink was deposited were non-conductive.

Comparative example 2

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this comparative example are as follows: molten compound: 1 part of AgNO ₃

Polar solvent deionized water: 99 parts.

Referring to Example 3, the above ink was deposited on the metal nanowire substrate.

The experiment found that after 10 minutes of post-baking at 200°C, the areas where ink was not deposited were still conductive, while the areas where ink was deposited were non-conductive.

Comparative example 3

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this comparative example are as follows: molten compound: 1 part of diphenyl iodine nitrate

Polar solvent: 99 parts of deionized water.

Referring to Example 3, the above ink was deposited on the metal nanowire substrate.

Experiments have found that when the substrate is heated at 145°C, the areas where ink is not deposited are still conductive, while the areas where ink is deposited are non-conductive.

Comparative example 4

In terms of parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this comparative example are as follows: molten compound: 1 part of diphenyl iodine triflate

Polar solvent: 99 parts of deionized water.

Referring to Example 3, the above ink was deposited on the metal nanowire substrate.

Experiments have found that when the substrate is heated at 260°C, both the areas where ink is not deposited and the areas where ink is deposited are still in a conductive state, indicating that the ink in this comparative example does not have an obvious effect of lowering the melting point.

Comparative example 5

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this comparative example are as follows: molten compound: 1 part of 2,4-dinitrophenylhydrazine hydrochloride

Polar solvent: 99 parts of deionized water.

Referring to Example 3, the above ink was deposited on the metal nanowire substrate.

Experiments have found that when the substrate is heated at 200°C, the areas where ink is not deposited are still conductive, while the areas where ink is deposited are non-conductive.

According to the test data of Comparative Examples 1, 2, 3 and Example 1, it can be seen that compared with the ink containing only one molten compound component, the ink containing two molten compound components has a lower melting point after being deposited on the metal nanowires. Better results. In addition, comparing the ink formulas in Comparative Example 2 and Example 1, it can be seen that by mixing and formulating two molten compound components, on the one hand, the effect of the prepared ink in reducing the melting point of metal nanowires is improved, and on the other hand, it also reduces The total molten compound added to the ink.

Example 6

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires in this embodiment are as follows:

Molten compound: 0.25 parts of diphenyl iodine nitrate, 0.3 parts of AgNO ₃ ;

Polar solvent: 25.9 parts of deionized water, 3.2 parts of acetone, 69.35 parts of absolute ethanol;

Dispersing agent: 1 part chitosan.

Silver nanowire networks with specifications of 60nm, 30nm, and 17nm were deposited on several substrates.

An invisible pattern electrode was prepared with reference to Example 1.

Using the ink of this embodiment to modify or unmodify metal nanowires of different specifications, the melting point changes of the metal nanowires are shown in Figure 6. The ordinate in the figure is the substrate sheet resistance _RS after the heated substrate and the heated substrate The former substrate sheet resistance R ₀ ratio. Figure 6 shows that after using the ink of this embodiment to modify different metal nanowires, the melting point of the metal nanowires can be significantly reduced.

Example 7

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires are as follows:

Molten compound: 0.25 parts of diphenyl iodine nitrate, 2.5 parts of AgNO ₃ ;

Polar solvent: 23.7 parts of deionized water, 3.2 parts of acetone, 69.35 parts of absolute ethanol;

Dispersing agent: 1 part chitosan.

An invisible pattern electrode was prepared with reference to Example 1.

Experiments have found that when the heating stage temperature is adjusted to 140°C to heat the substrate, the areas where ink is not deposited are still conductive, while the areas where ink is deposited are non-conductive.

Example 8

In parts by weight, the components of the ink used to reduce the melting point of metal nanowires are as follows:

Molten compound: 0.5 parts of silver iodate, 0.25 parts of AgNO ₃ , 0.25 parts of silver iodide;

Polar solvent: 25.5 parts of deionized water, 3.5 parts of acetone, 69 parts of absolute ethanol;

Dispersing agent: 1 part chitosan.

Deposit a 17nm metallic silver nanowire network on a clean substrate, and prepare an invisible pattern electrode with reference to Example 4.

The experiment found that after heating on the heating table at 50°C for 10 minutes, the area where ink was not deposited was still conductive, while the area where ink was deposited was non-conductive.

Example 9

The following table can be obtained by organizing the above examples and comparative examples. This table shows that the effect of ink composed of two molten compounds in reducing the melting point of metal nanonetworks is more significant than that of a single-component molten compound; further, the ink composed of three molten compounds The ink has a better melting point lowering effect than an ink composed of two molten compounds; in addition, adding the same molten compound mixture in different proportions to the metal nanonetwork will have different melting point lowering effects.

Obviously, the above-mentioned embodiments of the present invention are only examples to clearly illustrate the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (10)

1. An ink for reducing the melting point of metal nanowires, which is characterized by comprising the following components in parts by weight:

0.1 to 1 part of melted compound, 95.2 to 99.7 parts of polar solvent;

wherein the molten compound is selected from iodonium salt, nitrate composition or acetic acid, nitric acid, metal oxide composition or iodonium salt, brine composition or metal halide, nitrate composition or iodate, nitrate, metal halide composition.

2. The ink for lowering the melting point of metal nanowires according to claim 1, wherein the melted compound is selected from diphenyl iodide nitrate, a silver nitrate composition or acetic acid, nitric acid, an iron oxide composition or diphenyl triflate iodine, an iodowater composition or silver iodide, potassium iodide, a silver nitrate composition or a silver iodate, silver nitrate, silver iodide composition; and/or the polar solvent is selected from one or more of water, acetone, monohydric alcohol and polyhydric alcohol.

3. The ink for reducing the melting point of metal nanowires of claim 2, further comprising 0.1 to 0.8 parts by weight of metal nanowires.

4. The ink for reducing the melting point of metal nanowires according to claim 3, wherein the metal nanowires are one or more of silver nanowires, copper nanowires, iron nanowires; and/or the diameter of the metal nanowire is smaller than 200nm.

5. The ink for lowering the melting point of metal nanowires as recited in claim 2, further comprising 0.1 to 1 part of a dispersant in parts by weight.

6. The ink for lowering melting point of metal nanowires according to claim 5, wherein the dispersant is one or more selected from the group consisting of fluorine-containing nonionic surfactants, sodium dodecylbenzenesulfonate, sodium 3-mercapto-1-propanesulfonate, 4- (1, 3-tetramethylbutyl) phenyl-polyethylene glycol, hydroxypropyl methylcellulose, polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylenimine, polyvinylpyrrolidone, polyethylene glycol, chitosan, polyether defoamers, acrylics, acetylenic glycols, silicones, fluorocarbons.

7. A method for preparing an optically invisible patterned electrode, comprising the steps of:

s1, depositing a metal nanowire network on a substrate, and drying for later use;

s2, selectively depositing the ink for reducing the melting point of the metal nanowires according to any one of claims 1 to 6 on the substrate obtained in the step S1, wherein the metal nanowires deposited with the ink for reducing the melting point of the metal nanowires according to any one of claims 1 to 6 form low melting point parts, and the metal nanowires not deposited with the ink for reducing the melting point of the metal nanowires according to any one of claims 1 to 6 form high melting point parts;

s3, heating the substrate obtained in the step S2 to fuse the metal nanowire at the low-melting point part, obtaining an insulating region fused by the metal nanowire at the low-melting point part, and obtaining a complete conductive region of the metal nanowire at the high-melting point part to form an optically invisible pattern electrode;

alternatively, the method comprises the following steps:

s01, depositing the ink for reducing the melting point of the metal nano wire in the method for reducing the melting point of the metal nano wire on a substrate, and drying;

s02, placing a mask plate above the substrate obtained in the step S01, wherein the mask plate is provided with an exposure area allowing light to pass through and a shading area preventing the light from passing through; a light source is adopted to irradiate the substrate above the mask plate, a high-melting-point metal nanowire network is formed on the substrate corresponding to the exposure area, and a low-melting-point metal nanowire network is formed on the substrate corresponding to the shading area;

s03, heating the substrate obtained in the step S02, fusing the low-melting-point metal nanowire network, and keeping the high-melting-point metal nanowire network intact, so that an optically invisible pattern electrode is formed.

8. The method of producing an optically invisible patterned electrode according to claim 7, further comprising, before performing step S1 or step S01, the steps of: and coating an anti-reflection layer on the substrate, wherein the anti-reflection layer is a polymer film layer or a two-dimensional material coating.

9. The method for producing an optically invisible patterned electrode according to claim 7 or 8, wherein in step S02, the light source wavelength for irradiation is 200nm to 1600nm; and/or, in step S3 or step S03, the heating temperature is 50 ℃ to 200 ℃.

10. An optically invisible patterned electrode produced by the production method according to any one of claims 7 to 9.