阅读说明：本技术 透明电极制造方法 (Method for manufacturing transparent electrode ) 是由 徐志勋 于 2018-11-14 设计创作，主要内容包括：本发明将形成在玻璃基板上的银纳米线转印到聚合物及柔性膜来制造透明电极或者透明热线。在用碘混合物加工转印到所述聚合物及所述柔性膜的所述银纳米线的情况下,所述银纳米线表现变色。(The present invention transfers silver nanowires formed on a glass substrate to a polymer or a flexible film to manufacture a transparent electrode or a transparent heat wire. In the case of processing the silver nanowires transferred to the polymer and the flexible film with an iodine mixture, the silver nanowires exhibit discoloration.)

1. A method of manufacturing a transparent electrode, comprising the steps of:

preparing a base substrate;

forming silver nanowires in contact with one side of the base substrate;

heating the base substrate and the silver nanowires with a predetermined heat;

applying an uncured polymer on said one side of said base substrate to cover said silver nanowires;

disposing a flexible film on the uncured polymer;

applying a predetermined pressure between the flexible membrane and the base substrate of the arrangement;

irradiating light having a specific wavelength on the flexible film, curing the uncured polymer to transform into a cured polymer;

separating the base substrate and the cured polymer to form a silver nanowire assembly comprising the silver nanowires, the cured polymer, and the flexible film in order to separate the silver nanowires from the base substrate to bind to the cured polymer;

exposing the silver nanowire assembly to an iodine mixture including a chloride-based mixture and potassium for a predetermined time, transforming only a portion of the surface of the silver nanowire into silver chloride of gray or black, and maintaining conductivity of the other portion of the silver nanowire; and

annealing the silver nanowire assembly once exposed to the iodine mixture at a temperature of 100 to 110 degrees celsius for 2 to 5 minutes;

wherein the predetermined pressure is applied by a roller having a hardness of 30HB to 50 HB.

2. The method for manufacturing a transparent electrode according to claim 1, wherein the base substrate is a glass substrate.

3. The method of claim 1, wherein the base substrate is a stone surface plate.

4. The method of manufacturing a transparent electrode according to claim 1, wherein the flexible film comprises PET.

5. The method for manufacturing a transparent electrode according to claim 1, wherein the predetermined heat is 200 to 300 degrees celsius.

6. A method of manufacturing a transparent electrode, comprising the steps of:

preparing a base substrate;

forming silver nanowires in contact with one side of the base substrate;

heating the base substrate and the silver nanowires with a predetermined heat;

exposing the silver nanowire assembly to an iodine mixture containing a chloride-based mixture and potassium for a predetermined time, converting only a portion of the surface of the silver nanowire into silver chloride of gray or black color, and maintaining conductivity of the other portion of the silver nanowire to generate a color-changed silver nanowire;

applying an uncured polymer to said one side of said base substrate to cover said silver nanowires that have been discolored;

disposing a flexible film on the uncured polymer;

applying a predetermined pressure between the flexible membrane and the base substrate of the arrangement;

irradiating light having a specific wavelength on the flexible film, curing the uncured polymer to transform into a cured polymer;

separating the base substrate and the cured polymer to form a silver nanowire assembly comprising the color-changing silver nanowires, the cured polymer, and the flexible film in order to separate the color-changing silver nanowires from the base substrate to bind to the cured polymer;

annealing the silver nanowire assembly at a temperature of 100 to 110 ℃ for 2 to 5 minutes;

wherein the predetermined pressure is applied by a roller having a hardness of 30HB to 50 HB.

Technical Field

The present invention relates to a method for manufacturing a transparent electrode or a transparent heat wire including silver nanowires.

Background

Generally, electrodes are widely used in various fields. The electrodes are used for transferring energy, and transferring electric charge to each electric element drives each electric element. Therefore, it is necessary to have stability and resistivity as low as possible. In general, metals such as silver and copper are the main materials constituting electrodes, and transparent electrodes (such as ITO) are widely used in the field of display panels.

Transparent electrodes are electronic parts having high transparency of usually 80% or more, and are widely used in the electronic field, such as L CD front electrodes, displays such as O L ED electrodes, touch panels, solar cells, optoelectronic elements, and the like.

However, ITO electrodes applied to conventional Touch Screen Panels (TSPs) are not flexible and are difficult to be used for curved or curved flexible display panels, and thus Graphene (Graphene), CNT, and silver nanowires (AgnW) are attracting attention as new generation materials that can replace ITO films.

Among them, the silver nanowire is an electrode having high conductivity while having conductivity. Accordingly, the demand for transparent electrodes comprising silver nanowires is gradually increasing.

Disclosure of Invention

(problem to be solved)

The invention aims to provide a method for manufacturing a transparent electric or transparent heat wire with low surface resistance, flexibility and improved visibility.

(means for solving the problems)

The method for manufacturing the transparent electrode according to an embodiment of the present invention includes the steps of: preparing a base substrate; forming silver nanowires in contact with one side of the base substrate; heating the base substrate and the silver nanowires with a predetermined heat; applying an uncured polymer to the one side of the base substrate to cover the silver nanowires that have cooled down; disposing a flexible film on the uncured polymer; applying a predetermined pressure between the flexible membrane and the base substrate of the arrangement; irradiating light having a specific wavelength on the flexible film, curing the uncured polymer to transform into a cured polymer; separating the base substrate and the cured polymer to form a silver nanowire assembly comprising the silver nanowires, the cured polymer, and the flexible film in order to separate the silver nanowires from the base substrate to bind to the cured polymer; exposing the silver nanowire assembly to an iodine mixture for a predetermined time to convert only a portion of the surface of the silver nanowires to a gray or black color; and annealing the silver nanowire assembly that was exposed to the iodine mixture.

In an embodiment of the invention, the base substrate may be a glass substrate.

In an embodiment of the present invention, the base substrate may be a stone surface plate.

In an embodiment of the present invention, the flexible film may comprise PET.

In an embodiment of the present invention, the predetermined heat may be 200 to 300 degrees celsius.

In an embodiment of the present invention, the predetermined pressure may be applied by rolling of a roller. The roller may have a hardness of 30HB to 50 HB.

In one embodiment of the present invention, the iodine mixture may comprise a mixture of chlorinated species. The iodine mixture may also include potassium.

In an embodiment of the present invention, the portion of the silver nanowires that become the gray or black may be silver chloride.

In one embodiment of the present invention, the return process may be performed at a temperature of 100 to 150 degrees celsius for 2 to 5 minutes.

The method for manufacturing the transparent electrode according to an embodiment of the present invention includes the steps of: preparing a base substrate; forming silver nanowires in contact with one side of the base substrate; heating the base substrate and the silver nanowires with a predetermined heat; exposing the silver nanowire assembly to an iodine mixture for a predetermined time to transform a portion of the surface of the silver nanowires to a gray or black color; applying an uncured polymer to said one side of said base substrate to cover said silver nanowires that have been discolored; disposing a flexible film on the uncured polymer; applying a predetermined pressure between the flexible membrane and the base substrate of the arrangement; irradiating light having a specific wavelength on the flexible film, curing the uncured polymer to transform into a cured polymer; separating the base substrate and the cured polymer to form a silver nanowire assembly comprising the color-changing silver nanowires, the cured polymer, and the flexible film in order to separate the color-changing silver nanowires from the base substrate to bind to the cured polymer; and annealing the silver nanowire assembly.

(Effect of the invention)

According to an embodiment of the present invention, a transparent electrode or a transparent heat wire in which silver nanowires are disposed on a flexible film to improve flexibility may be provided.

In addition, since the transparent electrode has a bottom surface resistance, a transparent electrode or a transparent heat line which can realize a large area can be provided.

In addition, a phenomenon that the image is blurred like fog (also called a fog phenomenon) when seen with the naked eye is reduced, and a transparent electrode or a transparent heat ray with improved visibility can be provided.

In addition, according to an embodiment of the present invention, the silver nanowires are disposed to have a predetermined depth from the surface of the flexible film, and a transparent electrode or a transparent heat wire for improving durability may be provided.

Drawings

Fig. 1 exemplarily shows that silver nanowires are disposed on a base substrate.

Fig. 2a and 2b exemplarily show the application of heat to the silver nanowire of fig. 1.

Fig. 3 exemplarily shows that an uncured polymer covering silver nanowires is coated on the base substrate of fig. 1.

Fig. 4 illustrates the disposition of a flexible membrane over the uncured polymer of fig. 3.

Fig. 5a illustrates the application of pressure to the assembly of fig. 4 using rollers.

Fig. 5b shows the processing quality of the flexible film according to the hardness comparison of the rollers.

Fig. 6 schematically illustrates the application of ultraviolet light for curing the uncured polymer.

Fig. 7 schematically shows the separation of the silver nanowire assembly from the base substrate.

Fig. 8a illustrates a silver nanowire assembly.

Fig. 8b illustrates a cross section taken along the line I-I' of fig. 8 a.

Fig. 9 schematically shows processing of the silver nanowire assembly of fig. 8a with a solution containing a mixture of iodine.

Fig. 10a schematically shows a silver nanowire assembly processed with an iodine mixture.

Fig. 10b schematically shows a section along the line II-II' of fig. 10 a.

Fig. 11 is a flowchart of a method for manufacturing a transparent electrode according to an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the drawings, the scale and size of components are exaggerated for effective explanation of technical contents.

The terms "comprises" and "comprising" and the like should be interpreted as specifying the presence of the stated features, integers, steps, acts, elements, components, and combinations thereof, as referred to in the specification, and does not preclude the presence or addition of one or more other features, integers, steps, acts, elements, components, and combinations thereof.

Fig. 1 to 10b exemplarily show a transparent electrode manufacturing method according to an embodiment of the present invention. Fig. 11 is a flowchart of a method for manufacturing a transparent electrode according to an embodiment of the present invention.

Fig. 1 illustrates a configuration of a silver nanowire NW on a base substrate BS.

The base substrate BS may be a glass substrate or a stone surface plate. The glass substrate and the stone surface plate have high heat resistance. Accordingly, there is an advantage that deformation does not occur even when heat having a high temperature of 200 degrees celsius or more is applied in the subsequent heat treatment process.

The silver nanowire NW is directly arranged on the base substrate BS. At this time, means such as dispensing, bar coating, slit extrusion coating, applicator, spin coating, or spray coating may be used.

According to an embodiment of the present invention, in the case of coating silver nanowires using a spin coater, the silver nanowire ink may be coated by keeping the spin coater at 1000 to 3000rpm after dropping the silver nanowire ink on a glass substrate; if this condition is exceeded, the silver nanowire NW cannot be applied to the base substrate BS in a uniform thickness.

According to an embodiment of the invention, 1 to 100 cm/sec can be applied using a bar coater (bar coater).

According to an embodiment of the present invention, in the case of using the spray coater, a nozzle size of 0.2 to 0.3 may be used at 1 to 5kgf/cm²Pressure is applied to the base substrate BS.

According to an embodiment of the present invention, in case of using an applicator (applicator), the silver nanowire ink droplets may be applied with 1 to 100 cm/sec after being dropped into one row.

If the above numerical range is not satisfied, the silver nanowire NW cannot be coated on the base substrate BS in a uniform thickness.

For the silver nanowire NW, silver nanowires with a diameter of 1 to 100nm and a length of 2 to 100 μm can be used. In the case of a diameter less than 5nm, since mechanical stability is very poor and it is easily broken, there is a problem that it is difficult to maintain a stable network; in the case of more than 100nm, there may occur a problem that the transparency (light transmittance) is drastically reduced to 70% or less.

In addition, in the case of a length less than 2 μm, the length of silver nanowires constituting the mesh is too short, a large amount of silver nanowires are required, and transparency is lowered, and there may occur a problem that conductivity is lowered because many contact points are present. In the case of a length greater than 100 μm, there may occur a problem in that it is difficult to manufacture silver nanowires and a problem in that the silver nanowires are too long to be easily broken at the time of coating.

Fig. 2a and 2b exemplarily show that heat is applied to the silver nanowire NW of fig. 1.

Heating may be achieved by melt-off, micro-pulse photonic, continuous photonic, microwave, or bake heating.

Referring to fig. 2b, the contact CT between the first silver nanowire NW1 and the second silver nanowire NW2 enhances conductivity due to the applied heat, and thus the sheet resistance of the entire silver nanowire NW can be reduced. More specifically, the contact portion CT between the first silver nanowire NW1 and the second silver nanowire NW2 is not simply physically contacted, but slightly melted, so that the contact portion CT is flexible, the contact area is enlarged, and the overall resistivity is improved. In addition, the silver nanowires having tension become flexible by heat and also more closely attached to the base substrate BS, resulting in an effect of increasing the surface area, and thus, the adhesive force (adhesion) can also be increased.

The heat applied to the silver nanowire NW is approximately 100 to 300 degrees celsius, and preferably, may be approximately 200 to 300 degrees celsius. When the temperature is lower than 200 ℃, the sheet resistance of the silver nanowire NW cannot be sufficiently reduced; in case the temperature is higher than 300 degrees celsius, a portion of the base substrate BS or the silver nanowire NW may be damaged due to the high temperature of heat.

Only in the case where the base substrate BS is a glass substrate or a quartz plate, processing at 200 degrees celsius or more is possible, and if the base substrate BS is a substrate including a polymer, thermal deformation may occur in the case of processing at such a high temperature.

Fig. 3 schematically shows the application of an uncured polymer RS-N covering the silver nanowires NW on the base substrate BS of fig. 1.

The uncured polymer RS-N is a liquid substance in a gel form, and can be thinly applied to about 3 μm or less by bar coating, dispensing, or the like.

The uncured polymer RS-N may be cured by reacting with light of a specific wavelength band, and particularly, may be cured by reacting under Ultraviolet (UV) light.

The uncured polymer RS-N can be selected from materials having excellent optical characteristics such as light transmittance. The silver nanowire NW of an embodiment of the present invention is used to manufacture a transparent electrode because a transparent electrode can be manufactured only if it is necessary to ensure that accompanying other materials have light permeability.

Fig. 4 exemplarily shows that a flexible film FM is configured on the uncured polymer RS-N of fig. 3.

The flexible film FM may comprise PET (Polyethylene terephthalate). Since the flexible film FM has flexibility, it is advantageous to mount a transparent electrode completed later on a flexible display device such as a folder type display device, a roll type display device, or a dual screen display device.

FIG. 5a illustrates the application of pressure to the assembly of FIG. 4 (FM, RS-N, BS) using roller R L FIG. 5b shows the quality of the processing of the flexible film based on a hardness comparison of the rollers of FIG. 5 a.

To transfer the silver nanowires NW once coated on the base substrate BS to the uncured polymer RS-N and flexible film FM side, pressure is applied to the assembly of fig. 4 (FM, RS-N, BS) by, for example, a roller R L.

The hardness of the roller R L is 30 to 50HB, and preferably about 40 HB., in the case where the hardness of the roller R L is less than 30HB, the hardness is insufficient and the silver nanowire NW cannot be transferred, and in the case where the hardness of the roller R L is more than 50HB, the flexible film FM has wrinkles due to blocking or pressing, and the processing quality can be reduced.

Referring to fig. 5b, in view of the processing quality of the flexible film FM when the hardness of the roller is 80HB, a large number of wrinkles are generated on the surface, and the clear visibility cannot be secured, so that the rear side is not clearly seen. In contrast, from the viewpoint of the processing quality of the flexible film FM of which the hardness of the roller is 40HB, the surface is smooth to ensure clear visibility, and thus the things on the rear side can be clearly seen.

The uncured polymer RS-N is applied with pressure by the roller R L to have a thickness of about 4 to 6 μm, in case the uncured polymer RS-N has a thickness of less than 4 μm, there is a risk of damaging the silver nanowire NW because of being too thin, and in case of more than 6 μm, wrinkles may be generated in a subsequent process because of thermal stress, and accordingly, the uncured polymer RS-N is preferably about 4 to 6 μm in consideration of a subsequent continuous process.

FIG. 6 schematically shows the application of UV light for curing the uncured polymer RS-N.

The light source for irradiating ultraviolet rays may be a lamp or L ED.

The uncured polymer RS-N can be cured within seconds by acrylic polymerization in response to Ultraviolet (UV) light. However, without being limited thereto, the uncured polymer RS-N may be cured by light of a specific wavelength band other than ultraviolet rays.

The uncured polymer RS-N is cured to become a cured polymer RS-H, whereby the silver nanowire NW (see fig. 3) once covered by the uncured polymer RS-N is immobilized on the cured polymer RS-H.

Fig. 7 exemplarily shows the separation of the silver nanowire assembly NWA from the base substrate BS.

When the cured polymer RS-H and the flexible film FM are separated from the base substrate BS side end, the silver nanowire NW is detached from the base substrate BS and transferred to the cured polymer RS-H.

When the cured polymer RS-H and the flexible film FM are all separated from the base substrate BS, the silver nanowire unit nwa including the silver nanowires NW, the cured polymer RS-H, and the flexible film FM is formed.

Fig. 8a exemplarily shows a silver nanowire assembly NWA. Fig. 8b illustrates a cross section taken along the line I-I' of fig. 8 a.

Referring to fig. 8b, the silver nanowire NW is immobilized in a buried form on the cured polymer RS-H. This form is formed because the silver nanowire NW is covered with the uncured polymer RS-N (refer to fig. 3) in the transfer process.

The thickness H1 of the cured polymer RS-H is the same as the thickness of the uncured polymer RS-N described in FIG. 5, and is preferably about 4 to 6 μm. The reason for this is the same as described above. However, the thickness H1 of the cured polymer RS-H can be about 4 to 15 μm, as desired.

The thickness H2 of the flexible film FM is preferably about 50 to 100 μm. This is because the flexibility is reduced in the case where the thickness H2 of the flexible film FM is larger than the numerical range.

Fig. 9 exemplarily shows the processing of the silver nanowire assembly nwa of fig. 8a with the processing solution P L containing an iodine mixture fig. 10a exemplarily shows the silver nanowire assembly nwa processed with an iodine mixture fig. 10b exemplarily shows a section cut along II-II' of fig. 10 a.

The process solution P L contains a mixture of iodine, which contains a mixture of chlorinated species.

The iodine mixture containing the mixture of chlorines reacts with the silver nanowire NW, whereby silver chloride is formed on the surface of the silver nanowire NW, so that the color of the surface of the silver nanowire NW becomes gray or black. As such, the portion where the silver nanowire NW discolors may be referred to as a discolored portion BK.

The discolored portion BK reduces a Haze (Haze) phenomenon in which the silver nanowire assembly NWA is blurred as a whole due to an optical effect.

The preferable proportion of the chlorinated mixture in the iodine mixture is 20 to 30% by mass. In the case where the ratio of the chlorinated species mixture is out of the numerical range, the fogging phenomenon is promoted instead because the iodine mixture generates precipitates on the surface of the silver nanowire assembly NWA.

In the case where potassium is mixed in a predetermined ratio in the iodine mixture, the color change reaction is promoted. In this case, the ratio of the iodine mixture to potassium may be about 1:1 to 1:5 by mass. In the case where the proportion of potassium is less than the numerical range, the reaction rate is improved very slightly, and in the case where it is greater than the numerical range, there may occur a problem of increasing the fogging phenomenon.

A return process may be performed with respect to the silver nanowire assembly NWA in which the formation of the color-changed portion BK is completed. In the case of processing the silver nanowire assembly NWA with the iodine mixture, the sheet resistance of the silver nanowire NW increases by about 10% or so, but the increased resistance may be reduced by the annealing treatment.

The annealing treatment may be performed by a box oven or an IR oven.

In an embodiment of the present invention, the annealing treatment is performed in a box oven at a temperature of about 100 to 150 ℃ for about 10 to 60 minutes.

In one embodiment of the present invention, the annealing treatment is performed in an IR oven at a temperature of about 100 to 150 ℃ for about 1 to 20 minutes.

In the annealing process, under the condition that the heating temperature and the heating time are less than the numerical value range, the surface resistance cannot be sufficiently reduced; above the value range, the silver nanowire assembly NWA may be damaged by heat instead.

More specifically, in the case of annealing treatment using an IR oven, the treatment time can be adjusted according to the degree of increase in sheet resistance. For example, when the sheet resistance of the silver nanowire NW is increased by about 10% by the iodine mixture, the silver nanowire NW is heated at 100 to 150 ℃ for about 2 minutes; when the sheet resistance of the silver nanowire NW is increased by about 20% by the iodine mixture, the silver nanowire NW can be heated at 100 to 150 degrees celsius for about 5 minutes.

Fig. 11 is a flowchart of a method for manufacturing a transparent electrode according to an embodiment of the present invention. Fig. 11 is a flow chart schematically illustrating the process illustrated in fig. 1 to 10 b.

The base substrate preparation step (S100) and the AgNW formation step (S110) may correspond to fig. 1.

The heating and cooling step (S120) may correspond to fig. 2a and 2 b.

The uncured polymer coating step (S130) may correspond to fig. 3.

The flexible film disposing step (S140) may correspond to fig. 4.

The pressure applying step (S150) may correspond to fig. 5a and 5 b.

The UV irradiation step (S160) may correspond to fig. 6.

The silver nanowire assembly separating step (S170) may correspond to fig. 7 to 8 b.

The step of reacting with the iodine mixture (S180) may correspond to fig. 9 to 10 b.

In one embodiment of the present invention, the step of reacting with the iodine mixture (S180) may be performed between the step of heating and cooling (S120) and the step of coating the uncured polymer (S130). In this case, the silver nanowire NW reacted with the iodine mixture has an effect of better visibility due to the enlarged area.

The annealing process step (S190) is not separately illustrated but has been described above.

Although the present invention has been described with reference to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention as set forth in the following claims. In addition, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but should be construed that all technical spirit within the scope of claims and the scope equivalent thereto are included in the scope of the claims.

Industrial applicability

Transparent electrodes that cannot be recognized with the naked human eye are being used in large quantities in various electronic device-related fields including the field of display screens.

Accordingly, the present patent for manufacturing a transparent electrode having low sheet resistance and high visibility has high industrial applicability.