KR20160059531A - Preparing method of transparent electrode having silver nanowires - Google Patents

Abstract

The present invention provides a method for preparing a silver nanowire transparent electrode, which comprises: a first step of preparing an electrode including a silver nanowire on a substrate; a second step of preparing a release film in which a polymer layer is formed; a third step of transferring the electrode on a release film by compressing the electrode and the release film; and a fourth step of collecting a transparent electrode by separating the substrate of the electrode from the release film. Therefore, the silver nanowire transparent electrode can be prepared by reducing the roughness of an electrode surface using the silver nanowire. The silver nanowire electrode can control the thickness that the transparent electrode is stacked since the electrode surface is flattened, and a more thinned thickness can improve physical properties of the electrode. Moreover, the release film including the polymer layer on which the silver nanowire is transferred has excellent bonding force to the silver nanowire and is suitable for a roll-to-roll (R2R) continuous process pursued in next generation flexible electrode development since the transferring is possible at low temperature and pressure.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a silver nanowire transparent electrode,

The present invention relates to a method of manufacturing a transparent electrode using silver nano wires.

In general, electrodes are widely used in various fields. The role of the electrode is to transfer electric charge to each electric element, thereby performing energy transfer for driving each electric element. Therefore, it is essential to have a resistivity and stability as low as possible. Generally, metals such as silver and copper are the main materials for the electrodes, and transparent electrodes (such as ITO) are used particularly in the display field.

The transparent electrode is an electronic component having a transparency of not less than 80% and a sheet resistance of 500 Ω / sqm or less, and is widely used in electronic fields such as LCD front electrodes, OLED electrodes, displays, touch screens, solar cells, and optoelectronic devices. In particular, transparent conductive electrodes (TCE) are widely used in organic light emitting diodes (OLED), liquid crystal displays (LCD), organic solar cells and the like. In these devices, indium tin oxide (ITO) is commonly used as a transparent electrode. ITO electrodes have many advantages such as optical transparency, electrical conductivity, and environmental stability. With the rapid growth of the display industry, there is a growing demand for transparent electrodes. As a result, the problem of indium depletion has become an important issue in the world, and this increase in industrial demand is causing the problem of distribution of rare-earth metal resources. Therefore, for transparent electrodes that replace ITO, transparent metal oxide, carbon nanotube Carbon Nano Tube; (Hereinafter " CNT "), conductive polymer, and graphene. However, these alternative materials do not meet all of the requirements such as high transparency, high conductivity, uniform conductivity and high adhesion to the substrate.

Meanwhile, the transparent electrode technology market, led by ITO and CNT, has realized many functions by making a transparent electrode conductor instead of an opaque conductor such as copper in a transparent film. Since the ITO electrode material applied to the existing touch screen panel (TSP) is difficult to use for flexible displays that are not flexible or curved, it is a next-generation new material to replace the ITO film. Graphene, CNT, (Ag nanowires) have attracted attention.

Silver nanowires are used as materials for electrodes with high conductivity and electrical conductivity. In the case of silver nanowires, however, they have a three-dimensional network structure, and the wire network provides electrodes with high surface roughness. When the transparent electrode is applied to the device, the surface roughness can control the thickness of the materials to be laminated, and the improvement in performance due to the thin layer thickness can be expected.

Korean Patent Laid-Open Publication No. 2014-0028416 discloses a nanowire-carbon nanotube hybrid film and a method for producing the same. The nanowire-carbon nanotube hybrid film is formed on a substrate and a base material. The nanowire layer includes a metal nanowire as a main component. And a top coat layer formed on the carbon nanotube layer and having an insulating property, the carbon nanotube layer including a carbon nanotube as a main component, the carbon nanotube layer having a nanowire layer and a network structure, Discloses a method capable of manufacturing a transparent electrode, but a method of improving the surface roughness by including metal nanowires to increase the permeability and conductivity has not been disclosed.

An object of the present invention is to provide a method for manufacturing a silver nano wire electrode in which the surface roughness of a transparent electrode is improved by using a silver nano wire, and the transparency and electrical conductivity of the transparent electrode are increased.

In order to accomplish the above object, the present invention provides a method for manufacturing a semiconductor device, comprising the steps of: (a) preparing an electrode including a silver nanowire on a substrate; Producing a release film on which a polymer layer is formed (second step); A step of pressing the electrode and the release film to transfer the electrode to the release film (third step); And separating the substrate of the electrode from the release film to recover the transparent electrode (fourth step).

In addition, the first step may coat the silver nano wire ink by any one coating method selected from the group consisting of spin coating, bar coating, spray coater and applicator.

Also, the polymer layer may be formed of at least one selected from the group consisting of polyvinylpyrrolidone (PVP), polydimethylsiloxane (PDMS), and polyvinylacetate; PVA). ≪ / RTI >

The polymer layer may have an average molecular weight of 10,000 to 1,500,000.

The third step may be performed at a temperature of 20 to 80 ° C at a pressure of 6 to 100 MPa to transfer the electrode to the release film.

The present invention can produce a planarized silver nano wire electrode by reducing the roughness on the surface of the electrode using silver nano wire. The thickness of the silver nano wire electrode can be adjusted by flattening the surface of the silver nano wire electrode, and the thickness of the electrode can be improved.

In addition, the release film containing the polymer layer transferred with the silver nano wire has excellent adhesion to the silver nano wire and can be transferred at a low temperature and pressure. Thus, roll-to-roll, which is pursued in the development of the next generation flexible electrode, -roll; R2R) Suitable for continuous process.

1 is a schematic view showing a process of a method of manufacturing a silver nano wire transparent electrode according to an embodiment of the present invention.
2 is a flowchart showing the flow of a process of a method of manufacturing a silver nano wire transparent electrode according to an embodiment of the present invention.
FIG. 3 is a scanning electron microscopy (SEM) image of a transparent electrode manufactured according to a method of manufacturing a planarized silver nano wire transparent electrode according to an embodiment of the present invention.
4 is an atomic force microscopy (AFM) image showing the surface roughness characteristic of a silver nano wire transparent electrode according to an embodiment of the present invention.
5 is a graph showing transmittance and electrical conductivity of a silver nano wire transparent electrode according to an embodiment of the present invention.

The inventors of the present invention have been studying a method of manufacturing a transparent electrode including silver nano wires to replace indium tin oxide (ITO) used in a transparent electrode. In the case where the roughness of the transparent electrode surface is improved, It is possible to transfer the silver nano wire electrode even at low temperature and pressure when transferring the silver nano wire onto a release film containing a polymer layer rather than directly coating the glass nano wire with an insulating substrate, The efficiency of the silver nano wire electrode is greatly increased.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method of manufacturing an electrode comprising a step of manufacturing an electrode including a silver nanowire on a substrate (first step); Producing a release film on which a polymer layer is formed (second step); A step of pressing the electrode and the release film to transfer the electrode to the release film (third step); And separating the substrate of the electrode from the release film to recover the transparent electrode (fourth step).

1 is a schematic view showing a process of a method of manufacturing a transparent electrode including a silver wire according to an embodiment of the present invention.

2 is a flowchart showing the flow of a process of a method of manufacturing a silver nano wire transparent electrode according to an embodiment of the present invention.

Referring to FIG. 1, the substrate has to serve as a support for supporting silver nano wires to be coated. Therefore, the substrate must have a strength higher than a certain level that can be coated with silver nano wires and not be reactive with the polymer layer.

The substrate may be any one selected from the group consisting of a glass substrate, a polymer substrate, and a metal substrate. It is preferable that the substrate has a strength of more than glass and is rigid so that the glass substrate can be selected, but the present invention is not limited thereto .

In addition, the first step may coat the silver nano wire ink by any one coating method selected from the group consisting of a spin coater, a bar coating, a spray coater and an applicator.

According to an embodiment of the present invention, when silver nano wire is coated using a spin coater, the silver nano wire ink may be coated on the glass substrate by holding the spin coater at 1000 to 3000 rpm, If the above conditions are exceeded, the silver nano wire can not be uniformly coated on the substrate.

According to another embodiment of the present invention, a bar coater can be used at a coating rate of 1 to 100 cm / sec. When using a spray coater, a nozzle size of 0.2 to 0.3 can be applied at a pressure of 1 to 5 kgf / (Polyethylene terephthalate) substrate. When an applicator is used, the silver nano wire ink may be dropped in a line and then applied at a rate of 1 to 100 cm / sec.

When the coating condition of the first step is out of the range, the silver nano wire ink can not be coated on the substrate with a uniform thickness.

The silver nano wire ink may contain silver nano wire particles in an amount of 0.2 to 5 wt%, and may include the same material as the polymer layer in an amount of 0.01 to 0.2 wt%.

When the same material as the polymer layer is included under the above conditions, the adhesion of the polymer layer to the polymer layer can be increased, so that the electrode including the silver wire can be easily transferred to the polymer layer.

On the other hand, after coating the silver wire of the first step, the coated electrode can be dried at 40 to 120 ° C for 10 minutes to produce an electrode.

In the step of producing the release film on which the polymer layer is formed (the second step), the mixed solution containing the polymer is applied on the top of PET at a rate of 2 to 100 cm / sec using a bar coater or a spray coater Annealing may be performed for 10 to 60 minutes.

The release film supports the polymer layer so that the polymer layer and the electrode can be pressed against each other.

Also, the polymer layer may be formed of at least one selected from the group consisting of polyvinylpyrrolidone (PVP), polydimethylsiloxane (PDMS), and polyvinylacetate; PVA). ≪ / RTI >

Wherein the polymer layer has an average molecular weight of from 10,000 to 1,500,000 Lt; / RTI >

The average molecular weight represents a weight average molecular weight (Mw).

When the polymer layer is made of PVP, it can be used regardless of the molecular weight of PVP, but it is preferable to use 100,000 or more.

In the range of the average molecular weight, the electrode including the silver nanowire can be transferred to the release film including the polymer layer. The third step may be performed at a temperature of 20 to 80 ° C at a pressure of 6 to 100 MPa to transfer the electrode to the release film.

The efficiency of the transparent electrode manufacturing method which can be transferred at a low temperature and a low pressure is inferior when the condition of the third step is exceeded.

In the present invention, the electrode including the silver nano wire can be transferred to the polymer layer even at a low temperature and a pressure, so that the manufacturing efficiency of the silver nano wire electrode can be greatly increased and the roughness due to the silver nano wire of the transparent electrode can be reduced And a flat silver wire electrode can be manufactured.

Further, in order to use a press for pressing when the electrode and the release film are squeezed, an electrode is disposed on a sus plate for pressing, a release film on which a polymer layer is formed is interfaced, And a pressing structure for transferring the electrode to the release film by disposing a pressing suscept plate on the upper portion of the silicon pad.

In the case of transferring with the compression bonding structure, the transmittance and electrical conductivity of the silver nano wire electrode can be increased, and the thickness of the polymer layer to which the silver nano wire is transferred can be controlled.

In the fourth step, the transferred substrate of the electrode may be separated from the release film.

In the polymer layer formed on the release film, an electrode including silver nano and glass is transferred, and the polymer layer forms a transparent electrode including silver nano wire.

When the release film is PET and the substrate is a glass substrate, it is possible to easily separate and recover the electrode including the silver nano wire.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Example 1: Fabrication of planarized silver nano wire transparent electrode

1. Fabrication of electrodes containing silver nano wires

Silver nano wire ink was coated on a glass substrate. The coating conditions were such that 500 ㎕ of silver nano wire ink was dropped on a glass substrate and then coated with a spin coater at 2000 rpm for 10 seconds.

To confirm that the electrode can be manufactured according to various coating methods, 20 ml of silver nano wire ink was dropped on the glass and applied with a bar coater (rod No. 2-9) at a rate of 2 cm / sec To prepare an electrode.

In addition, 30 ml of silver nano wire ink was sprayed onto the organic substrate at a pressure of 3 kgf / cm 2 using a spray coater (nozzle size: 0.2 to 0.3 mm) to prepare electrodes. 500 μl of silver nano wire ink was arrayed on the PET And then applied at 2 cm / sec using an applicator to complete the electrode.

2. Manufacture of PVP-coated PET release film

PVP (average molecular weight: 300,000) was added with isopropylalcohol as a solvent to prepare a 5 wt% mixed solution. Then, 200 ㎕ of the solution was dropped in a line on top of PET, and then an applicator After coating at a rate of 2 cm / sec, the PVP-coated PET was placed in an oven and annealed at 120 ° C for 10 minutes.

3. Fabrication of transparent electrodes including planarized silver nano wires

An electrode including a silver nano wire and a release film having a polymer layer formed thereon were pressed and transferred onto a release film while planarizing the silver nano wire electrode. In order to use the press for the transfer, an electrode is disposed on the upper side of a sus-plate for pressing, a release film on which the polymer layer is formed is interposed with the electrode, a silicon pad is disposed on the release film And a compression bonding structure for transferring the electrode to the release film by disposing a compression susceptor on the top of the silicon pad.

After the compression structure was inserted into the center of the compact, the compact was pressed at 40 DEG C at a pressure of 10 MPa for 5 minutes to transfer the electrode including the silver nano wire to the release film.

After the transfer, the glass substrate was separated from the release film and the transparent electrode including the planarized silver nano wire was recovered.

Comparative Example 1 Production of transparent electrode directly transferred to a release film

In order to compare the transparency and electrical conductivity of the transparent electrode according to Example 1 in which the polymer layer was formed on the release film, a silver nano wire was directly formed on the PET film without forming a polymer layer to form a transparent electrode Ⅱ) was prepared. After silver nano wire ink was printed on a glass substrate, it was transferred to PET to prepare transparent electrode (III) including silver nano wire.

<Experimental Example 1> Properties of the recovered transparent electrode

FIG. 3 is a scanning electron microscopy (SEM) image of a transparent electrode manufactured according to a method of manufacturing a planarized silver nano wire transparent electrode according to an embodiment of the present invention.

It was confirmed that the transparent electrodes prepared in Example 1 were connected to each other by one or more points formed by forming a network of silver nano wires and transferred to the PET manufactured in the comparative example to form transparent electrodes III ) Showed more nanowire junctions and cross-connections than transparent electrodes.

4 is an atomic force microscopy (AFM) image showing the surface roughness characteristics of a silver nano wire transparent electrode according to an embodiment of the present invention.

In order to confirm the roughness of the transparent electrode with the AFM photograph, the attractive force or repulsion between the tip and the transparent electrode prepared in Example 1 and Comparative Example 1 was measured. The tip was scanned along the surface of the transparent electrode sample after finely approaching the tip and the transparent electrode corresponding to the tip of the cantilever using a repulsive contact method.

Referring to the drawing, the vertical deflection of the cantilever is generated according to the change in the surface height of the transparent electrode, and this is detected. The contact method was able to confirm the surface information by detecting the repulsive force between the tip and the transparent electrode.

On the other hand, manpower was measured using the non-contact method. Through pressure transfer, the surface roughness was reduced and a smooth surface was obtained by confirming that the change in height of the sample was reduced by a surface roughness of 9 nm at a surface roughness of 84 nm.

 Accordingly, the surface roughness of the transparent electrode prepared in Example 1 was increased to confirm that the transparent electrode including the planarized silver nano wire was manufactured.

5 is a graph showing transmittance and electrical conductivity of a transparent electrode according to an embodiment of the present invention.

Referring to the drawing, the transmittance was 87.6% according to the wavelength, and the electrical conductivity was also directly transferred to PET, which was confirmed to be superior to the transparent electrode (III) including silver nano wire.

As described above, according to the manufacturing method of the silver nano wire transparent electrode according to the present invention, the roughness of the surface of the transparent electrode can be greatly improved and the thickness of the transparent electrode can be controlled. Also, the transparent electrode having transparency and electrical conductivity An electrode can be manufactured.

While the invention has been described with reference to a limited number of embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (5)

Manufacturing an electrode including a silver nanowire on a substrate (first step);
Producing a release film on which a polymer layer is formed (second step);
A step of pressing the electrode and the release film to transfer the electrode to the release film (third step); And
And separating the substrate of the electrode from the release film to recover the transparent electrode (fourth step). The silver nano wire according to claim 1, wherein the first step is coating a silver nano wire ink by any one coating method selected from the group consisting of a spin coater, a bar coater, a spray coater and an applicator. A method of manufacturing a transparent electrode. [2] The method of claim 1, wherein the polymer layer is selected from the group consisting of polyvinylpyrrolidone (PVP), polydimethylsiloxane (PDMS), and polyvinylacetate; PVA). &Lt; RTI ID = 0.0 &gt; 21. &lt; / RTI &gt; The method according to claim 1, wherein the polymer layer has an average molecular weight of 10,000 to 1,500,000. [4] The method of claim 1, wherein the third step is performed at a temperature of 20 to 80 [deg.] C at a pressure of 6 to 100 MPa to transfer the electrode to the release film.

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