KR101163940B1 - Method for forming conducting polymer electrode containing metal nano particle and the electrode material - Google Patents

Abstract

PURPOSE: An electrode material and a method for forming a conductive polymer electrode are provided to improve electric conductivity by forming an electrode including metal of the type of a conductive polymer and a nano-wire. CONSTITUTION: A conductive polymer solution comprises a first solvent and a conductive polymer. A mixture is formed by mixing a first solution and a second solution(S501). The first solution is formed by mixing the conductive polymer solution and the first solvent. The second solution comprises a metal nano-wire and D.I(Deionize Water) water. The first solution is formed by mixing the conductive polymer solution and a second solvent. The mixture is coated on a substrate(S503). The mixture is heat-treated(S504).

Description

METHODS FOR FORMING CONDUCTING POLYMER ELECTRODE CONTAINING METAL NANO PARTICLE AND THE ELECTRODE MATERIAL}

The present disclosure relates to an electrode material and an electrode forming method using the same.

Display devices, solar cells, touch panels and the like are provided with electrodes for the movement of charge or the supply of power.

Indium tin oxide (ITO), the most widely used electrode, is expensive and requires high temperature deposition and vacuum process to form the electrode. In addition, there is a problem that physically easily hit by the bending and bending of the substrate to deteriorate the characteristics to the electrode, thereby not suitable for flexible elements.

In order to solve this problem, active researches on alternative electrodes are being conducted.

The embodiment provides an electrode material capable of improving conductivity and excellent physical stability and an electrode forming method using the same.

An electrode material according to an embodiment includes a conductive polymer, a dopant and a metal nanowire, wherein the conductive polymer is a π-conjugated polymer.

Electrode forming method according to an embodiment, preparing a conductive polymer solution; Mixing an additional solvent with the conductive polymer solution to form a first solution; Preparing a second solution including metal nanowires and ultrapure water (Dionize Water, D.I water); Mixing the first solution and the second solution to form a mixed solution; Coating the mixed solution on a substrate; And heat treating the mixed solution.

In the electrode material according to the embodiment, since the electrode including the conductive polymer and the metal in the form of nanowires is formed, the electrical conductivity is very excellent compared to the conventional touch panel. In addition, due to the nature of the conductive polymer can be applied to a large-area flexible device can greatly improve the physical properties. These electrodes have high transmittance and conductivity, and have low sheet resistance, thereby improving performance of the display to which the electrodes are applied.

On the other hand, in the electrode forming method according to the embodiment, the electrode can be formed without a high temperature process and a vacuum process, so the process is simple, and defects and manufacturing costs can be reduced.

1 is a schematic plan view illustrating an embodiment of a touch panel.
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1.
3 is a chemical formula for explaining the molecular structure of the electrode material according to the embodiment.
4 is a photograph illustrating a structure of a nanowire included in an electrode material according to an embodiment.
5 is a flowchart illustrating a method of forming an electrode according to an exemplary embodiment.
6 is a photograph of an electrode surface according to Example 1;
7 is a photograph of an electrode surface according to Example 2. FIG.
8 is a graph for comparing the transmittance of Example 2 and Comparative Example.

In the description of embodiments, each layer, region, pattern, or structure may be “on” or “under” the substrate, each layer, region, pad, or pattern. Substrate formed in ”includes all formed directly or through another layer. Criteria for the top / bottom or bottom / bottom of each layer will be described with reference to the drawings.

The thickness or the size of each layer (film), region, pattern or structure in the drawings may be modified for clarity and convenience of explanation, and thus does not entirely reflect the actual size.

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

An electrode material according to an embodiment will be described in detail with reference to FIGS. 1 to 4.

First, an example in which an electrode material according to an embodiment may be applied to FIGS. 1 and 2 will be described, and an electrode material that can be applied thereto will be described in detail with reference to FIGS. 3 and 4.

1 is a schematic plan view illustrating an embodiment of a touch panel, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1. 3 is a chemical formula for explaining the molecular structure of the electrode material according to the embodiment, Figure 4 is a photograph for explaining the structure of the nanowires included in the electrode material according to the embodiment.

1 and 2, in the touch panel according to the embodiment, an effective area AA for detecting a position of an input device and a dummy area DA positioned outside the effective area AA are defined. .

Here, the electrode 30 may be formed in the effective area AA to detect the input device. In the dummy area DA, a wiring 40 connected to the electrode 30 and a printed circuit board (not shown, the same below) that connects the wiring 40 to an external circuit (not shown, the same below), etc. This can be located. An outer dummy layer 20 may be formed in the dummy area DA, and a logo 20a may be formed in the outer dummy layer 20. The touch panel will be described in more detail as follows.

The outer dummy layer 20 is formed on the substrate 10, and the electrode 30 and the wiring 40 are formed on the polyethylene terephthalate (PET) substrate 60. An optically clear adhesive (OCA) 50 may be formed to adhere the substrate 10 and the polyethylene terephthalate substrate 60. Although not shown, a printed circuit board may be connected to the wiring 50.

In the drawings and description, the touch panel is illustrated as a device to which the electrode material of the present invention can be applied, but the present invention is not limited thereto. Thus, the electrode material according to the present invention can also be used to form electrodes or wiring of display devices such as plasma display panels, liquid crystal display panels, electrodes or dashed lines of solar cells, and the like.

The thickness of the electrode 30 may be 10 nm to 1000 nm. If the thickness of the electrode 30 is less than 10 nm, the sheet resistance is too large to deteriorate the conductivity, and if the thickness of the electrode 30 is greater than 1000 nm, the resistance is lowered, but the transmittance is also lowered, thereby degrading the visibility of the display to which the electrode 30 is applied. .

3 and 4, an electrode material according to an embodiment includes a conductive polymer, a dopant and a metal 32.

The conductive polymer may include at least one of polyethylene (3,4-Ethylenedioxythiophene, PEDOT), polyaniline, polypyrrole, polythiophene, and derivatives thereof. That is, the conductive polymer is a π-conjugated polymer, and may include a material in which electrical conductivity is increased by the addition of a dopant. The π-conjugated polymer has a chain structure in which carbon atoms repeat a single bond and a double bond, and the π-electron can move freely.

The dopant may include at least one of polystyrene sulfonate (PSS), dodecylbenzene sulfonate, toluene sulfonyl, chemposulfonic acid, benzenesulfonic acid, hydrochloric acid, and derivatives thereof. That is, the dopant may include a material capable of increasing the electrical properties of the conductive polymer.

As such, when the electrode material includes the conductive polymer and the dopant, the electrode material may be variously applied to forming the electrode of the flexible device due to the flexible characteristics of the conductive polymer. In addition, compared to the conventional indium tin oxide (ITO) used inexpensive price and easy manufacturing process can improve the productivity when forming the electrode.

In one embodiment, a composite (PEDOT: PSS complex) 31 of polyethylenedioxythiophene (hereinafter referred to as "PEDOT") 31b and polystyrenesulfonic acid (hereinafter referred to as "PSS") 31a is formed. It can be used as an electrode material.

PEDOT 31b is a conjugated polymer based on polythiophene and serves to transfer positive charges. The sulfonyl group of PSS 31a is deprotonated to become negatively charged. Both positively and negatively charged materials are hydrophilic.

Specifically, the PSS 31a induces the PEDOT 31b to be effectively dispersed in the aqueous solution. In addition, by matching the charge balance between the PEDOT 31b and the PSS 31a, the PEDOT 31b performs ionic bonding to the PSS 31a polymer chain very strongly, whereby the PEDOT 31b and the PSS 31a are in an aqueous solution. ) Can be well dispersed without being separated from each other. PEDOT 31b serves to maintain electrical conductivity for electrode characteristics. At this time, the weight ratio of PEDOT 31b: PSS 31a may be 1: 0.01 to 1:20. When the PSS has a weight ratio of less than 1: 0.01 to 0.01, it is difficult to disperse the PEDOT: PSS composite material 31 in a solvent or the like, and when the weight ratio is greater than 1:20 to 20, the weight ratio of the PEDOT 31b is relatively high. It may be reduced and the conductivity may be weakened.

Referring to FIG. 3, n and m of the PSS 31a and PEDOT 31b units may be 1000 or more, respectively.

Although the drawings and the description include including both the PSS and the PEDOT, the embodiment is not limited thereto and may include only the PEDOT maintaining the electrical conductivity.

Since the conductive polymer alone has a conductivity of about 10% lower than that of the conventional indium tin oxide, the metal 32 may be compensated for this. In addition, the metal 32 may be in the form of a nano wire in order to minimize the decrease in the transmittance due to the metal 32. The metal 32 in the form of nanowires has a very high conductivity, which helps to transfer charges, and may reduce the sheet resistance of the electrode 30. The metal 32 may include silver (Ag) as an example.

The length of such nanowires may be 1 um to 100 um. When the length of the nanowires is less than 1 um, the length is too short to form a network well, and nanowires having a length longer than 100 um are impossible in the process.

Subsequently, the diameter of the nanowires may be 10 nm to 200 nm. If the diameter is smaller than 10 nm, the cross-sectional area of the nanowire is reduced, the resistance is increased, and if the diameter is larger than 200 nm, the nanowire may be visible, which is a problem in visibility.

Hereinafter, a method of forming an electrode will be described in detail with reference to FIG. 5. For the sake of clarity and simplicity, the same or very similar parts to those described above will be omitted, and the different parts will be described in detail.

5 is a flowchart illustrating a method of forming an electrode according to an exemplary embodiment.

First, the step of mixing the solution (S501) will be described in detail. In this step, a mixed solution is formed by including a first solution including a conductive polymer solution and a second solution including a metal.

The first solution is a solution containing a conductive polymer solution and an additional solvent, and will be described first with respect to the conductive polymer solution.

First, the conductive polymer solution includes a conductive polymer, a dopant and a solvent. The conductive polymer may be prepared in a dispersed state in a solvent. In one embodiment, the conductive polymer may comprise PEDOT and the dopant may comprise PSS. The solvent may be, for example, water. However, as described above, PSS may not be included and only PEDOT may be included, which is also within the scope of the present embodiment.

In addition, the addition solvent includes dimethyl sulfoxide (DMSO) or en-methylpyrrolidone (N-Methyl-pyrrolidone, NMP), it is preferable to add dimethyl sulfoxide. However, the embodiment is not limited thereto, and various organic solvents such as methanol, dimethyl formamide (DMF), and ethylene glycol may be used. These solvents can grow the PEDOT particles during the heat treatment after coating the mixed solution to make the grain size of the PEDOT to an appropriate size can greatly improve the electrical properties.

Here, the volume ratio of the addition solvent: the conductive polymer solution may be 1: 20 to 3: 10. If the amount of the added solvent is less than 1: 20, it is difficult to improve the particles as much as desired, and if it contains more than 3 of 3: 10, the mixed solution may be diluted, which may be a problem when coating later.

Subsequently, a second solution containing a metal and ultrapure water (Dionize Water, D.I water) is prepared.

Specifically, the second solution refers to a solution in which a metal in the form of nanowires is dispersed in ultrapure water. The second solution may be so that the nanowires are well dispersed during the sonication step. Specifically, the sound wave processing may be performed for 1 minute to 30 minutes. When sonication for less than 1 minute, the nanowires are not dispersed well and become agglomerated. This is a problem in network formation, and interferes with the transmission of light, which contributes to the improvement of conductivity. Charges in these aggregated nanowires can also cause electrical shorts. If the sonication step is performed for more than 30 minutes, the nanowires may be broken by the sonication force.

The first solution and the second solution are mixed to form a mixed solution, wherein the volume ratio of the first solution to the second solution may be 20: 1 to 2: 1. That is, the amount of the metal contained in the form of nanowires dispersed in ultrapure water, if less than 20: 1 to 1 does not form a network of nanowires can not contribute to the improvement of conductivity. In addition, when contained in more than 2: 1 to 1 nanowires may be aggregated (aggregation) may interfere with the transmittance.

The volume ratio of the nanowires dispersed in such ultrapure water may be 200: 1 to 20: 1 of ultrapure water: nanowire.

Subsequently, a pretreatment of the polyethylene terephthalate substrate to which the mixed solution is coated may be included (S502). The polyethylene terephthalate substrate is hydrophobic and the mixed solution above is hydrophilic, so coating may not be easy. Therefore, the coating can be easily carried out through the pretreatment step (S502) of treating the hydrophobic surface of the polyethylene terephthalate substrate having hydrophobicity. In addition, the pre-processing step (S502) can reduce the defect (defect) so as not to affect the conductivity of the electrode material formed on the substrate. This pretreatment step (s502) may be performed by coating with a hydrophilic material or UV ozone treatment of the substrate.

However, since the exemplary embodiment is not limited thereto, the step S502 of pretreating the substrate may be omitted.

Coating the mixed solution on the polyethylene terephthalate substrate (S503). It can be formed by conventional wet coating methods of spin coating, flow coating, spray coating, dip coating, slit die coating and roll coating. This wet coating method is advantageous in that it is easy for mass production and low in equipment cost compared to the dry coating method.

Subsequently, the coated mixture solution is subjected to a heat treatment step (S504). Through this step (S504) it is possible to evaporate the solvent and the added solvent contained in the mixed solution, and to form a morphology (morphology formation) of the conductive polymer. Conventional indium tin oxide requires a high temperature process of more than 300 ℃ to make a crystalline structure, in this embodiment, it is possible to form an electrode having high conductivity and transmittance even in a low temperature process (approximately, 90 ℃).

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the examples are only for illustrating the present invention, and the present invention is not limited thereto.

Example  One

To a glass vial was added 3 ml of a conductive polymer solution in which PSS and PEDOT (CLEVIOS PH 510, H.C. Starck) and 0.21 ml of dimethyl sulfoxide were added. This was stirred for one day to prepare a first solution. In addition, a second solution was prepared by sonicating 0.1 ml of silver nanowires having a length of 10 μm and a diameter of 100 μm dispersed in 10 ml of ultrapure water for 30 minutes. 0.321 ml of this second solution was mixed into the first solution to prepare a mixed solution, and the mixed solution was stirred for one hour.

The mixed solution was bar coated onto a polyethylene terephthalate substrate and heat-treated for about 30 minutes in a heating stirrer heated to a temperature of about 90 ° C.

Example  2

Prior to coating, the polyethylene terephthalate substrate was fabricated in the same manner as in Example 1, except that UV ozone treatment was performed for 20 minutes.

Comparative example

It was produced in the same manner as in Example 1 except that the second solution was not included.

Pictures for comparing Examples 1 and 2 are shown in FIGS. 6 and 7. 6 is a photograph of a substrate surface according to Example 1, and FIG. 7 is a photograph of a substrate surface according to Example 2. FIG.

Referring to FIG. 6, Example 1 looks like a stain because the coating is uneven. In contrast, referring to FIG. 7, Example 2 shows that the substrate surface is clean and the coating is uniformly well.

Therefore, it can be seen from the above results that it is advantageous to uniform coating to make the polyethylene terephthalate substrate hydrophilic by UV ozone treatment.

Next, the graph for comparing the transmittance | permeability of Example 2 and a comparative example is shown in FIG. In Example 2 and Comparative Example, the transmittance was measured at a wavelength of 300 nm to 900 nm with a Perkin-Elmer Lambda 12 UV / Vis spectrophotometer. It can be seen that the transmittance of Comparative Example is about 82% and the transmittance of Example 2 is about 86% at a wavelength of about 550 nm.

Although not shown in the drawings, the sheet resistance of Example 2 and Comparative Example was measured using a four-point probe. As a result, the sheet resistance of Example 2 was 250 kPa / sq, and the sheet resistance of the comparative example was 430 Pa / sq.

As a result of the above, it can be seen that the transmittance of Example 2 was increased by 4% compared to the comparative example, the sheet resistance is reduced by 180 Ω / sq.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. In addition, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

30: electrode
31: PEDOT: PSS Complex
31a: polystyrene sulfonate (PSS)
31b: Poly (3,4-Ethylenedioxythiophene), PEDOT
32: metal

Claims (18)

Preparing a conductive polymer solution comprising a first solvent and a conductive polymer;
Mixing a second solvent with the conductive polymer solution to form a first solution;
Preparing a second solution including metal nanowires and ultra pure water (Deionize Water, DI water);
Mixing the first solution and the second solution to form a mixed solution;
Coating the mixed solution on a substrate; And
Electrode forming method comprising the step of heat-treating the mixed solution. The method of claim 1,
In the preparing of the conductive polymer solution, the first solvent, the conductive polymer and the dopant are mixed,
The conductive polymer is formed of an electrode including at least one of polyethylene (3,4-Ethylenedioxythiophene, PEDOT), polyaniline, polypyrrole, polythiophene and derivatives thereof Way. The method of claim 2,
The dopant is at least one of polystyrene sulfonate (PSS), dodecylbenzene sulfonate (Dodecylbenzene sulfonate), toluene sulfonyl (Toluene sulfonyl), chemposulfonic acid, benzenesulfonic acid, hydrochloric acid and derivatives thereof. The method of claim 1,
The metal nanowire is an electrode forming method comprising silver (Ag). The method of claim 4, wherein
The metal nanowire has a length of 1 um to 100 um and a diameter of 10 nm to 200 nm electrode forming method. The method of claim 1,
The second solvent comprises at least one of dimethylsulfoxide (dimethylsulfoxide, DMSO) and N-methyl-pyrrolidone (NMP). The method of claim 6,
In the step of forming the first solution,
The method of forming an electrode, wherein the volume ratio of the second solvent: the conductive polymer solution is 1:20 to 3:10. The method of claim 1,
In the step of forming the mixed solution,
The volume ratio of the first solution: the second solution is 20: 1 to 2: 1. The method of claim 1,
Preparing the second solution includes the step of sonicating the second solution (sonication). 10. The method of claim 9,
The sound wave treatment is performed for 1 minute to 30 minutes. The method of claim 1,
Prior to the coating, the method of forming an electrode comprising the step of treating the surface of the substrate to hydrophilic. The method of claim 11,
Treating the substrate surface with hydrophilicity comprises coating the substrate with a hydrophilic material. The method of claim 11,
Treating the substrate surface with hydrophilicity comprises treating the substrate with ultraviolet ozone. Including conductive polymers, dopants and metal nanowires,
The conductive polymer is a π-conjugated polymer,
The metal nanowire has a length of 1 um to 100 um and an electrode material having a diameter of 10 nm to 200 nm. The method of claim 14,
The conductive polymer is an electrode material including at least one of polyethylene (3,4-Ethylenedioxythiophene, PEDOT), polyaniline, polypyrrole, polythiophene and derivatives thereof . The method of claim 14,
The dopant is an electrode material comprising at least one of polystyrene sulfonate (PSS), dodecylbenzene sulfonate, toluene sulfonyl, chemposulfonic acid, benzenesulfonic acid, hydrochloric acid and derivatives thereof. The method of claim 14,
The metal nanowires include silver (Ag). delete

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