KR20120086208A - Method for forming conducting polymer electrode and the electrode material - Google Patents

Abstract

PURPOSE: A method for forming a conductive polymer electrode and an electrode material are provided to reduce defects and manufacturing costs in a simple process by forming electrodes without a high temperature process and a vacuum process. CONSTITUTION: A conductive polymer solution is prepared. A mixture solution is formed by mixing an addictive solvent with the conductive polymer solution(S401). The mixture solution is coated on a substrate(S402). The mixture solution is thermally treated(S403).

Description

METHOD FOR FORMING CONDUCTING POLYMER ELECTRODE AND THE ELECTRODE MATERIAL}

The present disclosure relates to a method of forming a conductive polymer electrode and an electrode material.

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 in that the characteristics of the electrode deteriorate due to physically easily hit by the bending and the bending of the substrate, thereby not suitable for a flexible device.

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

Embodiments provide an electrode material capable of improving conductivity and excellent physical stability and a method of forming a conductive polymer electrode using the same.

An electrode material according to an embodiment includes a conductive polymer and a dopant, 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 mixed solution; Coating the mixed solution on a substrate; And heat treating the mixed solution.

Since the electrode material according to the embodiment includes a conductive polymer, the electrical conductivity is very excellent compared to the existing electrode material. 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 schematic view for explaining an electrode forming method according to an embodiment.
FIG. 5 is a graph for describing the transmittance and sheet resistance of the electrodes formed by Examples 1 to 4. FIG.
6 is a graph for comparing the efficiency change according to the bending test of the electrode formed by Example 3 and Comparative Example.
7 is a photograph of the surface of the electrode after the bending test of the electrode formed by Example 3. FIG.
8 is a photograph of the surface of the electrode after the bending test of the electrode formed by the 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 3. First, an example in which an electrode material according to an embodiment may be applied to FIGS. 1 and 2 will be described in detail with reference to FIG. 3.

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.

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.

Referring to FIG. 2, the outer dummy layer 20 is formed on the first substrate 10, and the electrode 30 and the wiring 40 are formed on the second substrate 60. An optically clear adhesive (OCA) 50 may be formed to adhere the first substrate 10 and the second 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. .

Referring to FIG. 3, an electrode material according to an embodiment includes a conductive polymer and a dopant. 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.

Hereinafter, a method of forming an electrode will be described in detail with reference to FIG. 4. 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.

4 is a schematic view for explaining an electrode forming method according to an embodiment.

First, the step (S401) of mixing the solution will be described in detail. This step forms a mixed solution including the conductive polymer solution and the addition solvent.

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 water, for example. 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.

The conductive polymer and the dopant may include 0.1 wt% to 20 wt% of the conductive polymer solution. Therefore, if less than 0.1% by weight is included, it is difficult to act as an electrode because of the low electrical conductivity, when contained in more than 20% by weight, it does not dissolve well in the solvent and may be agglomerated in the solvent (aggregation) may be a problem during coating. .

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 particle as much as desired, and if it is included more than 3 of 3: 10, the mixed solution may be diluted, which may be a problem when coating later.

Subsequently, the mixed solution is coated on the substrate (S402). The substrate may comprise polyethylene terephthalate (poly) or glass.

Coating methods can be conventional wet coating methods of spin coating, flow coating, spray coating, dip coating, slit die coating and roll coating. have. 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 (S403). Through this step (S403) it is possible to evaporate the solvent and the addition solvent contained in the mixed solution, and to form the morphology (morphology formation) of the conductive polymer. Conventional indium tin oxide requires a high temperature process of 300 ° C. or higher to form a crystalline structure. However, in the present embodiment, an electrode having high conductivity and transmittance may be formed even by a low temperature process (about 150 ° C.).

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 1

A mixed solution was formed by adding 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 to a glass vial. Here, the weight ratio of PEDOT: PSS in 3 ml of the conductive polymer solution is 1: 2.5. In addition, the PSS and PEDOT were included in the conductive polymer solution 1.5% by weight. This mixed solution was spin coated at 1000 rpm on a glass substrate and heat treated at about 150 ° C.

Example  2

It was manufactured in the same manner as in Example 1 except for spin coating at 2000 rpm.

Example  3

Except that the spin coating at 3000 rpm was produced in the same manner as in Example 1.

Example  4

It was manufactured in the same manner as in Example 1 except for spin coating at 5000 rpm.

Comparative example

Indium tin oxide was deposited on a glass substrate to prepare an electrode.

As a result of the preparation according to Examples 1 to 4, electrodes having a thickness of 300 nm, 170 nm, 140 nm and 90 nm were formed, respectively, and each of these electrodes was absorbed (Perkin-Elmer Lambda 12 UV / Vis spectrophotometer) and 4 probe method. Transmittance and sheet resistance were measured using (four-point-probe) and are shown in FIG. 5.

Referring to FIG. 5, it can be seen that the electrodes of Examples 1 to 4 have a transmittance of about 88% to about 73% at a wavelength of 550 nm. In addition, it can be seen that the sheet resistance is about 250 kW / sq to about 50 kW / sq. Through this, it can be seen that the electrodes according to Examples 1 to 4 have very high transmittance and very low sheet resistance values.

Subsequently, the change in efficiency according to the bending test was measured for the electrodes formed by Examples 3 and Comparative Examples, and the results are shown in FIG. 6. In the case of the comparative example, it can be seen that after about 100 bending tests, the efficiency drops to 0%. That is, in the case of the comparative example it can be seen that the electrode is destroyed at the initial stage of the bending test. On the other hand, in the case of Example 3, even after 500 bending tests, it can be seen that there is almost no change in efficiency.

After this bending test, the surface photograph of each electrode is shown in FIGS. 7 and 8. FIG. 7 is a surface photograph of an electrode after 500 bending tests of an electrode formed by Example 3, and FIG. 8 is a surface photograph of an electrode after 100 bending tests of an electrode formed by Comparative Example.

In the case of Example 3, even after 500 bending tests, as shown in FIG. 7, no crack was generated and a very clean surface could be seen. On the other hand, in the comparative example, it can be seen that the crack of the electrode surface is very severe even after 100 bending tests as shown in FIG. 8.

From the above results, it can be seen that the electrode formed by this embodiment is very suitable for a large area flexible device.

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

Claims (14)

Preparing a conductive polymer solution;
Mixing an additional solvent with the conductive polymer 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, a solvent, a conductive polymer and a dopant are mixed,
And the conductive polymer is a π-conjugated polymer. The method of claim 2,
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 2,
Wherein the conductive polymer: the weight ratio of the dopant is 1: 0.01 to 1: 20 electrode formation method. The method of claim 2,
In the preparing of the conductive polymer solution,
An electrode forming method comprising 0.1 to 20% by weight of the conductive polymer and the dopant with respect to the conductive polymer solution. The method of claim 1,
The additive solvent includes at least one of dimethyl sulfoxide (DMSO) and N-Methyl-pyrrolidone (NMP). The method of claim 7, wherein
In the step of forming the mixed solution,
A method of forming an electrode, wherein the volume ratio of the added solvent: the conductive polymer solution is 1:20 to 3:10. The method of claim 1,
The coating step may be selected from the group consisting of spin coating, flow coating, spray coating, dip coating, slit die coating and roll coating. Electrode formation method comprising. The method of claim 1,
And the substrate comprises at least one of a polyethylene terephthalate (poly) film and a glass. A conductive polymer and a dopant,
The conductive polymer is an π-conjugated polymer. The method of claim 11,
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 11,
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 11,
The conductive material: the electrode material of the weight ratio of the dopant is 1: 0.01 to 1: 20.

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