KR20160142271A - Method for manufacturing of transparent conductor containing copper nanowire and the transparent conductor containing copper nanowire thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a transparent electrode containing a copper nanowire and to a transparent electrode containing a copper nanowire manufactured thereby. More specifically, the method for manufacturing a transparent electrode containing a copper nanowire comprises the following steps of: coating a composition containing a copper nanowire on a substrate; and laser-scanning the copper nanowire coated on the substrate at a scanning velocity of 10-1000 mm/s. According to the method for manufacturing a transparent electrode in accordance with the present invention, the copper nanowire coated on the substrate is laser-scanned in a short period of time to increase adhesion between copper nanowires to reduce contact resistance. Copper nanowires outside an adhesion portion are oxidized to prevent an increase in resistance by oxidization to manufacture a copper nanowire transparent electrode with improved electrical performance even at a room temperature and in air. Accordingly, inexpensive copper is used, and a process condition is simplified to provide a transparent electrode at relatively low costs.

Description

[0001] The present invention relates to a transparent electrode including a copper nanowire and a transparent electrode including a copper nanowire produced thereby,

The present invention relates to a method of manufacturing a transparent electrode comprising copper nanowires and a transparent electrode comprising copper nanowires produced thereby. And more particularly, to a method of manufacturing a transparent electrode including copper nanowires having a small increase in oxidation resistance at room temperature and in air, and a transparent electrode including copper nanowires produced thereby.

The transparent electrodes used in various electronic devices are expected to increase in the future, such as large-area energy storage devices and bending displays, and various studies are being conducted. ITO (Indium Tin Oxide) is widely used up to now.

ITO has the advantages of high transparency and low sheet resistance in the visible light region, but it is basically a ceramic based material, so it is very weak in tensile strength and there is a limitation that the price rise due to the rareness of indium is concerned.

Accordingly, various transparent electrode manufacturing studies for replacing ITO have been conducted. Many researchers have studied carbon nanotubes (CNTs), graphene, metal grids, and metal nanowires (Ag, Au). Among them, metal nanowires Of the transparent electrode.

However, the general price of silver, gold, and other precious metals, and the complexity of the synthesis process, are merely aimed at improving the performance of ITO, and studies that do not consider price competitiveness are underway.

Copper (Cu) has the problem of oxidation despite its abundant reserves and low raw material prices, and research is not being actively conducted in various academic or industrial fields. To overcome the oxidation problem, separate equipment is needed This is because the processing time is long. Until now it has been accepted that machining (heat-treating) copper in air is almost impossible.

Korean Patent No. 10-1305710 discloses a nanowire composition and a method of manufacturing a transparent electrode as a conventional technique related to a method of manufacturing a transparent electrode using nanowires. Specifically, there is provided a method comprising: preparing a nanowire composition; Coating the nanowire composition on a substrate; And heat treating the nanowire composition, wherein the nanowire composition comprises: a metal nanowire; Organic binders; Surfactants; And a solvent, wherein the metal nanowires have a diameter of 30 to 50 nm and a length of 15 to 40 탆, a weight percentage of the metal nanowires is 0.01 to 0.4%, a weight percentage of the organic binder is 0.01% to 0.5% by weight of the transparent electrode.

However, since the nanowire is thermally treated as a whole, when the copper nanowire is used, there is a problem that the resistance of the electronic device produced due to the oxidation problem of copper increases.

Accordingly, the inventors of the present invention have found that by rapidly laser-coating coated copper nanowires to fabricate transparent electrodes using copper nanowires at room temperature and air, it is possible to prevent the increase in resistance due to oxidation while improving the bonding property between copper nano- And completed the manufacturing method of the transparent electrode including the copper nanowire.

WO2013 / 095971

SUMMARY OF THE INVENTION [0006]

And a method of manufacturing a transparent electrode including copper nanowires.

Another object of the present invention is to provide

And a transparent electrode including copper nanowires manufactured according to the above-described method.

A further object of the present invention is to provide

And a transparent electrode including the copper nanowire.

According to an aspect of the present invention,

Coating a composition comprising a copper nanowire on a substrate; And

And laser scanning the copper nanowires coated on the substrate at a scanning rate of 10 to 1000 mm / s. The present invention also provides a method of manufacturing a transparent electrode comprising copper nanowires.

Further, according to the present invention,

A transparent electrode including copper nanowires manufactured according to the above-described method is provided.

Further,

And a transparent electrode including the copper nanowire.

According to the method of manufacturing a transparent electrode including the copper nanowire according to the present invention, the copper nanowire coated on the substrate is laser-scanned in a short time to increase the bonding property between the copper nanowires to reduce the contact resistance, It is possible to prevent the oxidation due to oxidation of the nanowire from being increased, and thus, a copper nanowire transparent electrode having improved electrical performance at room temperature and in the air can be manufactured. This makes it possible to provide transparent electrodes at a lower cost by using inexpensive copper and simplifying the process conditions.

FIG. 1 (a) is a schematic view of a method of manufacturing a transparent electrode including copper nanowires according to the present invention, and FIG. 1 (b) is a schematic view of a conventional method of manufacturing a transparent electrode including copper nanowires.
FIG. 2 is a photograph of a transparent electrode including copper nanowires prepared in Example 1 and Comparative Examples 1 and 2;
FIG. 3 is a graph of a transparent electrode including copper nanowires prepared in Example 1 and Comparative Examples 1 and 2 with an X-ray diffractometer; FIG.
FIG. 4 is a photograph of a transparent electrode including copper nanowires prepared in Example 1 and Comparative Examples 1 and 2, observed with a transmission electron microscope and an electron diffraction pattern; FIG.
5 is a photograph showing a conductivity of a transparent electrode including copper nanowires prepared in Example 1 and Comparative Example 1;
6 is a graph showing the transmittance and the resistance of the transparent electrode including copper nanowires prepared in Examples 1 to 8;
7 is a visual observation of a transparent electrode including copper nanowires prepared in Examples 1, 9 to 13;
FIG. 8 is a photograph of a touch screen panel drive including a transparent electrode including the copper nanowires manufactured in Example 14, and FIG.
FIG. 9 is a graph and simulation result showing the electric field intensity around the copper nanowire according to the wavelength.

According to the present invention,

Coating a composition comprising a copper nanowire on a substrate; And

And laser scanning the copper nanowires coated on the substrate at a scanning rate of 10 to 1000 mm / s. The present invention also provides a method of manufacturing a transparent electrode comprising copper nanowires.

FIG. 1 is a schematic view of a method of manufacturing copper nanowires according to the present invention. Hereinafter, a method of manufacturing a transparent electrode including copper nanowires according to the present invention will be described in detail.

In the method of manufacturing a transparent electrode including copper nanowires according to the present invention, step 1 is a step of coating a composition comprising copper nanowires on a substrate.

In this step, a transparent conductive substrate having a transparent electrode formed thereon can be prepared by coating a desired substrate with a composition containing copper nanowires.

The step 1 may be performed by raising a copper nanowire in a mesh form using a vacuum filter method. However, the coating method is not limited thereto, and a method of forming a copper nanowire on a substrate may be appropriately selected Can be used.

At this time, at least one substrate selected from the group consisting of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PDMS (polydimethylsiloxane), platinum-cure silicone rubber, PI (polyimide) , The type of the substrate is not limited thereto, and a flexible substrate can be appropriately selected and used.

By using such a substrate, a curled electronic device including a transparent electrode including copper nanowires can be manufactured.

In the method of manufacturing a transparent electrode including copper nanowires according to the present invention, step 2 is a step of laser-scanning the copper nanowires coated on the substrate at a scanning rate of 10 to 1000 mm / s.

Copper is being studied as a substitute for transparent electrode materials such as ITO and gold and silver nanowires with abundant reserves and low raw material prices. However, because of the problem of oxidation, separate vacuum equipment is required, the process time is lengthened, and the process conditions are complicated. It is accepted that it is almost impossible to process (heat-treat) copper in the air until now.

In order to solve the above problem, in the present invention, the copper nanowires coated on the substrate can be laser-scanned in a short period of time to prevent the resistance of the copper nanowires other than the bonding portion from being oxidized due to oxidation at room temperature without additional vacuum equipment. In addition, the bonding property of the bonding portion is increased, so that the contact resistance is reduced and the electrical characteristics are improved.

More specifically, it was first verified through FDTD simulations that field enhancement occurs by plasmonic phenomenon at the junction of nanowires when the nanowires on the substrate are randomly irradiated with a laser . Since the photothermal reaction by the laser is proportional to the intensity of the electric field at the junction, unnecessary heating is not generated in other parts of the nanowire excluding the substrate and the junction due to the plasmonic effect generated at the junction, Can be minimized.

On the other hand, if the photothermal reaction occurs selectively at the junction, the contact resistance can be decreased by the increase of the nano-wire bond and the resistance due to oxidation can be increased simultaneously.

However, in the present invention, since the laser light is rapidly scanned, the heating time is minimized, and the resistance reduction effect becomes dominant due to no time margin for oxidation. Using this phenomenon, we have developed a process to make transparent electrodes using copper nanowires in air or at room temperature.

At this time, the laser scanning speed in step 2 is 10 to 1000 mm / s.

If the laser scanning speed of the step 2 is less than 10 mm / s, an oxide film may be formed on the copper nanowire due to the laser irradiation for a long time. If the laser scanning speed of the step 2 exceeds 1000 mm / s There is a problem that the laser power required due to the high speed is increased.

The wavelength of the laser in step 2 may be 400 to 1000 nm.

If the laser wavelength of the step 2 is less than 400 nm or more than 1000 nm, the effect of increasing the electric field at the junction is insufficient, which is more inefficient than using a wavelength within the range of 400 to 1000 nm .

The laser scanning in the step 2 can be performed using a 2D galvanomirror. The galvanometer mirror can be used to enable fast scanning of laser light, but the equipment for fast laser scanning is not limited thereto.

In addition, the scan path of the laser can be set so that only desired shapes and optional portions can be heat-processed through the CAD, but the equipment for setting the scan path is not limited thereto.

The laser scanning of step 2 may be performed at room temperature and air.

Conventionally, when the copper nanowire is heat-treated in air, the oxidation resistance is increased, and therefore, a vacuum atmosphere must be provided, which increases the cost of the process.

However, in the present invention, by scanning the laser in a short time, the bonding property of the copper nanowires can be increased, and the increase of the oxidation resistance can be prevented. Therefore, even when a transparent electrode including copper nanowires is formed at room temperature and in air, oxidation of copper can be prevented.

The laser of step 2 may have an intensity of 50 to 200 mW.

If the laser of step 2 has a strength of less than 50 mW, the contact of the copper nanowires can not be sufficiently performed and the contact resistance may not be reduced. If the laser of step 2 has a strength of more than 200 mW The temperature is excessively increased due to the excessive energy irradiation, so that the nanowire itself is ablated and the electrical contact is lost.

According to the present invention,

A transparent electrode including copper nanowires manufactured according to the above-described method is provided.

According to the manufacturing method of the present invention, it is possible to provide a transparent electrode including a copper nanowire having a high electrical characteristic at room temperature and in air, because the contact resistance can be reduced without increasing the oxidation resistance by laser scanning of the copper nanowire in a short time .

The transparent electrode including the copper nanowire has a low contact resistance and a low oxidation resistance, and thus has a high electrical characteristic. Further, since it is manufactured at room temperature, it can be applied to a flexible substrate and thus can be applied to a flexible device. Further, since copper is used without requiring a separate process such as a vacuum device, it can be provided at an inexpensive price.

At this time, the transparent electrode including the copper nanowire may have a low sheet resistance of 1 to 20? / Sq. In addition, the transparent electrode including the copper nanowire may have a high transmittance of 95 to 99%.

According to the present invention,

And a transparent electrode including the copper nanowire.

Since the transparent electrode including the copper nanowire can be manufactured in a flexible substrate because it can be manufactured at room temperature and air through a short-time laser scanning, it can provide a touch screen panel of a curled electronic device .

However, the device including the copper nanowire transparent electrode is not limited thereto, and can be widely used in electronic fields such as LCD front electrode, display such as OLED electrode, solar cell, and photoelectric device.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are intended to illustrate the present invention, but the present invention is not limited to the following examples.

≪ Example 1 >

Step 1: Copper nanowires were coated in a mesh form on a glass substrate using a vacuum filter method using 25 占 퐇 in a solution containing copper nanowires in a weight ratio of 10% to 20 ml of isopropanol.

Step 2: For a 40 mm x 40 mm portion of a copper nanowire formed in the form of a mesh on the substrate, a 2D galvano mirror A laser having a wavelength of 532 nm was scanned at a power of 100 mW and a scanning speed of 100 mm / s for 60 seconds to prepare a transparent electrode including copper nanowires.

At this time, the process was performed at room temperature and air.

≪ Examples 2 to 8 &

Except that the amount of the copper nanowire-containing composition in step 1 of Example 1 was 50 μl, 75 μl, 100 μl, 125 μl, 150 μl, 175 μl and 200 μl, respectively To prepare a transparent electrode containing copper nanowires.

≪ Examples 9 to 13 &

Except that the substrates of step 1 of Example 6 were polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), platinum-cure silicone rubber (Eco-flex) A copper nanowire transparent electrode was prepared in the same manner as in Example 6.

≪ Example 14 >

The touch screen panel including the transparent electrode including the copper nanowire manufactured in Example 4 was manufactured.

≪ Comparative Example 1 &

Only the step 1 of Example 3 was performed to fabricate a transparent electrode including copper nanowires.

≪ Comparative Example 2 &

The copper nanowires were formed in the same manner as in Example 3, except that the entire substrate on which the copper nanowires were formed was heat-treated at a temperature of 200 to 250 ° C for 3 to 5 minutes instead of the laser irradiation in the step 2 of Example 3 Was prepared.

In the production methods of Examples 1 to 14 and Comparative Examples 1 and 2, the laser irradiation condition, the total heat treatment condition, the amount of the composition, and the types of the substrates are summarized in Table 1 below.

Laser irradiation Whole heat treatment Amount of composition Type of substrate Example 1 ○ × 25 μl Glass Example 2 ○ × 50 μl Glass Example 3 ○ × 75 쨉 l Glass Example 4 ○ × 100 μl Glass Example 5 ○ × 125 쨉 l Glass Example 6 ○ × 150 μl Glass Example 7 ○ × 175 μl Glass Example 8 ○ × 200 쨉 l Glass Example 9 ○ × 150 μl PET Example 10 ○ × 150 μl PEN Example 11 ○ × 150 μl PDMS Example 12 ○ × 150 μl Eco-flex Example 13 ○ × 150 μl PI Example 14 ○ × 75 쨉 l Glass Comparative Example 1 × × 75 쨉 l Glass Comparative Example 2 × ○ 75 쨉 l Glass

<Analysis> Strength of electric field on copper nanowire with laser wavelength

The photothermal reaction by laser light is proportional to the magnitude of the electric field at its periphery. It is known that the magnitude of the electric field becomes strong near a very small metal nano structure such as a nanowire junction. In addition, the increase of the electric field size due to the plasmonic effect is determined by the wavelength and the shape and size of the nanostructure used, and it is known that the plasmonic reaction occurring at the junction of the nanowires for each laser of each wavelength is different.

On the other hand, in order to observe how the electric field strength on the copper nanowire having a diameter of 100 nm according to the laser wavelength changes, the copper nanowire having a diameter of 100 nm has a wavelength of 355 nm, 532 nm and 1064 nm After laser irradiation, electric field simulations were performed near the junction, and the results are shown in Fig.

As shown in FIG. 9, the electric field synergy effect at a wavelength of 355 nm and 1064 nm was 10 to 40, but the electric field enhancement effect at the wavelength of 532 nm was 80 to 100 It can be seen that the increase is twice as much as that of the other wavelengths.

As a result, it can be seen that, in the case of copper nanowires having a diameter of 100 nm, irradiation with a laser having a wavelength of 532 nm has the highest efficiency in photothermal reaction.

EXPERIMENTAL EXAMPLE 1 Observation of oxidation of transparent electrodes including copper nanowires

In order to observe the oxidation of the transparent electrodes including the copper nanowires prepared in Example 1 and Comparative Examples 1 and 2, the results were observed with naked eyes and the results are shown in Fig. 2. X-ray diffraction analysis (XRD ). The results are shown in FIG. 3, and the composition was observed with a transmission electron microscope (TEM) and an electron diffraction pattern (SAED), and the results are shown in FIG.

As shown in Fig. 2, it can be seen that the red color inherent to copper was observed in Comparative Example 1 in which laser irradiation or heat treatment was not performed. In the case of Example 1 in which the laser irradiation was performed locally only at the junction portion of the copper nanowires, the red color also appeared. However, in Comparative Example 2 in which the copper nanowires were subjected to the heat treatment as a whole, .

As shown in FIG. 3, it was confirmed that only copper was observed in Comparative Example 1, and a weak copper oxide (CuO) peak appeared in the laser irradiated Example 1, indicating that oxidation hardly occurred. In Comparative Example 2 in which the entire heat treatment was performed, the peaks of CuO and CuO ₂ were strongly observed, but Cu peaks were not observed, so that most copper was oxidized.

In the case of Example 1, it can be seen that the material observed through the lattice structure shown in Fig. 4 and having d (111) of 2.1 Å is copper, and an oxide film is not formed around the copper nanowire .

As a result, it can be seen that when the laser is irradiated only to the junction portion of the copper nanowires at room temperature and air, the transparent electrode can be manufactured without oxidizing the copper nanowires as a whole.

<Experimental Example 2> Observation of electrical characteristics and transmittance of a transparent electrode including copper nanowires

The transparent electrode including the copper nanowire fabricated according to Example 1 was fabricated in the same manner as in Example 1 except that the laser scanning time was 60 seconds or less (after all areas were sintered) and the transparent electrode including the copper nanowires prepared in Comparative Example 1 The conductivity of the electrode was measured with a measuring device (MS Tech, M4P 302-System), and the result is shown in FIG. The transparency of the transparent electrode including the copper nanowires prepared in Examples 1 to 8 was observed with a UV-Visible spectrophotometer (EVOLUTION 220), and the sheet resistance was measured with M4P 302-system (MS TECH) , And the results are shown in Fig.

As shown in Fig. 5, in the case of Comparative Example 1 in which the laser was not irradiated, the conductivity was not shown due to the bonding resistance of the copper nanowires. However, in the transparent electrode including the copper nanowires prepared in Example 1, When the scanning time is 10 seconds, 30 seconds, and 60 seconds, the values are 7.19 MΩ / sq, 1.279 KΩ / sq and 47.2 Ω / sq, respectively. Also, it can be seen that the laser scanning process actually proceeds at room temperature and in the air.

As shown in FIG. 6, Example 1, which was prepared using 20 microliters of composition, exhibited a high transmittance of about 95%, and in Example 8, which was prepared using 200 microliters of the composition, 18 &lt; sq. &lt; / RTI &gt;

Also, as the amount of the composition increases, the permeability tends to decrease to 70%, and as the amount of the composition decreases, the resistance increases to 5000 Ω / sq or more.

It can be seen from this that through the copper nanowire manufacturing method of the present invention, a transparent electrode including a copper nanowire having high conductivity, transparency and low resistance even at room temperature and air can be manufactured.

&Lt; Experimental Example 3 > Production of transparent electrode including copper nanowire according to the type of substrate

The transparent electrodes including the copper nanowires, each of which was manufactured in a different manner according to Examples 1, 9 to 13, were visually observed, and the results are shown in FIG.

As shown in FIG. 7, it can be seen that transparent electrodes including copper nanowires can be formed on flexible substrates such as PET, PEN, PDMS, Eco-flex and PI as well as on glass substrates, It can be seen that it can be applied to a device.

<Experimental Example 4> Application of copper nanowires

A touch screen panel including a transparent electrode including the copper nanowires manufactured in Example 14 was manufactured and a picture of driving the device was shown in FIG.

As shown in FIG. 8, it can be confirmed that the touch screen panel is normally driven, and according to the present invention, a transparent electrode including copper nanowires manufactured at low cost in room temperature and air can be practically applied to a smart electronic device .

Claims (2)

Coating copper nanowires on the substrate with 25 占 퐇 in a solution containing copper nanowires in a weight ratio of 10% to 20 ml of isopropanol; And
A laser having a wavelength of 532 nm was applied to the copper nanowire coated on the substrate using a 2D galvanomirror for 60 seconds at a power of 100 mW and a scanning speed of 100 mm / To produce a transparent electrode having a transmittance of 95% and a sheet resistance of 47.2? / Sq.
The method according to claim 1,
Wherein the substrate of step 1 is at least one selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polydimethylsiloxane (PDMS), platinum-cure silicone rubber, polyimide A method of manufacturing a transparent electrode comprising a wire.

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