KR102187987B1 - Transparent heaters electrode with multilayered structure. - Google Patents

Abstract

The present invention relates to an Ag/Al_2O_3 transparent heater electrode with a multilayer thin film structure. Provided is the Ag/Al_2O_3 transparent heater electrode with a multilayer thin film structure, which has excellent heat generation performance, high transmittance, and anti-oxidation effect.

Description

Electrodes for transparent heaters having a multilayered thin film structure {TRANSPARENT HEATERS ELECTRODE WITH MULTILAYERED STRUCTURE.}

The present invention relates to an electrode for a transparent heater having an Ag/Al ₂ O ₃ multilayer thin film structure. More specifically, it is a transparent heater electrode including an Ag metal layer and an Al ₂ O ₃ layer on the upper surface of the Ag metal layer, and has a transparent Ag/Al ₂ O ₃ multilayer thin film structure with excellent heat generation performance, high transmittance, and antioxidant effect. It relates to an electrode for a heater.

Transparent electrode plastics or transparent electrode glass are used in processes such as touch panels, OLED flexible displays, and organic solar cells, which are rapidly growing in recent years, as well as existing displays such as LCD or PDP. As such a transparent electrode, an ITO (Indium Tin Oxide) electrode manufactured by a sputtering method is mainly used. This is because ITO is easy to form a thin film, has excellent light transmission properties, and has relatively low electrical resistance. However, problems such as increased material cost due to the increase in the price of the main raw material, indium, market instability and depletion, device deterioration due to the diffusion of indium, high reducibility under hydrogen plasma, and bending instability such as cracks in flexible substrates. Is being raised.

In particular, the ITO transparent thin film has many problems in the large-area thin film process that requires a continuous process because it is produced by the sputtering method under high temperature vacuum conditions. It is understood that the development of a transparent electrode that can exhibit optimal physical properties on a plastic substrate applied to a flexible electronic device should be preceded. In the case of conventional ITO, there are problems such as a problem in that the substrate is deformed during processing and driving due to the difference in thermal expansion coefficient between the ITO electrode and the plastic substrate, and a change in surface resistance due to electrode destruction due to bending of the electrode substrate.

In addition, transparent electrodes used in various electronic devices such as organic light-emitting diodes, displays, and solar cells are applied to transparent film heaters (TFHs) based on Joule heating. The conductive oxide mainly used in such a transparent film heater is also Indium-Tin Oxide (ITO), which has excellent conductivity and transparency.

In order to replace this, organic transparent electrodes using organic materials such as conductive polymers, carbon nanotubes (CNT), and graphene have been developed. However, in order to have sufficient electrical resistance for the organic transparent electrode, a thick film must be formed, and there is a problem in that transparency is lowered. Accordingly, a method for solving a problem occurring in the conventional transparent film heater is urgently required.

On the other hand, in order to solve the problem of such a conventional transparent electrode, there is a technique of using an electrically conductive electrode liquid as a transparent electrode by printing it in a grid type. In particular, by printing a metal grid on a plastic or glass substrate, it is possible to manufacture a transparent electrode having very low electrical resistance and high transparency. To this end, gravure offset printing and a printing method using inkjet are applied.

However, when the above printing method is used, there is a problem that it is very difficult to manufacture with a grid line width of less than 10 μm, and there is a problem that the height of the grid electrode line is low (about 200 nm) and sheet resistance is high. In addition, although the transparent electrode should have excellent optical properties, these grid electrodes have optical problems such as visibility and haze when the grid is visible due to a backlight when applied to a display or a touch panel. In addition, according to the above printing method, there is a problem in that the metal may be directly exposed to air and thus oxidized.

Accordingly, development of a transparent electrode suitable for preventing oxidation, as well as visibility, transparency, and optical properties, is required.

KR 10-1843364 B1

An object of the present invention is an electrode for a transparent heater comprising an Ag metal layer and an Al ₂ O ₃ layer on the upper surface of the Ag metal layer, and has an Ag/Al ₂ O ₃ multilayer thin film structure having excellent heat generation performance, high transmittance, and antioxidant effect. It is to provide an electrode for a transparent heater.

In order to achieve the above object, the electrode for a transparent heater having an Ag/Al ₂ O ₃ multilayer thin film structure according to an embodiment of the present invention includes an Ag metal layer; And an Al ₂ O ₃ layer on the upper surface of the Ag metal layer.

The thickness of the Ag metal layer is 9 nm, and the thickness of the Al ₂ O ₃ layer is 120 nm.

The transparent heater electrode has a light transmittance of 71% or more in a visible light wavelength band.

The Al ₂ O ₃ layer on the upper surface of the Ag metal layer is formed by magnetron sputtering.

An automobile window defroster according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

An aircraft display according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

An LCD panel according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

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

An electrode for a transparent heater having an Ag/Al ₂ O ₃ multilayer thin film structure according to an embodiment of the present invention includes an Ag metal layer; And an Al ₂ O ₃ layer on the upper surface of the Ag metal layer.

Ag is an element symbol of silver, which is a transition metal belonging to period 5 of group 11 of the periodic table. It has an atomic weight of 108 g/mol, a melting point of 961.78° C., a boiling point of 2162° C., and a density of 10.49 g/cm 3. I never do that. In particular, the degree of absorption of light is low, and since it reflects light well, an achromatic color appears.

In addition, Ag has excellent electrical conductivity and high visible light transmittance, so it is used as a double Ag layer structure by repeating the single Ag layer structure. The double Ag layer structure has a lower transmittance than the single Ag layer structure as the thickness of the layer increases, but the sheet resistance is doubled, and the reflectance in the near-infrared region is high, so it is used as a selective solar control glass and due to its good electrical conductivity. It is also used as heating glass and glass antenna for automobile defrost, transparent electrode for display, and electromagnetic wave shielding glass (EMI).

However, Ag has a disadvantage in that its reflectivity may decrease due to discoloration by reacting with oxygen in the air or scratching due to external impact.

Accordingly, the present invention includes an Al ₂ O ₃ layer on the upper surface of the Ag metal layer, and an oxide thin film capable of protecting the Ag layer while being dense and transparent on the Ag layer is laminated in a sandwich type.

The intermediate layer/oxide structure is a thin film that improves conductivity and transmittance by supplementing the disadvantages of an oxide thin film and an intermediate layer (metal) thin film, and an oxide thin film is mainly used as an anti-reflection layer. The reason is that the oxide thin film optically has low light absorption, suppresses surface reflection, and has a high refractive index (n>2), and a metal is used as the IRFreflection layer. Ag of Ag/Al ₂ O ₃ structure is characterized by having a high reflectivity and a low refractive index in the infrared region.

The thickness of the Ag metal layer is 9 nm, and the thickness of the Al ₂ O ₃ layer is 120 nm.

If the thickness of the Ag metal layer is too thin, the size effect and continuous thin film cannot be formed. Therefore, heat is not generated. If the thickness is too thick, the current flows too far, damaging the thin film and preventing heat generation. Therefore, it is important to set the thickness of the Ag metal layer in order to simultaneously meet the heat generation performance and high transmittance required for the transparent heater electrode.

Preferably, the thickness of the Ag metal layer is 9 nm.

When the thickness of the Ag metal layer is 9 nm, excellent heating performance and high transmittance can be simultaneously satisfied.

The electrode for a transparent heater having a multilayer Ag/Al ₂ O ₃ thin film structure of the present invention is obtained by stacking an Al ₂ O ₃ layer with a thickness of 9 nm and an Al ₂ O ₃ layer of 120 nm with a thickness of the Ag metal layer.

Preferably, an Al ₂ O ₃ layer 30 to 150 nm may be stacked on the Ag metal layer 9 nm.

When the Al ₂ O ₃ layer 30 to 150 nm is stacked on the Ag metal layer 9 nm, the heat generation performance and the transmittance can be simultaneously increased.In particular, the optimum characteristics are obtained when the thickness of the Al ₂ O ₃ layer is 120 nm from the results of the following example. It was confirmed that it can be achieved.

In addition, when stacked to the above thickness, an excellent antioxidant effect can be achieved, and a transparent heater electrode having excellent transparency can be provided.

The transparent heater electrode has a light transmittance of 71% or more in a visible light wavelength band.

The wavelength of visible light that we can see is about 380~780nm, violet 380~440nm, blue 440~510nm, green 510~565nm, yellow 565~590nm, orange The physical range can be classified into 590~620nm, red 620~780nm, and such light absorbs, reflects, transmits, and reflects light energy when hitting an object. ) It determines the quality of transparency perceived by the eyes.

Transmittance refers to the relative amount of light that passes through an object. Light (light source) is reflected or transmitted by the transparency of the substrate it collides with. In the case of reflection, the amount of reflected light depends on the characteristics of the substrate and the angle of incidence. In this case, the refraction of the substrate affects the transmittance.

Therefore, the electrode for a transparent heater having a multilayer Ag/Al ₂ O ₃ thin film structure of the present invention has a high light transmittance of 71% or more, and has a relatively high transparency with a visible light absorption rate.

The Al ₂ O ₃ layer on the upper surface of the Ag metal layer is formed by magnetron sputtering.

The sputtering was first discovered by Grove in 1852, and is now widely used in the formation of various thin films. Sputtering is a phenomenon in which particles with high energy (>30eV) collide with a target contributing to thin film formation and transfer energy to target atoms, thereby releasing target atoms to form a thin film. Sputtering occurs through three processes: acceleration of ions, collision of ions into target, and emission of target atoms. The incident ions must have a fairly large energy (20~30eV) to emit target atoms. This means that there is a threshold energy for sputtering to occur. All of the incident ions become neutral atoms on the target surface, and are scattered as neutral particles and gradually lose their energy as they transform the atomic layer on the target surface. At the same time, it is scattered by the target atoms. Some of the incident particles are also emitted from the target. Some of the target atoms that have been displaced by the incident particles diffuse to the target surface or are sputtered when their energy is very large enough to overcome the binding energy. At this time, the target atoms also exchange momentum. Meanwhile, ions with very high energy are neutralized on the target surface and implanted into the target. Atoms sputtered away from the target leave the target in an activated or ionized state, so reactive sputtering is possible. The ions (neutral atoms) that were initially implanted into the target are worn out as the target is sputtered, so they are eventually sputtered and released from the target.

Such sputtering can be largely divided into a DC sputtering method, an RF sputtering method, and a magnetron sputtering method.

The DC sputtering method is simple to use, but has several drawbacks. DC sputtering is also referred to as diode sputtering or cathode sputtering, and the deposition rate depends on the pressure and current density of the gas. DC sputtering has the advantage of simple equipment installation and operation, but low deposition rate, high substrate temperature (a large amount of heat is emitted from the target to heat the substrate), damage to the substrate by the incidence of electrons, inefficiency of energy, There is a disadvantage that the purity of the thin film is degraded due to the high working pressure. When discharging, the pressure of the gas is high and the diffusion of sputtering atoms from the target by the gas is large, so the substrate must be brought close to the target. In addition, heat radiation and secondary electron radiation occur in the target due to the temperature increase of the anode and the substrate. In addition, there is a major drawback that the discharge is unstable, monitoring is always required, and sputtering of the insulator does not occur due to charging by positive ions.

In contrast, the RF sputtering method was developed to reduce the pressure of the discharge gas to cause stable discharge, and to deposit a thin film of an insulator. In other words, in the discharged state, the mobility of electrons is large and can be moved relatively easily, and it can reach the target, the substrate or other grounding parts. However, one of the crystals of such sputtering is an obstacle in terms of industrial use due to the slow formation rate of a thin film. The reasons why the thin film formation rate cannot be accelerated in the sputtering method using discharge is that it is difficult to increase the generation efficiency of ions and the rate at which the atoms sputtered from the target are scattered by atoms in the discharge gas to reach the substrate decreases. have.

The magnetron sputtering method was devised to overcome this point, which can lower the pressure of the discharge gas, reduce the scattering of thin film atoms, and cause the high-energy electrons that cause ionization to rotate in the vicinity of the target. At the same time, electrons can be confined near the surface of the substrate to increase the efficiency of generating ions.

Therefore, the electrode for a transparent heater of the present invention can be deposited evenly and in a short time with a more uniform thickness by depositing an Al ₂ O ₃ layer on the upper surface of the Ag metal layer by a magnetron sputtering method, thereby providing excellent surface properties and bonding properties. have. This can give remarkable heat and heat insulation properties.

An automobile window defroster according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

Transparent heaters are used in various ways, such as defrosting automobile glass and headlamps, insulation and heating of buildings, medical use, and military use. In particular, automobile window defrosters are used as window defrosting devices.

Car window defroster installs a defroster on the side of the crash pad so that the wind from the heater or air conditioner comes out, removes moisture from the window, clears the side view in rainy weather, and secures the view of the rear view mirror. It is a device that enables safe operation. In some passenger cars, the air passage is installed on the bottom of the door glass and above the rearview mirror by connecting the air passage itself into the door.

Therefore, a transparent heater having a thin thin film structure is required, and the electrode for a transparent heater having a Ag/Al ₂ O ₃ multilayer thin film structure of the present invention can be applied to the automobile window defroster because it has excellent transparency with high transmittance. .

In addition, the vehicle window defroster of the present invention is a transparent heater manufactured according to an electrode for a transparent heater having an Ag/Al ₂ O ₃ multilayer thin film structure according to an embodiment of the present invention, and is not limited to the above example. , Heating windows, windows of buildings, etc.

An aircraft display according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

The aircraft display manufactured using the electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure is a transparent display, and the display area where the display appears is literally transparent and has a shape in which objects behind it can be seen. Not limited.

In particular, since it was developed in response to the need to secure a field of view to the pilot as well as to transmit information at the same time, an electrode for a transparent heater having a multi-layered Ag/Al ₂ O ₃ thin film structure of the present invention is used in the aircraft display. , It can be provided as an aircraft display having excellent heat generation performance, high transmittance and antioxidant effect.

The display may further include a water-repellent coating layer. In the case of an aircraft display, when considering a part where visibility by water such as rain is very important, a water-repellent coating layer is additionally included to further prevent the formation of water droplets due to external water, and the excellent heat generation performance of the present invention This can prevent sexual love from occurring.

The water-repellent coating layer may be additionally formed in a place where a water-repellent layer is required, such as an automobile window defroster, a heating window, and a glass window of a building, in addition to an aircraft display.

More specifically, the water-repellent coating layer may include tetraethyl orthosilicate (TEOS), a catalyst, ethanol, and a fluorine silane-based organic compound.

The catalyst may be ammonium fluoride (NH ₄ F), but it is not limited to the above example, and any catalyst that can be easily selected by a person skilled in the art may be used without limitation.

More preferably, the water-repellent coating layer may include 30 to 60 parts by weight of tetraethyl orthosilicate, 0.1 to 1 part by weight of a catalyst, and 3 to 5 parts by weight of a fluorine silane-based organic compound, based on 100 parts by weight of ethanol. When included in the above weight ratio, it is possible to obtain a coating composition having high transparency and super water repellency by facilitating bonding within the substrate with the coating composition of the present invention, and treating with a fluorine silane-based organic compound.

The fluorine silane-based organic compound may be a compound represented by the following Formula 1:

[Formula 1]

The coating composition is a mixture of tetraethyl orthosilicate (TEOS), a catalyst, ethanol, and a fluorine silane-based organic compound, and coating on one side of a multilayer Ag/Al ₂ O ₃ thin film to form a silica nanostructure, and fluorine silane It is possible to form a water-repellent coating layer having super water repellency and high transparency by bonding with the organic compound.

An LCD panel according to another embodiment of the present invention is manufactured by using an electrode for a transparent heater having the Ag/Al ₂ O ₃ multilayer thin film structure.

According to the transparent heater electrode having the Ag/Al ₂ O ₃ multilayer thin film structure of the present invention, it is a transparent heater electrode including an Ag metal layer and an Al ₂ O ₃ layer on the upper surface of the Ag metal layer, and has excellent heat generation performance, high transmittance, and oxidation. It is possible to provide an electrode for a transparent heater having an Ag/Al ₂ O ₃ multilayer thin film structure having a preventive effect.

1 shows a heating test of an Ag metal layer according to an embodiment of the present invention.
2 is a graph showing a temperature change according to a voltage for each thickness of an Ag metal layer according to an embodiment of the present invention.
3 is a graph showing the transmittance of an electrode for a transparent heater manufactured according to the thickness of an Al ₂ O ₃ thin film according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[Production Example 1: Preparation of transparent heater electrode]

1. Preparation of Ag metal layer

The flexible substrate made of PET was washed, and the Ag metal layer was prepared in different thicknesses of 9 nm, 10 nm, and 14 nm using a magnetron sputtering method on the substrate at room temperature.

The RF output applied to the Ag target was 50 W, the working vacuum degree was 10 mTorr, and Ar gas of 10 sccm was used as the sputtering gas.

2. Exothermic test of Ag metal layer

The thickness of the prepared Ag metal layer 9nm, 10nm, and 14nm is shown in FIG. 2 by measuring the maximum heating temperature for each voltage through the heating test shown in FIG. 1.

As a result, only the 9nm-thick Ag metal layer produced an exothermic reaction at a voltage of 5V, and the 14nm-thick Ag metal layer did not exhibit an exothermic reaction at the end of the 2V voltage. It was confirmed that the thickness of the thin film was too thick and the current flowed too much, and it was confirmed that heat was not generated by damaging the thin film.

Therefore, it was confirmed that the Ag metal layer having a thickness of 9 nm has excellent heat generation performance.

3. Manufacture of electrode for transparent heater

The same magnetron sputtering method as for the preparation of the Ag metal layer was used, and by using an Al ₂ O ₃ target on the Ag thin film 9 nm having excellent heat generation performance, RF output of 50 W, deposition pressure of 10 mTorr, and Ar gas flow rate of 10 sccm. Under the conditions, Al ₂ O ₃ layers were differently stacked to have a thickness of 30, 84.75, 91.8, 120, and 150 nm to prepare a transparent heater electrode.

4. Formation of water repellent coating layer

(1) Preparation of coating composition

A coating composition was prepared by mixing ethanol, tetraethyl orthosilicate, ammonium fluoride (NH ₄ F) and a fluorine silane-based organic compound represented by the following Formula 1:

[Formula 1]

The water-insoluble silane-based organic compound of the coating composition was purchased and used from JESSICACHEM.

The content of the coating composition is shown in Table 1 below.

AG1 AG2 AG3 AG4 AG5 ethanol 100 100 100 100 100 TEOS 15 30 45 60 75 catalyst 0.05 0.1 0.5 One 1.5 Fluorine silane-based organic compounds 2 3 4 5 6

(Unit weight part)

(2) Formation of water repellent coating layer

The water-repellent coating composition of AG1 to AG5 was uniformly applied to an electrode for a transparent heater in which an Al ₂ O ₃ layer 120 nm was stacked on an Ag metal layer 9 nm and reacted at 25° C. for 24 hours. Then, it was further dried at 80° C. for 1 hour.

[Experimental Example 1: Measurement of the transmittance of the electrode for a transparent heater according to the present invention]

In order to compare the transmittance of the transparent heater electrode manufactured according to the thickness of the Al ₂ O ₃ thin film, the light transmittance in the wavelength range of 200 to 900 nm was measured using a spectrophotometer (Hitachi Manufacturing, U-4100 type).

The results are shown in FIG. 3 below, and when the thickness of the Al ₂ O ₃ thin film is 120 nm, it was confirmed that the highest transmittance was 94% in the 330 nm wavelength region. After that, as a result of measuring the average transmittance in the visible light wavelength band of 380 nm to 780 nm, it was confirmed that it had a light transmittance of 71%.

[Experimental Example 2: UV stability of the electrode for a transparent heater according to the present invention]

To test for UV stability, measure the sheet resistance value after 240 hours at a temperature of 50℃ and an amount of light of 0.5W/m ² using Q-LAB CORPORATION, QUV/[0048] SE, and the amount of change (△). I did.

Ag(9) Al ₂ O ₃ (30) Ag(9) Al ₂ O ₃ (84.75) Ag(9) Al ₂ O ₃ (91.8) Ag(9) Al ₂ O ₃ (120) Ag(9) Al ₂ O ₃ (150) UV stability T=0(Ω/sq) 84.5 84.5 85.6 85.3 86.5 T=240hrs(Ω/sq) 501.4 501.4 495.7 108.5 111.1 Change △(%) 493.4 493.4 479.1 27.2 28.4

As shown in Table 2, when the Al ₂ O ₃ layer 120 nm is stacked on the 9 nm Ag metal layer, it can be confirmed that the amount of change (△) of the sheet resistance is small, so it is also effective in environmental resistance, which can be used as the role of UV protection and antioxidant protective film. You can see that you can.

[Experimental Example 3: Measurement of the contact angle of the electrode for a transparent heater according to the present invention]

AG1 AG2 AG3 AG4 AG5 Contact angle 105 145 147 146 107

(Unit diagram) The results of measuring the contact angle according to the formation of the coating layer according to AG1 to 5 are shown in Table 3 above.

According to Table 3, in the case of AG2 to AG4, it can be seen that a super water-repellent coating layer of 145 degrees or more is formed.

In the case of preparing a coating composition by mixing within the scope of the present invention, it is possible to implement a super water-repellent coating layer, but if it is less than or exceeding the range, the combination between the constituents is non-uniform, and it is confirmed that the super water-repellent coating layer cannot be formed I did.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention defined in the following claims are also present. It belongs to the scope of rights of

Claims (7)

Ag metal layer;
Including an Al ₂ O ₃ layer on the upper surface of the Ag metal layer,
It includes a water-repellent coating layer on the upper surface of the Al ₂ O ₃ layer,
The water-repellent coating layer is formed by applying a water-repellent coating composition
The water-repellent coating composition includes tetraethyl orthosilicate (TEOS), a catalyst, ethanol, and a fluorine silane-based organic compound represented by the following Formula 1,
The water-repellent coating composition comprises 30 to 60 parts by weight of tetraethyl orthosilicate, 0.1 to 1 parts by weight of catalyst, and 3 to 5 parts by weight of a fluorine silane-based organic compound represented by the following formula (1), based on 100 parts by weight of ethanol.
Transparent heater electrode:
[Formula 1]

delete delete delete Comprising the transparent heater electrode according to claim 1
Car window defroster. Comprising the transparent heater electrode according to claim 1
Aircraft display. Comprising the transparent heater electrode according to claim 1
LCD panel.

Images