WO2014175578A1

WO2014175578A1 - Method for fabricating light extraction substrate

Info

Publication number: WO2014175578A1
Application number: PCT/KR2014/002948
Authority: WO
Inventors: 강동호; 황용운; 김태진
Original assignee: 엔라이팅 주식회사
Priority date: 2013-04-22
Filing date: 2014-04-07
Publication date: 2014-10-30
Also published as: TW201500310A

Abstract

The present invention provides a method for mass-producing light extraction transparent substrates, wherein a highly efficient light extraction substrate is fabricated by producing a mixed solution, in which SiO₂ powder or transparent nanosized powder of another material having a similar or higher melting point to or than the SiO₂ powder is mixed into a polar solvent, on a transparent substrate, forming a two-dimensional structure on the substrate in a mixed particle size by spraying the mixed solution onto the transparent substrate using an electric spray gun, and spraying a liquid for forming a planarization layer by using a spray gun so as to cover a nanostructure to form the planarization layer. The fabrication of a light extraction substrate, according to the present invention, is suitable for mass-production since equipment costs are relatively low while light extraction efficiency is high.

Description

Manufacturing Method of Light Extraction Substrate

The present invention relates to a transparent substrate for use in a light emitting device module, and more particularly, to a method for manufacturing a transparent substrate in which a nanostructure is formed in order to extract light generated by the light emitting device contained therein out of the transparent substrate. will be.

A light emitting device such as an OLED is a self emitting device that emits light when a voltage is applied, and has been spotlighted as a display pixel formation or white OLED lighting. OLED structure is composed of cathode / electron transport layer / active layer / hole hole layer / anode / transparent substrate, and the light generated from the active layer, which is a light emitting layer, has a very low ratio of penetrating a glass transparent substrate having a refractive index of about 1.5% by about 20%. Therefore, the remaining 80% of the light is not extracted outside the transparent substrate and stays inside the device, and ultimately, the device is converted into thermal air inside the device, which damages the device and shortens the device life. The low light extraction efficiency is also a problem of lowering the brightness as illumination or a pixel, but as such causes a deterioration of the device, various attempts have been made to increase the light extraction efficiency.

Korean Patent No. 10-1177064 attempts to attach metal nanoparticles to a glass substrate in order to increase light extraction efficiency of an OLED device, and in addition to forming or attaching microlens to a glass substrate, a nanostructure It may also form (see FIG. 1).

Attaching the microlens array (MLA) sheet to the outside of the glass substrate is one of the methods of increasing the light extraction efficiency separately from the internal nanostructure. Therefore, using both methods at the same time can yield greater efficiency.

In general, in the absence of a nanostructure, only about 20% of the light emission comes out of the glass substrate, but when the nanostructure is formed, the effect is 40% of the light emission out, and thus the brightness of the device can be doubled.

In US 2012/0305966 A1, in the case of forming a nanostructure inside a glass substrate, a quartz (SiO ₂ ) layer is formed on the glass substrate, and silver (Ag) is uniformly deposited thereon, and then the glass substrate is heated. ) And then annealed at about 400 ° C, the silver particles are randomly agglomerated. The agglomerate particle size and spacing can be controlled to some extent depending on the thickness of the Ag deposition layer or the annealing method. Ag-ag particles here act as masks. After etching the quartz layer between the Ag particles by dry etching using the Ag particles as a mask, Ag is removed by wet etching to become a light extraction substrate having a nanostructure.

Although the nanostructure formation method as described above improves the light extraction efficiency, it is not practically acceptable as a productive method suitable for a large area substrate size.

That is, the fabrication of the light extraction substrate as described above requires a large heating furnace according to the Ag coating system as well as the large area of the substrate and the uniform annealing on the entire surface. Makes it difficult. Large furnaces are expensive to install and maintain, uniform heating to large-area substrates is difficult, and silver (Ag) nanoparticles are very expensive, causing the need for regeneration.

On the other hand, after forming a flat layer for flattening the surface of the transparent substrate surface having a nano-concave-convex structure, the OLED emitting layer is placed on the flat surface. The flatness of the flat surface should not generate more than 2nm unevenness in 1μm ㅧ 1μm area. However, a gentle hill surface does not matter.

Conventionally, planarization of a transparent substrate having a nanostructure is performed by a slit coating system or a spin coating system. The former is a costly process, while the latter is suitable for small and medium-sized substrates such as wafers, but not for large area substrates larger than 5.5 generations, because of the large variation in thickness between the center and the outside depending on the radius of the coater.

Therefore, the conventional methods all lack the mass production method of planarizing a substrate that can be applied to a large area substrate, and require an improved method.

Accordingly, an object of the present invention is to improve the light extraction efficiency of the light extraction transparent substrate, to provide a method for producing a light extraction transparent substrate with a productivity to the mass production possible.

According to the above purpose

According to the present invention, a transparent thin film layer is formed on a transparent substrate such as glass or plastic, and at least one of the nano-sized metal powder, ceramic powder or polymer powder is mixed with a polar solvent to prepare a mixed liquid, and the mixed liquid is formed on the transparent substrate. To form a nanopattern layer by spraying with an electric sprayer, and then drying and patterning the transparent thin film layer by dry etching, and then removing the nanopattern layer sprayed by wet etching. Provided is a method for manufacturing a nanostructure substrate, characterized in that the nanostructure formed light extraction substrate is produced.

In addition, the present invention is to prepare a mixture of a mixture of SiO ₂ nano-size powder of a desired size on a transparent substrate such as a glass substrate in a polar solvent and an adhesive liquid, and sprayed the mixture with an electric sprayer, SiO ₂ powder on a transparent substrate Is attached to the substrate to be two-dimensionally arranged on the substrate in a nano-size thickness, and then annealed the sprayed SiO ₂ attached substrate to remove the adhesive material on the SiO ₂ to complete the nanostructure substrate It provides a nanostructure substrate manufacturing method.

In addition, the present invention, under a constant temperature and humidity environment, by spraying a liquid with a nebulizer on the transparent substrate on which the nanostructures are formed to cover the nanostructures to form a flat layer.

In the flat layer formation process, ultraviolet rays are irradiated onto the substrate before spraying to improve the flatness, and an ultrasonic wave generator is installed on the substrate stage to uniformly distribute the sprayed liquid with respect to the large-area substrate to emit ultrasonic waves. Gave a vibration.

In the above process, a plurality of nebulizers may be installed according to the substrate area, and the flat layer may be formed while transferring the substrate in an inline manner.

According to the nanostructure forming method of the present invention, since the nanoparticles are mixed with the polar solvent using the electrospray method, the mixture is charged and the electrostatic repulsive force is applied to each other while being sprayed, The enclosed bundles of nanoparticles themselves also repel each other, forming a uniform nanostructure of very small size. Above all, according to the present invention, all the processes can be carried out in the air in place of the existing vacuum process, and the equipment cost is greatly reduced, and the nanostructure of the desired randomness is formed on the large-area substrate at random but uniformly. can do.

In addition, according to the present invention, there is no need for a separate SiO ₂ coating by PECVD, a nanostructure mask manufacturing process. Therefore, the equipment cost is greatly reduced, and it is possible to form a two-dimensional nanostructure on the large-area substrate on the whole, randomly or uniformly.

The method of forming the flat layer of the spray method of the present invention has the advantage of being independent of the area of the substrate, the process progressing speed is good, the mass production is good, and all of the sprayed liquid is used to form the flat layer is not wasted and low cost process This can be

In addition, in-line method enables a quick and convenient process design, and the uniformity of the flat layer is good due to the ultrasonic device and ultraviolet irradiation pretreatment.

According to the present invention, it is possible to exhibit the same light extraction efficiency while significantly lowering the production cost compared to the conventional process.

1 is a schematic cross-sectional view showing a state in which a nanostructure is formed on a transparent substrate in order to improve light extraction efficiency of the light extraction transparent substrate.

2 is a schematic diagram illustrating an apparatus for forming a nanopattern mask using an electrostatic spray according to a preferred embodiment of the present invention.

3 is a schematic diagram illustrating a process of forming a nanostructure using the nanopattern mask formed by FIG. 2.

4 is a schematic diagram illustrating an apparatus for forming nanostructures using electrostatic spray in accordance with a preferred embodiment of the present invention.

5 is a schematic view showing a cross-sectional configuration of a transparent substrate on which a nanostructure is formed after annealing the nanostructures fixed on the transparent substrate by electrostatic spraying.

6 is a cross-sectional view illustrating a state in which a flat layer is formed on a transparent substrate on which a nanostructure is formed.

Figure 7 is a schematic diagram showing the formation of a nanostructure and a flat layer by the spray method according to the present invention.

FIG. 8 is a schematic diagram illustrating a step of forming a flat layer by the spray method of FIG. 7 in a constant temperature and humidity condition. FIG.

9 is a schematic diagram illustrating the formation of nanostructures and flat layers using multiple spraying devices in accordance with the present invention.

FIG. 10 is a schematic diagram illustrating an in-line process of annealing in a heating furnace after pretreatment by ultraviolet irradiation and forming a flat layer by spraying according to the present invention.

100: substrate

25, 170: nanostructures

150: SiO ₂ layer

155: adhesive

160: polar solvent

180: mixed solution

200: substrate holder

300: nano pattern mask

400: chamber

500: UV irradiation device

700: nozzle

800: ultrasonic generator

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

Nanostructure Formation Example 1

The transparent substrate 100 of the present invention may be a glass substrate. SiO ₂ layer 150 is formed on the transparent substrate 100 to a nano-size thickness. The SiO ₂ layer can be formed by a method such as CVD or sputtering.

In the manufacture of the transparent substrate on which the nanostructure of the present invention is formed, a metal, ceramic, or polymer nanopowder is mixed with a polar solvent and sprayed onto the transparent substrate by an electrospray.

First, at least one of metal, ceramic or polymer powder is prepared as shown in FIG. 2 and mixed in a polar solvent.

_One or more of various metal powders such as Ag, Cu, Fe, WO ₃ , ZnO, Fe ₂ O ₃ , various ceramic powders such as SiO ₂ , TiO ₂ , CuO, ZrO ₂ , and polymer powder may be used as water, alcohol, acetone, or the like. Mix with polar solvent to form mixed solution. This mixed solution is present in solution or colloidal solution. The adhesive substance (PVP etc.) which can give a viscosity can also be mixed here. The concentration of the mixed solution is to be sprayed to the particle size is several to several tens nm as described later, in the present embodiment was prepared at a concentration of about 15% by weight, of course, can vary depending on the conditions of the structure.

The mixed liquid is placed in a hopper, and the large-area transparent substrate 100 is disposed while maintaining a proper distance (for example, 50 mm to 500 mm) from a nozzle mounted below the hopper. Multiple spray nozzles can be placed on large area substrates to increase production speed. As described above, the SiO ₂ layer 150 is formed on the transparent substrate 100 to have a nano size thickness. Since the transparent substrate 100 is an insulator, the transparent substrate 100 is placed on the conductor substrate holder 200.

A small nozzle having a diameter of about several mm is formed at a lower end of the hopper, and connects a positive electrode of the power supply device to the nozzle, and connects a negative electrode to the substrate holder 200. The voltage at both ends applies a high voltage of several kV to several tens of kV (which may be 1 to 50 kV).

When a high voltage is applied in this way, when the mixed liquid is injected from the nozzle of the hopper, positive charges are charged to the mixed liquid to exert a repulsive force with each other, thereby dispersing widely in the space as if the mixed liquid is strongly sprayed with the nebulizer. The powder particles contained in the mixed liquid are dispersed and spread widely in the space without being aggregated by the electrostatic repulsion even in the state surrounded by the polar solvent. Therefore, it is settled down on the large area substrate 100 with an overall uniform distribution and deposited on the SiO ₂ layer 150. In the above, the polarity of the power supply device may be reversely connected to (-) and (+), respectively, to the nozzle and the substrate holder. The polarity of the solution and spray will be negative accordingly.

The diameter size d of the agglomerate to be adhered according to the spraying conditions of the mixed liquid may be approximated by the following formula (document).

Where Q is the flow rate of the liquid, ρ is the density of the liquid, ε ₀ is the dielectric constant in vacuum, γ is the surface tension of the liquid, and K is the electrical conductivity of the liquid.

Hartman RPA, Brunner DJ, Camelot DMA, Marijnissen JCM, Scarlett B. J. Aerosol Sci. 31, p65 (2000)

Drying the transparent substrate 100 in this state is a result of forming a nano pattern mask on the SiO ₂ layer 150. As a drying means, various drying means, such as natural drying, hot air drying, and ultraviolet drying, can be used.

The nano substrate is formed by etching the SiO ₂ layer 150 by dry etching such as plasma etching on the transparent substrate 100 having the nano pattern mask formed thereon. Plasma etching is performed by mixing fluorine (F) with an inert gas such as argon (Ar) to cause plasma discharge. Details of the plasma etching implementation are already well known and follow.

Next, the nano pattern mask is removed by wet etching to obtain a light extraction glass substrate on which the SiO ₂ layer nanostructure 170 is formed. The wet etching solution may be various acid solutions or basic solutions such as nitric acid and hydrochloric acid. Wet etching may be applied by spray (spray), down flow or dip method.

The light extracting glass substrate having the SiO ₂ layer nanostructure formed therein extracts light generated therein and escapes out of the substrate, thereby improving luminance and device life. When the production of such a high efficiency light extracting transparent substrate is made by the above-mentioned electrostatic spraying, it is preferable to carry out in a clean room. In this case, it can be carried out in the air without requiring a special vacuum chamber, thereby reducing the equipment cost and the process cost.

Nanostructure Formation Example 2

First, as shown in FIG. 4, a SiO ₂ powder or a transparent powder of another transparent, similar or higher refractive index material is prepared and mixed in a polar solvent. As the polar solvent, water, alcohol, or the like can be used. Such a mixed solution is present in a solution or colloidal solution state, and is electrically charged with a positive charge. An adhesive 155 capable of imparting viscosity and adhesiveness is added to the mixed solution. The concentration of the mixed solution is prepared from 10 to 30% by weight, but can of course vary. In addition, the polarity of the charge may be negative.

The mixed solution is placed in a hopper, and the large-area transparent substrate 100 is disposed while maintaining a proper distance (for example, 50 mm to 500 mm) under the nozzle connected to the bottom of the hopper. In large areas, multiple spray nozzles can be arranged to increase production speed. Since the transparent substrate 100 is an insulator, the transparent substrate 100 is placed on the conductor substrate holder 200.

At the bottom of the hopper, a small nozzle having a diameter of about several millimeters or less is located, and connects a positive electrode of the power supply to the nozzle and a negative electrode of the substrate holder 200 (polarity You can also reverse the connection). The voltage at both ends applies a high voltage of several kV to several tens of kV (which may be 1 to 50 kV). The voltage can be set according to the structure to be formed.

When a high voltage is applied in this manner, when the mixed liquid is injected from the nozzle of the hopper, a positive charge ((-)) is charged to the mixed liquid to exert a repulsive force against each other. It is widely distributed in space as given. The powder particles contained in the mixed liquid are dispersed and spread widely in the space without being aggregated by the electrostatic repulsion even in the state surrounded by the polar solvent. Therefore, it is attached on the transparent substrate 100 while forming an overall irregular but uniform two-dimensional distribution on the large area substrate 100.

Since the nanostructured substrate is determined as it is by the powder particles in the spray liquid, the size of the powder particles may be selected as the desired size. Therefore, the powder particle diameter may generally be used in the range of about 100 nm to 1500 nm when making an OLED nanostructure.

When the transparent substrate 100 in this state is dried and annealed to a temperature at which the adhesive material can be removed, the SiO ₂ nanostructure substrate is completed (see FIG. 5). The annealing temperature may be determined in consideration of the sublimation point of the adhesive material, and may generally be about 300 ° C. or more.

The light extraction glass substrate on which the nanostructures 170, such as SiO ₂ , are formed, can escape a large amount of light generated inside the substrate to improve brightness and device life. When the light extraction transparent substrate is manufactured by the electrostatic spraying described above, it is preferable to carry out in a clean room, but it can be carried out in the air without requiring a special vacuum chamber, thereby reducing the equipment cost.

Flat Layer Formation Example

As shown in FIG. 7, in order to form a flat layer on the transparent substrate 100 having the nanostructured uneven surface, a liquid constituting the flat layer is placed in a sprayer, and the transparent substrate 100 is mounted on a stage under the sprayer. 6 shows a nebulizer and a stage and a transparent substrate 100 mounted thereon according to the present invention, and the nebulizer controls the distance between the nozzle 700 and the transparent substrate 100 and is relative to the transparent substrate 100. It is driven by an XZ motor that feeds in the XZ direction for movement. In addition, the stage itself may be driven by a motor for transferring the transparent substrate 100 in the Y direction. When the liquid is ejected from the nozzle 700, a very large number of fine droplets cover a considerable area of the transparent substrate 100, but the ultrasonic generator which imparts additional vibration to the stage so that the droplets spread uniformly over the front surface of the substrate ( 800 is installed. That is, the fine droplets settled down on the transparent substrate 100 on which the nanostructures are formed fill the recesses formed by the irregularities of the nanostructures by the micro-vibration of the ultrasonic generator 800, and serve to connect the droplets to the droplets. The layer makes the height flatter and more uniform.

As described above, as soon as the liquid is sprayed into the fine droplets, its surface area is significantly increased, leading to a sharp increase in volatility. Fine droplets reach over the nanostructures If volatilized before, a flat layer cannot be formed, so it is preferable to make the surrounding environment constant temperature and humidity. Humidity should be as high as possible to delay the volatility of the solution. However, high voltage requires a spraying condition having a usable voltage, humidity, and temperature while maintaining a state where discharge does not occur because high discharge can occur directly through air. Therefore, in this embodiment, both the substrate and the sprayer were placed in the constant temperature and humidity chamber 400, and the process was performed (see FIG. 9).

In addition, before spraying the liquid, the transparent substrate 100 is preferably subjected to ultraviolet irradiation pretreatment by the ultraviolet irradiation device 500 as shown in FIG. This modifies the surface of the transparent substrate 100 on which the nanostructure is formed to impart hydrophilicity to allow the liquid to settle well on the surface. Therefore, the flatness of the flat layer formed by liquid spraying after UV irradiation is made more uniform.

A nebulizer for spraying liquid may be arranged in large numbers (see FIG. 10) to improve productivity and may be carried out while transferring the substrate 100 in an inline manner.

After finishing the liquid spray to form the flat layer can be annealed for about 40 minutes at 400 ℃ in a heating furnace to firmly fix the flat layer to the transparent substrate 100.

The liquid that can be used in the present invention may be a high refractive solution such as TiO ₂ , ZnO, ZrO _2, or a mixture thereof.

The constant temperature and humidity environment is maintained at a constant value of any one of the actual temperature of 20 to 30 ℃, relative humidity of 30 to 60% and is preferably maintained with 99% accuracy.

In this manner, it is possible to form a flat layer having a high level of flatness and high speed at low cost.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

The present invention can be used to fabricate a cover glass or the like applied to an OLED display or an OLED lighting.

Claims

Forming a transparent thin film layer of any one of SiO 2 , TiO 2 , WO 3 , ZnO on the transparent substrate,

At least one of a metal powder, a ceramic powder, and a polymer powder is mixed with a polar solvent to prepare a mixed liquid,

Spraying the mixed solution on the transparent substrate with an electric atomizer to form a nano pattern layer,

Drying and dry etching the patterned transparent thin film layer,

Transparent by removing the nano pattern layer by wet etching Method for producing a transparent substrate for light extraction formed nanostructures.
2. The electrospray of claim 1, wherein the electrospray comprises a hopper with a nozzle, wherein the mixed liquid is placed in the hopper, and the transparent substrate is mounted on a ceramic substrate holder to mount a positive pole of a power source to the hopper. The negative electrode is connected to the substrate holder to apply a voltage to charge the mixed liquid injected from the nozzle of the hopper with positive charge, or the negative electrode to the nozzle mounted to the hopper, A method of manufacturing a transparent substrate for light extraction, comprising connecting a (+) electrode to a substrate holder to apply a voltage to charge the mixed liquid injected from the nozzle of the hopper with negative charge to disperse it with electrostatic repulsive force.
The method of manufacturing a transparent substrate for light extraction according to claim 1, wherein the size of the particles forming the nanopattern layer is controlled by the concentration of the mixed liquid.
The method of manufacturing a transparent substrate for light extraction according to claim 2, wherein the size of the particles forming the nanopattern layer and the distance between the particles are controlled by the concentration of the mixed liquid and the nozzle size of the hopper.
The method of manufacturing a transparent substrate for light extraction according to claim 1, further comprising a viscosity and adhesion imparting agent to the mixture.
The method of claim 1 or 2, wherein the dry etching comprises plasma etching, and the wet etching uses an acidic solution or a basic solution.
The method of claim 2, wherein the hopper comprises a plurality of nozzles.
SiO 2 , ZnO, ZrO 2 or on a transparent substrate A mixed liquid obtained by mixing a nano-sized powder of any one of WO 3 in a polar solvent was prepared, and the mixed liquid was sprayed with an electric sprayer to deposit SiO 2 , ZnO, ZrO 2 or Method for producing a transparent substrate for extracting light in which the nanostructure of any one of WO 3 formed.
For preparing a liquid mixture of a transparent nano-sized powder made of a material having the same refractive index or higher than the SiO 2 powder in a polar solvent on a transparent substrate, and spraying the mixture liquid with an electric atomizer to extract transparent nanostructures formed on the transparent substrate. Method of manufacturing a transparent substrate.
10. The apparatus according to claim 8 or 9, wherein the electric nebulizer comprises a hopper having a nozzle, the mixed liquid is placed in the hopper, and the transparent substrate is mounted on a substrate holder made of a conductor, A voltage is applied by connecting a pole to a nozzle mounted on the hopper and a negative electrode to a substrate holder to charge a mixed liquid injected from the nozzle of the hopper with a positive charge or to discharge a negative pole of a power source. Light extraction is characterized in that the positive electrode is connected to the substrate holder to apply a voltage to the nozzle mounted on the hopper, thereby charging the mixed liquid injected from the nozzle of the hopper with negative charge to disperse the electrostatic repulsive force. Method for producing a transparent substrate for use.
The method of manufacturing a transparent substrate for light extraction according to claim 8 or 9, further comprising an adhesive imparting agent to the mixed solution.
The method of manufacturing a transparent substrate for light extraction according to claim 10, wherein the hopper includes a plurality of nozzles.
A method of flattening the nano-concave-convex surface of a transparent substrate on which a nanostructure is formed, the transparent substrate and the atomizer having a nano-concave-side surface are placed in a constant temperature and humidity chamber, and the liquid to form the flat layer is sprayed onto the transparent substrate by spraying the liquid The liquid fills the nano-concave-convex surface to form a flat layer, the flat layer manufacturing method of the substrate for light extraction.
The light extracting substrate of claim 13, wherein the transparent substrate is mounted on a stage, and the ultrasonic generator is installed on the stage so that the liquid sprayed on the transparent substrate is uniformly spread over the entire surface of the transparent substrate. How to make a flat layer.
15. The method of claim 13 or 14, wherein before the liquid is injected onto the transparent substrate, ultraviolet rays are irradiated to the entire surface of the transparent substrate to form a hydrophilic transparent substrate surface.
15. The method of claim 13 or 14, wherein one or more of the atomizer is installed, the atomizer is capable of vertical motion (XZ) motion and the transparent substrate of the light extraction substrate, characterized in that the front and rear (Y) motion is possible. How to make a flat layer.
15. The method of claim 13 or 14, wherein the transparent substrate is annealed in a heating furnace after the liquid is injected.
A method for manufacturing a light extraction substrate, wherein the nanostructure is formed by any one of claims 1, 8, or 9, and a flat layer is formed by the method of claim 13.