KR20160061744A - Method for preparation of getter layer comprising magnesium oxide thin film - Google Patents

Abstract

The present invention relates to a method for manufacturing a getter layer. According to the present invention, the method for manufacturing a getter layer not only has excellent hygroscopicity and transparency, but also can manufacture a uniformly formed getter layer on a substrate. Therefore, the getter layer manufactured thereby can protect an element sensitive to moisture included in an organic electronic device. The method for manufacturing a getter layer comprises the following steps: manufacturing a coating solution including magnesium acetate and a bonding agent; coating the coating solution on a substrate; drying the substrate having the coating solution coated thereon; and treating the dried substrate with heat.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing a getter layer containing a magnesium oxide thin film,

The present invention relates to a method for producing a getter layer comprising a magnesium oxide thin film.

An organic electronic device (OED) refers to an apparatus that includes an organic material layer that generates holes and electrons to generate an alternating current. Examples thereof include a photovoltaic device, a rectifier, A transmitter and an organic light emitting diode (OLED).

Organic light emitting diodes (OLEDs) among the organic electronic devices have lower power consumption, faster response speed, and are advantageous for thinning display devices or illumination. In addition, OLEDs are expected to be applied in various fields covering various portable devices, monitors, notebooks, and televisions because of their excellent space utilization.

In order to improve the durability and lifetime of the organic electronic device, sealing of the organic electronic device is considered important in the manufacturing process because the light emitting device which is an important element in the organic electronic device has a disadvantage that it is oxidized when it comes into contact with moisture. In order to effectively block the contact between the light emitting element and moisture, moisture is blocked from two viewpoints. One is to block moisture with a physical seal, and the other is to remove a substance capable of absorbing moisture, Sealing together the inside of the device.

The physical sealing method is a method of connecting the front substrate and the rear substrate so that the light emitting device is not exposed to the outside with a highly adhesive sealing material. However, since moisture can be permeated by the external environment in which the organic electronic device is used, the moisture absorber together with the light emitting element can be sealed together to prevent the light emitting element from coming into contact with moisture. Thus, a composition containing a moisture absorbent is referred to as a getter composition.

Generally, an organic electronic device is manufactured by forming a light emitting device on a rear substrate and forming a getter layer on the front substrate with a getter composition to seal the front substrate and the rear substrate. The getter layer should not only have a high moisture absorption amount but also a material which does not easily discharge the absorbed moisture. In addition, the getter layer must be transmissive to transmit light emitted from the light emitting device.

Conventionally, a metal can or a glass is processed into a cap shape having grooves, and a moisture-absorbing agent for absorbing moisture is mounted on the grooves in powder form or made into a film form and adhered using a double-sided tape. However, the method of mounting the humidity control agent is complicated in the process, and the material and process cost are increased, the thickness of the entire substrate is increased, and the substrate used for sealing is not transparent, so that it can not be used for the whole light emission.

Korean Patent Laid-Open Publication No. 10-2007-0072400 discloses a method of chemically adsorbing moisture introduced into an organic light emitting element by including a moisture adsorbent in an epoxy sealant to further slow down the rate at which moisture permeates into the organic light emitting element have. However, when the moisture adsorbent reacts with moisture to expand the volume, it may cause physical damage to the organic light emitting device. In the case of using a metal oxide as a moisture adsorbent, it reacts with water to form a strong basic material, May cause chemical damage.

In addition, the conventional wetting or wetting agents can not be applied to a top-emission type organic electronic device, for example, an OLED device, which can maximize the luminous efficiency because it is difficult to realize a transparent getter layer because of its large particle size, There is a problem that the durability and lifespan of the organic electronic device deteriorate due to poor absorption ability.

Therefore, the present inventors have intensively studied a process for producing a getter layer which can not only have excellent hygroscopicity and transparency but also can be uniformly formed on a substrate. When a method of coating a substrate with magnesium acetate in a liquid phase is used It was confirmed that the getter layer satisfying the above can be manufactured, and thus the present invention has been completed.

The present invention relates to a method for producing a getter layer which not only has excellent hygroscopicity and transparency but also can be uniformly formed on a substrate.

The present invention also relates to an organic electronic device comprising a getter layer produced by the above production method.

In order to solve the above problems, the present invention provides a method for producing a getter layer including a magnesium oxide thin film including the following steps.

Preparing a coating solution comprising magnesium acetate and a binder (step 1);

Coating the coating solution on a substrate (step 2);

Drying the coated substrate (step 3); And

And heat treating the dried substrate (step 4).

The term " getter layer " used in the present invention means a layer containing a substance capable of absorbing moisture, and includes a layer that absorbs water permeated into a device including moisture sensitive devices such as organic electronic devices . Particularly, since the light emitting device of the organic electronic device requires a getter layer that is small in size and can transmit light generated from the light emitting device, a getter layer having permeability and uniform thickness as well as hygroscopicity is needed.

Accordingly, the getter layer manufacturing method according to the present invention can form a getter layer containing a magnesium oxide thin film on a substrate with a uniform thickness, and protect moisture sensitive elements of organic electronic devices due to hygroscopicity of magnesium oxide .

Hereinafter, the present invention will be described in detail.

(Step 1) of preparing a coating solution comprising magnesium acetate and a binder,

A step of preparing a coating solution for coating on a substrate is a step of preparing a coating solution comprising magnesium acetate, which is a precursor of magnesium oxide, and a binder for coating.

Magnesium acetate is an acetate of magnesium as a compound of the formula Mg (CH ₃ COO) ₂ . As will be described later, when magnesium acetate is decomposed by heating, it is converted to magnesium oxide (MgO). Therefore, the magnesium acetate is used as a precursor of magnesium oxide in the present invention. In addition, magnesium acetate may be present as a hydrate, and in the present invention, such hydrate is also included in the magnesium acetate.

In addition, the coating solution contains a binder in addition to magnesium acetate. The binder is used for imparting viscosity to the coating solution to improve the adhesion when coating the substrate, and to uniformly disperse the magnesium acetate in the coating solution. Examples of the binder include polyvinyl pyrrolidone, citric acid, cellulose, acrylate polymer, polyurethane or polyester.

The mass ratio of the magnesium acetate and the binder (magnesium acetate / binder) is preferably 1 to 5. If the mass ratio is less than 1, the content of the binder becomes too high, so that uniform coating is difficult. When the mass ratio is more than 5, the content of the binder is too low to sufficiently coat.

In addition, the solvent of the coating solution is not particularly limited as long as it is a solvent capable of dissolving magnesium acetate and a binder. For example, water, alkyl acetate, alkyl monoglycol ether and the like can be used.

The coating solution may further contain ethanol, methanol, isopropanol or the like to stabilize the wettability of the coating solution and the substrate so that the coating layer has a uniform thickness.

The coating solution On the substrate  The coating step (step 2)

Since the coating solution prepared in the step 1 has a viscosity suitable for coating on a substrate in a liquid phase, it can be coated on the substrate with a uniform thickness. In particular, since the uniform thickness of the getter layer influences the transparency of the getter layer, the efficiency of the manufacturing process of the organic electronic device, and the hygroscopicity of the getter layer, the present invention can realize this by using a liquid coating solution.

The coating method is not particularly limited, and can be coated by, for example, dip-coating, spin-coating, printing-coating and spray-coating methods.

Dip-coating is to deposit a coating solution on a substrate by immersing the substrate in a coating solution, spin-coating is to uniformly adhere the coating solution to the substrate by centrifugal force by supplying the coating solution onto a rotating substrate, Coating means supplying the coating solution onto the substrate through a screen, and spray-coating means supplying the coating solution onto the substrate with a spray device.

The substrate is not particularly limited as long as it is a substrate used in an organic electronic device. For example, a glass substrate or a transparent plastic substrate can be used. In the case of a plastic substrate, the inner surface of the plastic substrate may further include a protective film for protecting it from moisture.

Drying the substrate coated with the coating solution (step 3)

In step 2, the liquid material of the coating solution coated on the substrate is removed, and the solvent is removed before the heat treatment to be described below.

Since the coating solution is formed on the substrate to have a uniform thickness, the solid material remains in a uniform thickness even after the drying.

The drying temperature is preferably 100 to 200 ° C. When the temperature is lower than 100 ° C, the drying efficiency is lowered. When the temperature is higher than 200 ° C, the liquid material rapidly evaporates, which is unlikely to cause uneven surface.

It is preferable that the drying time is sufficiently dried for a time during which most of the liquid material is evaporated. For example, the drying time is preferably 30 minutes to 2 hours.

Heat treating the dried substrate (step 4)

The substrate dried in step 3 is heat-treated to form a magnesium oxide thin film.

Magnesium acetate is decomposed into magnesium oxide in the heat treatment process, thereby forming a magnesium oxide thin film having a uniform thickness on the substrate. Since the magnesium oxide is hygroscopic, the magnesium oxide thin film can absorb moisture as a getter layer, thereby protecting the moisture sensitive device of the organic electronic device. Further, since magnesium oxide has transparency, it is possible to transmit light generated from the light emitting element.

The heat treatment is preferably performed at a temperature of 300 to 500 ° C. When the temperature is less than 300 ° C, magnesium oxide formation is insignificant, and when the temperature exceeds 500 ° C, there is a problem that the substrate is deformed.

Preferably, the heat treatment is performed for a sufficient time during which the magnesium oxide thin film is formed. For example, the heat treatment is preferably performed for 30 minutes to 2 hours.

The magnesium oxide thin film formed as described above serves as a getter layer in the organic electronic device, and the thickness of the getter layer formed according to the present invention is preferably 0.1 to 1 탆.

An example of a method of using a getter layer containing the magnesium oxide thin film in an organic electronic device is schematically shown in Fig.

1, an organic electroluminescent portion 12 is formed on a rear substrate 10, a getter layer 13 is formed on a front substrate 11, and then an organic electroluminescent portion 12, The back substrate 10 and the front substrate 11 may be sealed with a sealing material 14 so that the getter layer 13 faces each other.

The organic electroluminescent unit 12 may be formed by deposition, and may be formed in the order of a first electrode, an organic layer, and a second electrode. Further, the organic film includes a hole injection layer, a hole transporting layer, a light emitting layer, an electron injection layer and / or an electron transporting layer.

As the front substrate 11, a glass substrate or a transparent plastic substrate can be used. When the front substrate 11 is formed of a plastic substrate, a protective film for protecting the inner surface of the plastic substrate from moisture can be additionally formed.

The inner space defined by the front substrate 11 and the rear substrate 10 may be maintained in a vacuum state or filled with an inert gas.

Further, the present invention provides an organic electronic device including the getter layer. Examples of the organic electronic device include a photovoltaic device, a rectifier, a transmitter, and an organic light emitting diode (OLED).

The getter layer manufacturing method according to the present invention can produce a getter layer which has not only excellent hygroscopicity and transparency but also can be uniformly formed on a substrate, It is possible to protect the moisture sensitive device contained therein.

Fig. 1 schematically shows the structure of an organic electronic device to which the getter layer of the present invention is applied.
2 shows XRD analysis results of a magnesium oxide thin film produced according to an embodiment of the present invention.
Fig. 3 is a graph showing the hygroscopicity of the magnesium oxide thin films prepared in Examples and Comparative Examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited thereto.

Example  One

3.14 g of magnesium acetate (Mg (CH ₃ COO) ₂ .4H ₂ O) was dissolved in 100 mL of distilled water and then 1 g of PVP (polyvinylpyrrolidone, molecular weight: 40,000) was added. 50 mL of ethanol was added to the solution, followed by stirring to prepare a coating solution.

A glass substrate was dip-coated on the coating solution, and the substrate was sufficiently dried at 150 ° C to remove distilled water and ethanol. The dried substrate was placed in an electric furnace and heat-treated at 400 DEG C for 1 hour to form a magnesium oxide thin film.

Example  2

The same procedure as in Example 1 was carried out except that a magnesium oxide thin film was formed using citric acid instead of PVP.

Comparative Example  One

Magnesium oxide (MgO) granules were deposited on a glass substrate by electron-beam evaporation to a thickness of 300 nm. At this time, the deposition pressure was 6 × 10 ^-5 Pa and the electron-beam output was 30 kV and 0.2 A, respectively.

The deposited substrate was placed in an electric furnace and heat-treated at 400 ° C for 1 hour to form a magnesium oxide thin film.

Comparative Example  2

A magnesium oxide target (MgO target, diameter 6 inches) was prepared and deposited with a thickness of 300 nm on a glass substrate by RF magnetron sputtering (pressure: 5 mTorr, power: 250 W, Ar: 10 sccm).

The deposited substrate was placed in an electric furnace and heat-treated at 400 ° C for 1 hour to form a magnesium oxide thin film.

Experimental Example  One

The magnesium oxide thin film prepared in Example 1 was subjected to XRD analysis. The results are shown in FIG.

As shown in FIG. 2, it showed a peak inherent to magnesium oxide, and it was confirmed that magnesium oxide was well formed therefrom.

Experimental Example  2

The hygroscopicity of the magnesium oxide thin films prepared in the above Examples and Comparative Examples was evaluated.

Specifically, calcium oxide (CaO) was vapor-deposited on the glass substrate to a thickness of 1 탆, and the glass substrate on which the magnesium oxide thin film prepared in Examples and Comparative Examples was formed was bonded to the glass substrate deposited with calcium oxide. The edges of the upper and lower glass substrates were closed with a sealing material and sealed.

The sample thus prepared was stored in a chamber at 85 ° C and a relative humidity of 85%, and a calcium oxide pad was changed into Ca (OH) ₂ by moisture permeated with time to change the color from the edge of the pad to a length Respectively. The measured results are shown in Fig.

As shown in FIG. 3, the penetration length of the Example was smaller than that of Comparative Example, and it was confirmed that the getter layer according to the present invention had significantly better hygroscopicity than the getter layer formed by the vapor deposition method.

Experimental Example  3

The surfaces of the magnesium oxide thin films prepared in Examples and Comparative Examples were analyzed by AFM to measure the surface roughness. The results are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Ra (nm) 340 250 20 34

As shown in Table 1, in the case of the comparative example manufactured by the vapor deposition method, the surface roughness was too low and the area capable of reacting with moisture was small, so that the moisture absorption effect was not sufficiently exhibited.

On the other hand, as the magnesium oxide thin film according to the present invention was prepared from a liquid coating solution, sufficient porosity appeared on the surface, and thus it was confirmed that the magnesium oxide thin film exhibited excellent hygroscopicity compared with the comparative example.

10: rear substrate
11: front substrate
12: organic electroluminescence unit
13: getter layer
14: Seal material

Claims (12)

Preparing a coating solution comprising magnesium acetate and a binder;
Coating the coating solution on a substrate;
Drying the substrate coated with the coating solution; And
And heat treating the dried substrate.
A method for producing a getter layer comprising a magnesium oxide thin film.
The method according to claim 1,
Characterized in that the binder is polyvinylpyrrolidone, citric acid, cellulose, acrylate polymers, polyurethanes or polyesters.
Gt;
The method according to claim 1,
Characterized in that the mass ratio of the magnesium acetate and the binder (magnesium acetate / binder) is from 1 to 5. < RTI ID = 0.0 >
Gt;
The method according to claim 1,
Wherein the solvent of the coating solution is water, an alkyl acetate, or an alkyl monoglycol ether.
Gt;
5. The method of claim 4,
Characterized in that the coating solution further comprises ethanol, methanol or isopropanol.
Gt;
The method according to claim 1,
Characterized in that the drying is carried out at a temperature of from 100 to < RTI ID = 0.0 > 200 C. <
Gt;
The method according to claim 1,
Characterized in that the heat treatment is carried out at a temperature of 300 to < RTI ID = 0.0 > 500 C. <
Gt;
8. The method of claim 7,
Characterized in that the heat treatment is carried out for 30 minutes to 2 hours.
Gt;
The method according to claim 1,
Wherein the getter layer has a thickness of 0.1 to 1 占 퐉.
Gt;
The method according to claim 1,
Characterized in that the substrate is a glass substrate or a plastic substrate.
Gt;
A getter layer produced by the method of any one of claims 1 to 10.
An organic electronic device comprising the getter layer of claim 11.

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