KR102236190B1 - Thin film encapsulation for organic photonic and electronic devices and method for fabricating the same - Google Patents

Abstract

In the present invention, a three-layered thin film in _{which SiN x} , SiO _x N _y , and SiO _x are sequentially stacked on both sides of a polymer substrate is _{repeatedly laminated twice, and SiO x} N _y formed at the interface between _{SiN x} and SiO _x It relates to a sealing film of an organic optoelectronic device having a very excellent water vapor transmission rate (WVTR, water vapor transmission rate) of ^{2x10 -6} g/m ² /day or less by enhancing the physical properties of, and a method for manufacturing the same, according to the present invention. The encapsulation film of the organic optoelectronic device may include a flexible substrate; And a three-layered thin film laminate formed on each side of the flexible substrate, wherein the three-layered thin film laminate is a SiN _x thin film, a SiO _{x Ny} thin film, and a SiO _x thin film sequentially stacked. The three-layered thin film laminate is repeatedly laminated on each side of the flexible substrate twice, and a SiO _x N _y thin film is _{formed between the SiO x thin film of the first thin film stack and the SiN x} thin film of the second thin film stack. It is further provided, characterized in that the water vapor transmission rate (WVTR, water vapor transmission rate) of the encapsulation film is 2x10 ^-6 g/m ² /day or less.

Description

Encapsulation film for organic optoelectronic devices and manufacturing method thereof {Thin film encapsulation for organic photonic and electronic devices and method for fabricating the same}

The present invention relates to a sealing film for an organic optoelectronic device and a method of manufacturing the same, and more particularly, a three-layered thin film in _{which SiN x} , SiO _x N _y , and SiO _{x are sequentially stacked on both sides of a polymer substrate is formed twice.} It has a very excellent water vapor transmission rate (WVTR, water vapor transmission rate) of ^{2x10 -6} g/m ² /day or less by repeatedly stacking and enhancing the physical properties of _{SiO x} N _y formed at the interface between _{SiN x} and SiO _x. It relates to an organic optoelectronic device encapsulation film and a method of manufacturing the same.

Organic optoelectronic devices such as organic light-emitting diodes (OLED), quantum dot light-emitting diodes (QLEDs), and organic solar cells are attracting attention as next-generation optoelectronic devices because they have flexibility and excellent flatness as they use organic materials.

On the other hand, organic substances have a weak characteristic of reacting sensitively to external factors such as moisture or oxygen. In particular, in the case of OLED, the light emitting material and the electrode material are oxidized by oxygen or moisture, causing problems such as black spots and shrinking of pixels in the display, resulting in a reduction in lifespan. Accordingly, an encapsulation technique is one of essential technologies to prevent the related constituent materials from being decomposed by oxygen or moisture.

In order to obtain the required durability against moisture, the encapsulation layer formed on the polymer substrate or the glass substrate of the organic optoelectronic device is extremely low of 10 ^-5 g/m ² /day to 10 ^-6 g/m ² /day. (ultra low) moisture permeability must be provided.

Metal cans and glass lids are widely used as encapsulation films for optoelectronic devices, and glass encapsulation films have excellent moisture permeation properties, but are not suitable for application to organic optoelectronic devices that require flexibility. not.

As an organic optoelectronic device encapsulation technology, Vitex System Corp. proposed the Barix method (US Patent No. US7767498). The Barix method is a technology that repeatedly stacks an inorganic film and an organic film to complete the encapsulation film. Specifically, after depositing an organic monomolecule, it is polymerized through ultraviolet curing to form an organic film, and then an _{inorganic film such as aluminum oxide (Al 2} O ₃ ) is formed on the organic film, and the stacking process of the organic film and the inorganic film Repeat 4 or more times to complete the encapsulation film. The Barix method has excellent moisture permeation resistance, but the process time and cost increase as the lamination process is repeated four or more times, and there is a limit to the selection of organic materials.

Recently, 3M has proposed a multi-layer vacuum thin film encapsulation technology, and GE has a multi-layered thin film structure hybrid encapsulation technology. 3M's multi-layer vacuum thin film encapsulation technology is the same organic/inorganic multi-layer thin film technology as the Barix method, and the difference is a technology that reduces process time and cost by using a multi-layer vacuum thin film process. GE's hybrid encapsulation technology of a multi-layered thin film structure is a technology that sequentially stacks a _{silicon oxynitride film (SiO x} N _y ) and a silicon oxy carbide film (SiO _x C _{y) using a single chemical vapor deposition device.} In the case of GE's encapsulation technology, the process time can be shortened by a single device process, but the moisture-resistance penetration characteristics are poor due to defects such as pin holes.

In addition to 3M and GE, many studies are being conducted on the encapsulation technology of organic optoelectronic devices, but the only technology that has been mass-produced among the encapsulation technologies of organic optoelectronic devices so far is Vitex System's Barix technology.

Meanwhile, the applicant of the present invention has proposed an encapsulation film of a single-layer silicon oxynitride (SiOxNy) film through Korean Patent No. 1610006. However, the encapsulation film disclosed in Korean Patent No. 1610006 of the present applicant exhibits a characteristic that does not correspond to an ultra low moisture permeability of ^{10 -5} g/m ² /day to 10 ^-6 g/m ^{2 /day.} .

US registered patent US7767498

The present invention was conceived to solve the above problems, and a three-layered thin film in _{which SiN x} , SiO _x N _y , and SiO _{x are sequentially stacked on both sides of a polymer substrate is repeatedly laminated twice, and SiN x} Encapsulation of an organic optoelectronic device having a very good water vapor transmission rate (WVTR) of less than ^{2x10 -6} g/m ² /day by enhancing the physical properties of _{SiO x} N _y formed at all interfaces of and SiO _x An object thereof is to provide a film and a method of manufacturing the same.

In addition, the present invention is a sealing film of an organic optoelectronic device that can realize a reduction in manufacturing cost by replacing organic materials and shortening the process time compared to the Barix method in which organic/inorganic films are repeatedly laminated and the encapsulation technology of 3M and GE. Its purpose is to provide a manufacturing method.

The sealing film of the organic optoelectronic device according to the present invention for achieving the above object comprises: a flexible substrate; And a three-layered thin film laminate formed on each side of the flexible substrate, wherein the three-layered thin film laminate is a SiN _x thin film, a SiO _{x Ny} thin film, and a SiO _x thin film sequentially stacked. The three-layered thin film laminate is repeatedly laminated on each side of the flexible substrate twice, and a SiO _x N _y thin film is _{formed between the SiO x thin film of the first thin film stack and the SiN x} thin film of the second thin film stack. It is further provided, characterized in that the water vapor transmission rate (WVTR, water vapor transmission rate) of the encapsulation film is 2x10 ^-6 g/m ² /day or less.

The flexible substrate is made of a polymer material.

The SiO _x N _y film is the thickness of the 3~8nm, SiO _x thin film has a thickness of 85~120nm.

The method for manufacturing an encapsulation film for an organic optoelectronic device according to the present invention comprises: a first step of preparing a flexible substrate; A second step of laminating a _{SiN x} thin film on both surfaces of the flexible substrate; A third step of dip coating a _{SiO 2} sol on the SiN _{x thin film;} A fourth step of heat-treating the flexible substrate to convert _{the SiO 2} sol into a SiO _x thin film and forming a _{SiO x} N _y thin film at the interface between the _{SiN x} thin film and the SiO _{x thin film;} The step of claim 5 is also laminated with a SiN _x thin film on the SiO _x film formed by the step 4, the SiO _x N _y thin film formed between the SiO _x film formed by the SiN _x film and the fourth step; A sixth step of dip coating a _{SiO 2 sol on the SiN x} thin film formed by the fifth step; And a seventh step of heat-treating the flexible substrate to convert _{the SiO 2} sol formed by the sixth step into a SiO _x thin film and forming a _{SiO x} N _y thin film at the interface between the _{SiN x} thin film and the SiO _{x thin film.} It is characterized in that the water vapor transmission rate (WVTR) of the produced encapsulation film is 2x10 ^-6 g/m ² /day or less.

In the third and sixth steps, _{the coating thickness of the SiO 2} sol is 85 to 120 nm. In addition, in the fourth step, the fifth step, and the seventh step, _{the thickness of the formed SiO x} N _y thin film is 3 to 8 nm.

In the fourth and seventh steps, the heat treatment temperature is 110 to 130°C, and the heat treatment time is 8 to 12 hours. In addition, in the third and sixth steps, the _{withdrawal speed during dip coating of the SiO 2} sol is 1 to 3 mm/s.

In the fourth step, the fifth step and the seventh step, is formed with a SiN _x film and the SiO _x thin film interface in SiN _x and SiO _x N _y film by solid phase diffusion SiO _x on the. In addition, in the second and fifth steps, a _{SiN x thin film is deposited on the SiO x} thin film by a PECVD process, and the process temperature is 110 to 130°C during the PECVD process.

The sealing film of an organic optoelectronic device and a method of manufacturing the same according to the present invention have the following effects.

It is possible to prepare an encapsulation film having a very excellent moisture permeability (WVTR) of 2x10 ^-6 g/m ^{2 /day or less.} In addition, since an expensive organic film _{can be replaced with SiO 2} sol, manufacturing cost can be reduced. In addition, as the encapsulation film is completed, the manufacturing process is completed by repeatedly laminating a three-layered thin film stack in which a SiN _x thin film, a SiO _x N _y thin film, and a SiO _{x thin film are sequentially stacked on the flexible substrate.} Can be simplified.

1 is a configuration diagram of an encapsulation film of an organic optoelectronic device according to an embodiment of the present invention.
2 is a flow chart illustrating a method of manufacturing an encapsulation film for an organic optoelectronic device according to an embodiment of the present invention.
3A to 3E are cross-sectional views illustrating a method of manufacturing an encapsulation film for an organic optoelectronic device according to an embodiment of the present invention.
Figure 4a is a SEM photograph of the encapsulation film prepared through Experimental Example 1.
Figure 4b is a TEM photograph of the encapsulation film prepared through Experimental Example 1.
Figure 5a is a SEM photograph of the encapsulation film prepared through Experimental Example 1.
Figure 5b is a TEM photograph of the encapsulation film prepared through Experimental Example 1.
6 is an atomic force microscope (AFM) photograph of each of the encapsulation films prepared through Experimental Example 1 and Experimental Example 2. FIG.
7A is a light transmission simulation result for the encapsulation film prepared through Experimental Example 1 and Experimental Example 2. FIG.
7B is an actual light transmission measurement result for the encapsulation film prepared through Experimental Example 1 and Experimental Example 2. FIG.
8A to 8D are SEM photographs of the encapsulation film according to Experimental Example 1 to which different dip coating withdrawal speeds were applied.
9 is a result of Aquatran2 moisture permeability of the encapsulation film according to Experimental Example 1 to which different dip coating withdrawal speeds were applied.
10 is a tritium method moisture permeability result of the encapsulation film according to Experimental Example 1 to which the drawing speed 1mm/s and 3mm/s were applied.
11 is a tritium method moisture permeability result of the encapsulation film according to Experimental Example 1 to which different heat treatment times were applied.
12 is a tritium method moisture permeability results of the encapsulation film according to Experimental Example 1 and Experimental Example 2.
13 is a half-life measurement result of the quantum dot light emitting diode to which the encapsulation film according to Experimental Example 1 and Experimental Example 2 was applied.

The present invention proposes a technology for an organic optoelectronic device encapsulation film.

In the present invention, the organic optoelectronic device refers to an optoelectronic device having flexibility, such as an organic light-emitting diode (OLED), a quantum dot light-emitting diode (QLED), and an organic solar cell, as mentioned above in'Technology behind the invention'.

The encapsulation thin film of the organic optoelectronic device according to the present invention serves to encapsulate the organic optoelectronic device to isolate all constituent materials, such as light absorbing layer, semiconductor layer, etc., formed on the substrate of the organic optoelectronic device from the external environment. In particular, it plays a role of preventing external moisture from penetrating into the organic optoelectronic device.

The encapsulation film according to the present invention is a form of encapsulating all of the constituent materials in a state in which an organic optoelectronic device having completed the constituent material deposition process such as a light absorbing layer and a semiconductor layer is prepared. Can be glued.

The encapsulation film according to the present invention is applied to an organic optoelectronic device having flexibility as described above, and accordingly, the encapsulation film according to the present invention must also have flexibility, and in order to have flexibility, the encapsulation film according to the present invention is a flexible substrate. Is the base substrate.

Previously, it was mentioned that the only technology that has been mass-produced as an encapsulation film of an organic optoelectronic device in'Technology behind the Invention' is Vitex System's Barix method, which completes the encapsulation film by repeatedly stacking an inorganic film and an organic film. . However, the Barix method increases the process time and cost as the lamination process is repeated four or more times, and there is a limitation in the selection of organic materials while using expensive organic materials.

The present invention proposes an encapsulation film in which a three-layered thin film _{in which SiN x} , SiO _x N _y , and SiO _x are sequentially stacked on both sides of a polymer substrate is repeatedly stacked twice. _{SiO 2} sol is coated on the SiN _x thin film _{, and the SiO 2} sol is converted into a _{SiO x thin film through heat treatment, and a SiO x} N _y thin film is formed at the interface between the _{SiN x} thin film and the SiO _{x thin film.} , By repeating this process twice, it is possible to manufacture the encapsulation film according to the present invention.

Some of the SiO ₂ sol is coated on a SiN _x thin film is filled in the pin hole (pin hole) of a SiN _x thin film blocks moisture penetration path, this role is corresponding to the organic film of Barix method. That is, by replacing the role of the organic film in the Barix method with SiO ₂ sol, it is possible to reduce the manufacturing cost. In addition, while the Barix method is repeatedly stacked four or more times in an organic film and an inorganic film, the encapsulation film according to the present invention is a _{three-layered thin film in which SiN x} , SiO _x N _y , and SiO _x are sequentially stacked twice. Due to its structure, it is possible to shorten the process time.

Meanwhile, the most important influence on the moisture permeation resistance of the encapsulation film according to the present invention is a _{SiO x} N _y thin film formed at the interface between the _{SiN x} thin film and the SiO _{x thin film.} SiO _x N _y film is formed of SiN _x and SiO _x solid phase diffusion (solid state diffusion) at the interface between the SiN _x film and the SiO _x thin film. SiO _x N _y As be a tissue structure of a thin film compact is improved the moisture permeation properties, SiO _x N _y thin film moisture permeation properties are the heat treatment when the heat treatment conditions for the coating thickness and SiO _x N _y thin film formed of SiO ₂ sol Is determined by Here, the coating thickness of the SiO ₂ sol may be adjusted via a take-off speed (withdrawal speed of dip coating) when dip coating of SiO ₂ sol control.

The invention SiN _x, SiO _x N _y, SiO _x is in as the thin film of the tri-layered structure sequentially stacked to form a two times a laminated sealant film, SiO ₂ sol dip coating thickness and SiO _x N _y during the coating of the We propose a technology that maximizes the moisture permeation resistance of the encapsulation film by optimizing the heat treatment conditions during heat treatment for thin film formation.

According to the present invention, the water vapor transmission rate (WVTR, water vapor transmission rate) of the encapsulation film in which a three-layered thin film in which _{SiN x} , SiO _x N _y , and SiO _x ^{are sequentially stacked twice is repeatedly stacked is 2x10 -6} g /m ² /day or less. When manufacturing an encapsulation film having such moisture permeability characteristics, the _{optimum coating thickness for dip coating of SiO 2} sol is 85 to 120 nm, and the _{optimum heat treatment condition for heat treatment for forming a SiO x} N _y thin film is 8 to at 110 to 130°C. It's 12 hours. 85~120nm thick coating of SiO ₂ sol may be achieved by controlling the take-off rate at the time of dip coating of SiO ₂ sol in 1~3mm / s.

Hereinafter, an encapsulation film of an organic optoelectronic device and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, an encapsulation film of an organic optoelectronic device according to an embodiment of the present invention includes a flexible substrate 10. The flexible substrate 10 is a flexible substrate and may be made of a polymer material such as polyethylene terephthalate (PET).

On both sides of the flexible substrate 10, a three-layered thin film laminate in which _{SiN x} , SiO _x N _y , and SiO _{x are sequentially stacked is repeatedly stacked twice.} Specifically, on one surface of the flexible substrate 10, a SiN _x thin film 21, a SiO _x N _y thin film 23, and a SiO _x thin film 22 are sequentially stacked, and such a SiN _x thin film 21, SiO _x N _y thin film 23 and the SiO _x thin film (22) 3-layer thin film multilayer body 20 of the structure composed of the form of two times the laminated form. Also on the other surface of the flexible substrate 10, the thin film stack 20 having the three-layer structure is repeatedly stacked twice, similarly to the one surface of the flexible substrate 10.

In the thin film stack 20 of a three-layer structure consisting of a _{SiN x} thin film 21, a SiO _x N _y thin film 23 and a SiO _{x thin film 22, the SiN x} thin film 21 is about 400 nm, SiO _x N _{The y} thin film 23 has a thickness of 3 to 8 nm, and the SiO _x thin film 22 has a thickness of 85 to 120 nm. SiN _x films 21 and the interface between SiO _x N _y thin film 23 formed on the SiO _x thin film 22 plays a decisive role in the moisture permeation properties of the sealing film provided with a dense tissue structures, SiO _x N _y films (23) is a heat treatment for forming an optimum coating thickness and SiO _x N _{y thin film 23 when dip coating of SiO 2} sol described in the method for manufacturing an organic optoelectronic device according to an embodiment of the present invention to be described later. Is determined by the optimum heat treatment conditions. In addition, the SiO _x thin film 22 _{is converted from SiO 2} sol by heat treatment, and the SiO _x N _y thin film 23 is formed by solid phase diffusion of _{SiN x} and SiO _{x during heat treatment.}

_{In addition, a SiO x Ny} thin film 23 is provided between the first thin film stack and the second thin film stack. Precisely, between the first thin-film laminate of the SiO _x thin film 22 and the second thin film SiN _x thin film 21 of the laminate is provided with a SiO _x N _y thin film 23 is formed. _{The SiO x} N _{y thin film 23 provided between the SiO x} thin film 22 of the first thin _{film stack and the SiN x} thin film 21 of the second thin film stack is SiN x N y thin film 23 of the second thin film stack when the SiN _x thin film 21 is deposited. _It is formed by solid phase diffusion of x and SiO _x.

Next, a method of manufacturing an organic optoelectronic device according to an embodiment of the present invention will be described.

2 and 3A, a flexible substrate 10 is prepared (S201). The flexible substrate 10 may be formed of a polymer substrate as a substrate having flexibility, and as an example, polyethylene terephthalate (PET) may be used as a polymer material constituting the polymer substrate.

With the flexible substrate 10 prepared, SiN _x thin films 21 are stacked on both surfaces of the flexible substrate 10 (S202) (see FIG. 3B). The SiN _x thin film 21 may be deposited using a plasma enhanced chemical vapor deposition (PECVD) method as an example. When the SiN _x thin film 21 is stacked _{using PECVD, SiH 4} , ammonia (NH ₃ ) and nitrogen (N ₂ ) are used as precursors, and the process temperature is 110 to 130°C and can be deposited to a thickness of 400 nm.

_{In a state in which SiN x} thin films 21 are stacked on both sides of the flexible substrate 10 _{, SiO 2} sol is dip coated _{on the SiN x} thin film 21 under a nitrogen atmosphere, It is coated with a thickness (S203) (see FIG. 3C). The coating thickness of the SiO ₂ sol can be achieved by adjusting the withdrawal speed of 1 to 3 mm/s during dip coating.

The coating thickness of the SiO ₂ sol (or take-off rate at the time of dip coating of SiO ₂ sol) will have a close affect on the moisture penetration characteristics of the sealant film to be finally completed. When _{the coating thickness of the SiO 2} sol is less than or greater than 85 to 120 nm, the moisture permeation resistance is deteriorated. As a result of confirming through the experiment of the present invention described later, when _{the coating thickness of the SiO 2} sol is 85 to 120 nm (withdrawal speed 1 to 3 mm/s), the water vapor transmission rate (WVTR) is 4.3 to 5.7x10 ^-4 While excellent at g/m ² /day, when _{the coating thickness of SiO 2} sol is about 40 nm (draw speed 0.5 mm/s), the moisture permeability (WVTR) is 2.0x10 ^-3 g/m ² /day, SiO ₂ When the coating thickness of the sol is about 225nm (withdrawal speed of 5mm/s), the moisture permeability (WVTR) is 1.8x10 ^-3 g/m ² /day, which is not good in moisture penetration resistance. This is because the coating thickness of the SiO ₂ sol is a crack (crack) occurred on the coated SiO ₂ sol is greater than 85~120nm pinholes and the SiO _x N _y resulting reaction decreases with balsaengdoem, the coating thickness of the SiO ₂ sol 85 If it is less than ∼120 nm, it is inferred that this is because the _{precursor for SiO x} N _y generation decreases and the SiO _x N _{y generation reaction is degraded.}

In a state in which the SiN _x thin film 21 and the SiO ₂ sol are sequentially stacked on both sides of the flexible substrate 10, heat treatment is performed. Through the heat-treated SiO ₂ sol is converted into a SiO _x thin film (22), SiN _x and SiO _x of the surface, the SiN _x and SiO _x of the solid phase diffusion (solid state diffusion) to the SiO _x N _y thin film 23 by the It is formed (S204) (see Fig. 3D). During the heat treatment, the heat treatment temperature is 110 to 130°C, and the heat treatment time is 8 to 12 hours. Even when the heat treatment temperature is lower than 110 to 130°C, the SiO _x N _y thin film 23 is formed, but the structure is not dense. If the heat treatment time is less than 8 to 12 hours, the SiO _x N _y thin film 23 has a similarly dense structure. ) Is not created.

Through the above process, a three-layered thin film stack 20 _{in which a SiN x} thin film 21, a SiO _x N _y thin film 23 and a SiO _x thin film 22 are sequentially stacked on both sides of the flexible substrate 10 is formed. It is completed. In the state where the three-layered thin film laminate 20 is completed, as shown in FIG. 3E, the process of forming the three-layered thin film laminate 20 is carried out once more to form a three-layered thin film laminate ( 20) completes the repeated stacked structure twice (S205).

The second thin-film stack while going through the body formation step, SiN _x thin film 21 during the deposition SiO _x N _y thin film between the first SiO _x thin film of the thin film multilayer body 22 and the SiN _x thin film 21 of the second thin film multilayer body (23) is formed. SiN _x thin film 21 is deposited through the PECVD process, as described above, at this time, when, SiN _x thin-film 21 deposited on the second thin film multilayer body according to the PECVD process proceeds under process temperature 110~130 ℃ SiN _x, and The SiO _x N _y thin film 23 is formed by solid phase diffusion of SiO _x.

Accordingly, finally, on both sides of the flexible substrate 10, the SiN _x thin film 21, the SiO _x N _y thin film 23, and the SiO _x thin film 22 are sequentially stacked in a three-layered thin film stack 20 ) is two times the layered structure is finished, between the first thin-film laminate of the SiO _x thin film 22 and the second thin film SiN _x thin film 21 of the laminated body and SiO _x N _y thin film 23 is additionally formed, The sealing film of the organic optoelectronic device according to the present invention includes three SiO _x N _y thin films 23 on the upper and lower surfaces of the flexible substrate 10, respectively.

In the final completed encapsulation film of an organic optoelectronic device according to an embodiment of the present invention, as three SiO _x N _y thin films 23 exist on each side of the flexible substrate 10, the moisture permeation resistance of the encapsulation film This doubles.

In the above, the sealing film of the organic optoelectronic device and a method of manufacturing the same according to an embodiment of the present invention have been described. Hereinafter, the present invention will be described in more detail through experimental examples.

<Experimental Example 1: Preparation of an encapsulation film having a single laminate structure>

With the PET substrate mounted in the PECVD chamber, SiH ₄ , NH ₃ , and N ₂ gases were injected into the chamber at 25, 100 and 380 sccm, respectively, and then 400W of RF power was applied and a process pressure of 430 mTorr was applied. _{By holding for 8 minutes, SiN x} having a thickness of about 400 nm was formed on both sides of the PET substrate. Then, _{SiO 2 sol was dip-coated on SiN x on} both sides of the PET substrate in an _{N 2} atmosphere, and heat-treated in an oven at 120° C. for 10 hours. When dip coating of a SiO ₂ sol, the take-off speed of 0.5mm / s, 1mm / s, by changing to 3mm / s, 5mm / s SiO 2 sol is about 40nm, from about 85nm, about 117nm, coated to a thickness of about 225nm It was made to be (see Figs. 8A to 8D).

<Experimental Example 2: Preparation of an encapsulation film having a double layered structure>

The process of Experimental Example 1 was carried out once more to complete the encapsulation film having a double laminate structure.

<Experimental Example 3: Structure of Encapsulation Film>

SEM and TEM measurements were performed to confirm the structure and thickness of the encapsulation films prepared through Experimental Example 1 and Experimental Example 2.

As a result of performing SEM and TEM measurements on the single layered encapsulation film coated with about 117 nm _{of the SiO 2} sol of Experimental Example 1, it can be seen that _{a SiO x thin film of about 100 nm was formed as shown in the SEM photograph of FIG. 4A.} And, referring to the TEM photograph of FIG. 4B, it was confirmed that _{a SiO x} N _y thin film having a thickness of about 4 to 5 nm _{was formed at the interface between the SiN x} thin film and the SiO _{x thin film.}

In addition, SEM and TEM measurements were performed on the double-layered encapsulation film coated with about 117 nm _{of the SiO 2} sol of Experimental Example 2, _{as a result of a SiN x} thin film, a SiO _x N _y thin film, and a SiO _x thin film through the SEM photograph of FIG. 5A. It can be seen that the three-layer structure of the thin film laminate is stacked by repeating twice, and referring to the TEM photograph of FIG. 5B, the SiO _x N _y thin film thickness of the first laminate is 4.16 nm, and the SiO _x N of the second laminate is _It can be seen that the thickness of the y thin film is 4.07 nm.

<Experimental Example 4: Surface roughness characteristics of the encapsulation film>

As a result of examining the surface roughness characteristics of the encapsulation films prepared through Experimental Example 1 and Experimental Example 2, Ra of the encapsulation film of Experimental Example 1 was 0.35 nm, and Ra of the encapsulation film of Experimental Example 2 was 0.32, as shown in FIG. Both are good in nm.

<Experimental Example 5: Light transmission characteristics of the encapsulation film>

In order to set the refractive index and thickness of each material constituting the encapsulation film, it was measured with an ellipsometer and simulated through the Essential Macleod program (see FIG. 7A). The refractive indices of SiN _x , SiO _x N _y , and SiO _x were measured to be 1.77, 1.66 and 1.48, respectively. As a result of the simulation, SiN _x showed an average transmittance of 85.36% (T _400-700nm ), and the encapsulation film according to Experimental Example 1 and the encapsulation film according to Experimental Example 2 were as high as _{91.71% and 89.21% (T 400-700nm).} It showed an average light transmittance.

Figure 7b is a result of measuring the actual light transmittance of the encapsulation film according to Experimental Example 1 and Experimental Example 2. Referring to FIG. 7B, as shown in the simulation result in FIG. 7A, the encapsulation films according to Experimental Example 1 and Experimental Example 2 exhibited high average light transmittances of _{86.62% and 84.35% (T 400-700nm), respectively.} It is inferred that the reflectance decreases due to the difference in refractive indices of _{SiN x} , SiO _x N _y , and SiO _{x and thus the transparency is improved.}

<Experimental Example 6: Moisture Penetration Resistance of Encapsulation Film>

The water vapor transmission rate (WVTR, water vapor transmission rate) was measured using Aquatran2 (MOCON) and the tritium method for the encapsulation films prepared through Experimental Example 1 and Experimental Example 2.

Water moisture permeability (WVTR) was measured for the encapsulation film prepared in Experimental Example 1 using Aquatran2 (MOCON). At this time, _{the coating thickness of the SiO 2} sol is about 40 nm (withdrawal speed of 0.5 mm/s), about 85 nm (withdrawal speed of 1 mm/s), about 117 nm (withdrawal speed of 3 mm/s), and about 225 nm (withdrawal speed of 5 mm/s) The moisture permeability (WVTR) was measured for each of the different encapsulation films. As a result of the measurement, as shown in FIG. 9, in the case of a drawing speed of 0.5 mm/s (coating thickness of about 40 nm) and a drawing speed of 5 mm/s (coating thickness of about 225 nm), 2.0x10 ^-3 g/m ² /day, 1.8, respectively. The moisture penetration resistance was not good at ^{x10 -3} g/m ^{2 /day.} On the other hand, in the case of withdrawal speed of 1mm/s (coating thickness about 85nm) and 3mm/s (coating thickness about 117nm), the moisture permeability (WVTR) is 4.3x10 ^-4 g/m ² /day, 5.7x10 ^-4 g, respectively. /m ² /day showed excellent moisture penetration resistance.

Using the tritium method for the encapsulation film according to the pullout speed of 1mm/s (coating thickness about 85nm) and 3mm/s (coating thickness about 117nm) of Experimental Example 1 showing excellent results of Aquatran2 (MOCON) moisture permeability characteristics Thus, the moisture permeability was measured again. Specifically, the moisture permeability of the encapsulation film was measured for up to 136 hours using water and water (HTO) containing tritium, which is a radioactive isotope. HTO molecules pass through the encapsulation membrane and are transported to the beta-ray detector, and such a measurement system can measure up to a transmittance level ^{of about 10 -7} g/m ^{2 /day.}

As a result of measuring the moisture permeability using the tritium method, the sealing film of Experimental Example 1 having a drawing speed of 1 mm/s (coating thickness of about 85 nm) was 6.46×10 ^-5 g/m ² /day, drawing speed as shown in FIG. The encapsulation film of Experimental Example 1 having 3mm/s (coating thickness of about 117nm) exhibited excellent moisture permeation resistance ^{at 6.23x10 -5} g/m ^{2 /day.} For reference, the encapsulation film of Experimental Example 1 with a pullout speed of 1 mm/s and 3 mm/s, which is the target of the moisture permeability measurement using the tritium method, was applied for 5 hours of heat treatment.

<Experimental Example 6: Moisture penetration resistance according to heat treatment time>

In the heat treatment for the conversion _{of SiO 2} sol into a SiO _{x thin film and to generate a SiO x} N _y thin film, the moisture permeation resistance according to the heat treatment time was examined.

Moisture moisture permeability (with a tritium method) for the sealing film of Experimental Example 1 with a drawing speed of 3mm/s (coating thickness of about 117nm) and a heat treatment temperature of 120°C, and heat treatment times of 5 hours, 10 hours, and 20 hours. WVTR) was measured. As a result of the measurement, as shown in FIG. 11, when the heat treatment time was 5 hours, the moisture permeability was 6.23x10 ^-5 g/m ² /day, and when the heat treatment time was 20 hours, 3.5x10 ^-4 g/m ² / It was confirmed that the moisture permeation resistance was deteriorated compared to the case where the heat treatment time was 5 hours. On the other hand, when the heat treatment time was 10 hours, the moisture permeability was the best as ^{1.6x10 -5} g/m ^{2 /day.} Based on these experimental results, it is judged that the optimum heat treatment time is 8-12 hours, and if the heat treatment time is shorter than 8 hours, _{the chemical reaction required to form a dense SiO x} N _y thin film cannot sufficiently proceed, and exceeds 12 hours. When the SiO ₂ sol and the resin, urethane acrylate, and polydimethylsiloxane introduced as additives, shrinkage and cracking are induced, which inhibits the densification of the _{SiO x} N _{y thin film.}

The moisture permeability (WVTR) was measured using the tritium method for the encapsulation films of Experimental Example 1 and Experimental Example 2 to which a heat treatment time of 10 hours was applied. In this case, the heat treatment temperature was 120°C, and the drawing speed was 3mm/s (coating thickness of about 117nm). As a result of the measurement, as shown in FIG. 12, the encapsulation film according to Experimental Example 1 had a moisture permeability of 1.6x10 ^-5 g/m ² /day, and the encapsulation film according to Experimental Example 2 was 2x10 ^-6 g/m ² / It showed ultra low moisture permeability in day.

<Experimental Example 7: Life Characteristics of Quantum Dot Light-Emitting Diode>

After applying the encapsulation film prepared through Experimental Example 1 and Experimental Example 2 as an encapsulation film of a quantum dot light-emitting diode, the lifespan characteristics of each quantum dot light-emitting diode were measured.

Quantum dot light emitting diodes are composed of glass/ITO/ZnO nanoparticles/PEIE/CdSe-ZnS QDs/Poly-TPD+PVK/MoO ₃ /Ag, ZnO nanoparticles are an electron transport layer (ETL), and PEIE is an electron injection layer (EIL). , CdSe-ZnS QDs was a green light emitting layer (EML), Poly-TPD+PVK was a hole transport layer (HTL), MoO ₃ was a hole injection layer (HIL), and Ag was used as an electrode. The hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer, and the electron injection layer were all produced by spin coating, and the Ag layer was produced by vacuum deposition.

For comparison of the experimental results, Comparative Example 1 and Comparative Example 2 were prepared. Comparative Example 1 is a quantum dot light-emitting diode without an encapsulation film, and Comparative Example 2 is a quantum dot light-emitting diode to which a glass lid is applied.

The life measurement experiment was conducted with a current of 1.2 mA and an initial efficiency of 1000 nit. 13 is a result of measuring the lifetime by measuring the brightness reduction ratio over time of the quantum dot light emitting diode device. Referring to FIG. 13, in the case of Comparative Example 1 without the encapsulation film, the time required to reach 50% of the initial brightness (t ₅₀ : half-life) was about 86 hours, and in the case of Comparative Example 2 to which the glass encapsulation film was applied, the half-life was 360 It was time. In the case of the quantum dot light-emitting diode to which the encapsulation film according to Experimental Example 1 was applied, the half-life was 305 hours, and the half-life of the quantum dot light-emitting diode to which the encapsulation film according to Experimental Example 2 was applied reached 354 hours. The results were close to time.

10: flexible substrate 20: thin film laminate having a three-layer structure
21: SiN _x thin film 22a: SiO ₂ sol
22: SiO _x thin film 23: SiO _x N _y thin film

Claims (3)

A flexible substrate; And
Containing a three-layer structure thin film laminate formed on each of both surfaces of the flexible substrate,
The three-layer structure of the thin film laminate is a form in which a SiN _x thin film, a SiO _x N _y thin film, and a SiO _x thin film are sequentially stacked,
The three-layered thin film laminate is repeatedly laminated twice on each of both sides of the flexible substrate,
A SiO _x N _y thin film is further provided _{between the SiO x} thin film of the first thin _{film stack and the SiN x} thin film of the second thin film stack,
The water vapor transmission rate (WVTR) of the encapsulation film is ^{less than 2x10 -6} g/m ² /day,
SiO _x N _y thin film provided between the three-layer structure of a thin film of SiO _x N _y having to laminate the thin film and the first thin-film laminate of the SiO _x thin film and the SiN _x film of the second thin film laminate, SiN _x film and the SiO _x is formed by solid phase diffusion of _{SiN x} and SiO _x by heat treatment of the substrate in a state in which thin films are sequentially stacked,
The SiO _x N _y thin film has a thickness of 3 to 8 nm, and the SiO _x thin film has a thickness of 85 to 120 nm.
The sealing film of claim 1, wherein the flexible substrate is made of a polymer material.
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