KR20150004241A - Method of forming an organic light emitting diode - Google Patents

Abstract

Provided is a method of manufacturing an organic light emitting diode. The method of manufacturing an organic light emitting diode includes forming a light scattering layer on a substrate, forming a metal mask layer on the light scattering layer, forming a metal mask pattern by performing a heat treatment process on the metal mask layer, forming a nano structure by pattering the light scattering layer by using the metal mask pattern as an etching mask, and forming a planar layer to cover the nano structure on the substrate. The heat treatment process is performed at temperature of about 80° C to 200° C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting diode (OLED)

The present invention relates to a method of manufacturing an organic light emitting diode, and more particularly, to a method of manufacturing an organic light emitting diode including a light scattering layer.

2. Description of the Related Art In recent years, there has been an increasing demand for lighter, smaller, and less expensive products in electronic products and lighting devices such as mobile phones and notebooks. Organic light emitting devices have been attracting attention as display devices and light emitting devices mounted in electronic products and lighting devices to meet these demands. In particular, organic light emitting devices have advantages of low voltage driving, light weight, and low cost, and thus are highly utilized in electronic products and lighting devices.

BACKGROUND ART [0002] In recent years, studies have been made to improve the luminous efficiency of an organic light emitting device. In particular, various studies have been conducted on extracting light, which is lost in the organic light emitting device, to the outside to have a high luminous efficiency even at a lower voltage.

SUMMARY OF THE INVENTION The present invention provides a method of manufacturing an organic light emitting diode having increased light extraction efficiency.

Another object of the present invention is to provide a method of manufacturing an organic light emitting diode which can be easily manufactured at low cost.

A method of manufacturing an organic light emitting diode according to the present invention includes: forming a light scattering layer on a substrate; forming a metal mask layer on the light scattering layer; and performing a heat treatment process on the metal mask layer, Patterning the light scattering layer using the metal mask pattern as an etching mask to form a nanostructure; and forming a flat layer covering the nanostructure on the substrate, wherein the heat treatment process Can be carried out at a temperature of 80 [deg.] C to 200 [deg.] C.

According to one embodiment, the heat treatment process may be performed in a vacuum state.

According to one embodiment, the heat treatment process may be performed in an inert gas atmosphere.

According to one embodiment, the refractive index of the light scattering layer may be smaller than the refractive index of the substrate.

According to one embodiment, the refractive index of the light scattering layer may be 1.1 to 1.5.

According to one embodiment, the light scattering layer may comprise a fluororesin, silicon oxide, magnesium oxide, or a combination thereof.

According to one embodiment, the nanostructure includes nano patterns protruding in a direction perpendicular to an upper surface of the substrate, and a recess region defined by sidewalls of the nano patterns, And the height of the nano patterns may be 150 nm or more and 600 nm or less.

According to one embodiment, the metal mask pattern has an opening exposing the light scattering layer, and the forming of the nanostructure may include etching the light scattering layer exposed by the opening to form the recess region ≪ / RTI >

The method of manufacturing an organic light emitting diode according to the present invention may further include removing the metal mask pattern after forming the nanostructure, wherein the metal mask pattern may be removed using an acid solution.

According to one embodiment, the acid solution may comprise nitric acid, sulfuric acid, aqua regia, or phosphoric acid.

A method of manufacturing an organic light emitting diode according to the present invention includes forming a first electrode on the flat layer, forming an organic light emitting layer on the first electrode, and forming a second electrode on the organic light emitting layer The refractive index of the flat layer may be substantially equal to the refractive index of the first electrode.

A method of manufacturing an organic light emitting diode according to the present invention includes forming a first electrode on the flat layer, forming an organic light emitting layer on the first electrode, and forming a second electrode on the organic light emitting layer The refractive index of the flat layer may be greater than the refractive index of the first electrode.

According to one embodiment, the refractive index of the flat layer may be 1.8 to 2.5.

The method of fabricating an organic light emitting diode according to the present invention may further comprise forming a polymer film between the substrate and the light scattering layer, wherein the polymer film is selected from the group consisting of polyacryl, polyimide, polycarbonate, perylene, polyethylene, polystyrene Or the like.

According to the concept of the present invention, a metal mask pattern can be easily formed at a relatively low temperature. A nanostructure including nano patterns having a relatively high height can be easily formed using the metal mask pattern. Accordingly, the organic light emitting diode having increased light extraction efficiency can be easily manufactured at low cost.

1 is a flowchart illustrating a method of manufacturing an organic light emitting diode according to embodiments of the present invention.
FIGS. 2 to 4 and FIGS. 6 to 8 are cross-sectional views illustrating a method of manufacturing an organic light emitting diode according to an embodiment of the present invention.
5 is a plan view of a metal mask pattern according to an embodiment of the present invention.
9 is a plan view of a metal mask pattern according to another embodiment of the present invention.
10 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode according to another embodiment of the present invention.
11 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode according to another embodiment of the present invention.
12 to 16 are SEM photographs of metal mask patterns according to heat treatment conditions.
17 is a graph showing the rate of increase of light extraction according to the height of the nano patterns.

In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms and various modifications may be made. It will be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof. In the accompanying drawings, the constituent elements are shown enlarged for the sake of convenience of explanation, and the proportions of the constituent elements may be exaggerated or reduced.

The terms used in the embodiments of the present invention may be construed as commonly known to those skilled in the art unless otherwise defined. Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing an organic light emitting diode according to embodiments of the present invention. FIGS. 2 to 4 and FIGS. 6 to 8 are cross-sectional views illustrating a method of manufacturing an organic light emitting diode according to an embodiment of the present invention. 5 is a plan view of a metal mask pattern according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, a light scattering layer 20 may be formed on a substrate 10 (S10). The substrate 10 may be made of a transparent material such as glass, quartz, or plastic. The refractive index of the substrate 10 may be about 1.5 to about 1.6. The refractive index of the light scattering layer 20 may be smaller than the refractive index of the substrate 10. The refractive index of the light scattering layer 20 may be about 1.1 to about 1.5. The light scattering layer 20 may include a fluororesin, silicon oxide, magnesium oxide, or a combination thereof. The light scattering layer 20 may be provided on the substrate 10 to a thickness of about 100 nm to about 1000 nm.

Referring to FIGS. 1 and 3, a metal mask layer 30 may be formed on the light scattering layer 20 (S20). The metal mask layer 30 may include, for example, silver or a silver alloy. The metal mask layer 30 may be provided on the light scattering layer 20 to a thickness of about 30 nm to about 200 nm. The metal mask layer 30 may be formed using, for example, a sputter deposition process.

Referring to FIGS. 1 and 4, a metal mask pattern 35 may be formed by performing a heat treatment process (A) on the metal mask layer 30 (S30). Specifically, the metal mask pattern 35 may be formed using a dewetting phenomenon of the metal mask layer 30 in the heat treatment step (A). The metal mask pattern 35 may have an opening 37 that exposes the light scattering layer 20.

The heat treatment step (A) may be performed in a vacuum state or an inert gas atmosphere (for example, nitrogen atmosphere). Accordingly, the heat treatment step (A) can be performed at a relatively low temperature, compared with the case where the heat treatment step (A) is performed in air. The heat treatment step (A) may be performed at a temperature of about 80 ° C to about 200 ° C. If the heat treatment step (A) is performed at a temperature lower than about 80 캜, the non-wetting phenomenon of the metal mask layer 30 may not sufficiently occur and it may be difficult to form the metal mask pattern 35. The substrate 10 and the light scattering layer 20 provided under the metal mask layer 30 during the heat treatment process A may be subjected to a heat treatment at a temperature higher than about 200 ° C, Yellowing and cracking may occur.

12 to 16 are SEM photographs of metal mask patterns according to heat treatment conditions.

[ Comparative Example ]

First, a light scattering layer containing silicon oxide was formed on a soda lime glass substrate. After forming a metal mask layer containing a silver alloy on the light scattering layer, a comparative sample was prepared by performing heat treatment in air at a temperature of 250 ° C for 30 minutes. 12 is an SEM photograph of the above comparative sample. Referring to FIG. 12, a metal oxide partially oxidized in the metal mask layer is formed on the surface of the metal mask layer, and the metal mask layer is not sufficiently wetted to form a metal mask pattern. Can be confirmed.

[ Experimental Example ]

First, a light scattering layer containing silicon oxide was formed on a soda lime glass substrate, and then a metal mask layer containing a silver alloy was formed on the light scattering layer. Thereafter, experimental samples were prepared, each of which was heat-treated under the following conditions.

1) Sample 1 was heat-treated in a vacuum oven at 200 ° C for 2 hours.

2) Experimental sample 2 was heat-treated at 180 ° C for 10 minutes in a hot plate of nitrogen atmosphere.

3) Experimental sample 3 was heat-treated at 160 ° C for 1 hour in a vacuum oven.

4) Sample 4 was heat treated in a vacuum oven at 120 ° C for 1 hour.

13 to 16 are SEM photographs of the above Experimental Samples 1 to 4, respectively. Referring to FIGS. 13 to 16, it can be confirmed that although the heat treatment process is performed at a relatively low temperature as compared with the comparative sample, a non-wetting phenomenon of the metal mask layer occurs and a metal mask pattern is formed.

5 is a plan view of a metal mask pattern according to an embodiment of the present invention. According to one embodiment, as shown in FIG. 5, the metal mask pattern 35 may include a plurality of patterns formed on the light scattering layer 20. The plurality of patterns may each be in the form of an island. In this case, the plurality of patterns may be spaced apart from each other by one opening 37.

Referring to FIGS. 1 and 6, the nanostructure 40 may be formed by patterning the light scattering layer 30 using the metal mask pattern 35 as an etching mask (S40). The formation of the nanostructure 40 may include forming the recess region R by etching the light scattering layer 20 exposed by the opening 37 of the metal mask pattern 35 .

According to one embodiment, forming the recessed region R may comprise dry etching the light scattering layer 20. [ The dry etching process may be, for example, a reactive ion etching (RIE) process or an inductively coupled plasma etching (ICP) process. The recess region R may be formed to expose a part of the upper surface of the substrate 10.

The nano structure 40 may have a plurality of nano patterns P protruding in a direction perpendicular to the upper surface of the substrate 10, (R) can be defined. The height h of the nanopatterns P defined by the distance between the top surface of the nanopatternes P and the bottom surface of the recessed region R may be about 150 nm to about 600 nm.

17 is a graph showing the rate of increase of light extraction according to the height of the nano patterns. Referring to FIG. 17, it can be seen that the light extraction efficiency is significantly increased when the height of the nanopatterns P is 200 nm or more, compared to when the height of the nanopatternes P is 100 nm.

According to the concept of the present invention, the metal mask pattern 35 can be easily formed at a relatively low temperature. The nanostructure 40 including the nanopatterns P having a relatively high height can be easily formed using the metal mask pattern 35. Accordingly, the organic light emitting diode having increased light extraction efficiency can be easily manufactured at low cost.

Referring to FIGS. 1 and 7, first, the metal mask pattern 35 may be removed. The metal mask pattern 35 may be removed using an acid solution. As the metal mask pattern 35 is removed using the acid solution, the nanostructure 40 can be prevented from being damaged. The acid solution may include, for example, nitric acid, sulfuric acid, aqua regia, or phosphoric acid.

Next, a flat layer 50 covering the nanostructure 40 may be formed on the substrate 10 (S50). The planar layer 50 may fill the recess region R of the nanostructure 40 and may cover the upper surface of the nanopatternes P. [ The flat layer 50 may have a flat upper surface. The surface roughness (Ra) value of the flat layer 50 may be less than 10 nm.

The flat layer 50 may include a transparent material. That is, the visible light transmittance of the flat layer 50 may be about 90% or more. The refractive index of the planarizing layer 50 may be about 1.8 to about 2.5. The planarizing layer 50 may be formed of an inorganic material such as TiO2, ZrO2, TiO2-SiO2, SnO2, or In2O3, an organic hybrid material containing the inorganic material, a polyimide or a composite material of the inorganic material and the polymer .

Specifically, the flat layer 50 may be formed using a spin coating method, a dip coating method, a slit coating method, a bar coating method, or a spray coating method. After the planarizing layer 50 is coated by the coating method as described above, the planarizing layer 50 may be cured using a heat treatment or an ultraviolet irradiation process.

Referring to FIG. 8, a first electrode 60, an organic light emitting layer 70, a second electrode 80, and a passivation layer 90 are sequentially stacked on the flat layer 50.

The first electrode 60 may be a transparent electrode or a reflective electrode. When the first electrode 60 is a transparent electrode, for example, it may be formed using indium tin oxide (ITO), indium zinc oxide (IZO), or tin oxide. For example, the first electrode 60 may be formed of silver (Ag), aluminum (Al), nickel (Ni), platinum (Pt), or palladium (Pd). The refractive index of the first electrode 60 may be substantially equal to the refractive index of the planar layer 50 or may be less than the refractive index of the planar layer 50.

The organic light emitting layer 70 may include at least one of a polyfluorene derivative, a polyparaphenylenevinylene derivative, a polyphenylene derivative, a polyvinylcarbazole derivative, At least one of a polythiophene derivative, an anthracene derivative, a butadiene derivative, a tetracene derivative, a distyrylarylene derivative, a benzazole derivative, or a carbazole Lt; RTI ID = 0.0 > luminescent < / RTI > In addition, the organic light emitting layer 70_ may be an organic light emitting material including a dopant, for example, the dopant may include at least one selected from the group consisting of xanthene, perylene, cumarine, rhodamine, And examples thereof include rubrene, dicyanomethylenepyran, thiopyran, (thia) pyrilium, periflanthene derivatives, indenoperylene derivatives, carbostyrates, And may include at least one of carbostyryl, Nile red, or quinacridone.

The organic light emitting layer 70 may include at least one of a hole injecting layer, a hole transporting layer, an electron transporting layer, and an electron injecting layer. The organic light emitting layer 70 may generate light using recombination of holes or electrons supplied from the first electrode 60 or the second electrode 80.

The second electrode 80 may comprise a semi-transparent or reflective conductive metal. The second electrode 80 may include at least one of gold, silver, iridium, molybdenum, palladium, and platinum.

The protective layer 90 may function to protect the second electrode 80. The protective layer 80 may include a transparent material and may be formed using a polymer material.

9 is a plan view of a metal mask pattern according to another embodiment of the present invention. In order to simplify the description, the same reference numerals are given to the same structures as the manufacturing method of the organic light emitting diode according to the embodiment of the present invention described with reference to Figs. 2 to 4 and Figs. 6 to 8, The description may be omitted.

First, as described with reference to FIGS. 1, 2 to 4, a light scattering layer 20 may be formed on a substrate 10, and a metal mask layer (not shown) may be formed on the light scattering layer 20, (30) may be formed (S20). A metal mask pattern 35 may be formed by performing a heat treatment process (A) on the metal mask layer 30 (S30).

Referring to FIG. 9, the metal mask pattern 35 may be a single metal film having a plurality of openings 37 exposing the light scattering layer 20. When the heat treatment process (A) is performed on the metal mask layer 30 for a predetermined time, the metal mask pattern 35 may be formed in a planar view as shown in FIG. Subsequently, when the heat treatment step (A) is performed on the metal mask layer 30 for a sufficiently long time, the metal mask pattern 35 may be formed in a planar view as shown in FIG. 5 have.

The subsequent steps are the same as the method of manufacturing the organic light emitting diode according to the embodiment of the present invention described with reference to FIGS.

10 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode according to another embodiment of the present invention. In order to simplify the description, the same reference numerals are given to the same structures as the manufacturing method of the organic light emitting diode according to the embodiment of the present invention described with reference to Figs. 2 to 4 and Figs. 6 to 8, The description may be omitted.

First, as described with reference to FIGS. 1, 2 to 4, a light scattering layer 20 may be formed on a substrate 10, and a metal mask layer (not shown) may be formed on the light scattering layer 20, (30) may be formed (S20). A metal mask pattern 35 may be formed by performing a heat treatment process (A) on the metal mask layer 30 (S30). The metal mask pattern 35 may be formed in a planar view, as shown in FIG. 5, or in a shape as shown in FIG.

Referring to FIG. 10, the nanostructure 40 may be formed by patterning the light scattering layer 30 using the metal mask pattern 35 as an etching mask (S40). The formation of the nanostructure 40 may include forming the recess region R by etching the light scattering layer 20 exposed by the opening 37 of the metal mask pattern 35 .

The formation of the recessed region R may include wet etching the light scattering layer 20. The wet etching process may be an etching process using, for example, hydrofluoric acid, BOE (Buffered Oxide Etchant), or an organic solvent. After the wet etching process, a part of the light scattering layer 20 may remain unetched under the recessed region R. [

The nano structure 40 may have a plurality of nano patterns P protruding in a direction perpendicular to the upper surface of the substrate 10, (R) can be defined. The height h of the nanopatterns P defined by the distance between the top surface of the nanopatternes P and the bottom surface of the recessed region R may be about 150 nm to about 600 nm.

The subsequent steps are the same as the method of manufacturing the organic light emitting diode according to the embodiment of the present invention described with reference to FIGS.

11 is a cross-sectional view illustrating a method of manufacturing an organic light emitting diode according to another embodiment of the present invention. In order to simplify the description, the same reference numerals are given to the same structures as the manufacturing method of the organic light emitting diode according to the embodiment of the present invention described with reference to Figs. 2 to 4 and Figs. 6 to 8, The description may be omitted.

Referring to FIGS. 1 and 11, a polymer film 12 may be formed on a substrate 10, and a light scattering layer 20 may be formed on the polymer film 12 (S10). Although not shown, the substrate 10 may include a color filter for display. The polymer film 12 may comprise at least one of polyacryl, polyimide, poly carbonate, perylene, polyethylene, polystyrene.

3, and FIG. 4, a metal mask layer 30 may be formed on the light scattering layer 20 (S20), and the metal mask layer 30 may be formed on the light scattering layer 20, The metal mask pattern 35 may be formed by performing the heat treatment process (A) on the substrate (S30). When the heat treatment step (A) is performed at a temperature of 230 ° C or higher, yellowing or cracking may occur in the polymer film (12). According to the concept of the present invention, the heat treatment step (A) can be performed at a relatively low temperature of about 80 ° C to about 200 ° C, so that during the heat treatment step (A) Can be prevented.

The subsequent steps are the same as the method of manufacturing the organic light emitting diode according to the embodiment of the present invention described with reference to FIGS.

The foregoing description of embodiments of the present invention provides illustrative examples for the description of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It is clear.

10: substrate 60: first electrode
20: light scattering layer 70: organic light emitting layer
30: metal mask layer 80: second electrode
35: metal mask pattern 90: protective layer
37: opening 12: polymer film
40: nanostructure
R: recess region
P: nanopatterns
50: flat layer

Claims (14)

Forming a light scattering layer on the substrate;
Forming a metal mask layer on the light scattering layer;
Performing a heat treatment process on the metal mask layer to form a metal mask pattern;
Patterning the light scattering layer using the metal mask pattern as an etching mask to form a nanostructure; And
And forming a flat layer on the substrate to cover the nanostructure,
Wherein the heat treatment process is performed at a temperature of 80 ° C to 200 ° C. The method according to claim 1,
Wherein the heat treatment process is performed in a vacuum state. The method according to claim 1,
Wherein the heat treatment process is performed in an inert gas atmosphere. The method according to claim 1,
Wherein the refractive index of the light scattering layer is smaller than the refractive index of the substrate. The method of claim 4,
Wherein the light scattering layer has a refractive index of 1.1 to 1.5. The method of claim 5,
Wherein the light scattering layer comprises a fluororesin, silicon oxide, magnesium oxide, or a combination thereof. The method according to claim 1,
The nanostructure comprises:
Nano patterns protruding in a direction perpendicular to an upper surface of the substrate; And
A recessed region defined by sidewalls of the nanopatterns,
The height of the nano patterns is defined as the distance between the top surface of the nano patterns and the bottom surface of the recess region,
Wherein the height of the nano patterns is 150 nm or more and 600 nm or less. The method of claim 7,
Wherein the metal mask pattern has an opening exposing the light scattering layer,
Wherein the forming of the nanostructure comprises forming the recessed region by etching the light scattering layer exposed by the opening. The method according to claim 1,
Further comprising removing the metal mask pattern after forming the nanostructure,
Wherein the metal mask pattern is removed using an acid solution. The method of claim 9,
Wherein the acid solution comprises nitric acid, sulfuric acid, kyanite, or phosphoric acid. The method according to claim 1,
Forming a first electrode on the planar layer;
Forming an organic light emitting layer on the first electrode; And
Further comprising forming a second electrode on the organic light emitting layer,
Wherein the refractive index of the flat layer is substantially equal to the refractive index of the first electrode. The method according to claim 1,
Forming a first electrode on the planar layer;
Forming an organic light emitting layer on the first electrode; And
Further comprising forming a second electrode on the organic light emitting layer,
Wherein the refractive index of the flat layer is greater than the refractive index of the first electrode. The method of claim 12,
And the refractive index of the flat layer is 1.8 to 2.5. The method according to claim 1,
Further comprising forming a polymer film between the substrate and the light scattering layer,
Wherein the polymer film comprises at least one of polyacryl, polyimide, polycarbonate, perylene, polyethylene, and polystyrene.

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