KR20130095549A - Method for manufacturing light extraction enhancing layer and organic light-emitting diode including the light extraction enhancing layer - Google Patents

Abstract

PURPOSE: A manufacturing method of a light extraction enhancement layer and an organic light-emitting device including the light extraction enhancement layer are provided to reduce manufacturing costs using a phase separation phenomenon of a polymer blend. CONSTITUTION: A light extraction enhancement layer is formed on a substrate. A first electrode (50) is formed on the light extraction enhancement layer. A second electrode (90) is faced with the first electrode. An organic layer (70) is placed between the first electrode and the second electrode. A planarization layer (35) is formed on a nano pillar layer.

Description

Method for manufacturing light extraction enhancing layer and organic light-emitting diode including the light extraction enhancing layer

A method of manufacturing a light extraction enhancement layer and an organic light emitting device including the light extraction enhancement layer, and more particularly, a method of forming a light extraction enhancement layer at low cost by using a phase separation principle, and a light extraction enhancement layer thus formed. It relates to an organic light emitting device.

Organic light emitting diodes are self-luminous devices that have a wide viewing angle, excellent contrast, fast response time, excellent luminance, driving voltage and response speed, and are capable of multicoloring. It is attracting attention.

The light extraction efficiency of the conventional organic light emitting device has been limited to about 20% due to total reflection due to the difference in refractive index of the inner layer. In order to overcome this problem, a method of improving light extraction efficiency between the glass-air interface, such as attaching a microlens array to the outside of the glass substrate, coating a scattering layer, or using a high refractive index glass substrate, has been attempted. However, this method is to improve the extraction efficiency of the light trapped in the glass substrate, called the glass mode (glass mode) has a limit to the maximum that can be improved. In order to improve light extraction efficiency at the interface between the transparent electrode such as ITO and the glass substrate where more light is trapped, a scattering layer is placed between the transparent electrode and the glass substrate, or a method of introducing a photonic crystal structure having a specific size and arrangement interval is used. This was tried. In addition, a method of making the device itself into a corrugated structure or a wrinkled structure has been proposed.

Among these methods, in particular, the method of inserting the photonic crystal structure into the interface in the light extraction between the transparent electrode and the glass substrate not only shows excellent efficiency but also excellent in terms of process control. In order to optimize the photonic crystal, nanoimprinting lithography, which is a simple and inexpensive process instead of photolithography, has been proposed for photonic crystal manufacturing, and photocuring patterning has been proposed instead of photonic crystal patterning using thermosetting. In addition, a sol-gel process has been proposed for the planarization layer on the top of the photonic crystal instead of vacuum deposition. Although the method using the photonic crystal is excellent in terms of efficiency, there is a problem of viewing angle dependence such that the spectrum of light emitted according to the viewing angle changes. To overcome this, a method of introducing a random change in the photonic crystal structure has also been proposed.

Although the photonic crystal research has made great progress in improving the light extraction at the interface between the transparent electrode and the glass substrate, the mold used for fabricating the photonic crystal still uses expensive photolithography and electron beam lithography. Since it has to be patterned repeatedly, there was a limit to the large area.

There is a need for a method for manufacturing a photonic crystal structure, particularly a photonic crystal structure composed of random nanopillar arrays, in a low cost and simple process.

The present invention provides a method for manufacturing a light extraction enhancement layer that can be manufactured by a simple process of low cost, and provides an organic light emitting device having excellent light extraction efficiency including the light extraction enhancement layer.

According to one aspect, a single-phase mold composition comprising a first polymer, a second polymer and a solvent is applied and dried on a substrate to form a mold coating layer phase-separated into the first polymer phase and the second polymer phase. Preparing a mold having a nano pattern by removing the second polymer phase from the mold coating layer; Adding a composition for a nano pillar layer on the mold having the nano pattern and curing the nano pillar layer; And forming a planarization layer on the nano pillar layer.

The phase-separated mold coating layer may be formed by evaporating the solvent from the single-phase mold composition.

The first polymer and the second polymer may include polymethylmethacrylate and polystyrene, polymethylmethacrylate and polycarbonate, or polymethylmethacrylate and polyvinylchloride, and the solvent may be tetrahydrofuran, Methylethylketone, toluene or acetone.

The weight average molecular weight of the first polymer and the second polymer may be 2,000 to 300,000 independently of each other.

The content of the first polymer and the second polymer may be 0.1 to 10% by weight independently of each other based on the total weight of the mold composition.

The mold composition may include a first polymer solution containing the first polymer and the solvent; And a second polymer solution including the second polymer and the solvent; may be produced by mixing at a volume ratio of 8: 2 to 5: 5.

The nanopattern may include a cylindrical pore.

According to another aspect, a substrate; A light extraction enhancement layer formed on the substrate, the light extraction layer including a nano pillar layer and a planarization layer; A first electrode formed on the light extraction enhancement layer; A second electrode facing the first electrode; And an organic layer interposed between the first electrode and the second electrode.

The nano pillar layer may include a nano pillar of a cylindrical shape.

The height of the nano pillars may be 50 nm to 500 nm, the diameter of the nano pillars may be 50 nm to 1,000 nm, and the interval between the nano pillars may be 50 nm to 1,000 nm.

According to another aspect, an illumination including the organic light emitting element is provided.

According to another aspect, a display device including the organic light emitting element is provided.

The method of manufacturing a light extraction enhancement layer according to one aspect provides a light extraction enhancement layer having excellent light extraction efficiency.

The method of manufacturing the light extraction enhancement layer according to one aspect provides a light extraction enhancement layer by a simple method of low cost using a phase separation phenomenon of the polymer blend.

The organic light emitting device including the light extraction enhancement layer according to one aspect effectively improves the light extraction efficiency of the organic light emitting device by controlling the thickness of the light extraction enhancement layer and the height and shape of the nanopillars.

The organic light emitting device including the light extraction enhancement layer according to one aspect is usefully applied to the display device.

1 schematically shows a method of manufacturing a light extraction enhancement layer according to one embodiment.
2 is a schematic cross-sectional view of an organic light emitting device having a light extraction enhancement layer according to an embodiment.
3 is an atomic force microscope (AFM) image of a nano pattern of a mold prepared according to Example 1 and Comparative Examples 1 to 2. FIG.
4 is an enlarged AFM image of a nano pattern of a mold prepared according to Example 1. FIG.
5 is an AFM image of a nano pillar layer constituting the light extraction enhancement layer formed according to Example 4. FIG.
6 is a graph showing a relationship between driving voltages, current densities, and luminances of organic light emitting diodes manufactured according to Example 4 and Comparative Example 1. FIG.
7 is a graph showing a relationship between current density and efficiency of organic light emitting diodes manufactured according to Example 4 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

1 schematically shows a method of manufacturing a light extraction enhancement layer according to one embodiment.

First, a single phase mold composition comprising a first polymer, a second polymer and a solvent is applied and dried on a substrate to form a mold coating layer phase-separated into the first polymer phase and the second polymer phase, and the mold The second polymer phase is removed from the coating layer for preparing a mold having a nano pattern.

The first polymer is a polymer that is the main component of the two polymers and the second polymer is the polymer that becomes the remaining component in the mold.

The mold composition may include a first polymer solution including a first polymer and a solvent capable of dissolving the first polymer, and a second polymer solution including a second polymer and a solvent capable of dissolving the second polymer. It can be prepared by mixing. The solvent capable of dissolving the first polymer and the solvent capable of dissolving the second polymer may preferably be the same solvent as each other.

Mixing of the first polymer solution and the second polymer solution may be performed using a known mixing method.

In a composition comprising a first polymer, a second polymer and a solvent, the first polymer and the second polymer are mixed with each other to form a single phase.

The first polymer and the second polymer have different affinity for the solvent. Therefore, the affinity for the solvent of the first polymer and the second polymer in the mold composition is different from each other.

As the first polymer and the second polymer, polymethyl methacrylate and polystyrene, polymethyl methacrylate and polycarbonate, or polymethyl methacrylate and polyvinyl chloride may be used.

The process of applying and drying the mold composition comprising the first polymer, the second polymer and the solvent on the substrate may be performed by spin coating.

By evaporating the solvent from the single-phase mold composition applied on the substrate, a coating layer for a mold phase-separated into the first polymer phase and the second polymer phase is formed.

That is, the mold composition including the first polymer, the second polymer, and the solvent is a mixed solution of a single phase, but the solvent and the solvent evaporate in the process of applying and drying the composition for the mold on the substrate, the first polymer phase and the second polymer. A coating layer for a mold phase separated into phases is formed

The coating layer for the mold is in a phase separation state in which the first polymer phase and the second polymer phase have a laterally irregular width due to the difference in affinity for the solvent of the first polymer and the second polymer.

The affinity of the first polymer and the second polymer to the solvent affects the interfacial properties of the first polymer and the second polymer to the substrate, respectively, since the affinity of the first polymer and the second polymer to the solvent is different. There is a difference in the interfacial properties of the first polymer and the second polymer with respect to the substrate. Due to this difference in interfacial properties, a coating layer for phase-separated mold is formed in which the first polymer phase and the second polymer phase are arranged in a lateral irregular width. In the phase-separated mold coating layer, the width and height of the first polymer phase and the second polymer phase are determined by the conditions such as the functional groups, molecular weights, compounding ratios, and concentrations of the first polymer solution and the second polymer solution of the first polymer and the second polymer. Can be adjusted by adjusting.

Removing the second polymer phase from the coating layer for the mold may be performed by immersing the coating layer in an optional solvent that is soluble only in the second polymer phase. Alternatively, the first polymer phase may be removed. In this case, the first polymer phase can be removed using an optional solvent having solubility only for the first polymer phase.

When the second polymer phase is removed, the coating layer for the mold from which the second polymer phase is removed has a nanopattern composed of the first polymer phase.

Next, the composition for nanopillar layers is added and hardened on the mold which has a nanopattern, and a nanopillar layer is formed.

In detail, the nano-pillar layer may be formed by placing the composition for the nano-pillar layer on a mold having a nano-pattern and pressing it with a substrate and then drying the solvent in the composition for the nano-pillar layer. Since the nanopillar of the nanopillar layer is formed in engagement with the nanopattern of the mold, the shape of the nanopillar is determined by the nanopattern. Various shapes of the nanopatterns of the mold may be designed to form nanopillar layers having nanopillars of various shapes.

The composition for nanopillar layers contains an ultraviolet curable resin and the solvent which has solubility with respect to the said ultraviolet curable resin. The composition for a nano pillar layer may be cured by ultraviolet rays.

Finally, a planarization layer is formed on the nanopillar layer.

That is, the cured nanopillar layer is removed from the mold, and then a planarization layer composition is added to the nanopillar layer to form a planarization layer.

As the material of the planarization layer, a material having a high refractive index may be used. For example, a TiO ₂ containing sol, a ZnO sol, a SiNx inorganic material, or the like in the form of an organic-inorganic composite material may be used. When the material is used as the material of the planarization layer, it has a high light transmittance and can contribute to the improvement of the light extraction effect.

Through this process, a light extraction enhancement layer including a nano pillar layer and a planarization layer is obtained.

The substrate for applying and drying the mold composition may be of any form as long as one surface of the material is flat. For example, the glass which does not react with the composition for molds can be used as a base material.

The first polymer and the second polymer constituting the mold composition may be selected from incompatible polymer blends. Here, the first polymer is a component that forms the main polymer phase in the coating layer for the mold.

For example, the first polymer and the copolymer may be polymethylmethacrylate and polystyrene, polymethylmethacrylate and polycarbonate, or polymethylmethacrylate and polyvinylchloride. Preferably, polymethyl methacrylate having excellent physical properties may be used as the first polymer, and polystyrene having good physical properties and excellent dissolution properties may be used as the second polymer.

Tetrahydrofuran, methyl ethyl ketone, toluene or acetone can be used as the solvent constituting the mold composition. It is preferable that the solvent has solubility in the first polymer and the second polymer so that a coating layer can be formed through an operation such as spin coating. For example, tetrahydrofuran may be used as the solvent.

For example, the mold composition may be prepared by mixing a polymethyl methacrylate solution containing polymethyl methacrylate and tetrahydrofuran and a polystyrene solution containing polystyrene and tetrahydrofuran.

The mold composition thus prepared is applied and dried to form a coating layer for the mold. At this time, the forming method of the coating layer for a mold is not specifically limited, For example, the method of spin-coating a composition for molds can be used.

When polymethyl methacrylate is used as the first polymer, the weight average molecular weight of the polymethyl methacrylate may be 2,000 to 300,000. If the weight average molecular weight of the polymethyl methacrylate is less than 2,000, the compatibility between the first polymer and the second polymer is increased and the solubility difference in the solvent is not so large that phase separation is difficult to occur, and if the molecular weight exceeds 300,000, The viscosity of the composition may be high, making it difficult to control operations such as spin coating.

When using polystyrene as the second polymer, the weight average molecular weight of the polystyrene may be 2,000 to 300,000. If the weight average molecular weight of the polystyrene is less than 2,000, the compatibility between the first polymer and the second polymer is increased and the solubility difference in the solvent is not so large that phase separation is unlikely to occur. If the molecular weight exceeds 300,000, the viscosity of the mold composition is increased. This may make it difficult to control operations such as spin coating.

Preparation of the composition for a mold may be formed by mixing a first polymer solution comprising a first polymer and a solvent and a second polymer solution comprising a second polymer and a solvent. In this case, the volume ratio of the first polymer solution and the second polymer solution used may be 8: 2 to 5: 5.

When the content of the first polymer solution and the second polymer solution satisfies the above range, the first polymer phase, which is a main component in the coating layer for the mold, forms a matrix while the second polymer phase, which is another component, may form an island shape. When the content of the first polymer solution and the second polymer solution is out of the above range, the first polymer phase and the second polymer phase do not phase separate and form a continuous nanostructure, or the nanopattern formed on the coating layer for the mold becomes too small or too Can be large.

In the composition for mold, the content of the first polymer and the second polymer may be 0.1 to 10 parts by weight independently of each other based on the composition for the mold. When the content of the first polymer and the content of the second polymer satisfies the above range, it is possible to form an appropriate coating layer by excellent solubility of the composition for mold and easy application and drying on a substrate.

When the mold composition formed by mixing the first polymer solution and the second polymer solution is applied and dried on a substrate, the solvent coating of the mold composition is evaporated to form a mold coating layer separated into a first polymer phase and a second polymer phase. .

Conditions such as the affinity of the first polymer and the solvent for the second polymer, the functional group, the molecular weight, the mixing ratio, and the concentration of the first polymer solution and the second polymer solution are determined by the rheological behavior of each polymer, and the interface characteristics between each polymer and the substrate. The first polymer phase and the second polymer phase have a laterally irregular width and alternately exist on the substrate, thereby forming a phase-separated mold coating layer. Phase separation may be formed to a width of several tens to hundreds of nanosizes.

The mold having an irregular nano-sized pattern (nano pattern) is formed by removing the second polymer phase from the phase-separated mold coating layer. Removal of the second polymer phase can be carried out by an optional solvent that is soluble only in the second polymer phase.

The nanopattern may include a cylindrical pore. When the nanopattern includes a cylindrical pore, a nanopillar having a shape engaged with the nanopattern may be easily manufactured.

Since the first polymer and the second polymer in the mold composition have different affinity for the solvent, the coating layer for the mold formed by applying and drying the mold composition is alternately formed with the first polymer phase and the second polymer phase phase separated. . Since the first polymer phase and the second polymer phase have different solubility, one polymer phase may be removed with a selective solvent to form a nanopattern. For example, the second polymer phase can be removed.

A mold having a nanopattern is obtained by removing the second polymer phase from the phase-separated mold coating layer.

The kind, functional group, molecular weight, and mixing ratio of the first polymer and the second polymer; Type of solvent; Concentration of the first polymer solution and the second polymer solution; And the shape, size, and width of the nanopattern formed on the mold by controlling the coating layer formation conditions and the like.

The nanopillar layer is formed by adding a composition for the nanopillar layer on the mold having the nanopattern thus formed and curing the nanopillar layer. Since the nanopillars are formed in engagement with the nanopatterns formed in the mold, the nanopillars may be adjusted to the desired shape, size, and width by controlling the nanopatterns of the mold.

Hereinafter, an organic light emitting device including a light extraction enhancement layer according to an embodiment will be described with reference to FIG. 2.

2 schematically illustrates a cross-sectional view of an organic light emitting device 100 having a light extraction enhancement layer 30 according to one embodiment.

The organic light emitting device 100 having the light extraction enhancement layer 30 according to the embodiment includes a substrate 10, a light extraction enhancement layer 30 formed on the substrate 10, and the light extraction enhancement layer 30. ) An organic layer 70 interposed between the first electrode 50, the second electrode 90 facing the first electrode 50, and the first electrode 50 and the second electrode 90. ).

The light extraction enhancement layer 30 includes a nano pillar layer 33 and a planarization layer 35 formed on the nano pillar layer.

The light extraction enhancement layer 30 improves the extraction rate of light extracted from the organic layer 70 to the outside by the nano pillar layer 33 and the planarization layer 35 constituting the light extraction enhancement layer 30.

The nano pillars constituting the nano pillar layer 33 may have a cylindrical shape. The cylindrical shape has a diameter of several hundred nanometers, and thus the cylindrical shape randomly arranged at intervals of several hundred nanometers can extract light with high efficiency without depending on the change of the wavelength spectrum and the viewing angle in the visible light region.

As described above, the type, functional group, molecular weight, and mixing ratio of the first polymer and the second polymer; Type of solvent; Concentration of the first polymer solution and the second polymer solution; And the nano-pattern formed in the mold by controlling the coating layer forming conditions and the like, and including the cylindrical pores. The nano-pillar layer composition is applied onto the mold thus prepared and pressurized with a substrate to engage with the cylindrical pores of the mold. The nanopillar layer 33 which has a nanopillar of a shape (cylindrical shape) can be formed.

The height of the nanopillars may be 50 nm to 500 nm, the diameter may be 50 nm to 1,000 nm, and the gap between the nano pillars may be 50 nm to 1,000 nm. When the height, diameter, and spacing of the nanopillars satisfy the above ranges, the nanopillars may have a height and a spacing of 1/4 or more of the wavelength of light extracted from the organic layer 70 to the outside, thereby increasing the light extraction effect. The higher the height of the nano-pillar can expect a better light extraction effect, but may have difficulties in the manufacturing process.

The planarization layer 35 is formed on the nano pillar layer 33. In detail, the lower part of the planarization layer 35 is formed by filling the planarization layer composition in the space between the nano pillars formed by the nano pillars constituting the nano pillar layer 33, and the upper part of the planarization layer 35. Is formed in a flat shape that is surface-treated so that there is no gap with the organic layer.

The nano pillar layer 33 may contact the planarization layer 33. When the nano pillar layer 33 contacts the planarization layer 33, the unevenness may occur at the interface between the nano pillar layer 33 and the planarization layer 33, which may contribute to the improvement of the light extraction efficiency.

The thickness of the light extraction enhancement layer 30 except for the height of the nano pillars constituting the nano pillar layer 33 may be 0 to 300 nm. When the planarization layer 35 is thinner and satisfies the above range, the planarization layer 35 may appropriately offset and planarize the unevenness generated by the nano pillar layer 33.

When the light generated in the organic layer 70 and extracted to the outside of the organic light emitting device 100 reaches the interface between the nano pillar layer 33 and the planarization layer 35, total reflection is minimized at the interface and constructive interference occurs. Therefore, the light extraction rate generated in the organic layer 70 and directed toward the substrate 10 is greatly improved in the light extraction enhancement layer 30.

Referring to the manufacturing method of the organic light emitting device 100 having the light extraction enhancement layer 30 according to an embodiment as follows.

As the board | substrate 10, the board | substrate used for the conventional organic light emitting element can be used. As the substrate forming material, a glass substrate or a transparent plastic substrate having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproofness can be used.

A nano pillar layer 33 having a nano pillar is formed on the substrate 10, and a planarization layer 35 is formed on the nano pillar layer 33.

The first electrode 50 is formed on the planarization layer 35. The first electrode 50 may be an anode which is a hole injection electrode. In this case, the first electrode forming material may be formed using transparent and excellent indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2), zinc oxide (ZnO), or magnesium (Mg). ), Aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In) or magnesium-silver (Mg-Ag) or the like may be formed as a reflective electrode. . For example, indium zinc oxide may be used as the first electrode forming material.

The organic layer 70 is formed on the first electrode 50. The organic layer 70 may include a hole injection layer, a hole transport layer, a buffer layer, a light emitting layer, an electron transport layer, and an electron injection layer in the structure of a single layer or a composite layer. As the organic layer forming material, a low molecular or high molecular organic material may be used. The hole injection layer may be formed using a known hole injection layer forming material on the first electrode 50. For example, 2-TNATA may be used as the hole injection layer forming material.

The hole transport layer may be formed on the hole injection layer by using a known hole transport layer forming material. Examples of the hole transport layer forming material include NPB (N, N'-di (1-naphthyl) -N, N'-diphenylbenzidine (N, N'-di (1-naphthyl) -N, N'-). diphenylbenzidine)) can be used.

An emission layer may be formed on the hole transport layer. The light emitting layer may be formed using a known light emitting layer forming material, or using a known host and dopant.

An electron transport layer may be formed on the emission layer. The electron transport layer can be formed using a known electron transport layer forming material. For example, Alq3, TPBI (2,2 ', 2 "-(1,3,5-phenylene) tris (1-phenyl) -1H-benzimidazol), PBD (2-Biphenyl- 4-yl-5- (4-tert-butyl-phenyl)-[1,3,4] oxadiazole), PF-6P (perfluoronated chemical) or PyPySPyPy (2,5-bis (6 ') -(2 ', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsiylol can be used.

An electron injection layer may be stacked on the electron transport layer to facilitate the injection of electrons from the cathode. As the electron injection layer forming material, any known material such as LiF, NaCl, CsF, Li ₂ O, or BaO may be used.

The second electrode 90 is formed on the organic layer 70. The second electrode 90 may be a cathode which is an electron injection electrode. In this case, as the metal for forming the second electrode, a metal, an alloy, an electrically conductive compound having a low work function, and a mixture thereof may be used. For example, the second electrode 90 may be lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), or magnesium. -Can be formed into a thin film using silver (Mg-Ag) or the like. On the other hand, the transmissive electrode may be formed using ITO and IZO to obtain a top light emitting device.

A display device according to an embodiment includes an organic light emitting device having the light extraction enhancement layer. The display device includes a transistor including a source, a drain, a gate, and an active layer, and an organic light emitting device including the light extraction enhancement layer, and a first electrode of the organic light emitting device may be electrically connected to one of the source and the drain. have.

Hereinafter, an organic light emitting diode according to an embodiment of the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples.

Example  One

A polymethyl methacrylate having a weight average molecular weight of 8,000 was dissolved in a tetrahydrofuran solvent to prepare a polymethyl methacrylate solution having a concentration of 1.5 wt%, and polystyrene having a weight average molecular weight of 10,000 was dissolved in a tetrahydrofuran solvent at 1.5 wt% Polystyrene solutions of concentration were prepared.

The polymethyl methacrylate solution and the polystyrene solution were mixed at a volume ratio of 6: 4 to prepare a mold composition.

The mold composition was spin-coated on a glass plate at 1000 rpm for 40 seconds to form a coating layer for a mold.

The mold coating layer was immersed in cyclohexane for 1 minute to remove the polystyrene phase, thereby preparing a mold having a nano pattern on one surface.

Example  2

A mold was prepared in the same manner as in Example 1 except that the polymethylmethacrylate solution and the polystyrene solution were mixed at a volume ratio of 5: 5 to prepare a mold composition.

Example  3

A mold was prepared in the same manner as in Example 1, except that the polymethyl methacrylate solution and the polystyrene solution were mixed at a volume ratio of 7: 3 to prepare a mold composition.

Example  4

A composition comprising tri (polypropylene glycol) diacrylate was added to the mold prepared according to Example 1, and pressed with a glass substrate to prepare a nano pillar layer on which nano pillars were formed.

A planarization layer was formed on the nano pillar layer using TiO ₂ sol.

An IZO transparent electrode is formed on the planarization layer, and a hole transport layer is formed on the IZO transparent electrode by using NPB. Ir (ppy) 3 (fac-tris (2-phenylpyridine) iridium and CBP (4,4) A light emitting layer was formed using '-N, N'-dicarbazole-biphenyl) in a weight ratio of 87:13, and an electron transport layer was formed using Alq3 (tris (8-hydroxyquinolinato) aluminum). And an Al (aluminum) cathode electrode were formed, and the organic light emitting element was produced.

Comparative Example  One

An organic light-emitting device was manufactured in the same manner as in Example 4, except that the nanopillar layer and the planarization layer were not formed.

Evaluation example

An AFM image (10 μm × 10 μm standard) of the nanopatterns of the molds formed according to Examples 1 to 3 was measured and shown in FIG. 3.

Referring to FIG. 3, in the mold formed according to Example 1, it was observed that polystyrene was removed from the surface of the coating layer to form pores. The shape of the pore is cylindrical (circular in two dimensions), the diameter is approximately tens of nanometers to hundreds of nanometers in scale, and the pore distribution is relatively evenly distributed. The mold formed according to Examples 2 to 3 also observed that polystyrene was removed from the surface of the coating layer to form pores. However, in Example 2, the nano-pattern may be regarded as an intermediate form between a cylindrical pore and a continuous irregular island, and in Example 3, it may be seen that the diameter of the pore is relatively small.

From this, if the polystyrene content of the mold composition is less than that of Example 3 (polymethylmethacrylate: polystyrene = 7: 3), when the polystyrene is removed, pores of too small size are formed, making it difficult to form nanopatterns properly. If the polystyrene content is greater than that of Example 2 (polymethylmethacrylate: polystyrene = 5: 5), the pores of too large size are formed upon removal of the polystyrene and the shape of the formed pores is very incomplete. Able to know.

In order to observe the nano-pattern of the mold formed according to Example 1 in more detail, a high-magnification AFM image was measured and shown in FIG. 4.

Referring to FIG. 4, it is observed that the nanopattern of the mold formed during the process according to Example 1 has a pore diameter of 100 nm to 200 nm. It is also observed that the shape of the pore is mostly cylindrical and the pore distribution is relatively evenly distributed.

It can be seen that the mold formed according to Example 1 effectively forms a nanopattern and the nanopattern is cylindrical.

AFM images of the nano-pillar layer according to Example 4 were measured and shown in FIG. 5.

Referring to FIG. 5, it is observed that the nanopillar of the nanopillar layer according to Example 4 has a cylindrical shape, and the cylindrical shape is relatively evenly dispersed. The surface roughness of the cylinder was measured and listed in Table 1 below.

division R _pv (nm) R _q (nm) R _a (nm) Example 4 144 38 34

Referring to Table 1, it can be seen that the nanopattern of the light extraction enhancement layer according to Example 4 has a height of about 144 nm.

The driving voltage, current density, and luminance of the organic light emitting diodes formed according to Example 4 and Comparative Example 1 were measured and shown in FIG. 6.

Referring to FIG. 6, the organic light emitting diode formed according to Example 4 exhibited a driving voltage and luminance similar to those of the organic light emitting diode formed according to Comparative Example 1. That is, it can be seen that the organic light emitting device including the light extraction layer as the enhancement layer exhibits a driving voltage and luminance similar to those of the organic light emitting device without the light extraction enhancement layer.

The current density, current efficiency, and luminous efficiency of the organic light emitting diodes formed according to Example 4 and Comparative Example 1 were measured and shown in FIG. 7.

Referring to FIG. 7, it can be seen that the organic light emitting diode formed according to Example 4 has improved current efficiency and luminous efficiency compared to the organic light emitting diode according to Comparative Example 1. FIG.

10: substrate
30: light extraction enhancement layer
33: nano pillar layer
35: planarization layer
50: first electrode
70: organic layer
90: second electrode
100: organic light emitting device

Claims (12)

Applying and drying a single-phase mold composition comprising a first polymer, a second polymer and a solvent on the substrate to form a mold coating layer phase-separated into the first polymer phase and the second polymer phase, the coating layer for the mold Removing the second polymer phase in a mold to prepare a mold having a nano pattern;
Adding a composition for a nano pillar layer on the mold having the nano pattern and curing the nano pillar layer; And
Forming a planarization layer on the nano pillar layer;
Method of producing a light extraction enhancement layer comprising a. The method of claim 1,
The phase-separated mold coating layer is a method of manufacturing a light extraction enhancement layer is formed by evaporating the solvent from the single-phase mold composition. The method of claim 1,
The first polymer and the second polymer comprise polymethylmethacrylate and polystyrene, polymethylmethacrylate and polycarbonate, or polymethylmethacrylate and polyvinylchloride, and the solvent is tetrahydrofuran, methylethyl Method for producing a light extraction enhancement layer containing ketone, toluene or acetone. The method of claim 1,
Method of producing a light extraction enhancement layer of the weight average molecular weight of the first polymer and the second polymer is independently from each other 2,000 to 300,000. The method of claim 1,
Method of producing a light extraction enhancement layer is the content of the first polymer and the second polymer is 0.1 to 10% by weight independently of each other based on the total weight of the composition for the mold. The method of claim 1,
The mold composition may include a first polymer solution containing the first polymer and the solvent; And a second polymer solution including the second polymer and the solvent; and mixing the second polymer solution in a volume ratio of 8: 2 to 5: 5. The method of claim 1,
The nano-pattern manufacturing method of the light extraction enhancement layer comprising a cylindrical pore. Board;
A light extraction enhancement layer formed on the substrate, the light extraction layer including a nano pillar layer and a planarization layer;
A first electrode formed on the light extraction enhancement layer;
A second electrode facing the first electrode; And
An organic layer interposed between the first electrode and the second electrode;
An organic light emitting device comprising a. 9. The method of claim 8,
The organic light emitting device of the nano-pillar layer comprises a cylindrical nano-pillar. The method of claim 13,
The height of the nano-pillar is 50nm to 500nm, the diameter of the nanopillar is 50nm to 1,000nm, the interval between the nanopillar is 50nm to 1,000nm organic light emitting device. An illumination comprising the organic light emitting device according to any one of claims 8 to 10. A display device comprising the organic light emitting device according to any one of claims 8 to 10.

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