KR101465882B1 - Organic Light Emitting Diode - Google Patents

Abstract

The present invention provides an organic light emitting diode. The organic light emitting diode comprises: a substrate; a lower transmissive electrode stacked on the substrate; an organic layer for self-emission stacked on the lower transmissive electrode; an upper electrode staked on the organic layer; a dielectric layer staked on the upper electrode; and a reflective layer staked on the dielectric layer. The dielectric layer randomly includes a concave-convex form or a porous form.

Description

[0001] The present invention relates to an organic light emitting diode (OLED)

The present invention relates to an organic light emitting diode, and more particularly to an organic light emitting diode including a dielectric layer having a curved upper surface for improving light extraction efficiency on an upper electrode.

Organic light emitting diodes (OLEDs) have been commercialized as small and medium display devices and have recently been commercialized as large displays for TV applications. Commercialization of an illumination device using an organic light emitting diode as a flat light source has also started.

In order to promote the commercialization of organic light emitting diodes and improve the competitiveness of products, improvement of luminous efficiency is the most important requirement. Up to now, optimization of the device structure of an organic light emitting diode in order to improve the luminous efficiency and development of a high-performance material have been the main technical development items. These efforts to develop the technology have increased the luminous efficiency of organic light emitting diodes and achieved commercialization. However, in order to further increase the market size of the organic light emitting diode and increase the product competitiveness, a higher level of luminous efficiency is required. However, the electrical device structure of the organic light emitting diode has already reached an optimized stage. Thus, further rapid improvement is difficult. In addition, the development of materials for organic light emitting diodes has reached a mature stage. Therefore, the speed of additional material development is very slow. Therefore, the efficiency improvement through material development is also reaching its limit.

The organic light emitting diode has an element structure including a multilayer thin film. Due to the interference phenomenon occurring in the device structure, a part of light generated in the organic layer can not be emitted to the outside. Therefore, the light which is not emitted can be trapped inside the device and eventually consumed by heat energy or the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device structure and a manufacturing method for greatly improving the light extraction efficiency of an organic light emitting diode having a bottom emission structure.

An organic light emitting diode according to an embodiment of the present invention includes a substrate; A transparent lower electrode laminated on the substrate; An organic layer laminated on the transparent lower electrode and self-emitting; An upper electrode stacked on the organic layer; A dielectric layer laminated on the upper electrode; And a reflective layer stacked on the dielectric layer, wherein the dielectric layer includes a random uneven shape or a porous shape.

In one embodiment of the present invention, one surface of the dielectric layer in contact with the upper electrode is planar, the other surface of the dielectric layer in contact with the reflective layer has a random irregular shape or a porous shape, and the roughness of the other surface of the dielectric layer, It may be more than 0.1 times the wavelength.

In one embodiment of the present invention, the refractive index of the dielectric layer may decrease with height.

In one embodiment of the present invention, the dielectric layer includes a first dielectric layer having a first refractive index; And a second dielectric layer laminated on the first dielectric layer and having a second refractive index lower than the first refractive index.

In one embodiment of the present invention, the dielectric layer is made of a material selected from the group consisting of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx, , And x and y represent molar ratios.

In one embodiment of the present invention, the thickness of the upper electrode may be 10 nm to 60 nm.

In one embodiment of the present invention, the thickness of the dielectric layer may be 100 nm to 600 nm.

A method of fabricating an organic light emitting diode according to an exemplary embodiment of the present invention includes forming a transparent lower electrode, an organic light emitting layer, and an upper electrode sequentially on a substrate; Forming a dielectric layer on the upper electrode; And forming a reflective layer on the upper electrode, wherein the refractive index of the dielectric layer decreases with height.

In one embodiment of the present invention, one surface of the dielectric layer in contact with the upper electrode is flat, and the other surface of the dielectric layer in contact with the reflective layer has a random irregular shape or a porous shape, May be simultaneously formed.

In one embodiment of the present invention, the dielectric layer may be formed by a vacuum thermal evaporation method, an electron beam evaporation method, or an ion beam evaporation method.

In one embodiment of the present invention, the dielectric layer is made of a material selected from the group consisting of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx, , And x and y represent molar ratios.

The organic light emitting diode according to one embodiment of the present invention can increase the light extraction efficiency by using the structure of the dielectric layer.

1 is a cross-sectional view illustrating a structure of a conventional bottom emission organic light emitting diode.
2 and 3 are views showing an organic light emitting diode according to one embodiment of the present invention.
FIG. 4 shows experimental results showing the current efficiency according to the thickness of the upper electrode according to an embodiment of the present invention.
FIG. 5 shows experimental results showing current efficiency according to thickness of a dielectric layer according to an embodiment of the present invention.
6 is a photograph of an upper surface taken along the thickness of CaFx which is a dielectric layer.
7A to 7D are views showing the structure of a dielectric layer according to an embodiment of the present invention.
8 is a graph showing the current efficiency according to the structure of FIG.

1 is a cross-sectional view illustrating a structure of a conventional bottom emission organic light emitting diode.

1, the organic light emitting diode 400 includes a transparent lower electrode 420, an organic layer 430, an upper electrode 440, a dielectric layer 450, and a reflective layer 460, which are sequentially stacked on a substrate 410. . ≪ / RTI > The transparent lower electrode 420 may be an anode, and the upper electrode 140 may be a reflective electrode and a cathode. The light emitted to the organic layer 430 passes through the substrate and is drawn out.

An organic layer waveguide mode in which light emitted from the organic layer 430 can travel along the organic layer 430 may be generated. The light emitted from the organic layer 430 may be emitted toward the upper electrode 440. In addition, a first surface plasmon polarity (SPP) mode may be generated at the interface between the upper electrode 440 and the organic layer 430. If the thickness of the upper electrode 440 is sufficiently thin, the first SPP mode may induce a second SPP mode on the opposite surface of the upper electrode 440. The light emitted from the organic layer 130 may be captured by the upper electrode 440 to generate a wave guide mode. In addition, light transmitted through the upper electrode 440 may be trapped by the dielectric layer 450 to generate a dielectric layer waveguide mode. In addition, light incident on the transparent lower electrode may be trapped by the transparent lower electrode to form a lower electrode waveguide mode. Further, the light incident on the substrate may be captured by the substrate to form a substrate waveguide mode.

About 80 percent of the light energy of the emitted light of the organic layer 430 is captured in the upper and lower electrode doping mode, the organic layer doping mode, and the SPP mode, As shown in FIG.

In a conventional organic light emitting diode, the ratio of light emitted from the inside to the outside through the substrate 410 is approximately 20 percent. A technique employing a micro resonance structure or a substrate scattering structure for extracting the captured light energy in these waveguide modes has been proposed.

In order to extract the light energy captured in the SPP mode or the organic layer waveguide mode, a scattering structure disposed under the device can be introduced. The scattering structure can suppress the occurrence of the SPP mode. When the above-described scattering structure is employed, problems such as a change in electrical characteristics of the device and a decrease in reliability may occur depending on the bent shape of the device. The scattering structure formed on the substrate can be realized by an expensive process such as lithography. Therefore, such a scattering structure is practically difficult to adopt.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

2 and 3 are views showing an organic light emitting diode according to one embodiment of the present invention.

2 and 3, the organic light emitting diode 500 includes a substrate 510, a transparent lower electrode 520 stacked on the substrate 510, and a transparent electrode 520 stacked on the transparent lower electrode 520, An upper electrode 540 stacked on the organic layer 530, a dielectric layer 550 stacked on the upper electrode 540, and a reflective layer 560 stacked on the dielectric layer 550. [ . The dielectric layer 550 includes a random irregular shape or a porous shape. The refractive index of the dielectric layer 550 decreases with height. One surface of the dielectric layer 550 in contact with the upper electrode 540 is planar and the other surface 551 of the dielectric layer 550 in contact with the reflective layer has a random irregular shape or a porous shape.

A method of manufacturing an organic light emitting diode includes forming a transparent lower electrode 520, an organic light emitting organic layer 530 and an upper electrode 540 on a substrate 510 in sequence, forming a dielectric layer 550 on the upper electrode 540 ), And forming a reflective layer on the dielectric layer. The dielectric constant of the dielectric layer 550 decreases with height. One surface of the dielectric layer 550 in contact with the upper electrode 540 is planar and the other surface of the dielectric layer 550 in contact with the reflective layer may have a random irregular shape or a porous shape.

The existing device fabrication process is not modified and only the fabrication process of the light extracting structure can be added. The electrical characteristics of the device are hardly affected. Therefore, it is advantageous in terms of practical applicability of the technique.

When a thin-thickness upper electrode 540 is used, light energy can be transmitted through the upper electrode 540. In this case, the first SPP mode formed at the interface between the upper electrode 540 and the organic layer 550 may transition to the second SPP mode of the opposite surface of the upper electrode 540 have. The light energy transferred to the second SPP mode on the opposite side of the upper electrode 540 may escape to the dielectric layer 550 by matching of the dielectric layer 550 located above the upper electrode 540 . The light energy exiting the dielectric layer 550 may be confined in the dielectric layer 550 in a waveguide mode. Therefore, generation of the dielectric layer waveguide mode by the dielectric layer 550 needs to be suppressed. The light reflected from the reflective layer 560 may pass through the upper electrode 540 and the organic layer 530 to be provided in the substrate direction.

Although the light energy of the second SPP mode is transferred to the dielectric layer 550 between the upper electrode 540 and the dielectric layer 550, the transferred light energy is captured in the dielectric layer doping mode of the dielectric layer 550 . Therefore, the phenomenon captured in the dielectric layer waveguide mode may be a factor limiting the light extraction efficiency.

In order to eliminate the dielectric layer waveguide mode, the upper portion of the dielectric layer 550 may have a random irregular shape, an irregular curved shape, or a porous shape. The dielectric layer 550 may be a refractive index matching layer. The curved shape may perform a scattering function. Incident light incident on the upper surface of the dielectric layer 550 may be scattered or reflected. Accordingly, the scattered light suppresses the dielectric layer guiding mode in the dielectric layer 550, and the light extraction efficiency can be improved.

It is advantageous for the dielectric layer 550 in contact with the upper electrode 540 to have a high dielectric constant in order to effectively draw the second SPP mode induced in the upper electrode 540 into the dielectric layer 550. A material that simultaneously satisfies both the high permittivity and the irregular curvature of the upper surface may be used as the dielectric layer 550. [

The dielectric layer 550 may include a first dielectric layer 552 having a high dielectric constant and a second dielectric layer 554 having a low dielectric constant and having a random irregular shape or an irregular curved shape on the upper surface thereof. The second dielectric layer 554 is deposited on the first dielectric layer 552. Accordingly, the first dielectric layer 552 serves to draw the second SPP mode into the first dielectric layer 552. [ In addition, the second dielectric layer 554 has a low refractive index and an irregular shape on the upper surface. Accordingly, the second dielectric layer 554 may provide a scattering function.

When the dielectric layer 550 is divided into a first dielectric layer having a high refractive index and a second dielectric layer having a low refractive index, a part of light incident on the first dielectric layer can not be transferred to the second dielectric layer, And can remain in the waveguide mode. In order to minimize the waveguide mode, the refractive index of the dielectric layer can be changed while gradually decreasing. The light incident on the dielectric layer can be scattered without being formed in the waveguide mode and drawn out to the outside.

The dielectric layer 550 may be divided into a lower high refractive index layer and an upper irregular shaped layer. In this case, in order to draw the first SPP mode toward the dielectric layer, the layer adjacent to the upper electrode may be formed of a high refractive index layer, and the layer located on the upper side may be formed of a layer having an irregular shape.

Referring to FIG. 3, the dielectric layer 550a may include first to fifth dielectric layers 552a to 556a. The dielectric constant of the dielectric layer 550a may decrease with height. The structure in which the refractive index of the dielectric layer gradually changes can be mixed with a first material having a high refractive index and no irregular shape and a second material having a low refractive index and having an irregular shape. Specifically, the deposition rate of the evaporation source of the first material gradually decreases, and the deposition rate of the evaporation source of the second material may increase sequentially. For example, as the thin film is deposited, the deposition rate of the first material gradually decreases, and the deposition rate of the second material may gradually increase. At the end of the deposition of the thin film, the deposition rate of the first material becomes zero, and the deposition rate of the second material may have a predetermined value. The first material may be WO ₃ or TiO 2, and the second material may be CaF ₂ . The refractive index of the dielectric layer may gradually decrease or gradually decrease as the deposition proceeds.

The reflective layer 560 may be a metal having high reflectivity. The reflective layer 560 may perform a sufficient reflection function. In the case of Al or Ag, the thickness may be more than skin depth. Specifically, the thickness of the reflective layer may be 50 nm or more.

The substrate 510 may be a transparent glass substrate or a transparent plastic substrate.

The transparent lower electrode 520 may be formed on the substrate 510. The transparent lower electrode 520 may operate as an anode. The transparent lower electrode 520 may function as a transparent electrode that transmits light. The transparent lower electrode 520 may transmit light incident on the transparent lower electrode 520 and provide the light in the direction of the substrate 510.

The transparent lower electrode 520 may be ITO having a thickness of about 150 nm. The ITO may be deposited by a sputtering method or an ion deposition method. Subsequently, the lower electrode 520 may be patterned.

The sheet resistance of the ITO is preferably as low as possible. The sheet resistance of the ITO preferably has a value of about 10? /? Or less. The smaller the surface roughness of the ITO, the better. It is preferable to have a degree of roughness of approximately Ra < 1 nm. The ITO can act as an anode of an organic light emitting diode. A transparent lower electrode pattern can be completed through a typical photolithography process. That is, a photoresist film is coated on the transparent lower electrode 520, and the photoresist film is irradiated with ultraviolet rays through a mask having a predetermined pattern. Thereafter, the photoresist film may provide a pattern through a development process. The transparent lower electrode may be etched using the pattern as an etching mask. The etching of the transparent lower electrode may be performed by a wet etching method.

The organic layer 530 may be formed on the completed lower electrode 520. The organic layer 530 may include a hole transport layer 532 and a light emitting layer 534 stacked on the hole transport layer 532. The hole transport layer 532 may be NPB (N, N'-diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine) have. The light emitting layer may be ALQ3 (Tris (8-hydroxyquinolinato) aluminum) having a thickness of about 60 nm. The light emitting layer 534 may perform light emitting and electron transporting functions. NPB and ALQ3 can be deposited by a vacuum thermal deposition process in which the material powder is heated to sublimate. Process conditions can be controlled so that the temperature of the substrate during deposition is not more than 100 degrees centigrade. The pattern of the organic layer 530 may be implemented using a shadow mask.

An upper electrode 540 may be deposited on the organic layer 530. The upper electrode 540 may include a first upper electrode 542 and a second upper electrode 544 stacked on the first upper electrode 542. The first upper electrode 542 may be Ca having a thickness of about 5 nm. The Ca layer can be deposited by a vacuum thermal deposition process. Ca acts as an electron injection layer. The second upper electrode 544 may be Ag having a thickness of about 50 nm. Ag can be deposited by a vacuum thermal deposition method. The second upper electrode 544 is used as a cathode. The process conditions are controlled so that the deposition temperature of Ca and Ag does not exceed 100 캜. The patterns of Ca and Ag can be realized by using a shadow mask made of a metal material.

The reflective layer 560 may be Ag having a thickness of about 100 nm. The reflective layer may be formed by a vacuum thermal evaporation method. The reflective layer may be patterned using a metal shadow mask. The process conditions are controlled so that the deposition temperature of the reflective layer does not exceed 100 degrees centigrade.

FIG. 4 shows experimental results showing the current efficiency according to the thickness of the upper electrode according to an embodiment of the present invention.

Referring to FIG. 4, the thickness of the upper electrode 540 may have a predetermined range. When the thickness exceeds the maximum value, the first SPP mode formed at the lower portion of the upper electrode 540 may be prevented from transitioning to the second SPP mode formed at the upper portion of the upper electrode 540. If the thickness is less than the minimum value, the upper electrode 540 may lose its function as an electrode. Specifically, in the case of the upper electrode using Ag, the thickness of the upper electrode may be in the range of about 10 nm to 60 nm.

Referring again to FIGS. 2 to 4, the higher the refractive index of the dielectric layer 550 disposed on the upper electrode 540, the more advantageous is the improvement in the light extraction efficiency. The dielectric layer 550 should not damage the organic light emitting diode device located under the dielectric layer during the deposition of the dielectric layer. In general, organic light emitting diodes can cause rapid deterioration when the temperature of the device rises above 100 degrees centigrade. Moreover, when a device is brought into contact with a highly reactive medium such as a plasma, an acid, or a base, the performance of the device sharply deteriorates. Therefore, the substrate temperature of the organic light emitting diode can be maintained at 100 degrees centigrade or less in the process of forming the dielectric layer. Also, the organic light emitting diode is prevented from contacting the reactive medium directly. Specifically, a vacuum thermal deposition method using an evaporation source sufficiently away from the substrate can be used.

The dielectric layer 550 may include a transparent high-refractive index material. The dielectric layer may include at least one of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx, have. Here, x and y may be molar ratio coefficients depending on the deposition conditions. In particular, the high refractive index material may be CaF2, WO3, LiF, FeO, ZnS, CeO2, Nb2O5, ZrO2, TiO, Ti3O5, Ta2O5, SrTiO3, Al2O3, ZrO2, SiC, HgS, GaP, GaAs, ZnO. When the dielectric layer 550 is deposited by a thermal evaporation method, the dielectric layer 550 may be in an amorphous state or in a non-crystal mixed state with an amorphous state. Mixtures or compositions of such materials may also have high refractive index properties. The refractive index n of the dielectric layer 550 may be n> 1.5. Preferably, the refractive index n of the dielectric layer 550 may be n > 1.8. The refractive index of the dielectric layer may decrease with height.

The dielectric layer 550 may include a first dielectric layer 552 having a first refractive index and a second dielectric layer 554 stacked on the first dielectric layer 552 and having a second refractive index lower than the first refractive index. have. The first refractive index n1 may be n1 > 1.5 or more. The second refractive index n2 may be less than 1.5. The first dielectric layer 552 may include at least one of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx, One can be included. The second dielectric layer 554 may be a material having a low refractive index such as CaFx and having a surface roughness.

The upper surface of the dielectric layer 550 may have a roughness satisfying Mie scattering due to particles having the same size as the wavelength of light. That is, the average peak-to-peak distance of the surface shape may have a magnitude of the center wavelength of the OLED. Specifically, the roughness may have a size of between 0.1 central wavelength and 10 central wavelength.

According to a modified embodiment of the present invention, the upper surface of the dielectric layer 550 may include a porous material.

FIG. 5 shows experimental results showing current efficiency according to thickness of a dielectric layer according to an embodiment of the present invention.

Referring to FIG. 5, the thickness of the dielectric layer 550 shows a current efficiency increase effect at about 100 nm or more. Preferably, the thickness of the dielectric layer may be between 100 nm and 600 nm. When the thickness is more than 600 nm, the increase in the current efficiency may be saturated with respect to the increase in the thickness of the dielectric layer.

In order to prevent image blur due to scattering on the dielectric layer 550, the distance from the light emitting region (organic layer) to the scattering portion, or the thickness of the dielectric layer 550, (The current device is on the order of tens of micrometers). In order to prevent screen fogging, it is advantageous that the thickness of the dielectric layer 550 is thin. Accordingly, the maximum thickness of the dielectric layer 550 may be several tens of micrometers or less.

The thickness upper limit of the dielectric layer 550 may be applied to OLEDs for display purposes. When the OLED is used as an illumination device, the upper limit of the thickness of the dielectric layer 550 may not be required.

The dielectric layer 550 may have a polycrystalline columnar structure. Specifically, the dielectric layer 550 may be ZnO. The dielectric layer 550 is deposited at a low temperature (substrate temperature of 100 degrees centigrade or less), and the dielectric layer 550 may be deposited by a vacuum thermal deposition method, an electron beam deposition method, or an ion beam deposition method. Accordingly, the dielectric layer 550 may have a film forming condition in which the substrate is not exposed to a highly reactive medium such as plasma. The dielectric layer 550 may have random roughness at the same time as deposition without additional patterning after deposition.

6 is a photograph of an upper surface taken along the thickness of CaFx which is a dielectric layer.

Referring to FIG. 6, the upper surface of the dielectric layer 550 may have a curved surface or a rough surface that can cause scattering. The dielectric layer 550 may be formed using a dielectric material in random irregularities, irregular curvature, or rough surfaces in the deposition step. At this time, an irregular curved shape or a rough surface does not appear at the initial stage of deposition of CaFx (i.e., the lower layer of the dielectric layer), and irregular curved shapes or rough surfaces may appear at a certain thickness or more. Accordingly, the thickness of the dielectric layer 550 may be 50 nm to 3000 nm. If the thickness of the dielectric layer 550 is too large, light of a predetermined pixel may affect neighboring pixels. If the thickness of the dielectric layer 550 is too small, it may be difficult to form a concave-convex structure on the upper surface. The thickness of the dielectric layer is in the order of 10 nm, 50 nm, 100 nm, 170 nm, 340 nm, and 500 nm. In the case of 100 nm or more, surface roughness is apparent.

CaFx can be deposited in an amorphous state. The mixture of CaFx and other materials (e.g., WOx) may have a similar randomly rough surface. The CaFx may be in an amorphous state and a random scattering structure may be formed on the upper surface of the thin film.

The size of the irregular curvature shape appearing on the upper surface of the dielectric layer 550 may be 0.1 to several times the center wavelength (for example, 500 nm) of the emission spectrum of the organic light emitting diode.

Specifically, the dielectric layer 550 may be CaF2. The CaF2 powder is contained in a boat made of tungsten, and the boat can be mounted inside the vacuum vessel. When power is applied to the boat in a vacuum state, a vacuum thermal deposition process can be performed.

When the thickness of CaF ₂ is 50 nm or less, irregular shapes do not appear. Therefore, CaF ₂ may preferably be formed to be about 100 nm or more. The deposition temperature of the dielectric layer 550 may not exceed 100 degrees centigrade.

7A to 7D are views showing the structure of a dielectric layer according to an embodiment of the present invention.

8 is a graph showing the current efficiency according to the structure of FIG.

7A to 7D, the dielectric layer may be formed of a material selected from the group consisting of WO ₃ 100% / WO ₃ 75% + CaF ₂ 25% / WO ₃ 50% + CaF ₂ 50% / WO ₃ 25% + CaF ₂ 75% / CaF ₂ And a layer having a total of five steps of change of 100%.

Referring to Figure 7a, a dielectric layer (ref structures) is _{WO 3 100% (60nm) /} WO 3 75% + CaF 2 25% (60nm) / WO 3 50% + CaF 2 50% (60nm) / WO 3 25% + CaF ₂ 75% (60 nm) / CaF ₂ 100% (60 nm). Here, the ratio is the molar ratio. The dielectric layer 550a may include first to fifth dielectric layers 552a to 556a.

Referring to Figure 7b, the dielectric layer (Hn structure) _{WO 3 100% (200nm) /} WO 3 75% + CaF 2 25% (25nm) / WO 3 50% + CaF 2 50% (25nm) / WO 3 25% + CaF ₂ 75% (25 nm) / CaF ₂ 100% (25 nm). The dielectric layer 550b may include first to fifth dielectric layers 552b to 556b.

Referring to Figure 7c, the dielectric layer (Mn structure) _{WO 3 100% (25nm) /} WO 3 75% + CaF 2 25% (25nm) / WO 3 50% + CaF 2 50% (200nm) / WO 3 25% + CaF ₂ 75% (25 nm) / CaF ₂ 100% (25 nm). The dielectric layer 550c may include first to fifth dielectric layers 552c to 556c.

Referring to Figure 7d, the dielectric layer (Ln structure) _{WO 3 100% (25nm) /} WO 3 75% + CaF 2 25% (25nm) / WO 3 50% + CaF 2 50% (25nm) / WO 3 25% + CaF ₂ 75% (25 nm) / CaF ₂ 100% (200 nm). The dielectric layer 550d may include first to fifth dielectric layers 552d to 556d.

Referring to FIG. 8, the Hn structure and the Mn structure have the same structure, thickness and material as the Hn and Mn structures up to the substrate / lower electrode / organic layer / Ca layer, and the Ag electrode layer formed on the Ca layer has a thickness of 150 nm The current efficiency of the Ag electrode layer was higher than that of the basic structure without the dielectric layer and the reflective layer by 15% or more.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

510: substrate
520: transparent lower electrode
530: Organic layer
540: upper electrode
550: dielectric layer
560: reflective layer

Claims (11)

Board;
A transparent lower electrode laminated on the substrate;
An organic layer laminated on the transparent lower electrode and self-emitting;
An upper electrode stacked on the organic layer;
A dielectric layer laminated on the upper electrode; And
And a reflective layer laminated on the dielectric layer,
The dielectric layer includes a random irregular shape or a porous shape,
Wherein the refractive index of the dielectric layer decreases with height. The method according to claim 1,
Wherein one surface of the dielectric layer in contact with the upper electrode is planar,
The other surface of the dielectric layer in contact with the reflective layer has a random irregular shape or a porous shape,
And the roughness of the other surface of the dielectric layer is 0.1 times or more of the wavelength of the luminescent center. delete Board;
A transparent lower electrode laminated on the substrate;
An organic layer laminated on the transparent lower electrode and self-emitting;
An upper electrode stacked on the organic layer;
A dielectric layer laminated on the upper electrode; And
And a reflective layer laminated on the dielectric layer,
The dielectric layer includes a random irregular shape or a porous shape,
Wherein the dielectric layer comprises:
A first dielectric layer having a first refractive index; And
And a second dielectric layer laminated on the first dielectric layer and having a second refractive index lower than the first refractive index. Board;
A transparent lower electrode laminated on the substrate;
An organic layer laminated on the transparent lower electrode and self-emitting;
An upper electrode stacked on the organic layer;
A dielectric layer laminated on the upper electrode; And
And a reflective layer laminated on the dielectric layer,
The dielectric layer includes a random irregular shape or a porous shape,
Wherein the dielectric layer comprises at least one of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx,
and x and y represent molar ratios. The method according to claim 1,
Wherein the thickness of the upper electrode is 10 nm to 60 nm. The method according to claim 1,
Wherein the thickness of the dielectric layer is 100 nm to 600 nm. Forming a transparent lower electrode, an organic light-emitting organic layer, and an upper electrode in sequence on the substrate;
Forming a dielectric layer on the upper electrode; And
And forming a reflective layer on the upper electrode,
Wherein the refractive index of the dielectric layer decreases with height. 9. The method of claim 8,
One surface of the dielectric layer in contact with the upper electrode is planar and the other surface of the dielectric layer in contact with the reflective layer has a random irregular shape or a porous shape,
Wherein a concave-convex shape or a porous shape of the dielectric layer is formed simultaneously with the deposition of the dielectric layer. 9. The method of claim 8,
Wherein the dielectric layer is formed by a vacuum thermal evaporation method, an electron beam evaporation method, or an ion beam evaporation method. 9. The method of claim 8,
Wherein the dielectric layer comprises at least one of CaFx, WOx, LiFx, ZnSx, CeOx, NbOx, TiOx, TaOx, SrTixOy, AlOx, ZrOx, SiCx, HgSx, GaPx, GaAsx, ZnOx, and x and y are molar ratios.

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