KR101958059B1 - Organic light emitting display device - Google Patents

Abstract

An organic light emitting display device is provided. An organic light emitting display according to an embodiment of the present invention includes an anode including a transparent conductive layer on a reflective layer and a reflective layer, a plurality of light emitting portions stacked on the anode, and a cathode disposed on the plurality of light emitting portions and made of a transparent conductive material do. The organic light emitting display includes an electron injection layer having a first layer made of a host and a dopant. The electron injection layer is disposed at a lower portion of the first layer, and the host And a third layer disposed on the first layer and made of a dopant. Thus, the efficiency and lifetime of the organic light emitting display device can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting diode (OLED) display, and more particularly, to a top emission organic light emitting display having improved efficiency and longevity.

The organic light emitting display device is a self light emitting display device, and unlike a liquid crystal display (LCD), a separate light source is not required, and thus the light emitting device can be manufactured in a light and thin shape. Further, the organic light emitting display device is not only advantageous from the viewpoint of power consumption by low voltage driving but also excellent in hue of color, response speed, color viewing angle, and contrast ratio (CR) and is being studied as a next generation display.

The organic light emitting display includes an organic light emitting layer in which electrons and holes are combined to emit light. 2. Description of the Related Art Generally, an OLED display includes an anode, a hole injection layer (HIL), a hole transport layer (HTL), an organic emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), and a cathode.

The OLED display is divided into a top emission type and a bottom emission type according to a direction in which light emitted from the organic light emitting layer is emitted. In the top emission organic light emitting display, light emitted from the organic light emitting layer is emitted upward through the cathode. Therefore, the bottom emission organic light emitting display, which is affected by the aperture ratio by the thin film transistor disposed under the organic light emitting layer, There is an advantage that a larger aperture ratio can be secured compared with the device. Therefore, in recent years, studies on a top emission type organic light emitting display have been actively conducted.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the performance of injecting electrons into an organic light emitting layer and to suppress the movement of holes to the electron injection layer through the organic light emitting layer to keep the holes in the organic light emitting layer, Emitting display device.

Another problem to be solved by the present invention is to change the structure of the electron injection layer of the light emitting portion located at the top of the plurality of light emitting portions without changing the structure of the organic layer optimized for the micro cavity, And a top emission type organic light emitting display device capable of improving the light emitting efficiency.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an organic light emitting display including an anode including a transparent conductive layer on a reflective layer and a reflective layer, a plurality of light emitting portions stacked on the anode, And a cathode made of a transparent conductive material. Further, the organic light emitting display includes an electron injection layer having a first layer made of a host and a dopant, the light emitting portion located at the top of the plurality of light emitting portions. The electron injection layer is disposed under the first layer and further comprises at least one of a second layer made of a host and a third layer made of a dopant disposed on the first layer. The efficiency and lifetime of the organic light emitting display can be improved by including an additional layer for suppressing diffusion of holes or an additional layer for improving electron injection performance in the electron injection layer disposed at the top.

An OLED display according to another embodiment of the present invention includes an anode and a cathode facing each other, an organic emitting layer between the anode and the cathode, and an electron injecting layer between the organic emitting layer and the cathode. In addition, the organic light emitting display includes a first layer composed of a dopant and a host, the electron injection layer. The electron injection layer further includes a second layer disposed on the lower portion of the first layer or a third layer made of a host disposed on the first layer and made of a dopant.

The details of other embodiments are included in the detailed description and drawings.

The present invention can improve the electron injection performance into the organic light emitting layer by including an additional layer for improving the electron injection performance in the electron injection layer disposed at the top.

In addition, the present invention can suppress the phenomenon that holes move through the organic light-emitting layer to the electron-injecting layer by including an additional layer for hindering the movement of holes in the electron-injecting layer disposed at the top.

Further, as described above, the present invention can improve the electron injection performance and suppress the movement of holes to the electron injection layer, thereby improving the efficiency and lifetime of the organic light emitting display device.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1A is a schematic cross-sectional view illustrating an organic light emitting display according to an embodiment of the present invention.
1B is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting display according to an embodiment of the present invention.
1C is a schematic cross-sectional view illustrating an optical path of light emitted from a third organic light emitting layer in an organic light emitting display according to an embodiment of the present invention.
2 is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting display according to another embodiment of the present invention.
3 is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting diode display according to another embodiment of the present invention.
4 is a schematic cross-sectional view for explaining a plurality of organic layers of the organic light emitting diode display according to Comparative Example 1. Fig.
5 is a schematic cross-sectional view for explaining a plurality of organic layers of an organic light emitting diode display according to a second comparative example.
6 is a diagram showing lifetime of blue light emission in the organic light emitting display devices according to Examples 1, 2, 3, and Comparative Example 1 and Comparative Example 2, respectively.
FIG. 7 is a diagram showing lifetime of yellow green light emission in the organic light emitting display according to Examples 1, 2, and 3 and Comparative Example 1, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Where the terms "comprises", "having", "done", and the like are used in this specification, other portions may be added unless "only" is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

An element or layer is referred to as being another element or layer "on ", including both intervening layers or other elements directly on or in between.

Although the first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

1A is a schematic cross-sectional view illustrating an organic light emitting display according to an embodiment of the present invention. 1A, an OLED display 100 according to an embodiment of the present invention includes a substrate 181, a thin film transistor 190, an anode 160, a plurality of organic layers EL1, and a cathode 170 .

The OLED display 100 includes a plurality of sub pixels. The sub-pixel is a minimum unit area in which the actual light is emitted. In addition, a plurality of sub-pixels may be gathered to form a minimum group capable of expressing white light, and for example, a red sub-pixel, a green sub-pixel and a blue sub-pixel may form a group. However, the present invention is not limited thereto, and a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel may form a group, and various sub-pixel designs are possible. In FIG. 1A, only one sub-pixel of the plurality of sub-pixels of the organic light emitting display 100 is shown for convenience of explanation.

The OLED display 100 according to an embodiment of the present invention is a top emission type OLED display. The OLED display 100 includes a plurality of OLEDs OLED1, OLED1, OLED2, OLED display device 100, OLED display device 100, OLED display device 100, OLED display device 100, OLED display device 100,

The substrate 181 is made of an insulating material to support various components of the organic light emitting diode display 100. For example, the substrate 181 may be made of a material having flexibility, such as glass or plastic.

A buffer layer 182 is formed on the substrate 181 to protect various components of the organic light emitting diode display 100 from the penetration of moisture (H ₂ O) and hydrogen (H ₂ ) from the outside of the substrate 181 do. However, the buffer layer 182 may be omitted depending on the structure and characteristics of the OLED display 100.

A thin film transistor 190 including a gate electrode 191, an active layer 192, a source electrode 193 and a drain electrode 194 is formed on the buffer layer 182. [ For example, an active layer 192 is formed on a substrate 181, and a gate insulating layer 184 is formed on the active layer 192 to insulate the active layer 192 from the gate electrode 191 . An interlayer insulating layer 183 for insulating the gate electrode 191 from the source electrode 193 and the drain electrode 194 is formed and the source electrode 193 is formed on the interlayer insulating layer 183 in contact with the active layer 192 193 and a drain electrode 194 are formed. 1A, only the driving thin film transistors among various thin film transistors that can be included in the OLED display 100 are shown for the sake of convenience, but switching thin film transistors, capacitors, and the like may be included in the organic light emitting display 100. Also, although the thin film transistor 190 is described as a coplanar structure in this specification, a thin film transistor having a staggered structure may also be used.

A planarization layer 185 is formed on the thin film transistor 190. The planarization layer 185 flattens the top of the substrate 181. The planarization layer 185 may be composed of a single layer or a plurality of layers, and may be formed of an organic material. For example, the planarization layer 185 may be made of an acryl based organic material, but is not limited thereto. The planarization layer 185 includes a contact hole for electrically connecting the thin film transistor 190 and the anode 160.

The anode 160 is disposed on the planarization layer 185. The anode 160 is an electrode configured to supply holes to the organic light-emitting layer among the plurality of organic layers EL1. The anode 160 includes a reflective layer 161 and a transparent conductive layer 162.

In the top emission type organic light emitting diode display, the reflective layer 161 is configured such that light emitted from the plurality of organic layers EL1 is reflected and emitted more smoothly upward. The reflective layer 161 may be made of a material having excellent reflectivity, for example, silver (Ag) or an alloy containing silver, for example, silver or APC (Ag / Pd / Cu). The transparent conductive layer 162 is formed of a transparent conductive material and may be formed of a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO) ). As described above, the anode 400 may have a two-layer structure in which a transparent conductive layer formed of a transparent conductive material and a reflective layer are sequentially stacked, and a three-layer structure in which a transparent conductive layer, a reflective layer, Structure.

The anode 160 is electrically connected to the thin film transistor 190 through the contact hole of the planarization layer 185 and may be electrically connected to the source electrode 193 of the thin film transistor 190, for example. The anode 160 is spaced apart from the sub-pixels.

A bank 186 is formed on the anode 160 and the planarizing layer 185. The bank 186 distinguishes adjacent sub-pixels. In addition, the bank 186 may divide pixels constituted by a plurality of sub-pixels. For example, the bank 186 may be made of an acryl based resin or a benzocyclobutene (BCB) based resin, but is not limited thereto

The cathode 170 is disposed on the anode 160. The cathode 170 supplies electrons to the plurality of organic layers EL1. The cathode 170 is formed of a conductive material having a low work function since it must supply electrons. In the OLED display 100 according to an exemplary embodiment of the present invention, the cathode 170 is formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin oxide (ITO), zinc oxide (ZnO), and tin oxide (TiO) based transparent conductive oxide.

A plurality of organic layers (EL1) are disposed between the anode (160) and the cathode (170). Hereinafter, FIG. 1B will be referred to for a more detailed description of the plurality of organic layers EL1.

1B is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting display according to an embodiment of the present invention. Referring to FIG. 1B, a plurality of organic layers EL1 includes a plurality of light emitting portions 110, 120, and 130 and a plurality of charge generating layers 140 and 150. Referring to FIG. The plurality of organic layers EL1 may include a first light emitting portion 110, a first charge generating layer 140, a second light emitting portion 120, a second charge generating layer 150, and a third light emitting portion 130 ).

The first light emitting portion 110 is stacked on the anode 160 to emit light of a first color. The first light emitting portion 110 includes a first hole injection layer (HIL) 111 disposed on the anode 160, a first hole injection layer 111 disposed on the first hole injection layer 111, A hole transport layer (HTL) 112, a first organic emission layer (EML) 113 disposed on the first hole transport layer 112, and a first organic emission layer And an electron transport layer (ETL) The first hole injection layer 111 is an organic layer that smoothly injects holes from the anode 160 into the first organic emission layer 113. The first hole injection layer 111 may be formed of, for example, HATCN (dipyrazino [2,3-f: 2 ', 3'-h] quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc ) And NPD (N, N'-bis (naphthalene-1-yl) -N, N'-bis (phenyl) -2,2'-dimethylbenzidine) It is not limited. The first hole injection layer 111 may be omitted depending on the structure and characteristics of the device.

The first hole transport layer 112 is an organic layer that transports holes from the first hole injection layer 111 to the first organic emission layer 113. The first hole transporting layer 112 facilitates the transport of holes and may be formed of NPD (N, N'-bis (naphthalene-1-yl) -N, N'- TPD (N, N'-bis- (3-methylphenyl) -N, N'-bis- (phenyl) benzidine), s-TAD (2,2 ', 7,7'- tetrakis ) -9,9-spirofluorene) and MTDATA (4,4 ', 4 "-Tris (N-3-methylphenyl-N-phenylamino) -triphenylamine). The first hole transporting layer 112 may be omitted depending on the structure and characteristics of the device.

The first organic light emitting layer 113 is disposed on the first hole transporting layer 112. The first organic emission layer 113 may include a material capable of emitting light of a specific color. For example, the first organic light emitting layer 113 may include a light emitting material capable of emitting red light, green light, blue light, or sulfur green light. However, it is not limited thereto and may include a luminescent material capable of emitting light of a different color.

For example, when the first organic emission layer 113 emits red light, the first organic emission layer 113 may include, for example, CBP (4,4'-bis) carbozol-9-yl) biphenyl or (piq) ₃ (tris (1-phenylisoquinoline) iridium), Ir (piq) ₂ (acac) (bis (DBM) 3 (Phen), or a phosphorescent material containing a dopant including at least one selected from the group consisting of 1-phenylisoquinoline (acetylacetonate) (iridium) and PtOEP (octaethylporphine platinum) ) Or a fluorescent material including perylene, but is not limited thereto.

When the first organic emission layer 113 emits green light or sulfur green light, the first organic emission layer 113 includes a host material including, for example, CBP or mCP, and Ir (ppy) And a phosphorescent material including a dopant material such as Ir complex including tris (2-phenylpyridine) iridium. Alternatively, the phosphorescent material may be composed of a fluorescent material containing Alq ₃ (tris (8-hydroxyquinolino) aluminum) But is not limited thereto.

When the first organic emission layer 113 emits blue light, the first organic emission layer 113 includes a host material including, for example, CBP or mCP, and FIrPic (bis (3,5- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium. The first organic emission layer 113 may include spiro-BDAVBi (2,7 at least one selected from the group consisting of -bis [4- (diphenylamino) styryl] -9,9'-spirofluorene), distybylbenzene (DSB), distyrylarylene (DSA), PFO- But it is not limited thereto.

The first electron transport layer 114 is an organic layer disposed on the first organic emission layer 113 and transferring electrons from the first charge generation layer 140 to the first organic emission layer 113. The thickness of the first electron transporting layer 114 can be adjusted in consideration of the electron transporting property. The first electron transport layer 114 may be formed of, for example, Liq (8-hydroxyquinolinolato-lithium), PBD (2- (4-biphenyl) -5- (4-phenyl-5-tert-butylphenyl-1,2,4-triazole), spiro-PBD and bis (2-methyl-8-quinolinolate) -4- (phenylphenolato) aluminum ), But the present invention is not limited thereto. The first electron transport layer 114 may be omitted depending on the structure or characteristics of the OLED display 100.

Although not shown in FIG. 1B, a first electron injection layer (EIL) may be disposed on the first electron transport layer 114 as needed. The first electron injection layer can smoothly inject electrons from the first charge generation layer 140 into the first organic emission layer 113. The first electron injection layer may be a HAT-CN (dipyrazino [2,3-f: 2 ', 3'-h] quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine) , N'-bis (naphthalene-1-yl) -N, N'-bis (phenyl) -2,2'-dimethylbenzidine).

A first charge generation layer (CGL) 140 is disposed between the first light emitting portion 110 and the second light emitting portion 120. The first charge generating layer 140 controls the charge balance of the first organic light emitting layer 113 of the first light emitting portion 110 and the second organic light emitting layer 123 of the second light emitting portion 120. The first charge generating layer 140 includes a first N-type charge generating layer (N-CGL) 141 and a first P-type charge generating layer (P-CGL) 142.

The first N-type charge generation layer 141 injects electrons into the first light emitting portion 110. The first N-type charge generation layer 141 may include an N-type dopant and an N-type host material.

More specifically, the N-type dopant improves the electric conductivity of the first N-type charge generation layer 141. The N-type dopant may be a metal of Group 1 and Group 2 on the periodic table, or an organic material capable of electron injection or a mixture thereof. Specifically, the N-type dopant may be any one of an alkali metal and an alkaline earth metal. Here, the alkali metal may be lithium (Li), cesium (Cs), sodium (Na) and potassium (K), and the alkaline earth metal may be Sr, Ba, Mg), and the like, but is not limited thereto.

The first P-type charge generation layer 142 injects holes into the second light emitting portion 120. The first P-type charge generation layer 142 is disposed on the first N-type charge generation layer 141 and has a structure bonded to the first N-type charge generation layer 141.

The first P-type charge generation layer 142 may include a P-type dopant and a P-type host material. The P-type dopant may be a metal oxide, tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), dipyrrazino [2,3-f: 2 ', 3'-h] quinoxaline-2,3,6 , 7,10.11-hexacarbonitrile), hexaazatriphenylene or the like, or a metal material such as V ₂ O ₅ , MoOx, WO _3, or the like. The P-type host material may be a material capable of transporting holes, for example, NPD (N, N'-bis (naphthalene-1-yl) -N, N'- TPD (N, N'-bis- (3-methylphenyl) -N, N'-bis- (phenyl) -benzidine) and MTDATA (4,4 ' -amino) -triphenylamine), but the present invention is not limited thereto.

On the other hand, the first N-type charge generation layer 141 and the first P-type charge generation layer 142 may be made of the same material or different materials. When the first P-type charge generation layer 142 and the first N-type charge generation layer 141 are made of the same material, the first P-type charge generation layer 142 and the first N-type charge generation layer 141 Since the interface can be removed, the lifetime of the device can be improved. On the other hand, when the first P-type charge generation layer 142 and the first N-type charge generation layer 141 are made of different materials, they may be advantageous in terms of transfer efficiency such as transfer and migration of carriers of electrons or holes.

In some embodiments, the first charge generating layer 140 may be formed as a single layer without including the first N-type charge generating layer 141 and the first P-type charge generating layer 142 as described above have. The first charge generation layer 140 may be omitted depending on the structure and the characteristics of the OLED display 100.

The second light emitting unit 120 is disposed on the first light emitting unit 110 to emit light of a second color. Specifically, the second light emitting portion 120 includes a second hole transporting layer 122, a second organic light emitting layer 123, and a second electron transporting layer 124.

The second hole transport layer 122 is an organic layer that transfers holes from the first P-type charge generation layer 142 to the second organic emission layer 123. The second hole transport layer 122 may be formed of the same material as the first hole transport layer 112 and may perform the same function, so that a detailed description thereof will be omitted.

The second organic light emitting layer 123 is disposed on the second hole transporting layer 122. The second organic light emitting layer 123 may include a material capable of emitting light of a specific color. For example, the second organic light emitting layer 123 may include a light emitting material capable of emitting red light, green light, blue light, or sulfur green light. However, it is not limited thereto and may include a luminescent material capable of emitting light of a different color. The second organic light emitting layer 123 may be formed of the same material as the first organic light emitting layer 113 when the second organic light emitting layer 123 is configured to emit light of the same color as that of the first organic light emitting layer 113.

The second electron transport layer 124 is disposed on the second organic light emitting layer 123. The second electron transporting layer 124 is made of the same material as the first electron transporting layer 114 and can perform the same function, so that a detailed description thereof will be omitted.

Although not shown in FIG. 1B, a second electron injection layer may be disposed on the second electron transport layer 124, and a second hole injection layer may be disposed below the second hole transport layer 122, if necessary.

The second charge generation layer 150 is disposed between the second light emitting portion 120 and the third light emitting portion 130. The second charge generating layer 150 regulates the charge balance of the second organic light emitting layer 123 and the third organic light emitting layer 133. The second charge generating layer 150 includes a second N-type charge generating layer 151 and a second P-type charge generating layer 152. The second N-type electron generating layer 151 of the second charge generating layer 150 is made of the same material as the first N-type electron generating layer 141 of the first charge generating layer 140 and performs the same function . The second P-type electron generating layer 152 of the second charge generating layer 150 is made of the same material as the first P-type electron generating layer 151 of the first charge generating layer 140 and has the same function Can be performed. Therefore, detailed description of the second charge generating layer 150 will be omitted.

The third light emitting portion 130 is disposed on the second charge generation layer 150 to emit light of a third color. The third light emitting unit 130 is a light emitting unit located at the top of the plurality of light emitting units 110, 120, and 130. The third light emitting portion 130 includes a third hole transport layer 132, a third organic emission layer 133, a third electron transport layer 134, and a third electron injection layer 135.

The third hole transport layer 132 is an organic layer that transports holes from the second P-type charge generation layer 152 to the third organic emission layer 133. The third hole transporting layer 132 is made of the same material as the first hole transporting layer 112 and can perform the same function, so a detailed description will be omitted.

The third organic light emitting layer 133 is an organic light emitting layer that is disposed on the third hole transporting layer 132 and emits light of a third color. The third organic emission layer 133 may include a material capable of emitting light of a specific color. For example, the third organic light emitting layer 133 may include a light emitting material capable of emitting red light, green light, blue light, or sulfur green light. However, it is not limited thereto and may include a luminescent material capable of emitting light of a different color. The second organic emission layer 133 may be formed of the same material as the first organic emission layer 113 when the third organic emission layer 133 is configured to emit light of the same color as that of the first organic emission layer 113.

As described above, the first organic light emitting layer 113, the second organic light emitting layer 123, and the third organic light emitting layer 133 can emit any one of red light, green light, blue light, and sulfur green light.

In the organic light emitting diode display 100 according to an embodiment of the present invention, the first organic light emitting layer 113 includes blue light, the second organic light emitting layer 123 includes yellow green light, and the third organic light emitting layer 133 ) Emit blue light, and the plurality of organic layers EL1 emit white light. Further, in the case of emitting white light in a plurality of organic layers EL1, a color filter may be disposed on the cathode 170. [

The third electron transporting layer 134 is disposed on the third organic light emitting layer 133. The third electron transporting layer 134 is made of the same material as the first electron transporting layer 114 and can perform the same function, so that a detailed description thereof will be omitted.

The third electron injection layer 135 is disposed on the third electron transport layer 134. The third electron injection layer 135 may facilitate the injection of electrons from the cathode 170 into the plurality of organic layers EL1 and the holes injected from the second charge generation layer 150 may pass through the third organic emission layer 133, To the third electron injecting layer 135 through the first electron injecting layer 135. The third electron injection layer 135 includes a first layer 135a composed of a host and a dopant and a second layer 135b disposed below the first layer 135a and composed of only the same host as the host constituting the first layer 135a 135b.

Specifically, the first layer 135a of the third electron injection layer 135 smoothly injects electrons from the cathode 170 into the third organic emission layer 133. [ The first layer 135a is a mixed layer of a host having an electron transporting property and a dopant.

The second layer 135b of the third electron injection layer 135 is made of the same host material as the host constituting the first layer 135a. The second layer 135b serves as a hole blocking layer for suppressing the phenomenon that the holes move in the cathode direction beyond the third organic light emitting layer 133. [

The dopant used in the first layer 135a may be a metal of Group 1 and Group 2 on the periodic table or an organic material capable of injecting electrons or a mixture thereof. Specifically, the dopant may be any one of an alkali metal and an alkaline earth metal. Here, the alkali metal is lithium (Li), cesium (Cs), sodium (Na), rubidium (Rb), potassium (K) and the like, and the alkaline earth metal is calcium (Ca), strontium (Sr) ), Radium (Ra), magnesium (Mg), and the like. Although not limited thereto, it may be more desirable to use a metal material such as an alkali metal or an alkaline earth metal rather than an alkali halide for improved electron injection performance as a dopant of the first layer 135a.

Host used for the first layer (135a) and second layer (135b) has, may be a compound having electron transporting performance, for _{example, Alq 3 (tris (8-} hydroxyquinolino) aluminum), BAlq (bis (2 (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole), BCP (2,9-Dimethyl -4,7-diphenyl-1,10-phenanthroline), but the present invention is not limited thereto. In particular, it is more preferable that the host is a heterocyclic compound having nitrogen molecules so that electrons can be stably transferred to the third organic luminescent layer 133. For example, the host used in the first layer 135a and the second layer 135b may be a triazine derivative, a hydroxyquinoline derivative, a benzazole derivative, a pyrimidine derivative, And phenanthroline derivatives, but the present invention is not limited thereto.

The host material used for the second layer 135b may be a material that is adjacent to the third electron injection layer 135 so as to block the holes that are transferred from the third organic emission layer 133 to the third electron injection layer 135 May be a compound having a HOMO level (Hest Occupied Molecular Orbitals Level) value smaller than that of the third electron transporting layer 134. More specifically, when the HOMO level value of the host constituting the second layer 135b in contact with the third electron transport layer 134 is smaller than the HOMO level value of the third electron transport layer 134, the second layer 135b, A high energy barrier is formed so that the holes to be formed in the third organic emission layer 133 through the third electron transport layer 134 can be further inhibited from being moved to the third electron injection layer 135 have. For example, the difference between the HOMO level value of the second layer 135b of the third electron injection layer 135 and the HOMO level value of the third electron transport layer 134 may be between 0.2 eV and 0.8 eV. When the HOMO level difference between the second layer 135b of the third electron injection layer 135 and the third electron transport layer 134 satisfies the above range, the lifetime and efficiency of the third organic emission layer 135 increase can do.

The HOMO level value of the second layer 135b of the third electron injection layer 135 and the HOMO level value of the third electron transport layer 134 of the OLED display 100 according to an embodiment of the present invention The HOMO level of the second layer 135b of the third electron injection layer 135 may be -5.9 eV to -6.1 eV so that the difference may satisfy 0.2 eV to 0.8 eV and the HOMO level of the third electron injection layer 135 The HOMO level is preferably -5.09 eV to -5.90 eV.

The host used for the first layer 135a and the second layer 135b may be a phenanthroline derivative in order to satisfy the above-mentioned HOMO level.

More preferably, the host used for the first layer 135a and the second layer 135b may be a compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, R ₁ to R ₃ each independently represent a substituted or unsubstituted C ₁ to C ₁₀ alkyl group, a substituted or unsubstituted C ₁ to C ₁₈ aryl group, a hydrogen atom, or a halogen atom . For example, R ₁ to R ₃ may be derivatives of phenyl, naphthalenyl, phenanthrolinyl or pyrenyl.

The Phenanthroline derivative represented by the formula (1) contains nitrogen atoms having a high electron density in the compound, so that electrons can be stably transported. In addition, since the phenansroline derivative represented by the formula (1) has a HOMO level value which is generally lower than that of the compound used in the electron transport layer, it is possible to minimize the phenomenon that the holes migrate to the electron injection layer.

On the other hand, the third electron transporting layer 134 which is in contact with the third electron injection layer 135 in correspondence with the phenanthroline derivative which is the host material constituting the first layer 135a and the second layer 135b The material is preferably an anthracene derivative. The anthracene derivative has a molecular structure that has an advantage in terms of the mobility of electrons as compared with other host materials and has excellent electron transporting ability. The HOMO level of the anthracene derivative is in the range of -5.09 eV to -5.20 eV. The difference between the HOMO level value and the phenanthroline derivative is large, and holes are injected from the third electron transport layer 134 to the third electron injection layer (135). Therefore, by using the phenanthroline derivative as the host of the third electron injection layer 135 and using the anthracene derivative as the material constituting the third electron transport layer 134, it is possible to improve the movement of electrons, Moving past can maximize the inhibiting effect.

At this time, the thickness of the first layer 135a of the third electron injection layer 135 may be 100 ANGSTROM to 300 ANGSTROM. When the thickness of the first layer 135a exceeds 300 ANGSTROM, the thickness of the organic layer increases more than necessary and the driving voltage can be increased. When the thickness of the first layer 135A is less than 100 ANGSTROM, .

In addition, the thickness of the second layer 135b of the third electron injection layer 135 may be in the range of 10 ANGSTROM to 100 ANGSTROM. When the thickness of the second layer 135b is more than 100 ANGSTROM, the electron injection performance of the third electron injection layer 135 may be deteriorated. When the thickness of the second layer 135b is less than 10 ANGSTROM, It may be difficult to suppress the phenomenon that the holes move from the gate electrode 133.

On the other hand, in the first layer 135a of the three electron injection layer 135, the dopant can be doped with a doping concentration of 1% to 5% with respect to the host. If the doping concentration of the dopant is more than 5%, leakage current may be generated and unintentional sub-pixels may operate. If the doping concentration of the dopant is less than 1%, electrons of the third electron injecting layer 135 The injection performance may be deteriorated.

The electron injection layer of a conventional organic light emitting display device is composed of a single layer doped with a metal compound or a metal halide compound on an electron transporting layer, or a single layer formed by mixing a host and a dopant. Generally, in an organic light emitting display, electrons provided from the anode and electrons provided from the cathode move to the organic light emitting layer, and holes and electrons recombine in the organic light emitting layer to form excitons, and light is emitted. However, in general, the mobility of holes is larger than the mobility of electrons. Due to this, some of the holes formed in the anode are not bound to the organic light emitting layer of the light emitting portion due to the fast mobility, and move to the electron transporting layer or the electron injecting layer beyond the organic light emitting layer. That is, a large number of holes can not form an exciton in the organic light emitting layer and form an exciton in the electron transporting layer or the electron injecting layer. As a result, the number of excitons excited in the organic light emitting layer decreases at the same driving voltage, thereby decreasing the efficiency and lifetime of the organic light emitting display.

Accordingly, the OLED display 100 according to an exemplary embodiment of the present invention includes a first layer 135a including a dopant and a host, and a first layer 135a disposed under the first layer 135a, And a third electron injection layer 135 in which a second layer 135b including only the same host as the first layer 135a is disposed. Accordingly, an energy barrier is formed between the third electron transporting layer 134 and the third electron injecting layer 135, so that it is difficult to move the holes. More specifically, the host constituting the second layer 135b is made of a material different from the host constituting the third electron transporting layer 134, so that the energy between the third electron transporting layer 134 and the third electron injecting layer 135 A barrier is formed. Therefore, it is difficult for holes to move from the third electron transport layer 134 to the third electron injection layer 135 due to the energy difference between adjacent materials. As a result, holes migrating from the third organic luminescent layer 113 to the third electron transporting layer 134 are accumulated in the third electron transporting layer 134 without being transferred to the third electron injecting layer 135. As a result, the rate of holes in the third electron injection layer 135 decreases and the number of holes that move from the third organic emission layer 113 to the third electron transport layer 134 decreases. As a result, a larger number of holes can be maintained in the third organic emission layer 133.

As described above, the organic light emitting diode display 100 has an efficiency and a lifetime of the third organic light emitting layer 133 of the third light emitting unit 130, which is the light emitting unit located at the uppermost one of the plurality of light emitting units 110, 120, And the efficiency and lifetime of the second organic light emitting layer 123 of the second light emitting portion 120 can be improved. Holes which are not moved to the third electron injection layer 135 are accumulated by the second layer 135b disposed under the first layer 135a and composed only of the host and the holes of the third organic emission layer 133 and the third electron- As the number of holes accumulated in the hole 134 increases, the movement of the hole to the upper portion is limited. As a result, the movement speed of the holes moving from the second organic emission layer 123 disposed under the third emission section 130 to the second electron transport layer 124 is also reduced, so that the holes are maintained in the second organic emission layer 123 And the number of excitons excited in the second organic light emitting layer 123 is increased. As a result, the efficiency and lifetime of the second organic light emitting layer 123 can be improved.

Hereinafter, FIG. 1C will be referred to in order to explain that the OLED display 100 according to an embodiment of the present invention may have a more advantageous effect in the OLED display of the top emission type.

1C is a schematic cross-sectional view illustrating an optical path of light emitted from a third organic light emitting layer in an organic light emitting display according to an embodiment of the present invention. 1C, among the light emitted from the third organic light emitting layer 133 of the third light emitting unit 130 located at the uppermost one of the plurality of light emitting units 110, 120, and 130, And the second light L2 is reflected by the reflective layer 161 of the anode 160 and then emitted upward.

The micro-cavity means that the light of a specific wavelength is amplified by the constructive interference because the light is reflected between two layers separated by the optical path length. The micro-cavity is also referred to as a micro-cavity effect, a micro-resonance effect. As described above, since the OLED display 100 according to an embodiment of the present invention is a top emission type OLED display, the cathode 170 disposed on the plurality of organic layers EL1 shown in FIG. Is made of a transparent conductive material. Accordingly, the first light L1 directly emitted to the upper portion of the third organic light emitting layer 133 and the second light L2 reflected to the upper portion of the reflective layer 161 of the anode 160 are subjected to constructive interference And the first distance d1, which is the distance between the third organic light emitting layer 133 and the reflective layer 161, should be set.

Although not shown in FIG. 1C, light emitted directly to the upper portion of the light emitted from the second organic light emitting layer 123 and the first organic light emitting layer 113 and light reflected from the reflective layer 161 of the anode 160 The distance between each of the organic light emitting layers 113 and 123 and the reflective layer 161 should be set appropriately so that the light emitted to the upper side is subjected to constructive interference. That is, the thicknesses of the organic layers in the plurality of organic layers EL1 are determined by the micro cavities for the light emitted from the first organic light emitting layer 113, the micro cavities for the light emitted from the second organic light emitting layer 123, The micro-cavities for the light emitted from the light-emitting layer 133 must be satisfied, and the thicknesses of the respective organic layers are set by a very complicated operation.

In particular, in order to realize white light, in order to suppress a shape in which a color shift occurs due to light of a specific wavelength in the pixel region and light of a specific color other than white is emitted, 123, and 133 and the reflective layer 161 should be appropriately set.

Thus, the thickness of each organic layer is optimized so as to satisfy the above three conditions, that is, the distance condition between the organic light emitting layers 113, 123, and 133 and the reflective layer 161. However, in order to improve the efficiency and lifetime of any one of the plurality of light emitting portions 110, 120, and 130, the thickness of the organic layers between the third organic light emitting layer 133, which is the uppermost organic light emitting layer, Or when a separate organic layer is added, all three conditions described above are broken. Therefore, the thickness of the organic layer between the third organic light emitting layer 133, which is the uppermost organic light emitting layer, and the reflective layer 161 in the organic light emitting diode display 100 according to an embodiment of the present invention, which is a top emission type organic light emitting display, Or the addition of an organic layer is difficult because the design of the plurality of light emitting units 110, 120, and 130 is required to be entirely modified in order to realize a micro cavity.

Therefore, in the organic light emitting diode display 100 according to the embodiment of the present invention, the lower structure of the third organic light emitting layer 133 optimized for the micro cavity is not changed, 3 Only the configuration of the electron injection layer 135 is changed. Therefore, the first distance d1, which is the distance between the third organic luminescent layer 133 and the reflective layer 161, is not changed, and the effect of improving the light efficiency by the micro cavity is maintained, The efficiency and lifetime of the OLED display 100 can be improved. In addition, in the OLED display 100 according to an exemplary embodiment of the present invention, the performance of the electron injection layer is improved by forming additional layers within the same thickness without changing the thickness of the third electron injection layer 135 . That is, the performance of the organic light emitting diode display 100 can be improved without changing the second distance d2, which is the distance between the third organic light emitting layer 133 and the cathode 170.

2 is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting display according to another embodiment of the present invention. Referring to FIG. 2, a plurality of organic layers EL2 of the organic light emitting display includes a first light emitting portion 110, a first charge generating layer 140, a second light emitting portion 120, a second charge generating layer 150 And a third light emitting unit 230. The plurality of organic layers EL2 of the organic light emitting display shown in FIG. 2 are different from the plurality of organic layers EL1 of the organic light emitting display 100 shown in FIGS. 1A to 1C, Only the configuration of the third electron injection layer 235 of the first electron injection layer 235 is different. Therefore, detailed description of the overlapping components will be omitted.

The third electron injection layer 235 further improves injection of electrons from the cathode 170 into the plurality of organic layers EL2. The third electron injection layer 235 includes a first layer 235a made of a host and a dopant and a third layer 235b disposed on the first layer 235a and made of only the same dopant as the dopant constituting the first layer 235a 235c. Since the first layer 235a of the third electron injection layer 235 is the same as the first layer 135a shown in FIG. 1B, a duplicate description thereof will be omitted.

The third layer 235c of the third electron injection layer 235 is disposed on the first layer 235a and is a layer composed only of a dopant. The dopant constituting the third layer 235c is at least one or more of alkali metals and alkaline earth metals and includes, for example, lithium (Li), cesium (Cs), sodium (Na), rubidium (Rb) , Calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), and magnesium (Mg).

The electron injection layer having the same thickness as that of the electron injection layer composed of only the first layer which is a mixed layer of the dopant and the host is used as the third electron injection layer 235 shown in FIG. The electron injecting performance of the electron injecting layer can be greatly improved when the electron injecting layer including the first layer 235a and the third layer 235c including the dopant only is formed. When a thin third layer 235c composed only of a purely dopant is disposed on the first layer 235a, the injection of electrons moving from the cathode to the third organic emission layer 133 by the third layer 235c is further performed It becomes smooth. When the injection of electrons having a smaller mobility than holes is improved, the number of excitons formed in the third organic light emitting layer 133 is greatly increased, so that the efficiency and lifetime of the organic light emitting display device can be improved.

At this time, the thickness of the third layer 235c of the third electron injection layer 235 may be 10 Å or less. If the thickness of the third layer 235c exceeds 10 ANGSTROM, the driving voltage of the organic light emitting display device may increase and the efficiency may decrease.

In the OLED display according to another embodiment of the present invention, a first layer 235a including a dopant and a host having a thickness of 100 ANGSTROM to 300 ANGSTROM and a third layer 235C having a thickness of 10 ANGSTROM ), The efficiency and lifetime of the OLED display device can be improved.

3 is a schematic cross-sectional view illustrating a plurality of organic layers of an organic light emitting diode display according to another embodiment of the present invention. Referring to FIG. 3, a plurality of organic layers EL3 of the organic light emitting display includes a first light emitting portion 110, a first charge generating layer 140, a second light emitting portion 120, a second charge generating layer 150 And a third light emitting unit 330. [ The plurality of organic layers EL3 of the organic light emitting display shown in FIG. 3 are different from the plurality of organic layers EL1 of the organic light emitting display 100 shown in FIGS. 1A to 1C, Only the structure of the third electron injection layer 335 of the second electron injection layer 335 is different. Therefore, detailed description of the overlapping components will be omitted.

The third electron injection layer 335 is formed in such a manner that holes are prevented from moving the third organic emission layer 133 to the third electron injection layer 335 and electrons injected from the cathode 170 to the plurality of organic layers EL3 . The third electron injection layer 335 includes a first layer 335a made up of a host and a dopant, a second layer 335b disposed below the first layer 335a and made of only the same host as the host constituting the first layer 335a And a third layer 335c disposed on the first layer 335a and made of only the same dopant as the dopant constituting the first layer 335a.

The first layer 335a of the third electron injection layer 335 has the same structure as that of the first layer 135a of FIG. 1B and the second layer 335b is the same as the second layer 135b of FIG. The configuration is the same, and the third layer 335c has the same configuration as the third layer 235c of FIG. That is, the first layer 335a of the third electron injection layer 335 smoothly injects electrons from the cathode 170 into the third organic emission layer 143, and the second layer 335b emits electrons 3 migration toward the cathode 170 through the organic light emitting layer 133 and the third layer 335c further increases the injection of electrons moving from the cathode 170 to the third organic light emitting layer 133 . 3, the organic light emitting diode display according to another embodiment of the present invention has a capability of suppressing the phenomenon that holes move through the third organic emission layer 133 and the third electron injection layer 335 And the electron injection performance are simultaneously improved, and the efficiency and lifetime of the organic light emitting display device can be improved.

Hereinafter, organic light emitting display devices of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were manufactured in order to examine the effects of the present invention. However, the embodiments described below are only examples of the present invention, and the present invention is not limited to the following embodiments.

Example 1

Embodiment 1 is an organic light emitting diode display having the structure disclosed in FIG. Specifically, an anode made of MoTi having a thickness of 100 Å as a reflection layer and ITO as a transparent conductive layer having a thickness of 70 Å was formed, and then patterned so as to have an area of 2 mm × 2 mm and then cleaned. On the anode, a first hole injection layer having a thickness of 100 A containing NPD, a first hole transport layer having a thickness of 200 A including an aryl amine series material, a host of an anthracene series material, and a pyrene having a doping concentration of 4% and a first electron transporting layer having a thickness of 100 A including a heteroaryl-based material was formed on the first light emitting portion. On the first light emitting portion, a first N-type charge generation layer having a thickness of 200 A including a heteroaryl-based material host and a dopant of an alkaline earth metal material having a doping concentration of 1.2% and a first N-type charge generation layer having a thickness of 120 A Thereby forming a first charge generation layer including a P-type charge generation layer. On the first charge generation layer, a second hole transporting layer having a thickness of 950 A including an arylamine-based material, a dopant of an iridium compound having a heteroaryl-based host of 200 ANGSTROM, one host of another 200 ANGSTROM and a doping concentration of 20% And a second electron transporting layer having a thickness of 110 A including a heteroaryl-based material was formed on the first light emitting portion. On the second light-emitting portion, a 150 Å thick second N-type charge generation layer containing a heteroaryl-based material host and a dopant of an alkaline earth metal material with a doping concentration of 1.0%, and a second N-type charge generation layer containing a heteroaryl- Thereby forming a second charge generation layer including a P-type charge generation layer. A third hole transporting layer having a thickness of 140 A including an arylamine-based material, a host of an anthracene-based material, and a dopant of a pyrene derivative having a doping concentration of 4% were formed on the second charge generating layer, And a third electron transporting layer having a thickness of 230 A including the heteroaryl-based material. At this time, a 50 Å thick second layer containing a phenanthroline derivative host and a 250 Å thick first layer containing a host of a phenanthroline derivative and an alkaline earth metal material having a doping concentration of 2% as a dopant were formed on the third electron transport layer To form a third electron injection layer. A 1300 A thick cathode made of IZO was formed on the third light emitting portion, that is, the third electron injection layer, to produce a top emission type OLED display.

Example 2

Example 2 is an organic light emitting display having the structure shown in FIG. 2, and an organic light emitting display having the same structure as that of the organic light emitting display of Example 1 except for the structure of the third electron injecting layer was manufactured.

The third electron injection layer of Example 2 was formed by forming a 250 Å -thick first layer containing a phenanthroline derivative host and a 2% alkaline earth metal dopant as a dopant on the third electron transport layer, and then forming an alkaline earth metal material Lt; RTI ID = 0.0 > 2 < / RTI > thick.

Example 3

Example 3 is an organic light emitting display having the structure disclosed in FIG. 3, and an organic light emitting display having the same structure as that of the organic light emitting display of Example 1 except for the structure of the third electron injecting layer was manufactured.

The third electron injecting layer of Example 3 was formed by forming a 50 Å thick second layer containing a phenanthroline derivative host on the third electron transporting layer and forming a host layer of a phenanthroline derivative on the second layer and a doping concentration of 2% Of an alkaline earth metal material as a dopant and doping a second layer of 2 Å thickness containing an alkaline earth metal material as a dopant on the first layer.

Comparative Example 1

Comparative Example 1 is an organic light emitting display having the structure disclosed in FIG. Referring to FIG. 4, an OLED display device having the same structure as the OLED display device of Example 1 except for the structure of the third electron injection layer 435 was manufactured.

The third electron injection layer 435 of Comparative Example 1 is formed on the third electron transport layer 134 as a single layer of 300 ANGSTROM thickness containing a host of a phenanthroline derivative and an alkaline earth metal material doping concentration of 2% as a dopant .

Comparative Example 2

Comparative Example 2 is an organic light emitting display having the structure disclosed in FIG. Referring to FIG. 5, an OLED display device having the same structure as the OLED display of Example 1 except for the structure of the third electron injection layer 535 was manufactured.

At this time, the third electron injection layer 535 is formed by first forming a 3 Å thick third layer 535c on the third electron transporting layer 134 containing an alkaline earth metal dopant as a dopant, and then depositing a phenanthroline derivative host and And forming a 250 Å thick first layer 535a containing a 2% alkaline earth metal dopant as a dopant.

6 and 7 for a more detailed description of the effect of the organic light emitting display according to an embodiment of the present invention

6 is a graph showing lifetime of blue light emission in the organic light emitting display device according to Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2. FIG. FIG. 7 is a diagram showing lifetime of yellow green light emission in the organic light emitting display devices according to Examples 1, 2, 3 and Comparative Example 1. FIG. Figs. 6 and 7 are the results of measuring the luminance under the condition that a current is applied at 40 DEG C at a current density of 22.5 mA / cm < ² > to the organic light emitting display manufactured by Examples and Comparative Examples. Hereinafter, the T95 lifetime is the time for which the luminance value of 95% of the initial luminance is measured after application of the current. The longer the T95 lifetime, the longer the lifetime and the shorter the T95 lifetime, the shorter the lifetime.

Referring to FIG. 6, in the organic light emitting display device having the third electron injection layer having the thickness of 300 Å, the electron injection layer is composed of a single layer in which the dopant and the host are mixed, It can be seen that the T95 lifetime for blue light emission of Examples 1 to 3 composed of a plurality of layers was remarkably improved from 180 hours to about 310 hours. However, in the case of Comparative Example 2 in which the third layer of the third electron injecting layer consisting only of the dopant was directly in contact with the third electron transporting layer, the T95 lifetime was remarkably higher than that of Examples 1 to 3 as well as Comparative Example 1 .

Referring to FIG. 7, it can be seen that the lifetime of the organic light emitting layer disposed in the middle as well as the top organic light emitting layer can be improved. 6, the T95 lifetime for the yellowish green emitting in the second organic emission layer disposed under the third organic emission layer, which is the uppermost organic emission layer, is from 420 hours to about 480 to 480 hours, 580 hours. That is, the third electron injection layer changed in the organic light emitting display of the present invention not only improves the lifetime of the third organic emission layer, which is the nearest organic emission layer, but also improves the lifetime of the second organic emission layer there was.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: organic light emitting display
110: first light emitting portion
111: first hole injection layer
112: First hole transport layer
113: first organic light emitting layer
114: first electron transport layer
120: a second light emitting portion
122: second hole transporting layer
123: second organic light emitting layer
124: Second electron transport layer
130: Third light emitting portion
132: Third hole transport layer
133: Third organic light emitting layer
134: Third electron transport layer
135, 235, 335: a third electron injection layer
135a, 235a, and 335a:
135b, 335b: second layer
235c, 335c: third layer
140: first charge generating layer
141: First N-type charge generation layer
142: First P-type charge generation layer
150: second charge generating layer
151: a second N-type charge generation layer
152: second P-type charge generation layer
160: anode
161: Reflective layer
162: transparent conductive layer
170: cathode

Claims (15)

An anode including a reflective layer and a transparent conductive layer on the reflective layer;
A plurality of light emitting units stacked on the anode; And
And a cathode disposed on the plurality of light emitting portions and made of a transparent conductive material,
Wherein the light emitting portion located at the top of the plurality of light emitting portions includes an electron injection layer having a first layer made of a host and a dopant and an electron transport layer disposed under the electron injection layer,
Wherein the electron injection layer further comprises at least one of a second layer disposed below the first layer and a third layer comprising the host and the dopant disposed over the first layer,
Wherein a value of a HOMO level of the host is less than a HOMO level of the electron transport layer. The method according to claim 1,
Wherein the plurality of light-
A first light emitting portion disposed on the anode, the first light emitting portion including a first organic light emitting layer;
A second light emitting portion disposed on the first light emitting portion and including a second organic light emitting layer; And
And a third light emitting portion disposed on the second light emitting portion and including a third organic light emitting layer,
Wherein the third light emitting portion is a light emitting portion located at the uppermost portion,
Wherein light emitted from the first organic light emitting layer, light emitted from the second organic light emitting layer, and light emitted from the third organic light emitting layer form white light. 3. The method of claim 2,
Wherein the first organic light emitting layer and the third organic light emitting layer are configured to emit blue light,
And the second organic emission layer is configured to emit yellow-green light. An anode and a cathode facing each other;
An organic light emitting layer between the anode and the cathode; And
An electron injection layer between the organic light emitting layer and the cathode, and an electron transport layer disposed under the electron injection layer,
Wherein the electron injection layer comprises a first layer of a dopant and a host,
The electron injection layer further comprises a second layer disposed below the first layer and made of the host or a third layer disposed on the first layer and made of the dopant,
Wherein a value of a HOMO level of the host is less than a HOMO level of the electron transport layer. 5. The method of claim 4,
Further comprising one or more additional organic light emitting layers between the anode and the organic light emitting layer. 5. The method of claim 4,
Wherein the organic light emitting display is a top emission type organic light emitting display. 7. The method according to any one of claims 1 to 6,
The host may be at least one organic electroluminescent display selected from the group consisting of a triazine derivative, a hydroxyquinoline derivative, a benzazole derivative, a pyrimidine derivative, and a phenanthroline derivative. Device. 7. The method according to any one of claims 1 to 6,
Wherein the dopant is an alkali metal or an alkaline earth metal. 7. The method according to any one of claims 1 to 6,
Wherein the dopant of the first layer is doped to the host at a doping concentration of 1% to 5%. delete The method according to claim 1 or 4,
Wherein the electron transport layer comprises an anthracene derivative. delete 7. The method according to any one of claims 1 to 6,
Wherein the first layer has a thickness of 100 to 300 ANGSTROM. 7. The method according to any one of claims 1 to 6,
And the thickness of the second layer is in the range of 10 to 100 ANGSTROM. 7. The method according to any one of claims 1 to 6,
And the third layer has a thickness of 10 A or less.

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