KR20220066029A - Organic light emitting device - Google Patents

Abstract

An organic light emitting element according to an embodiment of the present invention includes: a first electrode and a second electrode; a first light emitting unit positioned between the first electrode and the second electrode and including a hole injection layer and a first hole transport layer; and a second light emitting unit disposed on the first light emitting unit and including a second hole transport layer. The thickness of the second hole transport layer is greater than the thickness of the first hole transport layer. It is possible to improve the efficiency and lifespan of the organic light emitting element.

Description

Organic light emitting device {ORGANIC LIGHT EMITTING DEVICE}

The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device capable of improving efficiency and lifespan in the organic light emitting device.

An organic light emitting display device (OLED) is a self-emission type display device, in which electrons and holes are respectively injected into the light emitting layer from an electrode for electron injection and an anode for hole injection. This is a display device using an organic light emitting diode that emits light when excitons in which injected electrons and holes are combined fall from an excited state to a ground state.

The organic light emitting diode display is divided into a top emission method, a bottom emission method, a dual emission method, etc. according to a direction in which light is emitted, and a passive matrix type (Passive) type according to a driving method. Matrix) and active matrix type.

Unlike a liquid crystal display (LCD), an organic light emitting diode display does not require a separate light source, so it can be manufactured in a lightweight and thin form. In addition, the organic light emitting diode display is being researched as a next-generation display because it is advantageous in terms of power consumption due to low voltage driving and excellent color realization, response speed, viewing angle, and contrast ratio (CR).

As displays with high resolution develop, the number of pixels per unit area increases and high luminance is required. There are problems in that reliability is lowered and power consumption is increased.

Therefore, it is necessary to overcome the technical limitations of improving the luminous efficiency, lifespan, and power consumption of the organic light emitting device, which are factors that impede the quality and productivity of the organic light emitting display device. Various studies are being conducted for the development of an organic light emitting device capable of improving characteristics.

In order to improve the quality and productivity of the organic light emitting diode display, various organic light emitting device structures have been proposed to improve the efficiency, lifespan, and power consumption of the organic light emitting diode.

Accordingly, one stack, that is, a plurality of stacks, that is, to implement an organic light emitting device structure to which one electroluminescence unit (EL unit) is applied, as well as improved efficiency and lifespan characteristics. An organic light emitting device having a tandem structure using a stack of a plurality of light emitting units has been proposed.

However, simply forming a plurality of light emitting units by stacking does not increase the light emitting effect, and in emitting light from the plurality of light emitting units, the same effect as when a plurality of light emitting devices are connected in series do.

As described above, a charge generation layer (CGL) is applied between a plurality of stacked light emitting units in order to obtain an improved light emitting effect by connecting the plurality of light emitting devices.

However, as the charge generation layer (CGL) is applied in the tandem structure, that is, the organic light emitting device structure having a two-stack structure using a stack of a plurality of light emitting units, the p-type that serves to inject holes into the second light emitting unit The second charge generating layer (P-CGL), which is a charge generating layer, must include a p-type dopant, and, like the hole injection layer (HIL) including the p-type dopant, functions to smoothly inject and move holes. should be able

More specifically, in a two-stack organic light emitting device structure using a stacking of a plurality of light emitting units, the doping level of the p-type dopant in the hole injection layer (HIL), which includes a p-type dopant and serves to inject holes into the first light emitting unit, In addition, when the doping level of the p-type dopant in the second charge generating layer (p-CGL) that includes the p-type dopant and serves to inject holes into the second light-emitting unit is not at an appropriate level, the first light-emitting unit and the second light-emitting unit Electrons and holes are not balanced in the organic light emitting layer of each light emitting unit, and thus problems may occur in efficiency, driving voltage, and lifespan characteristics of the organic light emitting device.

That is, both the hole injection layer including the p-type dopant and the second charge generating layer including the p-type dopant capture electrons from the adjacent hole transport layer (HTL) and transfer electrons to the adjacent material. Although the same, in the case of the hole injection layer, the electrons are transferred to the first electrode and the second charge generation layer to the first charge generation layer (N-CGL) according to the difference between the hole injection layer and the second charge generation layer. A difference in optimal doping concentration of the included p-type dopant may occur.

Therefore, in a two-stack organic light emitting device structure using a stack of a plurality of light emitting units, in both the first light emitting layer of the first light emitting unit and the second organic light emitting layer of the second light emitting unit, holes and electrons smoothly recombine to emit light. Optimization of the doping concentration of the p-type dopant in each of the hole injection layer including the dopant and the second charge generating layer including the p-type dopant is required.

Accordingly, the inventor of the present invention invented an organic light emitting device capable of improving efficiency and lifespan in an organic light emitting device structure using a stack of a plurality of light emitting units.

A problem to be solved according to an embodiment of the present invention is to provide a hole injection layer including a first p-type dopant and a second charge generating layer including a second p-type dopant in an organic light emitting device using a stacking of a plurality of light emitting units. An object of the present invention is to provide an organic light-emitting device capable of improving efficiency and lifetime by optimally setting each p-type dopant doping concentration.

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

An organic light emitting diode according to an embodiment of the present invention includes: a first electrode and a second electrode; a first light emitting unit positioned between the first electrode and the second electrode and including a hole injection layer and a first hole transport layer ; and a second light emitting unit disposed on the first light emitting unit and including a second hole transport layer, wherein a thickness of the second hole transport layer is greater than a thickness of the first hole transport layer.

According to an embodiment of the present invention, an organic light emitting display device includes: the organic light emitting device; a substrate on which the organic light emitting device is disposed; a gate line and a data line intersecting each other on the substrate and defining a pixel area; and a thin film transistor disposed in the pixel region on the substrate, wherein the thin film transistor is connected to the first electrode of the organic light emitting diode.

In the organic light emitting device using the stacking of a plurality of light emitting units according to an embodiment of the present invention, each of the hole injection layer including the first p-type dopant and the second charge generation layer including the second p-type dopant An organic light-emitting device capable of improving efficiency and lifetime by optimally setting a p-type dopant doping concentration is provided.

The organic light emitting diode according to an embodiment of the present invention includes a first electrode and a second electrode and a first electrode positioned between the first electrode and the second electrode, and including a hole injection layer, a first hole transport layer, and a first organic light emitting layer. a second light emitting unit positioned between the light emitting unit and the first electrode and the second electrode, the second light emitting unit including a second hole transport layer and a second organic light emitting layer, and a first charge generating layer positioned between the first light emitting unit and the second light emitting unit and a second charge generation layer, wherein the hole injection layer includes a first p-type dopant, the second charge generation layer includes a second p-type dopant, and It is characterized in that the doping concentration and the doping concentration of the second p-type dopant included in the second charge generating layer are different from each other in the organic light emitting device.

A doping concentration of the first p-type dopant included in the hole injection layer may be smaller than a doping concentration of the second p-type dopant included in the second charge generation layer.

A doping concentration of the first p-type dopant included in the hole injection layer may be 1 to 5%.

A doping concentration of the second p-type dopant included in the second charge generation layer may be 5% to 12%.

The first p-type dopant and the second p-type dopant may be formed of any one of F4-TCNQ or NDP-9.

The first p-type dopant and the second p-type dopant may be formed of different materials.

The hole injection layer and the second charge generating layer are HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), PEDOT (poly (3,4)-ethylenedioxythiophene), PANI (polyaniline) ) and NPD(N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD(N,N′-Bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine), α-NPB(Bis [N-(1-naphthyl)-N-phenyl]benzidine), TDAPB(1,3,5-tris(4-diphenylaminophenyl)benzene), TCTA(Tris(4-carbazoyl-9-yl)triphenylamine), spiro- TAD(2,2′,7,7′-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene), CBP(4,4′-bis(carbazol-9-yl)biphenyl), BFA-1T( It may be made of at least one material selected from 4-[bis(9,9-dimethylfluoren-2-yl)amino]phenyl group), spiro-TCBz (triclabendazole), and TBA.

The hole injection layer and the second charge generation layer may be formed of different materials.

Each of the hole injection layer and the second charge generation layer may have a thickness of about 20 Å to about 150 Å.

The thickness of the hole injection layer and the second charge generation layer may be different from each other.

The first organic emission layer includes a first red emission layer located in the red sub-pixel region, a first green emission layer located in the green sub-pixel region, and a first blue emission layer located in the blue sub-pixel region, and the second organic emission layer may include a second red emission layer positioned in the red sub-pixel region, a second green emission layer positioned in the green sub-pixel region, and a second blue emission layer positioned in the blue sub-pixel region.

The first charge generation layer and the second charge generation layer may have an NP junction structure.

In the organic light emitting device having a two-stack structure using a stacking of a plurality of light emitting units according to an embodiment of the present invention, the second p-type dopant containing the second p-type dopant is higher than the doping concentration of the hole injection layer including the first p-type dopant. By setting the doping concentration of the dopant of the charge generating layer to be low, the efficiency and lifespan of the organic light emitting diode may be improved.

In addition, in the hole injection layer including the first p-type dopant and the second charge generating layer including the second p-type dopant, the doping concentration of each p-type dopant is optimally set to improve the efficiency of the organic light emitting diode. It is possible to reduce the power consumption of the device.

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

Since the content of the invention described in the problems to be solved above, the means for solving the problems, and the effects do not specify the essential characteristics of the claims, the scope of the claims is not limited by the matters described in the content of the invention.

1 is a diagram schematically showing the structure of an organic light emitting device according to an embodiment of the present invention.
FIG. 2 is a view illustrating electro-optical characteristics and lifespan evaluation results according to hole injection layer doping conditions in an organic light emitting diode according to an embodiment of the present invention.
3 is a view illustrating electro-optical characteristic evaluation results of a blue organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.
4 is a view showing a result of comparative evaluation of lifespan characteristics in a blue organic light emitting diode according to an embodiment of the present invention.
5 is a diagram illustrating electro-optical characteristics evaluation results of a green organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.
6 is a view showing results of comparative evaluation of lifespan characteristics in a green organic light emitting diode according to an embodiment of the present invention.
7 is a view illustrating electro-optical characteristic evaluation results of a red organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.
8 is a view showing a result of comparative evaluation of lifespan characteristics in a red organic light emitting diode according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be embodied in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative and the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless otherwise explicitly stated.

In interpreting the components, it is construed as including an error range even if there is no separate explicit description. In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used.

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

Each feature of the various embodiments of the present invention can be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be independently implemented with respect to each other or implemented together in a related relationship. may be

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a diagram schematically showing the structure of an organic light emitting device 1000 according to an embodiment of the present invention.

Referring to FIG. 1 , an organic light emitting diode 1000 according to an embodiment of the present invention is formed on a substrate in which a red sub-pixel region Rp, a green sub-pixel region Gp, and a blue sub-pixel region Bp are defined. The formed first electrode 110 (anode), the hole injection layer 120 (hole injection layer: HIL), the first hole transport layer 130 (1 ^st hole transporting layer: 1 ^st HTL), the first red light emitting layer 140, 1 ^st Red emission layer: 1 ^st Red EML), a first green emission layer (141, 1 ^st Green emission layer: 1 ^st Green EML), and a first blue emission layer (142, 1 ^st Blue emission layer: 1 ^st Blue EML) A first organic light emitting layer, a first electron transport layer (150, 1 ^st electron transporting layer: 1 ^st ETL), a first charge generation layer (160, 1 ^st charge generation layer: N-CGL), a second charge generation layer (165, 2 ^nd charge generation layer: P-CGL), second hole transporting layer (170, 2 ^nd hole transporting layer: 2 ^nd HTL), second red emission layer (180, 2 ^nd Red emission layer: 2 ^nd Red EML), second A second organic emission layer including a green emission layer (181, 2 ^nd Green emission layer: 2 ^nd Green EML) and a second blue emission layer (182, 2 ^nd Blue emission layer: 2 ^nd Blue EML), and a second electron transport layer (190, 2) It is configured to include an ^nd electron transporting layer: 2 ^nd ETL), a second electrode 200 (cathode), and a capping layer 210 (capping layer: CPL).

In addition, the organic light emitting device 1000 according to the embodiment of the present invention includes a first light emitting unit 1100 (1 ^st EL Unit) including a first organic light emitting layer between the first electrode 110 and the second electrode 200, and It is an organic light emitting device having a two-stack structure in which second light emitting units 1200 and 2 ^nd EL units including a second organic light emitting layer are stacked.

More specifically, in the organic light emitting device 1000 according to the embodiment of the present invention, the first light emitting unit 1100 includes the hole injection layer 120 , the first hole transport layer 130 , the first red light emitting layer 140 , and the first light emitting unit 1100 . It is configured to include a first organic light emitting layer including one green light emitting layer 141 and a first blue light emitting layer 142 and a first electron transport layer 150 .

In addition, in the organic light emitting device 1000 according to the embodiment of the present invention, the second light emitting unit 1200 includes a second hole transport layer 170 , a second red light emitting layer 180 , a second green light emitting layer 181 , and a second blue color. The light emitting layer 182 includes a second organic light emitting layer and a second electron transport layer 190 .

In addition, the organic light emitting device 1000 according to the embodiment of the present invention includes a first charge generation layer 160 that is an n-type charge generation layer positioned between the first light emitting unit 1100 and the second light emitting unit 1200 and and a second charge generation layer 165 that is a p-type charge generation layer.

In addition, although not shown, in the organic light emitting diode display including the organic light emitting diode according to an embodiment of the present invention, a gate line and a data line extending parallel to any one of a gate line and a data line that cross each other and define each pixel area on a substrate A power supply line is positioned, and a switching thin film transistor connected to a gate line and a data line and a driving thin film transistor connected to the switching thin film transistor are positioned in each pixel area. The driving thin film transistor is connected to the first electrode 110 (anode).

The first electrode 110 is positioned on the substrate to correspond to the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, respectively, and may be formed of a reflective electrode.

For example, the first electrode 110 may include a layer of a transparent conductive material having a high work function, such as indium-tin-oxide (ITO), and a reflective layer such as silver (Ag) or a silver alloy (Ag alloy). It may include a material layer.

The hole injection layer 120 is It is positioned on the first electrode 110 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp.

The hole injection layer 120 may serve to facilitate hole injection, and may include HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), PEDOT (poly(3) ,4)-ethylenedioxythiophene), PANI (polyaniline) and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N′-Bis(3-methylphenyl)-N,N′-bis(phenyl) )-benzidine), α-NPB(Bis[N-(1-naphthyl)-N-phenyl]benzidine), TDAPB(1,3,5-tris(4-diphenylaminophenyl)benzene), TCTA(Tris(4-carbazoyl) -9-yl)triphenylamine), spiro-TAD(2,2′,7,7′-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene), CBP(4,4′-bis(carbazol-9) -yl)biphenyl), BFA-1T(4-[bis(9,9-dimethylfluoren-2-yl)amino]phenyl group), spiro-TCBz(triclabendazole), and at least one material selected from the group consisting of TBA. can, but is not limited thereto.

The hole injection layer 120 may be formed by doping the material constituting the hole transport layer 130 with a first p-type dopant (p-dopant). In this case, the hole injection layer 120 and the hole transport layer 130 may be formed by a continuous process in one process equipment. The first p-type dopant may be formed of any one of F ₄ -TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanl-quinidimethane) or NDP-9, but is not limited thereto.

The first hole transport layer 130 and the second hole transport layer 170 correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, respectively. 130 is positioned on the hole injection layer 120 , and the second hole transport layer 170 is positioned on the second charge generation layer 165 .

The first hole transport layer 130 and the second hole transport layer 170 serve to facilitate hole transport, and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N'- bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), spiro-TAD(2,2',7,7'-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene ) and MTDATA (4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine) may consist of any one or more selected from the group consisting of, but is not limited thereto.

The first red emission layer 140 is located in the red sub-pixel region Rp on the first hole transport layer 130 , and the second red emission layer 180 is located in the red sub-pixel region Rp on the second hole transport layer 170 . ) is located in The first red light emitting layer 140 and the second red light emitting layer 180 may each include a red light emitting material, and the light emitting material may be formed using a phosphorescent material or a fluorescent material.

More specifically, the first red light emitting layer 140 and the second red light emitting layer 180 may include a host material including carbazole biphenyl (CBP) or 1,3-bis (carbazol-9-yl) (mCP), From the group consisting of PIQIr(acac)(bis(1-phenylisoquinoline) acetylacetonate iridium), PQIr(acac)(bis(1-phenylquinoline) acetylacetonate iridium), PQIr(tris(1-phenylquinoline) iridium) and PtOEP(octaethylporphyrin platinum) It may be formed of a phosphorescent material including a dopant including at least one selected one, and alternatively, may be formed of a phosphor material including PBD:Eu(DBM)3(Phen) or Perylene, but is not limited thereto.

The first green emission layer 141 is positioned in the green sub-pixel region Gp on the first hole transport layer 130 , and the second green emission layer 181 is located in the green sub-pixel region Gp on the second hole transport layer 170 . ) is located in The first green light emitting layer 141 and the second green light emitting layer 181 may include a green light emitting material, and the light emitting material may be formed using a phosphorescent material or a fluorescent material.

More specifically, the first green emission layer 141 and the second green emission layer 181 may include a host material containing CBP or mCP, and include Ir(ppy)3 (fac tris(2-phenylpyridine)iridium). It may be made of a phosphorescent material including a dopant material such as an iridium complex (Ir complex) _.

The first blue light-emitting layer 142 is located in the blue sub-pixel area Bp on the first hole transport layer 130 , and the second blue light-emitting layer 182 is in the blue sub-pixel area Bp on the second hole transport layer 170 . ) is located in The first blue light emitting layer 142 and the second blue light emitting layer 182 may include a blue light emitting material, and the light emitting material may be formed using a phosphorescent material or a fluorescent material.

More specifically, the first blue light emitting layer 142 and the second blue light emitting layer 182 may include a host material containing CBP or mCP, and a dopant material containing (4,6-F2ppy) ₂ Irpic. It may be made of a phosphorescent material. In addition, spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), may be made of a fluorescent material including any one selected from the group consisting of PFO-based polymers and PPV-based polymers, but limited thereto doesn't happen

The first electron transport layer 150 includes a first red emission layer 140 and a first green emission layer 141 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp. and a second electron transport layer 190 disposed on the first blue light emitting layer 142 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp. It is positioned on the red light emitting layer 180 , the second green light emitting layer 181 , and the second blue light emitting layer 182 .

The first electron transport layer 150 and the second electron transport layer 190 may serve to transport and inject electrons, and the thickness of the first electron transport layer 150 and the second electron transport layer 190 determines the electron transport characteristics. can be adjusted taking into account.

The first electron transport layer 150 and the second electron transport layer 190 serve to facilitate electron transport, and Alq ₃ (tris(8-hydroxyquinolino)aluminum), PBD(2-(4-biphenylyl)-5 -(4-tert-butylpheny)-1,3,4oxadiazole), TAZ, spiro-PBD, BAlq, and SAlq may be made of any one or more selected from the group consisting of, but is not limited thereto.

Also, although not shown in FIG. 1 , an electron injection layer (EIL) may be separately formed on the second electron transport layer 190 .

The electron injection layer (EIL) is Alq ₃ (tris(8-hydroxyquinolino)aluminum), PBD(2-(4-biphenylyl)-5-(4-tert-butylpheny)-1,3,4oxadiazole), TAZ, spiro- PBD, BAlq or SAlq may be used, but not limited thereto.

Here, the structure is not limited according to the embodiment of the present invention, and the hole injection layer 120 , the first hole transport layer 130 , the second hole transport layer 170 , the first electron transport layer 150 , and the second At least one of the electron transport layer 190 and the electron injection layer EIL may be omitted. In addition, at least one of the first hole transport layer 130 , the second hole transport layer 170 , the first electron transport layer 150 , the second electron transport layer 190 , and the electron injection layer (EIL) is formed into two or more layers. It is also possible to form

The first charge generation layer 160 is positioned on the first electron transport layer 150 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, and the second The charge generation layer 165 is disposed on the first charge generation layer 160 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, and the first charge The generation layer 160 and the second charge generation layer 165 may have an NP junction structure.

Referring to FIG. 1 , the first charge generating layer 160 and the second charge generating layer 165 are positioned between the first light emitting unit 1100 and the second light emitting unit 1200 , and the first charge generating layer ( 160 and the second charge generation layer 165 serve to adjust the charge balance between the two light emitting units of the first light emitting unit 1100 and the second light emitting unit 1200 .

The first charge generation layer 160 serves as an n-type charge generation layer (n-CGL) that helps injection of electrons into the first light emitting unit 1100 located under the first charge generation layer 160 , The second charge generation layer 165 serves as a p-type charge generation layer (p-CGL) that helps to inject holes into the second light emitting unit 1200 positioned on the second charge generation layer 165 .

More specifically, the first charge generation layer 160, which is an n-type charge generation layer (n-CGL) serving as an electron injection, is formed of an alkali metal, an alkali metal compound, or an organic material or a compound thereof serving as an electron injection. it is possible In addition, the host material of the first charge generation layer 160 may be made of the same material as the material of the first electron transport layer 150 and the second electron transport layer 190 . For example, it may be formed of a mixed layer in which an organic material such as an anthracene derivative is doped with a dopant such as lithium (Li), but is not limited thereto.

The second charge generation layer 165 is disposed on the first charge generation layer 160 . The second charge generation layer 165 serves as a p-type charge generation layer (p-CGL) that serves to inject holes, and the host material of the second charge generation layer 165 includes the hole injection layer 120 and the second charge generation layer 165 . The first hole transport layer 130 and the second hole transport layer 170 may be made of the same material, and may include a second p-type dopant made of a p-type material. For example, HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), PEDOT (poly(3,4)-ethylenedioxythiophene), PANI (polyaniline) and NPD (N, N-dinaphthyl-N,N'-diphenylbenzidine), TPD(N,N′-Bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine), α-NPB(Bis[N-(1- naphthyl)-N-phenyl]benzidine), TDAPB(1,3,5-tris(4-diphenylaminophenyl)benzene), TCTA(Tris(4-carbazoyl-9-yl)triphenylamine), spiro-TAD(2,2′) ,7,7′-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene), CBP(4,4'-bis(carbazol-9-yl)biphenyl), BFA-1T(4-[bis(9) ,9-dimethylfluoren-2-yl)amino]phenyl group), spiro-TCBz (triclabendazole), and may be made of any one or more materials selected from the group consisting of TBA, but is not limited thereto. It may be formed by doping with a dopant. In addition, the second p-type dopant may be formed of any one of F ₄ -TCNQ or NDP-9, but is not limited thereto.

The second electrode 200 is positioned on the second electron transport layer 190 to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp. For example, the second electrode 200 may be made of an alloy of magnesium and silver (Mg:Ag) to have transflective properties. That is, light emitted from the organic light emitting layer is displayed to the outside through the second electrode 200 , and since the second electrode 200 has a transflective property, some of the light is directed back to the first electrode 110 . .

As described above, the first electrode 110 and the second electrode 200 due to the micro-cavity effect in which repeated reflection occurs between the first electrode 110 and the second electrode 200 acting as a reflective layer. The light is repeatedly reflected in the cavity between them, increasing the light efficiency.

In addition to this, it is also possible to form the first electrode 110 as a transmissive electrode and form the second electrode 200 as a reflective electrode so that light from the organic light emitting layer is externally displayed through the first electrode 110 .

The capping layer 210 is positioned on the second electrode 200 . The capping layer 210 is for increasing the light extraction effect in the organic light emitting device, and includes a first hole transport layer 130, a second hole transport layer 170 material, a first electron transport layer 150, and a second electron transport layer ( 190) materials, and a first red light-emitting layer 140, a second red light-emitting layer 180, a first green light-emitting layer 141, a second green light-emitting layer 181, a first blue light-emitting layer 142, and a second blue light-emitting layer ( 182) may be formed of any one of the host materials. Also, the capping layer 210 may be omitted.

In the organic light emitting device 1000 according to the embodiment of the present invention, the hole injection layer 120 and the second charge generation layer 165 are selected from among the materials described above in consideration of hole injection and movement characteristics of the organic light emitting device. It can be formed from other organic materials. In addition, the first p-type dopant doped in the hole injection layer 120 and the second p-type dopant doped in the second charge generation layer 165 are the p-type dopants described above in consideration of hole injection and migration characteristics of the organic light emitting diode. It may be made of the same material or different materials selected from among the materials.

In addition, in the organic light emitting device 1000 according to the embodiment of the present invention, the thickness of the hole injection layer 120 and the second charge generation layer 165 is 20 Å to 150 Å in consideration of hole injection and movement characteristics of the organic light emitting device. In the thickness range, the hole injection layer 120 and the second charge generation layer 165 may be formed to have different thicknesses.

FIG. 2 is a view illustrating electro-optical characteristics and lifespan evaluation results according to hole injection layer doping conditions in an organic light emitting diode according to an embodiment of the present invention.

That is, FIG. 2 shows the organic light emitting diodes manufactured by varying the doping concentration conditions of the first p-type dopant included in the hole injection layer 120 according to Comparative Examples, Examples 1, 2, and 3, respectively. shows the results of comparative evaluation of electro-optical characteristics and lifespan characteristics of organic light-emitting devices.

First, the structure of the organic light emitting device according to Example 1 of FIG. 2 will be described in detail.

The first electrode 110 is formed on the substrate to a thickness of 240 Å in the structure of ITO/APC/ITO, and NPD (N,N-dinaphthyl-N) is formed thereon with the hole injection layer 120 and the first hole transport layer 130 . ,N'-diphenylbenzidine) was formed to a total thickness of 375 Å, and 50 Å of the 375 Å-thick NPD at the interface adjacent to the first electrode 110 was formed by doping with 3% NDP-9, a first p-type dopant. Here, APC means silver-palladium-copper alloy (Ag-Pd-Cu alloy).

Next, in the blue sub-pixel region Bp, an anthracene derivative is formed as a host material of the first blue light emitting layer 142 to a thickness of 200 Å, and 5% of a pyrene derivative is doped as a dopant material to form a first blue color. A light emitting layer 142 was formed.

Next, in the green sub-pixel region Gp, an anthracene derivative and CBP as a host material of the first green light emitting layer 141 are mixed to form a thickness of 370 Å, and ppy ₂ Ir(acac) (acetylacetonatobis(2) -phenylpyridine)iridium (acetylacetonate)) was doped with 5% to form a first green light emitting layer 141 . Next, in the red sub-pixel region Rp, a beryllium complex derivative is formed as a host material of the first red emission layer 140 to a thickness of 680 Å, and btp ₂ Ir(acac)(bis[2-() The first red emission layer 140 was formed by doping 5% of 20-benzo[4,5-a]thienyl)pyridinato-N, C ^3' ]iridium (acetylacetonate)).

Next, the first electron transport layer 150 on the upper part of Alq ₃ It was formed to a thickness of 250 Å, an anthracene derivative was formed thereon to a thickness of 100 Å as the first charge generation layer 160, and lithium (Li) was doped by 1% as a dopant to form the first charge generation layer 160 .

NPD is formed on the second charge generation layer 165 to a total thickness of 375 Å, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPD is NDP-9, which is the second p-type dopant. was doped with 9% to form a second charge generation layer 165 .

Next, a second hole transport layer 170 is formed thereon to a thickness of 400 Å with NPD, and an anthracene derivative is formed as a host material for the second blue light emitting layer 182 in the blue sub-pixel region Bp on the upper portion. The first blue light emitting layer 142 was formed by forming a thickness of 200 Å and doping 5% of a pyrene derivative as a dopant material.

Next, an anthracene derivative and CBP are mixed as a host material for the second green light emitting layer 181 in the green sub-pixel region Gp on the second hole transport layer 170 to have a thickness of 370 Å, and ppy2Ir is used as a dopant material. (acac) was doped by 5% to form a second green light emitting layer 181 .

Next, in the red sub-pixel region Rp on the second hole transport layer 170 , a beryllium complex derivative is formed as a host material of the second red light emitting layer 180 to a thickness of 680 Å, and btp ₂ Ir is used as a dopant material. (acac) was doped with 5% to form a second red light emitting layer 180 .

Next, a second electron transport layer 190 is formed thereon to a thickness of 350 Å by mixing Alq ₃ and Liq, and a silver-magnesium alloy (Ag:Mg) is formed thereon to a thickness of 160 Å as the second electrode 200 . An organic light emitting diode according to Example 1 was manufactured by forming a capping layer 210 on the upper portion to a thickness of 650 Å using NPD.

Next, the structure of the organic light emitting device according to the second embodiment of FIG. 2 will be described.

In describing the structure of the organic light emitting device of Embodiment 2, a configuration different from that of Embodiment 1 described above is a doping concentration of the first p-type dopant included in the hole injection layer 120, and thus is the same as or corresponding to that of Embodiment 1 described above. A detailed description of the components to be used will be omitted.

In the case of Example 2, the NPD is formed to a total thickness of 375 Å by the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the first electrode 110 of the 375 Å thick NPD. ) and 50Å of the adjacent interface was formed by doping 5% of NDP-9, the first p-type dopant.

Also, in the case of Example 2, in the same manner as in Example 1, the NPD was formed to a total thickness of 375 Å by the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPDs. The second charge generation layer 165 was formed by doping 9% of NDP-9, which is a silver second p-type dopant.

Next, the structure of the organic light emitting device according to Example 3 of FIG. 2 will be described.

In describing the structure of the organic light emitting diode according to the third embodiment, a configuration different from that of the first embodiment described above is the doping concentration of the first p-type dopant included in the hole injection layer 120 , so it is the same as or corresponding to the first embodiment described above. A detailed description of the components to be used will be omitted.

In the case of Example 3, the NPD is formed to a total thickness of 375 Å by the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the first electrode 110 of the 375 Å thick NPD. ) and 50Å of the adjacent interface was formed by doping 7% of NDP-9, the first p-type dopant.

Also, in the case of Example 3, in the same manner as in Example 1, the NPD was formed to a total thickness of 375 Å by the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPDs. The second charge generation layer 165 was formed by doping 9% of NDP-9, which is a silver second p-type dopant.

Next, the structure of the organic light emitting diode according to the comparative example of FIG. 2 will be described.

In explaining the structure of the organic light emitting device according to the comparative example, the configuration different from that of the first embodiment described above is the doping condition of the first p-type dopant included in the hole injection layer 120 , so it is the same as or corresponding to the previously described embodiment 1 A detailed description of the components to be used will be omitted.

In the case of the comparative example, the NPD was formed to a total thickness of 375 Å by the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and differently from Examples 1, 2 and 3 The first p-type dopant, NDP-9, was formed on the interface adjacent to the first electrode 110 without doping.

Also, in the case of the comparative example, in the same manner as in Example 1, the NPD was formed to a total thickness of 375 Å with the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPDs was the second charge generation layer 165. A second charge generation layer 165 was formed by doping 9% of NDP-9, which is a 2 p-type dopant.

According to Comparative Example, Example 1, Example 2, and Example 3 described above, the organic light emitting device was manufactured by varying the doping concentration of the first p-type dopant included in the hole injection layer 120 , and then each organic light emitting device The electro-optical properties and lifespan properties were comparatively evaluated.

Referring to FIG. 2 , comparing the driving voltage aspect of the organic light emitting device according to the comparative example and Examples 1, 2 and 3, the comparative example shows a luminance of 000 nit, but a driving voltage of 10.8V is required. became In addition, in the case of Example 1, a driving voltage of 7.2V level was required, in the case of Example 2, a driving voltage of 7.1V, and in Example 3, a driving voltage of 7.1V level was required, so that the first p-type dopant was applied to the hole injection layer 120 . In the case of Examples 1, 2, and 3 doped with , the driving voltage decreased as compared to the Comparative Example.

In addition, referring to FIG. 2 , comparing the current efficiency aspects of the organic light emitting diodes according to Comparative Example and Examples 1, 2, and 3, the comparative example exhibited an efficiency of 9.4 Cd/A level. In addition, Example 1 exhibited an efficiency of 10.8 Cd/A level, Example 2 exhibited an efficiency of 10.6 Cd/A level, and Example 3 exhibited an efficiency of 10.2 Cd/A level, so that the hole injection layer In the case of Examples 1, 2, and 3 in which the first p-type dopant was doped in (120), the efficiency was increased when compared with the Comparative Example.

Looking at the above results, Example 1 in which the first p-type dopant doping concentration of the hole injection layer 120 was 3% showed the best efficiency, and the first p-type dopant doping concentration of the hole injection layer 120 was 7 In the case of Example 3, which is %, the efficiency is lowered compared to Examples 1 and 2, and the doping of the first p-type dopant included in the hole injection layer 120 is considered in consideration of the efficiency of the organic light emitting diode. The concentration is preferably in the range of 1 to 5%.

Also, referring to FIG. 2 , in terms of external quantum efficiency (EQE), it can be seen that the organic light emitting devices according to Examples 1, 2 and 3 showed improved results compared to Comparative Examples.

Next, with reference to FIG. 2, comparing the lifetime characteristics of the organic light emitting device according to the comparative example and Examples 1, 2, and 3, the comparative example shows the light emitting luminance of 95% of the initial light emitting luminance. , that is, the 95% lifetime (T95) of the organic light emitting device did not exhibit the desired level of lifetime characteristics. In the case of Example 1, the 95% life time (T95) showed a level of about 3000 hours, in the case of Example 2, the 95% life time (T95) showed a level of about 2300 hours, and in the case of Example 3, A 95% lifetime (T95) showed a level of about 2000 hours.

That is, Example 1 in which the first p-type dopant doping concentration of the hole injection layer 120 was 3% exhibited the best lifetime characteristics, and the first p-type dopant doping concentration of the hole injection layer 120 was 7% In the case of Example 3, compared with Examples 1 and 2, the lifetime was decreased, and the doping concentration of the first p-type dopant included in the hole injection layer 120 was taken into consideration in consideration of the lifetime characteristics of the organic light emitting device. is preferably in the range of 1 to 5%.

From the above results, in the organic light emitting device having a stack structure using a stack of a plurality of light emitting units according to an embodiment of the present invention, the doping concentration of the first p-type dopant included in the hole injection layer 120 is 1 to 5%. It is preferable to apply in the range of, and more preferably, it can be applied in the range of 3 to 5%.

3 is a view illustrating electro-optical characteristic evaluation results of a blue organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.

That is, FIG. 3 shows that the organic light emitting device is manufactured by varying the doping concentration condition of the second p-type dopant included in the second charge generation layer 165 according to Examples 4, 5, 6, and 7; The results of comparative evaluation of electro-optical characteristics and lifespan characteristics of each blue organic light-emitting device are shown.

Also, FIG. 4 is a view showing the results of comparative evaluation of the lifespan characteristics of the blue organic light emitting diode according to the doping condition of the second charge generating layer in the organic light emitting diode according to an embodiment of the present invention.

In describing the structures of the organic light emitting diodes of Examples 4, 5, 6, and 7 of FIG. 3 , a configuration different from that of Embodiment 1 described with reference to FIG. 2 described above is the second charge generating layer 165 . ), since it is the doping concentration of the second p-type dopant included in ), a detailed description of the same or corresponding components as in Example 1 described above will be omitted.

In the case of Example 4, the NPD is formed to a total thickness of 375 Å by the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the first electrode 110 of the NPD is 375 Å thick. ) and 50 Å of the adjacent interface was formed by doping 3% of NDP-9, the first p-type dopant.

In addition, in the case of Example 4, the NPD is formed to a total thickness of 375 Å as the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPD is the second p-type dopant. A second charge generation layer 165 was formed by doping 9% phosphorus NDP-9.

In the case of Example 5, in the same manner as in Example 4, the NPD was formed to a total thickness of 375 Å using the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the NPD was 375 Å thick. 50 Å of the interface adjacent to the first electrode 110 was formed by doping 3% of NDP-9, which is a first p-type dopant.

In addition, in the case of Example 5, the NPD is formed to a total thickness of 375 Å as the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPD is the second p-type dopant. A second charge generation layer 165 was formed by doping with phosphorus NDP-9 by 6%.

In the case of Example 6, in the same manner as in Example 4, the NPD was formed to a total thickness of 375 Å using the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the NPD was 375 Å thick. 50 Å of the interface adjacent to the first electrode 110 was formed by doping 3% of NDP-9, which is a first p-type dopant.

Also, in the case of Example 6, the NPD is formed to a total thickness of 375 Å as the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPD is the second p-type dopant. A second charge generation layer 165 was formed by doping 12% phosphorus NDP-9.

In the case of Example 7, in the same manner as in Example 4, the NPD was formed to a total thickness of 375 Å by the hole injection layer 120 and the first hole transport layer 130 on the first electrode 110, and the NPD was 375 Å thick. 50 Å of the interface adjacent to the first electrode 110 was formed by doping 3% of NDP-9, which is a first p-type dopant.

In addition, in the case of Example 7, the NPD is formed to a total thickness of 375 Å as the second charge generation layer 165, and 50 Å of the interface adjacent to the first charge generation layer 160 among the 375 Å thick NPD is the second p-type dopant. A second charge generation layer 165 was formed by doping 15% phosphorus NDP-9.

Referring to FIG. 3 in comparison with the driving voltage side of the blue organic light emitting diodes according to Examples 4, 5, 6, and 7, a driving voltage of 7.4V was required in Example 4. In addition, in the case of Example 5, a driving voltage of 8.1V was required, in the case of Example 6, a driving voltage of 7.5V, and in Example 7, a driving voltage of 7.5V was required, so that the second p In the case of Examples 4, 6, and 7 in which 9% or more of the dopant was doped, the driving voltage decreased compared to Example 5 in which the second p-type dopant was doped by 6%.

In addition, referring to FIG. 3, comparing the current efficiency aspects of the blue organic light emitting diodes according to Examples 4, 5, 6, and 7, Example 4 shows an efficiency of 10.3 Cd/A level it was In addition, Example 5 showed an efficiency of 9.0 Cd/A level, Example 6 showed an efficiency of 10.3 Cd/A level, and Example 7 showed an efficiency of 9.8 Cd/A level of the second charge In the case of Examples 4, 6, and 7 in which the second p-type dopant is doped in the generation layer 165 by 9% or more, the efficiency is higher when compared to Example 5 in which the second p-type dopant is doped by 6%. It showed an elevated result.

That is, Example 4 in which the second p-type dopant is doped 9% and Example 6 in which the second p-type dopant is doped 12%, the second charge generating layer 165 exhibited the best efficiency, and the 2p In the case of Example 7 in which the type dopant was doped by 15%, the efficiency was slightly lower when compared to Examples 4 and 6, but the second p-type dopant showed high efficiency compared to Example 5 doped by 6%, blue color In consideration of the efficiency of the organic light emitting diode, the doping concentration of the second p-type dopant included in the second charge generating layer 165 is preferably in the range of 9 to 15%.

In addition, referring to FIG. 3 , in terms of external quantum efficiency (EQE), the external quantum efficiency (EQE) was improved in the blue organic light emitting diodes according to Examples 4, 6 and 7 compared to Example 5. it can be seen that

Next, with reference to FIG. 4, comparing the lifespan characteristics of the blue organic light emitting diodes according to Examples 4, 5, 6, and 7, until the emission luminance of 95% of the initial emission luminance is shown. It can be seen that the time, that is, the 95% lifetime (T95) of the blue organic light emitting device exhibits improved lifespan characteristics in Examples 4, 6, and 7 when compared to Example 5.

From the above results, in the organic light emitting device having a stack structure using the stacking of a plurality of light emitting units according to an embodiment of the present invention, considering the driving voltage, efficiency, and lifespan of the blue organic light emitting device, the second charge generating layer ( 165), the doping concentration of the second p-type dopant is preferably applied at a level of 9 to 15%, and more preferably in a range of 9 to 12%.

5 is a diagram illustrating electro-optical characteristics evaluation results of a green organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.

That is, FIG. 5 shows that the organic light emitting device is manufactured by varying the doping concentration condition of the second p-type dopant included in the second charge generation layer 165 according to Examples 4, 5, 6, and 7; The results of comparative evaluation of electro-optical characteristics and lifespan characteristics of each green organic light-emitting device are shown.

6 is a view showing results of comparative evaluation of lifespan characteristics of the green organic light emitting diode according to the doping condition of the second charge generating layer in the organic light emitting diode according to an embodiment of the present invention.

Embodiment 4, Embodiment 5, Embodiment 6 and Embodiment 7 shown in Figs. 5 and 6 are the same as Embodiment 4, Embodiment 5, Embodiment 6 and Embodiment 7 described with reference to Figs. 3 and 4 above. Since the hole injection layer 120 and the second charge generation layer 165 have doping conditions, a repetitive detailed description will be omitted.

Referring to FIG. 5 , comparing the driving voltages of the green organic light emitting diodes according to Examples 4, 5, 6, and 7, a driving voltage of 7.5V is required in Example 4. In addition, in the case of Example 5, a driving voltage of 8.3V was required, in the case of Example 6, a driving voltage of 7.6V, and in Example 7, a driving voltage of 7.7V was required, so that the second p In the case of Examples 4, 6, and 7 in which 9% or more of the dopant was doped, the driving voltage decreased compared to Example 5 in which the second p-type dopant was doped by 6%.

In addition, referring to FIG. 5 , comparing the current efficiency aspects of the green organic light emitting diodes according to Examples 4, 5, 6 and 7, the efficiency of Example 4 was 93.1 Cd/A. it was In addition, Example 5 showed an efficiency of 92.1 Cd/A level, Example 6 showed an efficiency of 96.0 Cd/A level, and Example 7 showed an efficiency of 93.1 Cd/A level, so that the second charge In the case of Examples 4, 6, and 7 in which the second p-type dopant is doped in the generation layer 165 by 9% or more, the efficiency is higher when compared to Example 5 in which the second p-type dopant is doped by 6%. It showed an elevated result.

That is, Example 6 in which the second p-type dopant was doped with 12% of the second p-type dopant showed the highest efficiency, and Examples 4 and 2p in which the second p-type dopant was doped 9% In the case of Example 7 in which the 15% dopant was doped, the efficiency was slightly lower compared to that of Example 6, but the second p-type dopant was doped by 6%, and the efficiency was higher than in Example 5, so that the green organic light emitting diode In consideration of efficiency, the doping concentration of the second p-type dopant included in the second charge generating layer 165 is preferably in the range of 9 to 15%.

In addition, referring to FIG. 5 , also in terms of external quantum efficiency (EQE), the result of improved external quantum efficiency (EQE) in the green organic light emitting devices according to Examples 4, 6 and 7 compared to Example 5 was shown. it can be seen that

Next, with reference to FIG. 6, comparing the lifespan characteristics of the green organic light emitting diodes according to Examples 4, 5, 6 and 7, until the emission luminance of 95% of the initial emission luminance is exhibited. It can be seen that the time, that is, the 95% lifetime (T95) of the green organic light emitting device exhibits improved lifespan characteristics in Examples 4, 6, and 7 when compared with Example 5.

From the above results, in the organic light emitting device having a stack structure using a stack of a plurality of light emitting units according to an embodiment of the present invention, considering the driving voltage, efficiency, and lifespan of the green organic light emitting device, the second charge generating layer ( 165), the doping concentration of the second p-type dopant is preferably applied in the range of 9 to 15%, and more preferably in the range of 9 to 12%.

7 is a view illustrating electro-optical characteristic evaluation results of a red organic light emitting diode according to a doping condition of a second charge generating layer in an organic light emitting diode according to an embodiment of the present invention.

That is, FIG. 7 shows that the organic light emitting device is manufactured by varying the doping concentration condition of the second p-type dopant included in the second charge generating layer 165 according to Examples 4, 5, 6, and 7; The results of comparative evaluation of electro-optical characteristics and lifespan characteristics of each red organic light-emitting device are shown.

8 is a view showing comparative evaluation results of lifespan characteristics of the red organic light emitting diode according to the doping condition of the second charge generating layer in the organic light emitting diode according to an embodiment of the present invention.

The 4th, 5th, 6th and 7th embodiments shown in FIGS. 7 and 8 are the 4th, 5th, and 7th embodiments described with reference to FIGS. 3, 4, 5 and 6 above. Since it has the same doping conditions for the hole injection layer 120 and the second charge generation layer 165 as in Examples 6 and 7, a repetitive detailed description will be omitted.

Referring to FIG. 7 by comparing driving voltages of the red organic light emitting diodes according to Examples 4, 5, 6, and 7, a driving voltage of 9.1V was required in Example 4. In addition, in the case of Example 5, a driving voltage of 9.6V level was required, in the case of Example 6, a driving voltage of 9.0V, and in Example 7, a driving voltage of 9.2V level was required, so that the second p In the case of Examples 4, 6, and 7 in which 9% or more of the dopant was doped, the driving voltage decreased compared to Example 5 in which the second p-type dopant was doped by 6%.

In addition, referring to FIG. 7, comparing the current efficiency aspects of the red organic light emitting diodes according to Examples 4, 5, 6, and 7, the efficiency of Example 4 was 77.6 Cd/A. it was In addition, Example 5 showed an efficiency of 81.1Cd/A level, Example 6 showed an efficiency of 81.6Cd/A level, and Example 7 showed an efficiency of 80.6Cd/A level, so that the second charge In Example 6 in which the generation layer 165 was doped with 12% of the second p-type dopant, the efficiency increased compared to Example 5 in which the second p-type dopant was doped with 6%.

In addition, referring to FIG. 7 , the external quantum efficiency (EQE) was improved in the red organic light emitting devices according to Examples 4, 6 and 7 compared to Example 5 in terms of external quantum efficiency (EQE). it can be seen that

Next, with reference to FIG. 8, comparing the lifespan characteristics of the red organic light emitting diodes according to Examples 4, 5, 6, and 7, up to 95% of the initial emission luminance level. It can be seen that the time, that is, the 95% lifespan time (T95) of the red organic light emitting device exhibits improved lifespan characteristics in Examples 4, 6, and 7 when compared to Example 5.

From the above results, in the organic light emitting device having a stack structure using the stacking of a plurality of light emitting units according to an embodiment of the present invention, considering the driving voltage, efficiency, and lifespan of the red organic light emitting device, the second charge generating layer ( 165), the doping concentration of the second p-type dopant is preferably applied in the range of 9 to 15%, and more preferably in the range of 9 to 12%.

Taken together, in the organic light emitting device having a two-stack structure using a stack of a plurality of light emitting units according to an embodiment of the present invention, the doping concentration of the first p-type dopant included in the hole injection layer 120 is 1 By applying in the range of 5% to 5% and the doping concentration of the second p-type dopant included in the second charge generating layer 165 is in the range of 9 to 15%, the driving voltage, efficiency, and lifespan of the organic light-emitting device are improved. effect can be obtained.

That is, in the organic light emitting device having a two-stack structure using a stack of a plurality of light emitting units according to an embodiment of the present invention, the second p-type dopant is higher than the doping concentration of the hole injection layer 120 including the first p-type dopant. By setting the doping concentration of the dopant of the second charge generating layer 165 including

In addition, in the hole injection layer 120 including the first p-type dopant and the second charge generation layer 165 including the second p-type dopant, the doping concentration of each p-type dopant is set to the optimal value of the organic light emitting diode. By improving the efficiency, power consumption of the organic light emitting diode can be reduced.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be implemented with various modifications within the scope without departing from the technical spirit of the present invention. there is. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

1000: organic light emitting device
110: first electrode
120: hole injection layer
130: first hole transport layer
140: first red light emitting layer
141: first green light emitting layer
142: first blue light emitting layer
150: first electron transport layer
160: first charge generation layer
165: second charge generation layer
170: second hole transport layer
180: second red light emitting layer
181: second green light emitting layer
182: second blue light emitting layer
190: second electron transport layer
200: second electrode
210: capping layer
1100: first light emitting unit
1200: second light emitting unit
Rp: red sub-pixel area
Gp: green sub-pixel area
Bp: blue sub-pixel area

Claims (22)

a first electrode and a second electrode;
a first light emitting unit positioned between the first electrode and the second electrode and including a hole injection layer and a first hole transport layer; and
and a second light emitting unit disposed on the first light emitting unit and including a second hole transport layer,
The thickness of the second hole transport layer is greater than the thickness of the first hole transport layer, an organic light emitting device. The method of claim 1,
The sum of the thicknesses of the hole injection layer and the first hole transport layer is smaller than the thickness of the second hole transport layer. The method of claim 1,
Further comprising a first electron transport layer included in the first light emitting unit and a second electron transport layer included in the second light emitting unit,
The thickness of the second electron transport layer is greater than the thickness of the first electron transport layer, the organic light emitting device. The method of claim 1,
The organic light emitting device further comprising a first charge generation layer and a second charge generation layer positioned between the first light emitting unit and the second light emitting unit. 5. The method of claim 4,
The hole injection layer includes a first p-type dopant, and the second charge generation layer includes a second p-type dopant. 6. The method of claim 5,
The doping concentration of the first p-type dopant included in the hole injection layer and the doping concentration of the second p-type dopant included in the second charge generation layer are different from each other. 6. The method of claim 5,
A doping concentration of the second p-type dopant included in the second charge generating layer is greater than a doping concentration of the first p-type dopant included in the hole injection layer. 6. The method of claim 5,
The doping concentration of the first p-type dopant included in the hole injection layer is 1 to 5% of the organic light emitting diode. 6. The method of claim 5,
The doping concentration of the second p-type dopant included in the second charge generation layer is 9% to 15%. 6. The method of claim 5,
The host material of the second charge generating layer is made of the same material as at least one of the hole injection layer, the first hole transport layer, and the second hole transport layer. 6. The method of claim 5,
The first p-type dopant and the second p-type dopant are made of different materials from each other. 11. The method according to claim 9 or 10,
Any one of the hole injection layer and the second charge generating layer is HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), PEDOT (poly(3,4)-ethylenedioxythiophene) ), PANI (polyaniline) and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N′-Bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine), α-NPB(Bis[N-(1-naphthyl)-N-phenyl]benzidine), TDAPB(1,3,5-tris(4-diphenylaminophenyl)benzene), TCTA(Tris(4-carbazoyl-9-yl) triphenylamine), spiro-TAD(2,2′,7,7′-Tetrakis(N,N-diphenylamino)-9,9-spirobifluorene), CBP(4,4′-bis(carbazol-9-yl)biphenyl) , BFA-1T (4-[bis(9,9-dimethylfluoren-2-yl)amino]phenyl group), spiro-TCBz (triclabendazole), and an organic light-emitting device comprising at least one of TBA. 6. The method of claim 5,
Any one of the first p-type dopant and the second p-type dopant is an organic light emitting device comprising any one of F ₄ -TCNQ or NDP-9. The method of claim 1,
The thickness of the hole injection layer or the second charge generation layer is 20 Å to 150 Å. 5. The method of claim 4,
The thicknesses of the hole injection layer and the second charge generation layer are different from each other. 5. The method of claim 4,
The first charge generation layer and the second charge generation layer have an NP junction structure. a first electrode, a second electrode, a first light emitting unit positioned between the first electrode and the second electrode and including a hole injection layer and a first hole transport layer, and a second hole disposed on the first light emitting unit an organic light emitting device including a second light emitting unit including a transport layer;
a substrate on which the organic light emitting device is disposed;
a gate line and a data line intersecting each other on the substrate and defining a pixel area; and
a thin film transistor disposed in the pixel region on the substrate;
The thin film transistor is connected to the first electrode of the organic light emitting device,
and a thickness of the second hole transport layer is greater than a thickness of the first hole transport layer. 18. The method of claim 17,
and a power supply line disposed on the substrate and extending parallel to one of the gate line and the data line. 18. The method of claim 17,
and the first electrode includes a transparent conductive material layer or a reflective material layer. 20. The method of claim 19,
The first electrode is
and indium-tin-oxide (ITO) as the transparent conductive material layer,
The organic light emitting diode display including silver (Ag) or a silver alloy (Ag) as the reflective material layer. 20. The method of claim 19,
The second electrode is made of a material having a transflective property. 22. The method of claim 21,
The second electrode of the organic light emitting diode is made of an alloy of magnesium and silver (Mg:Ag).

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