KR102471177B1 - Organic light emitting device - Google Patents

Abstract

An organic light emitting device according to an embodiment of the present invention includes a first light emitting unit and a first electrode positioned between a first electrode and a second electrode and between the first electrode and the second electrode and including a first hole transport layer and a first organic light emitting layer. and a second light emitting unit positioned between the second electrode and including a second hole transport layer and a second organic light emitting layer, and a first hole control layer and a second hole transport layer positioned between the first hole transport layer and the first organic light emitting layer; It is characterized in that the organic light emitting device includes a second hole control layer positioned between the second organic light emitting layer.

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 lifetime in a high-temperature environment.

An organic light emitting display device (OLED) is a self-emissive display device, which injects electrons and holes into the light emitting layer from a cathode for electron injection and an anode for hole injection, respectively. A display device using an organic light emitting device that emits light when excitons, a combination of injected electrons and holes, fall from an excited state to a ground state.

Organic light emitting display devices are classified into top emission, bottom emission, and dual emission modes depending on the direction in which light is emitted, and passive matrix type depending on the driving method. ) and active matrix type.

Unlike a liquid crystal display (LCD), an organic light emitting display device does not require a separate light source and can be manufactured to be lightweight and thin. In addition, organic light emitting display devices are not only advantageous in terms of power consumption due to low voltage driving, but also excellent in color implementation, response speed, viewing angle, and contrast ratio (CR), and are being studied as next-generation displays.

As the display develops with high resolution, the number of pixels per unit area increases and high luminance is required. There are problems in that reliability decreases and power consumption increases.

Therefore, it is necessary to overcome the technical limitations of luminous efficiency, lifespan improvement, and power consumption reduction of organic light emitting devices, which are factors that hinder the quality and productivity of organic light emitting display devices. Various studies have been conducted to develop an organic light emitting device capable of improving characteristics.

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

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

In such a tandem structure, that is, a stacked organic light emitting device structure using a stack of a plurality of light emitting units, a light emitting region in which light emission occurs through recombination of electrons and holes is provided in each of the first light emitting unit and the second light emitting unit. Since the organic light emitting device is positioned at room temperature, no problem occurs in the light emitting lifetime of the organic light emitting device due to the high efficiency and the resulting low current when the organic light emitting device is driven at room temperature.

However, in a high-temperature environment, as holes show higher mobility than electrons, holes pass through the organic light-emitting layer, which is a region where electrons and holes recombine to emit light, and move to the electron transport layer, leaving the light-emitting region. There is a problem that the efficiency and lifetime characteristics of the organic light emitting device are significantly deteriorated.

Accordingly, the inventor of the present invention invented an organic light emitting device capable of improving efficiency and lifetime at a high temperature 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 form a first hole control layer between the first hole transport layer and the first organic light emitting layer in an organic light emitting device having a stack structure using a stack of a plurality of light emitting units, and also to form a second hole transport layer. It is an object of the present invention to provide an organic light emitting device capable of improving efficiency and lifespan at a high temperature by forming a second hole controlling layer between the first organic light emitting layer and the second organic light emitting layer.

Solved problems according to embodiments of the present invention are not limited to the above-mentioned problems, and other problems not mentioned above will be clearly understood by those skilled in the art from the description below.

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, a first hole control layer is formed between the first hole transport layer and the first organic light emitting layer, and the second hole transport layer and the second hole transport layer are formed. An organic light emitting device capable of improving efficiency and lifespan at a high temperature by forming a second hole control layer between organic light emitting layers is provided.

An organic light emitting device according to an embodiment of the present invention includes a first light emitting unit and a first electrode positioned between a first electrode and a second electrode and between the first electrode and the second electrode and including a first hole transport layer and a first organic light emitting layer. and a second light emitting unit positioned between the second electrode and including a second hole transport layer and a second organic light emitting layer, and a first hole control layer and a second hole transport layer positioned between the first hole transport layer and the first organic light emitting layer and the above It is characterized in that it is an organic light emitting device including a second hole control layer positioned between the second organic light emitting layers.

The HOMO energy level of the first hole control layer may be lower than the HOMO energy level of the first hole transport layer by 0.1 eV or more.

The LUMO energy level of the first hole control layer may be lower than the LUMO energy level of the first hole transport layer by 0.1 eV or more.

The HOMO energy level of the second hole control layer may be lower than the HOMO energy level of the second hole transport layer by 0.1 eV or more.

The LUMO energy level of the second hole control layer may be lower than the LUMO energy level of the second hole transport layer by 0.1 eV or more.

A triplet energy level (T1) of the first hole control layer may be higher than a triplet energy level (T1) of a dopant included in the first organic emission layer.

A triplet energy level (T1) of the second hole control layer may be higher than a triplet energy level (T1) of a dopant included in the second organic emission layer.

The first hole control layer and the second hole control layer are respectively 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 TBA.

A first charge generation layer and a second charge generation layer positioned between the first light emitting unit and the second light emitting unit may be included.

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

The first organic light-emitting layer includes a first red light-emitting layer positioned in a red sub-pixel area, a first green light-emitting layer positioned in a green sub-pixel area, and a first blue light-emitting layer positioned in a blue sub-pixel area, and the second organic light-emitting layer may include a second red light-emitting layer positioned in the red sub-pixel area, a second green light-emitting layer positioned in the green sub-pixel area, and a second blue light-emitting layer positioned in the blue sub-pixel area.

The first hole control layer and the second hole control layer may be made of different materials.

An organic light emitting device according to another embodiment of the present invention includes at least two light emitting units disposed between a first electrode and a second electrode and between the first electrode and the second electrode, wherein the at least two light emitting units include a hole transport layer and an organic light emitting unit. It is characterized in that it is an organic light emitting device including a light emitting layer, and one of the at least two light emitting units includes a hole control layer positioned between the hole transport layer and the organic light emitting layer.

The at least two light emitting units may be a first light emitting unit and a second light emitting unit.

The hole control layer may be included in the first light emitting unit.

The hole control layer may be included in the second light emitting unit.

In the organic light emitting device of the stack structure using the stacking of a plurality of light emitting units according to an embodiment of the present invention, by forming a hole control layer between the hole transport layer and the organic light emitting layer, holes show higher mobility than electrons at high temperature Accordingly, it is possible to prevent a phenomenon in which holes move to the electron transport layer through the organic light emitting layer, which is a region where electrons and holes recombine to emit light, and leave the light emitting region.

In addition, since the electron-hole recombination region does not deviate from the emission region, an effect of improving the efficiency and lifespan of the organic light-emitting device at a high temperature can be obtained.

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

Since the content of the invention described in the problem to be solved, the means for solving the problem, and the effect above does not specify the essential features of the claim, the scope of the claim 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.
2 is a view showing conditions for HOMO energy levels and LUMO energy levels of a hole transport layer and a hole control layer in an organic light emitting device according to an embodiment of the present invention.
3 is a view showing triplet energy level (T1) conditions of a hole transport layer, a hole control layer, and a blue light emitting layer in an organic light emitting device according to an embodiment of the present invention.
4 is a view showing life evaluation results at room temperature and high temperature in an organic light emitting device according to an embodiment of the present invention.
5 is a diagram showing current density evaluation results according to voltage at room temperature and high temperature in an organic light emitting device according to an embodiment of the present invention.
6 is a diagram showing results of comparative evaluation of electro-optical characteristics of an organic light emitting device according to a comparative example and an embodiment of the present invention.
7 is a view showing the results of comparative evaluation of lifetime characteristics at room temperature in the organic light emitting device according to the comparative example and the embodiment of the present invention.
8 is a view showing the results of comparative evaluation of lifespan characteristics at a high temperature in the organic light emitting device according to a comparative example and an embodiment of the present invention.
9 is a view showing results of comparative evaluation of lifespan characteristics at room temperature and high temperature in an organic light emitting device according to an embodiment of the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be embodied in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, so the present invention is not limited to the details shown. Like reference numbers designate like elements throughout the specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

In interpreting the components, even if there is no separate explicit description, it is interpreted as including the error range. In the case of a description of a positional relationship, for example, 'on top of', 'on top of', 'at the bottom of', 'next to', etc. Or, unless 'directly' is used, one or more other parts may be located between the two parts.

In addition, although 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. Therefore, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, technically various interlocking and driving are possible, and each embodiment can be implemented independently of each other or can be 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 provided on a substrate on which a red sub-pixel area Rp, a green sub-pixel area Gp, and a blue sub-pixel area Bp are defined. A first electrode 110 formed, a hole injection layer (HIL) 120, a first hole transporting layer 130 (1 ^st hole transporting layer: 1 ^st HTL), a first hole control layer 135, 1 ^st hole control layer: 1 ^st HCL), a first red light emitting layer (140, 1 ^st Red emission layer: 1 ^st Red EML), a first green light emitting layer (141, 1 ^st Green emission layer: 1 ^st Green EML), and A first organic light emitting layer composed of 1 blue light emitting layer (142, 1 ^st Blue emission layer: 1 ^st Blue EML), a first electron transport layer (150, 1 ^st electron transporting layer: 1st ^ETL ), 1st charge generation layer (160, ^1st charge generation layer: N-CGL), 2nd charge generation layer (165, ^2nd charge generation layer: P-CGL), 2nd hole A transport layer (170, 2 ^nd hole transporting layer: 2 ^nd HTL), a second hole control layer (175, 2 ^nd hole control layer: 2 ^nd HCL), a second red light emitting layer (180, 2 ^nd Red emission layer: 2 ^nd Red EML), a second organic light emitting layer composed of a second green light emitting layer (181, 2 ^nd Green emission layer: 2 ^nd Green EML) and a second blue light emitting layer (182, 2 ^nd Blue emission layer: 2 ^nd Blue EML), and a second electron It is configured to include a transport layer (190, ^2nd electron transporting layer: ^2nd ETL), a second electrode (200, cathode), and a capping layer (210, capping layer: CPL).

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

More specifically, in the organic light emitting device 1000 according to an embodiment of the present invention, the first light emitting unit 1100 includes a hole injection layer 120, a first hole transport layer 130, a first hole control layer 135, A first organic light emitting layer including a first red light emitting layer 140 , a first green light emitting layer 141 , and a first blue light emitting layer 142 and a first electron transport layer 150 are included.

In addition, in the organic light emitting device 1000 according to an embodiment of the present invention, the second light emitting unit 1200 includes a second hole transport layer 170, a second hole control layer 175, a second red light emitting layer 180, and a second hole transport layer 170. It is configured to include a second organic light emitting layer composed of 2 green light emitting layers 181 and a second blue light emitting layer 182 and a second electron transport layer 190 .

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

Also, although not shown, in an organic light emitting display device including an organic light emitting element according to an embodiment of the present invention, a gate line and a data line defining each pixel area crossing each other on a substrate extend parallel to one of them. A power wiring is positioned, and a switching thin film transistor connected to the gate wiring and the data wiring and a driving thin film transistor connected to the switching thin film transistor are positioned in each pixel area. A driving thin film transistor is connected to the first electrode 110 (anode).

The first electrode 110 is positioned on the substrate to correspond to each of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, 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). A material layer may be included.

The hole injection layer 120 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, 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).

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

The first hole transport layer 130 and the second hole transport layer 170 play a role of facilitating hole transport, NPD (N, N-dinaphthyl-N, N'-diphenylbenzidine), TPD (N, N'- bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), s-TAD and MTDATA(4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino) -triphenylamine) may consist of one or more selected from the group consisting of, but is not limited thereto.

In the organic light emitting device 1000 according to an embodiment of the present invention, the first hole control layer 135 is provided in all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp. It is located on the first hole transport layer 130 to correspond.

In addition, the second hole control layer 175 is positioned on the second hole transport layer 170 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 first hole-controlling layer 135 and the second hole-controlling layer 175 are the first red light emitting layer 140, which is a region in which holes recombine with electrons to emit light as holes show higher mobility than electrons at high temperatures. ), the first organic light emitting layer consisting of the first green light emitting layer 141 and the first blue light emitting layer 142 and the second red light emitting layer 180, the second green light emitting layer 181 and the second blue light emitting layer 182 2 It serves to prevent a phenomenon of moving to the first electron transport layer 150 and the second electron transport layer 190 through the organic light emitting layer and leaving the light emitting area. The first hole-controlling layer 135 and the second hole-controlling layer 175 may be made of a material such as a carbazole derivative, a triarylamine derivative, or a triamine derivative. For example, 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 consist of at least one selected from the group consisting of TBA, but is not limited thereto. Materials of the first hole control layer 135 and the second hole control layer 175 may be represented by the following structural formulas.

The first hole control layer 135 and the second hole control layer 175 may be made of the same material selected from the materials described above, and holes move in the first light emitting unit 1100 and the second light emitting unit 1200. It may also be made of different materials selected from the materials described above in consideration of characteristics.

The first red light-emitting layer 140 is located in the red sub-pixel region Rp on the first hole transport layer 130, and the second red light-emitting 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 light emitting material that emits red light, 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 are CBP (4,4'-bis (carbozol-9-yl) biphenyl) or mCP (1,3-bis (N-carbozolyl) benzene ), and any one selected from the group consisting of PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium) and PtOEP (octaethylporphyrin platinum) It may be made of a phosphorescent material including a dopant including the above, and may be made of a phosphorescent material including PBD:Eu(DBM)3(Phen) or Perylene, but is not limited thereto.

The first green light-emitting layer 141 is located in the green sub-pixel region Gp on the first hole transport layer 130, and the second green light-emitting 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 light emitting layer 141 and the second green light emitting layer 181 may include a host material including 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), and alternatively, it may be made of a fluorescent material including Alq ₃ (tris(8-hydroxyquinolino)aluminum), but is not limited thereto.

The first blue light-emitting layer 142 is located in the blue sub-pixel region Bp on the first hole transport layer 130, and the second blue light-emitting layer 182 is located in the blue sub-pixel region 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 light emitting material that emits blue light, 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 including CBP or mCP, and a phosphorescent material including a dopant material including (4,6-F2ppy)2Irpic. can be made of material. In addition, it may be made of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distryl arylene (DSA), PFO-based polymer and PPV-based polymer, but is limited thereto It doesn't work.

The first electron transport layer 150 includes the first red light-emitting layer 140 and the first green light-emitting 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 disposed on the first blue light emitting layer 142, the second electron transport layer 190 corresponds to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp. It is located 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 this 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 formed of at least one selected from, but is not limited thereto.

Also, although not shown in FIG. 1 , it is possible to additionally configure an electron injection layer (EIL) separately 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 is 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, 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 as 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 positioned 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 generation layer 165 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 inject electrons into the first light emitting unit 1100 located below the first charge generation layer 160, The second charge generation layer 165 serves as a p-type charge generation layer (p-CGL) to help inject holes into the second light emitting unit 1200 positioned on the second charge generation layer 165 .

More specifically, the first charge generating layer 160, which is an n-type charge generating layer (n-CGL) serving as an electron injection, is formed of an alkali metal, an alkali metal compound, 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 consist of a mixed layer doped with a dopant such as lithium (Li) in an organic material such as an anthracene derivative , but is not limited thereto.

The second charge generating layer 165 is positioned on the first charge generating layer 160 . The second charge generation layer 165 serves as a p-type charge generation layer (p-CGL) serving as hole injection, and the host material of the second charge generation layer 165 is the first hole injection layer 120 , It may be made of the same material as the material of the first hole transport layer 130 and the second hole transport layer 170 . For example, p-type dopants in organic materials such as HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine) and TBAHA (tris(4-bromophenyl)aluminum hexacholroantimonate). ) may be made of a doped mixed layer, but is not limited thereto. In addition, the 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) and may have translucent properties. That is, the light emitted from the organic light emitting layer is displayed to the outside through the second electrode 200. Since the second electrode 200 has a transflective property, some of the light is directed to the first electrode 110 again. .

In this way, the first electrode 110 and the second electrode 200 are formed by the micro cavity effect in which repetitive reflection occurs between the first electrode 110 and the second electrode 200 serving as a reflective layer. Light is repeatedly reflected in the cavity between the two layers to increase 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 displayed to the outside through the first electrode 110 .

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

FIG. 2 is a diagram illustrating conditions for HOMO energy levels and LUMO energy levels of a hole transport layer and a hole control layer in an organic light emitting device 1000 according to an embodiment of the present invention. 3 is a view showing conditions of the triplet energy level (T1) of the host and dopant of the hole transport layer, the hole control layer, and the blue light emitting layer in the organic light emitting device 1000 according to an embodiment of the present invention.

By applying the structure of the organic light emitting device 1000 according to the embodiment of the present invention described above with reference to FIG. 1, each blue organic light emitting device according to the conditions of FIGS. 2 and 3 is manufactured to structure the hole control layer. evaluation proceeded. In the case of the blue organic light emitting device in this evaluation, the first electrode 110, the hole injection layer 120, the first hole transport layer 130, the first hole control layer 135, and the first blue light emitting layer 142 And a hole only device (HOD) unit element for structural evaluation of the hole control layer consisting of only the second electrode 200 was utilized.

2 and 3, Comparative Example 1 has a LUMO energy level of 2.1 eV and a HOMO energy level of 5.26 eV in the first hole transport layer 130 and the first hole control layer 135, respectively, and 2.58 eV A blue organic light emitting device was manufactured by forming a hole control layer 1 (HCL 1) material having a triplet energy level (T1). In addition, the dopant of the first blue organic light emitting layer 142 has a triplet energy level T1 of 2.4 eV. That is, in the case of Comparative Example 1, the HOMO energy level is 0.1 eV or more lower than the HOMO energy level of the first hole transport layer 130, the same for each of the first hole transport layer 130 and the first hole control layer 135, and the LUMO A hole whose energy level is lower than the LUMO energy level of the first hole transport layer 130 by 0.1 eV or more and whose triplet energy level T1 is higher than the triplet energy level T1 of the dopant of the first blue light emitting layer 142 It has a structure in which the control layer 1 (HCL 1) material is applied.

The LUMO energy level means the lowest unoccupied molecular orbital (LUMO), and the HOMO energy level means the highest occupied molecular orbital (HOMO).

Also, the triplet energy level T1 means the energy level of non-emitting triplet excitons that are lost in fluorescence emission. In addition, as shown in FIG. 3, in the blue organic light emitting device according to an embodiment of the present invention, the hole control layer 1 (HCL 1) material applied to the hole control layer (HCL), the hole control layer 2 (HCL 2) material, and The triplet energy level (T1) of the material of the hole control layer 3 (HCL 3) is the dopant ( BD) has an energy level higher than the triplet energy level (T1).

In addition, in the case of Comparative Example 2, each of the first hole transport layer 130 and the first hole control layer 135 has a LUMO energy level of 2.0 eV, a HOMO energy level of 5.13 eV, and a triplet energy level of 2.50 eV ( A blue organic light emitting device was fabricated by forming NPD, which is a hole transport layer (HTL) material having T1), respectively. In addition, the dopant of the first blue organic light emitting layer 142 has a triplet energy level T1 of 2.40 eV. That is, in the case of Comparative Example 2, each of the first hole transport layer 130 and the first hole control layer 135 has a LUMO energy level of 2.0 eV and a HOMO energy level of 5.13 eV, and has a triplet energy level (T1) It has a structure in which NPD, which is a hole transport layer (HTL) material higher than the triplet energy level (T1) of the dopant of the first blue light emitting layer 142, is applied.

In addition, in the case of Example 1, NPD, which is a hole transport layer (HTL) material having a LUMO energy level of 2.0 eV and a HOMO energy level of 5.13 eV, was formed on the first hole transport layer 130, and the first hole control layer ( 135), a hole control layer 1 (HCL 1) material having a LUMO energy level of 2.1 eV and a HOMO energy level of 5.26 eV and a triplet energy level (T1) of 2.58 eV was formed to fabricate a blue organic light emitting device. In addition, the dopant of the first blue organic light emitting layer 142 has a triplet energy level T1 of 2.4 eV. That is, in the case of Example 1, NPD is applied to the first hole transport layer 130, and the HOMO energy level of the first hole control layer 135 is 0.1 eV higher than the HOMO energy level of the first hole transport layer 130. or lower, the LUMO energy level is 0.1 eV or more lower than the LUMO energy level of the first hole transport layer 130, and the triplet energy level (T1) is the triplet energy level (T1) of the dopant of the first blue light emitting layer 142 ) has a structure in which a higher hole control layer 1 (HCL 1) material is applied.

In addition, in the case of Example 2, NPD, which is a hole transport layer (HTL) material having a LUMO energy level of 2.0 eV and a HOMO energy level of 5.13 eV, was formed on the first hole transport layer 130, and the first hole control layer ( 135), a hole control layer 2 (HCL 2) material having a LUMO energy level of 2.1 eV and a HOMO energy level of 5.20 eV and a triplet energy level (T1) of 2.57 eV was formed to fabricate a blue organic light emitting device. In addition, the dopant of the first blue organic light emitting layer 142 has a triplet energy level T1 of 2.40 eV. That is, in the case of Example 2, NPD is applied to the first hole transport layer 130 in the same manner as in Example 1, and the HOMO energy level to the first hole control layer 135 is the same as that of the first hole transport layer 130. lower than the HOMO energy level by less than 0.1 eV, the LUMO energy level lower than the LUMO energy level of the first hole transport layer 130 by less than 0.1 eV, and the triplet energy level T1 of the first blue light emitting layer 142 It has a structure in which a hole control layer 2 (HCL 2) material higher than the triplet energy level (T1) of the dopant is applied.

In addition, in the case of Example 3, NPD, which is a hole transport layer (HTL) material having a LUMO energy level of 2.0 eV and a HOMO energy level of 5.13 eV, was formed on the first hole transport layer 130, and the first hole control layer ( 135), a hole control layer 3 (HCL 3) material having a LUMO energy level of 1.95 eV and a HOMO energy level of 5.1 eV and a triplet energy level (T1) of 2.50 eV was formed to fabricate a blue organic light emitting device. In addition, the dopant of the first blue organic light emitting layer 142 has a triplet energy level T1 of 2.40 eV. That is, in the case of Example 3, NPD is applied to the first hole transport layer 130 in the same manner as in Examples 1 and 2, and the HOMO energy level is applied to the first hole control layer 135. ), the LUMO energy level is higher than the LUMO energy level of the first hole transport layer 130, and the triplet energy level T1 is the triplet energy level of the dopant of the first blue light emitting layer 142 ( T1) has a structure in which a higher hole control layer 3 (HCL 3) material is applied.

Each blue organic light emitting device was manufactured by forming the first hole transport layer 130 and the first hole control layer 135 under the conditions described above with reference to FIGS. 2 and 3, and at room temperature and high temperature of each blue organic light emitting device. Efficiency and life characteristics of were compared and evaluated.

FIG. 4 is a view showing life evaluation results at room temperature and high temperature according to the application conditions of the hole control layer in the organic light emitting device 1000 according to an embodiment of the present invention.

That is, in FIG. 4 , each blue organic light emitting device is manufactured by forming a hole transport layer and a hole control layer under the conditions described above with reference to FIGS. ) shows the results of comparative evaluation of life characteristics in

Referring to FIG. 4, in the case of the blue organic light emitting diode according to the conditions of Comparative Example 1, the 95% lifespan time (T95), which is the time from the initial light emission luminance to the 95% level of luminance of the initial light emission luminance at room temperature, is about 310 hours. In the case of the blue organic light emitting diodes according to the conditions of Comparative Example 2, Example 1, Example 2 and Example 3, the 95% lifespan time (T95) at room temperature was all about 2650 hours. That is, in the case of the blue organic light emitting device according to the conditions of Comparative Example 2, Example 1, Example 2, and Example 3, the same level of excellent lifespan characteristics at room temperature was exhibited, but in the case of the blue organic light emitting device according to Comparative Example 1 showed low lifetime characteristics even at room temperature.

In addition, in the case of the blue organic light emitting device according to the conditions of Comparative Example 1, 80% life time measured after storage at a high temperature, that is, at about 85? T80) showed about 215 hours, the 80% lifespan time (T80) of the blue organic light emitting device according to the conditions of Comparative Example 2 was about 240 hours, and the 80% lifespan of the blue organic light emitting device according to the conditions of Example 1 % life time (T80) is about 865 hours, 80% life time (T80) of the blue organic light emitting device according to the conditions of Example 2 is about 520 hours, 80% lifespan of the blue organic light emitting device according to the conditions of Example 3 Time (T80) showed a result of about 280 hours.

That is, looking at the above results together, the life characteristics at high temperature compared to room temperature were reduced in all conditions of Comparative Example 1, Comparative Example 2, Example 1, Example 2 and Example 3, but Example 1 In the case of the blue organic light emitting device according to , the best lifespan characteristics were exhibited at high temperatures. According to an embodiment of the present invention, this means that the HOMO energy level of the first hole control layer 135 is lower than the HOMO energy level of the first hole transport layer 130 by 0.1 eV or more, and the LUMO energy level of the first hole transport layer 130 is 0.1eV or more lower than the LUMO energy level, and the triplet energy level (T1) is higher than the triplet energy level (T1) of the dopant of the first blue light emitting layer 142. The first hole control layer 135 having a characteristic In the case of the applied blue organic light emitting device, the first hole control layer 135 exhibits a higher mobility of holes than electrons at a high temperature. Accordingly, by preventing holes from moving to the electron transport layer through the organic light emitting layer, which is a region where electrons and holes recombine to emit light, and leaving the light emitting region, the luminous efficiency in the organic light emitting layer is improved and excellent lifespan characteristics are exhibited even at high temperatures. can know that

5 is a diagram showing current density evaluation results according to voltage at room temperature and high temperature in the organic light emitting device 1000 according to an embodiment of the present invention.

That is, FIG. 5 shows each of the blue organic light emitting devices according to conditions of the hole transport layer and the hole control layer according to Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3 described above with reference to FIGS. 2 and 3 It shows the result of evaluating the current density level according to the voltage at room temperature and high temperature.

In FIG. 5, the rectangular EML region shown as a solid line in the voltage-current density (J-V) curve is a desired current density region that contributes to light emission in the organic light emitting device, and means an organic light emitting layer (EML) contribution prediction period. The rectangular ETL section shown as a solid line in the curve is an undesired current density region and means an ETL contribution prediction section.

Referring to FIG. 5, in the blue organic light emitting device according to Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, voltage-current density (J-V) curve results at room temperature (25?) and high temperature Looking at the results of the voltage-current density (J-V) curve in (85?), as the voltage-current density (J-V) curve moves to the left as a whole from room temperature to high temperature, the blue organic light emitting device at a lower voltage than at high temperature It can be seen that it is turned on and current begins to flow.

The above result is a phenomenon showing a difference in hole transfer characteristics between the case where holes are injected and moved at room temperature and the case where holes are injected and moved at high temperature. At high temperatures, holes move faster, and the voltage-current density (J-V) curve shifts to the left, indicating a lower turn-on voltage and more current flowing at lower voltages.

Looking at Comparative Example 1 and Comparative Example 2 with reference to FIG. 5, in the case of Comparative Example 1, at room temperature, the voltage-current density (J-V) curve is located on the right side of the desired current density region, that is, the EML contribution prediction interval, but at high temperature, the EML contribution It is located within the prediction interval. In the case of Comparative Example 2, it can be seen that the voltage-current density (J-V) curve is located within the desired current density region (EML contribution prediction interval) at room temperature, but is located on the left side of the EML contribution prediction interval outside the desired current density region at high temperature. have.

As in Comparative Example 1, when the hole-controlling layer 1 (HCL 1) material, which is the hole-controlling layer material, is formed in each of the first hole-transporting layer 130 and the first hole-controlling layer 135, the voltage-current density ( It can be seen that the J-V) curve is located outside the EML contribution prediction interval. Therefore, it can be seen that the efficiency of the blue organic light emitting device is lowered at room temperature, resulting in a low lifetime of the blue organic light emitting device.

In addition, looking at the case of Comparative Example 2, when NPD, which is a hole transport layer material, is equally formed on each of the first hole transport layer 130 and the first hole control layer 135, the desired current density region is due to general movement of holes at room temperature. It can be seen that light emission occurs in (EML contribution prediction interval). At high temperatures, as the hole movement ability increases, the turn-on voltage of the blue organic light emitting diode decreases, and light is emitted in an undesired current density region (ETL contribution prediction period), and energy does not contribute to light emission. It will be used as luminous energy (heat energy). Therefore, the light emission stability and efficiency of the blue organic light emitting device is lowered, and the lifespan of the blue organic light emitting device is reduced.

On the other hand, NPD is formed on the first hole transport layer 130 according to the conditions of Example 1 according to the embodiment of the present invention, and hole control layer 1 (HCL 1), which is a hole control layer material, is formed on the first hole control layer 135. When is formed, the voltage-current density (J-V) curve at room temperature is located within the EML contribution prediction interval, which is the desired current density region. In addition, even when the voltage-current density (J-V) curve moves to the left as the hole movement ability increases even at high temperature, it is found that the voltage-current density (J-V) curve is located within the EML contribution prediction interval, which is the desired current density region. can

In this way, in the case of Example 1 according to the embodiment of the present invention, that is, the HOMO energy level of the first hole control layer 135 is lower than the HOMO energy level of the first hole transport layer 130 by 0.1 eV or more, and the LUMO energy level is 0.1eV or more lower than the LUMO energy level of the first hole transport layer 130, and having a triplet energy level (T1) higher than the triplet energy level (T1) of the dopant of the first blue light emitting layer 142. 1 In the case of a blue organic light emitting device to which the hole control layer 135 is applied, as the first hole control layer 135 exhibits higher mobility than electrons at a high temperature, holes recombine with electrons to emit light. It is possible to prevent a phenomenon of leaving the light emitting area by passing through the organic light emitting layer, which is the area, and moving to the electron transport layer. Accordingly, it can be seen that the luminous efficiency in the organic light emitting layer is improved and excellent lifespan characteristics are exhibited even at high temperatures.

In addition, referring to FIG. 5, referring to Example 2 and Example 3, in both cases, at room temperature, the voltage-current density (J-V) curve is located within the EML contribution prediction region, which is the desired current density region, but at high temperature, voltage-current It can be seen that the density (J-V) curve partially deviated from the EML contribution prediction region, which is the desired current density region, and is located in the ETL contribution prediction region.

Therefore, in the case of Example 2 and Example 3, when compared with Comparative Example 1 and Comparative Example 2, it exhibits improved life characteristics at high temperatures, but when compared with Example 1, it can be seen that the life characteristics at high temperatures are lowered.

That is, in the case of applying the hole control layer (HCL) structure that satisfies the conditions of Example 1, from the above results, as the hole exhibits high mobility characteristics at high temperature, the hole is a region in which electrons and holes recombine to emit light. It is possible to prevent a phenomenon of moving to the electron transport layer (ETL) through the organic light emitting layer and leaving the light emitting region. Accordingly, it can be seen that by stably maintaining the charge balance of holes and electrons in the organic light emitting layer, it is possible to secure excellent lifespan characteristics of the organic light emitting device even at a high temperature.

FIG. 6 is a view showing results of comparative evaluation of electro-optical characteristics of the organic light emitting device 1000 according to the comparative example and the embodiment of the present invention.

Referring to FIG. 6, Comparative Example 2-1 has a blue organic light emitting device structure according to the conditions of Comparative Example 2 described above with reference to FIG. It shows the result of comparative evaluation of the electro-optical characteristics of each blue organic light emitting device having a blue organic light emitting device structure according to conditions.

Hereinafter, the structure of the blue organic light emitting diode according to Comparative Example 2-1 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 the hole injection layer 120 is formed with HATCN to a thickness of 100 Å thereon, and then the first hole transport layer ( 130) was formed with NPD to a thickness of 400 Å.

Next, an anthracene derivative is formed to a thickness of 200 Å as a host material of the first blue light emitting layer 142 thereon, and a pyrene derivative is doped by 5% as a dopant material to form the first blue light emitting layer 142. formed.

Next, the first electron transport layer 150 is formed thereon with Alq ₃ It was formed to a thickness of 250 Å, and an anthracene derivative was formed to a thickness of 100 Å as the first charge generation layer 160 thereon, and the first charge generation layer 160 was formed by doping 2% of lithium (Li) as a dopant. NPD was formed to a thickness of 375 Å as the second charge generation layer 165 thereon, and F4-TCNQ, a p-type material, was doped with 8% to form the second charge generation layer 165 .

Next, the second hole transport layer 170 is formed with NPD to a thickness of 400 Å thereon, and an anthracene derivative is formed thereon as a host material for the second blue light emitting layer 182 to a thickness of 200 Å, and as a dopant material. The second blue light emitting layer 182 was formed by doping a pyrene derivative by 5%.

Next, the second electron transport layer 190 is formed on the Alq ₃ and Liq are mixed to form a thickness of 350 Å, and a silver-magnesium alloy (Ag:Mg) is formed to a thickness of 160 Å as the second electrode 200 thereon, and a capping layer 210 is formed on top of the second electrode 200 to a thickness of 650 Å with NPD. A blue organic light emitting device according to Comparative Example 2-1 was manufactured by forming the same thickness.

Next, the structure of the blue organic light emitting device according to Example 1-1 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 the hole injection layer 120 is formed with HATCN to a thickness of 100 Å thereon, and then the first hole transport layer ( 130) was formed with NPD to a thickness of 300 Å, and a first hole control layer 135 was formed thereon with a thickness of 100 Å with a hole control layer 1 (HCL 1) material.

Next, an anthracene derivative is formed to a thickness of 200 Å as a host material of the first blue light emitting layer 142 thereon, and a pyrene derivative is doped by 5% as a dopant material to form the first blue light emitting layer 142. formed.

Next, the first electron transport layer 150 is formed thereon with Alq ₃ It was formed to a thickness of 250 Å, and an anthracene derivative was formed to a thickness of 100 Å as the first charge generation layer 160 thereon, and the first charge generation layer 160 was formed by doping 2% of lithium (Li) as a dopant. NPD was formed to a thickness of 375 Å as the second charge generation layer 165 thereon, and F4-TCNQ, a p-type material, was doped with 8% to form the second charge generation layer 165 .

Next, the second hole transport layer 170 is formed on the top with NPD to a thickness of 300 Å, and the second hole control layer 175 is formed on top with a thickness of 100 Å with hole control layer 1 (HCL 1) material. An anthracene derivative was formed to a thickness of 200 Å as a host material for the second blue light emitting layer 182 thereon, and a pyrene derivative was doped with 5% as a dopant material to form the second blue light emitting layer 182. .

Next, a second electron transport layer 190 is formed on the upper portion to a thickness of 350 Å by mixing Alq ₃ and Liq, and a silver-magnesium alloy (Ag:Mg) is formed on the upper portion to a thickness of 160 Å as the second electrode 200. Then, a capping layer 210 was formed with NPD to a thickness of 650 Å on top of the capping layer 210 to manufacture a blue organic light emitting device according to Example 1-1. Electro-optical characteristics of each blue organic light emitting diode according to Comparative Example 2-1 and Example 1-1 were compared and evaluated.

Referring to FIG. 6, comparing the driving voltage side of the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1, in the case of Comparative Example 2-1, a luminance of 650 nit was obtained, and a driving voltage of 7.7V was obtained. it was demanded In the case of Example 1-1, a driving voltage of 7.6V was required to show the same luminance of 650 nits, and the driving voltage was reduced to about 0.1 V in Example 1-1 compared to Comparative Example 2-1. .

In addition, referring to FIG. 6 , comparing the current efficiency of the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention, the Comparative Example showed an efficiency of 11.6 Cd/A. In the case of Example 1-1, the efficiency was 12.2 Cd/A, and the efficiency was increased to 0.6 Cd/A in Example 1-1 compared to Comparative Example 2-1.

In addition, referring to FIG. 6, it can be seen that the blue organic light emitting device according to Example 1-1 showed improved results in terms of power efficiency (lm/W) and external quantum efficiency (EQE) compared to Comparative Example 2-1. have.

In the case of Example 1-1 according to an embodiment of the present invention, it can be seen that the luminous efficiency is improved at high temperature and the driving voltage is lowered. Therefore, in order to improve luminous efficiency at a high temperature and obtain a low driving voltage, the HOMO energy level of the first hole control layer 135 is lower than that of the first hole transport layer 130 by 0.1 eV or more, and the LUMO energy level is It may be set at least 0.1 eV lower than the LUMO energy level of the first hole transport layer 130 . In addition, the first hole control layer 135 having a higher triplet energy level T1 than the triplet energy level T1 of the dopant of the first blue light emitting layer 142 may be applied. In addition, the HOMO energy level of the second hole control layer 175 is 0.1 eV or more lower than the HOMO energy level of the second hole transport layer 170, and the LUMO energy level is 0.1 eV or more than the LUMO energy level of the second hole transport layer 170. can be set lower. In addition, the second hole control layer 135 having a higher triplet energy level T1 than the triplet energy level T1 of the dopant of the second blue light emitting layer 182 may be applied.

7 is a view showing the results of comparative evaluation of lifetime characteristics at room temperature in Comparative Example 2-1 and the blue organic light emitting device according to Example 1-1 of the present invention. 8 is a view showing the results of comparative evaluation of lifetime characteristics at a high temperature in Comparative Example 2-1 and the blue organic light emitting device according to Example 1-1 of the present invention. 9 is a view showing the results of comparative evaluation of lifetime characteristics at room temperature and high temperature in Comparative Example 2-1 and the blue organic light emitting device according to Example 1-1 of the present invention.

First, referring to FIGS. 7 and 9 , comparing the lifespan characteristics at room temperature in Comparative Example 2-1 and the blue organic light emitting device according to Example 1-1 of the present invention, Comparative Example 2 at room temperature (25?) In the case of -1, the time required to reach 95% of the initial light emission luminance, that is, the 95% lifespan time (T95) of the blue organic light emitting device was about 245 hours. In the case of Example 1-1, the 95% life time (T95) was about 250 hours, and at room temperature, the lifespan of the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 was equivalent. .

On the other hand, referring to FIGS. 8 and 9, comparing the lifespan characteristics at high temperatures in Comparative Example 2-1 and the blue organic light emitting device according to Example 1-1 of the present invention, Comparative Example at high temperature (85?) In the case of 2-1, the time required to reach 80% of the initial light emission luminance, that is, the 80% lifetime (T80) of the blue organic light emitting device, was about 125 hours. In the case of Example 1-1, the 80% lifespan time (T80) is about 275 hours, and the lifespan of the blue organic light emitting device according to Example 1-1 is greatly improved compared to Comparative Example 2-1 at high temperatures. It can be seen that the results are displayed.

In the case of Example 1-1 according to an embodiment of the present invention, luminous efficiency in the organic light emitting layer can be improved at a high temperature, and lifespan characteristics can be improved at a high temperature. Therefore, in order to obtain luminous efficiency in the organic light emitting layer at high temperature and improved lifetime characteristics at high temperature, the HOMO energy level of the first hole control layer 135 is lower than that of the first hole transport layer 130 by 0.1 eV or more, The LUMO energy level may be set to be 0.1eV or more lower than the LUMO energy level of the first hole transport layer 130 . In addition, the first hole control layer 135 having a higher triplet energy level T1 than the triplet energy level T1 of the dopant of the first blue light emitting layer 142 may be applied. In addition, the HOMO energy level of the second hole control layer 175 is 0.1 eV or more lower than the HOMO energy level of the second hole transport layer 170, and the LUMO energy level is 0.1 eV or more than the LUMO energy level of the second hole transport layer 170. can be set lower. In addition, the second hole control layer 135 having a higher triplet energy level T1 than the triplet energy level T1 of the dopant of the second blue light emitting layer 182 may be applied. As a result, as the first hole control layer 135 and the second hole control layer 175 exhibit higher mobility than electrons at a high temperature, holes pass through the organic light emitting layer, which is a region in which electrons and holes recombine to emit light. By preventing the electron transport layer from moving out of the light emitting region, the light emitting efficiency in the organic light emitting layer can be improved at a high temperature, and lifespan characteristics can be improved at a high temperature.

In the present specification, according to an embodiment of the present invention, an organic having a first hole-controlling layer 135 included in the first light-emitting unit 1100 and a second hole-controlling layer 175 included in the second light-emitting unit 1200 Although the light emitting device structure has been specifically described, it is not limited thereto, and the organic light emitting device structure having a hole control layer in at least one light emitting unit of the first light emitting unit 1100 and the second light emitting unit 1200 has the same high temperature. It is possible to obtain the effect of increasing the luminous efficiency and improving the lifetime.

In addition, in the present specification, a blue organic light emitting device to which a hole control layer is applied is manufactured, and the results of evaluating efficiency and lifespan at a high temperature are described in detail. Although not described, when the hole control layer having the same conditions as in the blue organic light emitting device structure according to the embodiment of the present invention is applied, the luminous efficiency is increased at a high temperature and the lifespan is the same in the red organic light emitting device and the green organic light emitting device. This enhancing effect can be obtained.

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 various modifications can be made without departing from the technical spirit of the present invention. have. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea 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 construed according to the scope of 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 element
110: first electrode
120: hole injection layer
130: first hole transport layer
135: first hole control 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
175: second hole control 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 (20)

a substrate including a red sub-pixel area, a green sub-pixel area, and a blue sub-pixel area;
a first electrode and a second electrode disposed on the substrate;
a first light emitting unit disposed between the first electrode and the second electrode and including a first hole transport layer and a first organic light emitting layer;
a second light emitting unit positioned between the first electrode and the second electrode and including a second hole transport layer and a second organic light emitting layer;
a first hole control layer positioned between the first hole transport layer and the first organic light emitting layer; and
A second hole control layer positioned between the second hole transport layer and the second organic light emitting layer;
the first organic emission layer disposed in the red sub-pixel region is a first red emission layer, and the second organic emission layer disposed in the red sub-pixel region is a second red emission layer;
the first organic emission layer disposed in the green sub-pixel region is a first green emission layer, and the second organic emission layer disposed in the green sub-pixel region is a second green emission layer;
the first organic emission layer disposed in the blue sub-pixel region is a first blue emission layer, and the second organic emission layer disposed in the blue sub-pixel region is a second blue emission layer;
The HOMO energy level of each of the first hole control layer and the second hole control layer is lower than the HOMO energy level of each of the first hole transport layer and the second hole transport layer, and the first organic light emitting layer and the second organic light emitting layer, respectively The HOMO energy level of the host and the dopant of is lower than the HOMO energy level of each of the first hole control layer and the second hole control layer,
The LUMO energy level of each of the first hole control layer and the second hole control layer is lower than the LUMO energy level of each of the first hole transport layer and the second hole transport layer, and the first organic light emitting layer and the second organic light emitting layer, respectively The LUMO energy level of the host and the dopant of is lower than the LUMO energy level of each of the first hole control layer and the second hole control layer,
The triplet energy level (T1) of each of the first hole-controlling layer and the second hole-controlling layer is higher than the triplet energy level (T1) of the dopant included in each of the first organic light-emitting layer and the second organic light-emitting layer. organic light emitting device. According to claim 1,
The organic light emitting device of claim 1 , wherein the HOMO energy level of the first hole control layer has an energy level lower than that of the first hole transport layer by 0.1 eV or more. According to claim 2,
The organic light emitting device of claim 1 , wherein the LUMO energy level of the first hole control layer has an energy level lower than that of the first hole transport layer by 0.1 eV or more. According to claim 1,
The HOMO energy level of the second hole control layer has an energy level lower than the HOMO energy level of the second hole transport layer by 0.1 eV or more. According to claim 2,
The organic light emitting device of claim 1 , wherein the LUMO energy level of the second hole control layer has an energy level lower than that of the second hole transport layer by 0.1 eV or more. delete delete According to claim 1,
The first hole control layer and the second hole control layer are respectively 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 consisting of any one of TBA. According to claim 1,
An organic light emitting device comprising a first charge generating layer and a second charge generating layer positioned between the first light emitting unit and the second light emitting unit. According to claim 9,
The first charge generating layer and the second charge generating layer are organic light emitting devices made of an NP junction structure. delete According to claim 1,
The organic light emitting device of claim 1 , wherein the first hole control layer and the second hole control layer are made of different materials. According to claim 9,
The first charge generating layer and the second charge generating layer have different thicknesses. According to claim 9,
The thickness of the first charge generation layer is thicker than the thickness of the second charge generation layer organic light emitting device. According to claim 1,
The organic light emitting device further comprises a capping layer disposed on the second electrode. According to claim 15,
The capping layer is disposed in the red sub-pixel area, the green sub-pixel area, and the blue sub-pixel area. According to claim 15,
A thickness of the capping layer is greater than a thickness of each of the layers included in the first light emitting unit and the second light emitting unit. According to claim 1,
The first blue light emitting layer and the second blue light emitting layer include a fluorescent material. According to claim 1,
The first red light emitting layer, the second red light emitting layer, the first green light emitting layer, and the second green light emitting layer include a phosphorescent material.
delete

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