KR102687297B1 - Organic light emitting device - Google Patents

Abstract

The organic light emitting device according to an embodiment of the present invention is located between the first electrode and the second electrode and the first electrode and the second electrode and includes a first light emitting unit and a first electrode including a first hole transport layer and a first organic light emitting layer. and a second light emitting unit located 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 located between the first hole transport layer and the first organic light emitting layer, and It is characterized as an organic light-emitting device including a second hole control layer located between the second organic light-emitting layers.

Description

Organic light emitting device {ORGANIC LIGHT EMITTING DEVICE}

The present invention relates to an organic light emitting device, and more specifically, to an organic light emitting device capable of improving efficiency and lifespan in a high temperature environment.

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

Organic light emitting display devices include top emission, bottom emission, and dual emission methods depending on the direction in which light is emitted, and passive matrix types 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 in a lightweight and thin form. In addition, organic light emitting display devices are not only advantageous in terms of power consumption due to low voltage driving, but also have excellent color reproduction, response speed, viewing angle, and contrast ratio (CR), and are being studied as next-generation displays.

As displays develop with high resolution, the number of pixels per unit area increases and high luminance is required. However, there is a limit to the unit area current (A) due to the light emitting structure of organic light emitting display devices, and the increase in applied current causes the organic light emitting device to deteriorate. There are problems with reduced reliability and increased power consumption.

Therefore, it is necessary to overcome the technical limitations of improving the luminous efficiency, lifespan, and reducing power consumption of organic light-emitting devices, which are factors that impede the quality and productivity of organic light-emitting display devices, and maintain the color gamut while maintaining luminous efficiency, lifespan of the light-emitting layer, and viewing angle. Various research is being conducted to develop organic light-emitting devices that can improve their 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 the efficiency and lifespan of organic light emitting devices and reduce power consumption.

Accordingly, in order to implement not only one stack (1 stack), that is, one electroluminescence unit (EL unit), an organic light emitting device structure, but also improved efficiency and lifespan characteristics, a plurality of stacks (stacks), i.e. An organic light-emitting device with a tandem structure that uses 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 located in each of the first light emitting unit and the second light emitting unit. Therefore, when the organic light emitting device is driven at room temperature, there is no problem with the light emission life of the organic light emitting device due to the high efficiency and the resulting low current.

However, in a high-temperature environment, as holes exhibit higher mobility than electrons, holes pass through the organic light-emitting layer, which is the area where electrons and holes recombine and emit light, and move to the electron transport layer, thereby escaping the light-emitting area. Accordingly, at high temperatures, holes appear to have higher mobility than electrons. There is a problem in which the efficiency and lifespan characteristics of organic light emitting devices are significantly reduced.

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

The problem to be solved according to an embodiment of the present invention is to form a first hole control layer between a first hole transport layer and a 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. The purpose is to provide an organic light-emitting device capable of improving efficiency and lifespan at high temperatures by forming a second hole control layer between the and the second organic light-emitting layer.

Problems to be solved according to embodiments 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 description below.

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

The organic light emitting device according to an embodiment of the present invention is located between the first electrode and the second electrode and the first electrode and the second electrode and includes a first light emitting unit and a first electrode including a first hole transport layer and a first organic light emitting layer. and a second light emitting unit located 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 located between the first hole transport layer and the first organic light emitting layer and the It is characterized as an organic light-emitting device including a second hole control layer located between the second organic light-emitting layers.

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

The LUMO energy level of the first hole control layer may be at least 0.1 eV lower than the LUMO energy level of the first hole transport layer.

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

The LUMO energy level of the second hole control layer may be at least 0.1 eV lower than the LUMO energy level of the second hole transport layer.

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

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

The first hole control layer and the second hole control layer are TPD (N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)-benzidine) and 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( It may be composed of any one of 9,9-dimethylfluoren-2-yl)amino]phenyl group), spiro-TCBz (triclabendazole), and TBA.

It may include a first charge generation layer and a second charge generation layer located between the first light emitting unit and the second light emitting unit.

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 located in the red sub-pixel area, a first green light-emitting layer located in the green sub-pixel area, and a first blue light-emitting layer located in the blue sub-pixel area, and the second organic light-emitting layer may include a second red light-emitting layer located in the red sub-pixel area, a second green light-emitting layer located in the green sub-pixel area, and a second blue light-emitting layer located 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 located between a first electrode and a second electrode and the first electrode and the second electrode, and the at least two light emitting units include a hole transport layer and an organic light emitting device. It includes a light-emitting layer, and one of the at least two light-emitting units is an organic light-emitting device including a hole control layer located 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 an organic light-emitting device with a stack structure using a stack of a plurality of light-emitting units according to an embodiment of the present invention, holes exhibit higher mobility characteristics than electrons at high temperatures by forming a hole control layer between the hole transport layer and the organic light-emitting layer. Accordingly, it is possible to prevent holes from escaping the light-emitting area by moving through the organic light-emitting layer, which is the area where electrons and holes recombine and emit light, to the electron transport layer.

In addition, since the recombination area of electrons and holes does not leave the light-emitting area, the efficiency and lifespan of the organic light-emitting device can be improved at high temperatures.

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 above in the problem to be solved, the means for solving the problem, and the effect do 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.
Figure 2 is a diagram showing the HOMO energy level and LUMO energy level conditions of the hole transport layer and the hole control layer in an organic light emitting device according to an embodiment of the present invention.
Figure 3 is a diagram showing the triplet energy level (T1) conditions of the hole transport layer, the hole control layer, and the blue light emitting layer in the organic light emitting device according to an embodiment of the present invention.
Figure 4 is a diagram showing the results of life evaluation at room temperature and high temperature for an organic light emitting device according to an embodiment of the present invention.
Figure 5 is a diagram showing the results of evaluating current density according to voltage at room temperature and high temperature in an organic light emitting device according to an embodiment of the present invention.
Figure 6 is a diagram showing the results of comparative evaluation of electro-optical characteristics in organic light-emitting devices according to comparative examples and embodiments of the present invention.
Figure 7 is a diagram showing the results of comparative evaluation of lifespan characteristics at room temperature in organic light-emitting devices according to comparative examples and embodiments of the present invention.
Figure 8 is a diagram showing the results of comparative evaluation of lifespan characteristics at high temperatures in organic light-emitting devices according to comparative examples and embodiments of the present invention.
Figure 9 is a diagram showing the 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.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms, but the present embodiments only serve to ensure that the disclosure of the present invention is complete, and are known to those skilled in the art 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 embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', 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 plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description. In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

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

*The features of various embodiments of the present invention can be partially or fully combined or combined with each other, and various technical interconnections and operations are possible, and each embodiment can be implemented independently of each other or together in a related relationship. You may.

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

Figure 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, the organic light emitting device 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), a hole injection layer (120, hole injection layer: HIL), a first hole transport layer (130, 1 ^st hole transporting layer: 1 ^st HTL), and a first hole control layer (135, 1 ^st hole control layer: 1 ^st HCL), first red emission layer (140, 1 ^st Red emission layer: 1 ^st Red EML), first green emission layer (141, 1 ^st Green emission layer: 1 ^st Green EML), and A first organic light-emitting layer made of 1 blue emission layer (142, 1 ^st Blue emission layer: 1 ^st Blue EML), a first electron transport layer (150, 1 ^st electron transporting layer: 1 ^st ETL), and a first charge generation layer (160, 1 ^st charge generation layer: N-CGL), 2nd charge generation layer (165, 2 ^nd charge generation layer: P-CGL), 2nd hole transport layer (170, 2 ^nd hole transporting layer: 2 ^nd HTL), 2nd Hole control layer (175, 2 ^nd hole control layer: 2 ^nd HCL), 2nd red emission layer (180, 2 ^nd Red emission layer: 2 ^nd Red EML), 2nd green emission layer (181, 2 ^nd Green emission layer: 2 ^nd Green EML) and a second blue emission layer (182, ^2nd Blue emission layer: ^2nd Blue EML), a second electron transport layer (190, ^2nd electron transporting layer: ^2nd ETL), a second It includes an electrode (200, cathode) and a capping layer (210, CPL).

In addition, the organic light-emitting device 1000 according to an 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 a second light-emitting unit (1200, 2 ^nd EL Unit) including a second organic light-emitting layer is an organic light-emitting device having 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, It is configured to include a first organic light-emitting layer and a first electron transport layer 150 including a first red light-emitting layer 140, a first green light-emitting layer 141, and a first blue light-emitting layer 142.

Additionally, 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 and a second electron transport layer 190 made of a green light-emitting layer 181 and a second blue light-emitting layer 182.

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, located between the first light-emitting unit 1100 and the second light-emitting unit 1200. It is configured to include a second charge generation layer 165, which is a p-type charge generation layer.

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

The first electrode 110 is located on the substrate to correspond to each of the red sub-pixel area (Rp), green sub-pixel area (Gp), and blue sub-pixel area (Bp), and may be made of a reflective electrode.

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

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

The hole injection layer 120 may play a role in facilitating hole injection, and may contain HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), and PEDOT (poly(3) ,4)-ethylenedioxythiophene), PANI (polyaniline), and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine). It may be composed of one or more selected from the group, but is not limited thereto.

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

The first hole transport layer 130 and the second hole transport layer 170 play a role in facilitating the transport of holes, and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine) and 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), 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 located in all of the red sub-pixel region (Rp), green sub-pixel region (Gp), and blue sub-pixel region (Bp). It is located on the first hole transport layer 130 to correspond.

Additionally, the second hole control layer 175 is located on the second hole transport layer 170 to correspond to all of the red sub-pixel area (Rp), green sub-pixel area (Gp), and blue sub-pixel area (Bp).

The first hole control layer 135 and the second hole control layer 175 are the first red light-emitting layer 140, which is a region where holes recombine with electrons to emit light as holes exhibit higher mobility than electrons at high temperatures. ), a first organic light-emitting layer consisting of a first green light-emitting layer 141 and a first blue light-emitting layer 142, a second red light-emitting layer 180, a second green light-emitting layer 181, and a second blue light-emitting layer 182. 2 It serves to prevent the phenomenon of moving beyond the light emitting area by moving through the organic light emitting layer to the first electron transport layer 150 and the second electron transport layer 190. The first hole control layer 135 and the second hole control layer 175 may be made of a material such as carbazole derivative, triarylamine derivative, or 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 TBA, but is not limited thereto. The materials of the first hole control layer 135 and the second hole control layer 175 can be expressed by the structural formula below.

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 the movement of holes in the first light emitting unit 1100 and the second light emitting unit 1200 It may be made of different materials selected from the materials described above in consideration of their properties.

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 ), 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 containing a dopant including the above, and alternatively, it may be made of a fluorescent material containing 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 area (Gp) on the first hole transport layer 130, and the second green light-emitting layer 181 is located in the green sub-pixel area (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 light-emitting material that emits green light, 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 containing a dopant material such as an iridium complex (Ir complex), and alternatively, it may be made of a fluorescent material containing 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 area (Bp) on the first hole transport layer 130, and the second blue light-emitting layer 182 is located 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 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 phosphorescent material including a dopant material including (4,6-F2ppy)2Irpic. It can be made of material. In addition, it may be made of a fluorescent material containing any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymer, and PPV-based polymer, but is limited thereto. It doesn't work.

The first electron transport layer 150 includes a first red light-emitting layer 140 and a first green light-emitting layer 141 to correspond to all of the red sub-pixel region (Rp), green sub-pixel region (Gp), and blue sub-pixel region (Bp). And located on the first blue light-emitting layer 142, the second electron transport layer 190 is a second electron transport layer 190 so as to correspond to all of the red sub-pixel area (Rp), green sub-pixel area (Gp), and blue sub-pixel area (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 play a role in transporting and injecting electrons, and the thickness of the first electron transport layer 150 and the second electron transport layer 190 determines the electron transport characteristics. It 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 It may be composed of one or more selected from the group consisting of -(4-tert-butylpheny)-1,3,4oxadiazole), TAZ, spiro-PBD, BAlq, and SAlq, but is not limited thereto.

In addition, 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 can be used, but are not limited to these.

Here, the structure is not limited according to the embodiment of the present invention, and includes a hole injection layer 120, a first hole transport layer 130, a second hole transport layer 170, a first electron transport layer 150, and a second hole transport layer 120. 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 divided into two or more layers. It is also possible to form

The first charge generation layer 160 is located on the first electron transport layer 150 to correspond to all of the red sub-pixel region (Rp), green sub-pixel region (Gp), and blue sub-pixel region (Bp), and the second The charge generation layer 165 is located on the first charge generation layer 160 to correspond to all of the red sub-pixel region (Rp), green sub-pixel region (Gp), and blue sub-pixel region (Bp), and generates 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 generation layer 160 and the second charge generation layer 165 are located between the first light-emitting unit 1100 and the second light-emitting unit 1200, and the first charge generation layer ( 160) and the second charge generation layer 165 serve to adjust the charge balance between the two light-emitting units, 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 assists the injection of electrons into the first light emitting unit 1100 located below the first charge generation layer 160, The second charge generation layer 165 functions as a p-type charge generation layer (p-CGL) that assists the injection of holes into the second light emitting unit 1200 located on top of the second charge generation layer 165.

More specifically, the first charge generation layer 160, which is an n-type charge generation layer (n-CGL) that plays the role of electron injection, is formed of an alkali metal, an alkali metal compound, an organic material that plays an electron injection role, or a compound thereof. It is possible. Additionally, the host material of the first charge generation layer 160 may be made of the same material as that of the first electron transport layer 150 and the second electron transport layer 190. For example , it may be composed 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 to this.

The second charge generation layer 165 is located on the first charge generation layer 160. The second charge generation layer 165 functions as a p-type charge generation layer (p-CGL) that functions as a hole injection, and the host material of the second charge generation layer 165 is the first hole injection layer 120. , may be made of the same material as that of the first hole transport layer 130 and the second hole transport layer 170. For example , p-type dopants are added to 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 composed of a doped mixed layer, but is not limited thereto. Additionally, the p-type dopant may be made of either 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 area (Rp), green sub-pixel area (Gp), and blue sub-pixel area (Bp). For example, the second electrode 200 may be made of an alloy of magnesium and silver (Mg:Ag) and may have transflective characteristics. That is, the 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 transflective characteristics, some of the light is directed back to the first electrode 110. .

In this way, the first electrode 110 and the second electrode 200 are formed by a micro cavity effect in which repetitive reflection occurs between the first electrode 110 and the second electrode 200, which act as a reflective layer. Light is reflected repeatedly within the cavity, increasing light efficiency.

In addition, it is possible to form the first electrode 110 as a transmission electrode and the second electrode 200 as a reflection 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 located on the second electrode 200. The capping layer 210 is to increase the light extraction effect in the organic light emitting device, and is composed of the first hole transport layer 130, the second hole transport layer 170 material, 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. Additionally, the capping layer 210 can be omitted.

FIG. 2 is a diagram showing the HOMO energy level and LUMO energy level conditions of the hole transport layer and the hole control layer in the organic light emitting device 1000 according to an embodiment of the present invention. In addition, FIG. 3 is a diagram showing the triplet energy level (T1) conditions of the host and dopant of the hole transport layer, hole control layer, and 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 was manufactured according to the conditions of FIGS. 2 and 3 to form a structure for the hole control layer. Evaluation was conducted. Here, 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 HOD (hole only device) unit device was used to evaluate the structure of the hole control layer consisting only of the second electrode 200.

Referring to Figures 2 and 3, in the case of Comparative Example 1, the first hole transport layer 130 and the first hole control layer 135 each have a LUMO energy level of 2.1 eV and a HOMO energy level of 5.26 eV, and a HOMO energy level of 2.58 eV. A blue organic light-emitting device was manufactured by forming a hole control layer 1 (HCL 1) material with a triplet energy level (T1). Additionally, the dopant of the first blue organic emission 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 of each of the first hole transport layer 130 and the first hole control layer 135 is 0.1 eV or more lower than the HOMO energy level of the first hole transport layer 130, and the LUMO Holes whose energy level is at least 0.1 eV lower than the LUMO energy level of the first hole transport layer 130 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 control layer 1 (HCL 1) material is applied.

The LUMO energy level refers to the Lowest Unoccupied Molecular Orbital (LUMO), and the HOMO energy level refers to the Hightest Occupied Molecular Orbital (HOMO).

Additionally, the triplet energy level (T1) refers to the energy level of a non-luminescent triplet exciton that is lost during fluorescence emission. In addition, as shown in FIG. 3, a hole control layer 1 (HCL 1) material, a hole control layer 2 (HCL 2) material, and The triplet energy level (T1) of the hole control layer 3 (HCL 3) material is all dopants ( It has a higher energy level than the triplet energy level (T1) of BD).

In addition, in the case of Comparative Example 2, each of the first hole transport layer 130 and the first hole control layer 135 had 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 manufactured by forming NPD, which is a hole transport layer (HTL) material with T1). Additionally, the dopant of the first blue organic emission 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 had the same LUMO energy level of 2.0 eV, a HOMO energy level of 5.13 eV, and a triplet energy level (T1). The first blue light-emitting layer 142 has a structure in which NPD, a hole transport layer (HTL) material higher than the triplet energy level (T1) of the dopant, is applied.

In addition, in 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 in the first hole transport layer 130, and the first hole control layer ( [135] A blue organic light-emitting device was manufactured by forming a hole control layer 1 (HCL 1) material with a LUMO energy level of 2.1 eV, a HOMO energy level of 5.26 eV, and a triplet energy level (T1) of 2.58 eV. Additionally, the dopant of the first blue organic emission layer 142 has a triplet energy level (T1) of 2.4 eV. That is, in 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 than the HOMO energy level of the first hole transport layer 130. The LUMO energy level is at least 0.1 eV lower than the LUMO energy level of the first hole transport layer 130, and the triplet energy level (T1) is lower than 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 in the first hole transport layer 130, and the first hole control layer ( [135] A blue organic light-emitting device was manufactured by forming a hole control layer 2 (HCL 2) material with a LUMO energy level of 2.1 eV, a HOMO energy level of 5.20 eV, and a triplet energy level (T1) of 2.57 eV. Additionally, the dopant of the first blue organic emission 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 way as Example 1, and the HOMO energy level of the first hole control layer 135 is that of the first hole transport layer 130. The HOMO energy level is less than 0.1 eV lower, the LUMO energy level is less than 0.1 eV lower than the LUMO energy level of the first hole transport layer 130, and the triplet energy level (T1) is lower than that 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 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 in the first hole transport layer 130, and the first hole control layer ( [135] A blue organic light-emitting device was manufactured by forming a hole control layer 3 (HCL 3) material with a LUMO energy level of 1.95 eV, a HOMO energy level of 5.1 eV, and a triplet energy level (T1) of 2.50 eV. Additionally, the dopant of the first blue organic emission 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 way as Examples 1 and 2, and the HOMO energy level is applied to the first hole control layer 135. ) is higher than the HOMO energy level, 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 higher than the triplet energy level of the dopant of the first blue light-emitting layer 142 ( It has a structure in which a higher hole control layer 3 (HCL 3) material than T1) 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 each blue organic light-emitting device was manufactured at room temperature and high temperature. The efficiency and lifespan characteristics were compared and evaluated.

Figure 4 is a diagram showing the results of life evaluation 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, Figure 4 shows that each blue organic light-emitting device was manufactured by forming a hole transport layer and a hole control layer under the conditions previously described with reference to FIGS. 2 and 3, and each blue organic light-emitting device was fabricated at room temperature (25?) and high temperature (85?). ) shows the results of comparing and evaluating the lifespan characteristics.

Referring to FIG. 4, in the case of the blue organic light emitting device according to the conditions of Comparative Example 1, the 95% life time (T95), which is the time from the initial emission luminance to a luminance level of 95% of the initial emission luminance at room temperature, is about 310 hours. In the case of the blue organic light emitting devices according to the conditions of Comparative Example 2, Example 1, Example 2, and Example 3, the 95% life time (T95) at room temperature was all about 2650 hours. That is, the blue organic light-emitting device according to the conditions of Comparative Example 2, Example 1, Example 2, and Example 3 showed the same excellent lifespan characteristics at room temperature, but the blue organic light-emitting device according to Comparative Example 1 showed low lifespan 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 (time from initial luminance to 80% of the initial luminance) measured after storage at high temperature, that is, at about 85°C, T80) was about 215 hours, and the 80% life time (T80) of the blue organic light-emitting device under the conditions of Comparative Example 2 was about 240 hours, and the 80% life time (T80) of the blue organic light-emitting device under the conditions of Example 1 was about 240 hours. The % life time (T80) is about 865 hours, the 80% life time (T80) of the blue organic light emitting device according to the conditions of Example 2 is about 520 hours, and the 80% life time of the blue organic light emitting device according to the conditions of Example 3 The time (T80) showed a result of about 280 hours.

In other words, looking at the above results comprehensively, the lifespan characteristics at high temperatures compared to room temperature were shown to be reduced in all conditions of Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, but Example 1 The blue organic light emitting device according to showed the best lifespan characteristics at high temperatures. This means that, according to an embodiment of the present invention, the HOMO energy level of the first hole control layer 135 is at least 0.1 eV lower than the HOMO energy level of the first hole transport layer 130, and the LUMO energy level is lower than that of the first hole transport layer 130. A first hole control layer 135 that is at least 0.1 eV lower than the LUMO energy level and has a triplet energy level (T1) higher than the triplet energy level (T1) of the dopant of the first blue light-emitting layer 142. In the case of the applied blue organic light emitting device, the first hole control layer 135 exhibits higher mobility characteristics for holes than for electrons at high temperatures. Accordingly, by preventing holes from moving to the electron transport layer through the organic light-emitting layer, which is the area where electrons and holes recombine to emit light, and escaping the light-emitting area, the luminous efficiency within the organic light-emitting layer is improved and exhibits excellent lifespan characteristics even at high temperatures. You can see that

Figure 5 is a diagram showing the results of evaluating current density 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, Figure 5 shows each of the blue organic light-emitting devices according to the hole transport layer and hole control layer conditions according to Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3 previously described with reference to Figures 2 and 3. This shows the results of evaluating the current density level according to voltage at room temperature and high temperature.

In FIG. 5, the rectangular EML region shown as a solid line within the voltage-current density (J-V) curve is the desired current density region that contributes to light emission in the organic light-emitting device and represents the organic light-emitting layer (EML) contribution prediction section. The rectangular ETL section shown as a solid line within the curve represents the predicted section for electron transport layer (ETL) contribution to the unwanted current density area.

Referring to FIG. 5, the voltage-current density (J-V) curve results at room temperature (25?) and high temperature in the blue organic light emitting devices according to Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3. 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 the temperature increases from room temperature, the blue organic light emitting device appears at a lower voltage than at high temperature. You can see that it turns on and current begins to flow.

The above result is a phenomenon showing a difference in hole movement characteristics when holes are injected and moved at room temperature and when holes are injected and moved at high temperature. At high temperatures, holes move faster, causing the voltage-current density (J-V) curve to shift to the left, lowering the turn-on voltage and showing 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 in the desired current density region, that is, to the right of the EML contribution prediction section, but at high temperature, the EML contribution is It is located within the prediction interval. In the case of Comparative Example 2, it can be seen that at room temperature the voltage-current density (J-V) curve is located within the desired current density area (EML contribution prediction section), but at high temperature, it is outside the desired current density area and is located to the left of the EML contribution prediction section. there is.

As in Comparative Example 1, when the first hole transport layer 130 and the first hole control layer 135 are made of the same hole control layer 1 (HCL 1) material, 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 lower lifespan 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 formed in each of the first hole transport layer 130 and the first hole control layer 135, the desired current density region is reached due to general hole movement at room temperature. It can be seen that light emission occurs in the (EML contribution prediction section). At high temperatures, as the hole movement ability increases, the turn-on voltage of the blue organic light-emitting device decreases, causing light emission in an unwanted current density region (ETL contribution prediction range), and energy does not contribute to light emission. It is used as luminous energy (heat energy). Therefore, as the emission stability and efficiency of the blue organic light emitting device decrease, the lifespan of the blue organic light emitting device decreases.

On the other hand, NPD is formed in 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 in the first hole control layer 135. In the case where , the voltage-current density (J-V) curve at room temperature is located within the EML contribution prediction section, which is the desired current density region. In addition, as the ability to move holes increases even at high temperatures, it can be seen that even when the voltage-current density (J-V) curve moves to the left, the voltage-current density (J-V) curve is located within the EML contribution prediction section, which is the desired current density region. You can.

As such, in the case of Example 1 according to an embodiment of the present invention, that is, the HOMO energy level of the first hole control layer 135 is 0.1 eV or more lower than the HOMO energy level of the first hole transport layer 130, and the LUMO energy level is The LUMO energy level of the first hole transport layer 130 is at least 0.1 eV lower, 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). 1 In the case of a blue organic light emitting device using the hole control layer 135, the first hole control layer 135 exhibits higher mobility characteristics than electrons at high temperatures, so that holes recombine with electrons to emit light. It can prevent the phenomenon of escaping from the light-emitting area by moving through the organic light-emitting layer and moving to the electron transport layer. Accordingly, it can be seen that the luminous efficiency within the organic light-emitting layer is improved and excellent lifespan characteristics are exhibited even at high temperatures.

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

Therefore, it can be seen that Examples 2 and 3 showed improved lifespan characteristics at high temperatures when compared with Comparative Examples 1 and 2, but showed deteriorated lifespan characteristics at high temperatures when compared with Example 1.

That is, from the above results, when applying the hole control layer (HCL) structure that satisfies the conditions of Example 1, it exhibits high mobility characteristics of holes at high temperatures, so that the holes are a region where electrons and holes recombine to emit light. It is possible to prevent the phenomenon of escaping from the emission area by moving through the organic emission layer to the electron transport layer (ETL). Therefore, it can be seen that excellent lifespan characteristics of the organic light-emitting device can be secured even at high temperatures by stably maintaining the charge balance of holes and electrons in the organic light-emitting layer.

FIG. 6 is a diagram showing the results of comparative evaluation of electro-optical characteristics of the organic light-emitting device 1000 according to a comparative example and an 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 previously described with reference to FIG. 2, and Example 1-1 has the structure of Example 1 previously described with reference to FIG. 2. It has a blue organic light-emitting device structure according to conditions, and shows the results of comparative evaluation of the electro-optical characteristics of each blue organic light-emitting device.

Hereinafter, the structure of the blue organic light emitting device according to Comparative Example 2-1 will be described in detail.

On the substrate, the first electrode 110 is formed with an ITO/APC/ITO structure to a thickness of 240 Å, and a hole injection layer 120 is formed with HATCN to a thickness of 100 Å on top of the first electrode 110, and a first hole transport layer ( 130) was formed with NPD to a thickness of 400 Å.

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

Next, the first electron transport layer 150 is made of Alq ₃ on top. 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 on top of it, and 2% of lithium (Li) was doped as a dopant to form the first charge generation layer 160. NPD was formed to a thickness of 375 Å as the second charge generation layer 165 on the top, and 8% of F4-TCNQ, a p-type material, was doped to form the second charge generation layer 165.

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

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

Next, the blue organic light emitting device structure according to Example 1-1 will be described in detail below.

On the substrate, the first electrode 110 is formed with an ITO/APC/ITO structure to a thickness of 240 Å, and a hole injection layer 120 is formed with HATCN to a thickness of 100 Å on top of the first electrode 110, and a first hole transport layer ( 130) was formed with NPD to a thickness of 300 Å, and the first hole control layer 135 was formed on top of it with a hole control layer 1 (HCL 1) material to a thickness of 100 Å.

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

Next, the first electron transport layer 150 is made of Alq ₃ on top. 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 on top of it, and 2% of lithium (Li) was doped as a dopant to form the first charge generation layer 160. NPD was formed to a thickness of 375 Å as the second charge generation layer 165 on the top, and 8% of F4-TCNQ, a p-type material, was doped to form the second charge generation layer 165.

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

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

Referring to FIG. 6, comparing the driving voltage aspects of the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1, Comparative Example 2-1 shows a luminance of 650 nits and has a driving voltage of 7.7 V. It was requested. In the case of Example 1-1, a driving voltage of 7.6 V 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. .

Also, with reference to FIG. 6, when 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 shown at the level of 12.2Cd/A, which showed that the efficiency increased to the level of 0.6Cd/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. there is.

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

Figure 7 is a diagram showing the results of comparative evaluation of lifespan characteristics at room temperature in the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention. In addition, Figure 8 is a diagram showing the results of comparative evaluation of lifespan characteristics at high temperatures in the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention. In addition, Figure 9 is a diagram showing the results of comparative evaluation of lifespan characteristics at room temperature and high temperature in the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention.

First, with reference to FIGS. 7 and 9, the lifespan characteristics at room temperature in the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention are compared. At room temperature (25?), Comparative Example 2 In the case of -1, the time required to achieve 95% of the initial luminance, that is, the 95% life 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 lifespans of the blue organic light-emitting devices according to Comparative Example 2-1 and Example 1-1 were equivalent. .

On the other hand, when comparing the lifespan characteristics at high temperature in the blue organic light emitting device according to Comparative Example 2-1 and Example 1-1 of the present invention with reference to FIGS. 8 and 9, the comparative example at high temperature (85?) In the case of 2-1, the time taken to achieve 80% of the initial luminance, that is, the 80% life time (T80) of the blue organic light emitting device, was about 125 hours. In the case of Example 1-1, the 80% life time (T80) was about 275 hours, and at high temperatures, the lifespan was greatly improved in the blue organic light emitting device according to Example 1-1 compared to Comparative Example 2-1. You can see that the results are shown.

In the case of Example 1-1 according to an embodiment of the present invention, luminous efficiency within the organic light-emitting layer can be improved at high temperature and improved lifespan characteristics can be obtained at high temperature. Therefore, in order to obtain luminous efficiency in the organic light-emitting layer at high temperatures and improved lifespan characteristics at high temperatures, 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 at least 0.1 eV, The LUMO energy level may be set to be 0.1 eV 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 triplet energy level (T1) higher than the triplet energy level (T1) of the dopant of the first blue light-emitting layer 142 can 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 lower than the LUMO energy level of the second hole transport layer 170. It can be set low. In addition, the second hole control layer 135 having a triplet energy level (T1) higher than the triplet energy level (T1) of the dopant of the second blue light-emitting layer 182 can be applied. As a result, the first hole control layer 135 and the second hole control layer 175 exhibit higher mobility characteristics than holes at high temperatures, allowing holes to pass through the organic light-emitting layer, which is a region where electrons and holes recombine to emit light. By preventing electrons from moving to the electron transport layer and leaving the light emitting area, the luminous efficiency within the organic light emitting layer can be improved at high temperatures and improved lifespan characteristics can be obtained at high temperatures.

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

In addition, in this specification, the results of evaluating the efficiency and lifespan at high temperature by manufacturing a blue organic light-emitting device using a hole control layer are explained in detail, and the red organic light-emitting device and the green organic light-emitting device are described in detail by giving examples. Although not explained, when applying a hole control layer having the same conditions as in the blue organic light emitting device structure according to an embodiment of the present invention, the luminous efficiency is increased at high temperature and the lifespan is increased in the red organic light emitting device and the green organic light emitting device as well. This improved effect can be achieved.

Although 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 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 idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. The scope of protection of the present invention should be interpreted in accordance with the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

1000: Organic light emitting device
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 (25)

a first electrode and a second electrode;
a substrate on which the first electrode and the second electrode are disposed and including a first sub-pixel region, a second sub-pixel region, and a third sub-pixel region that emit light of different colors;
a first light-emitting unit disposed between the first electrode and the second electrode and including a first hole transport layer, a first hole control layer, a first organic light-emitting layer, and a first electron transport layer; and
It is disposed between the first electrode and the second electrode, and includes a second light-emitting unit in which a second hole transport layer, a second hole control layer, a second organic light-emitting layer, and a second electron transport layer are sequentially disposed,
The thickness of the second hole transport layer is different from the thickness of the first electron transport layer,
The first organic emission layer and the second organic emission layer disposed in the first sub-pixel area each emit light of the same color and overlap each other,
The first organic emission layer and the second organic emission layer disposed in the second sub-pixel area each emit light of the same color and overlap each other,
The first organic emission layer and the second organic emission layer disposed in the third sub-pixel area each emit light of the same color and overlap each other,
The HOMO energy level of the first hole control layer is 0.1 eV or more lower than the HOMO energy level of the first hole transport layer, and the LUMO energy level of the first hole control layer is 0.1 eV or more than the LUMO energy level of the first hole transport layer. low,
The HOMO energy level of the second hole control layer is 0.1 eV or more lower than the HOMO energy level of the second hole transport layer, and the LUMO energy level of the second hole control layer is 0.1 eV or more than the LUMO energy level of the second hole transport layer. Low, display device. According to paragraph 1,
A display device wherein the second hole transport layer has a thickness greater than the first electron transport layer. According to paragraph 1,
The first light emitting unit further includes a hole injection layer disposed between the first electrode and the first hole transport layer,
A display device wherein the thickness of the hole injection layer is different from the thickness of the first hole transport layer. According to paragraph 3,
A display device wherein a thickness of the first hole transport layer is greater than a thickness of the hole injection layer. According to paragraph 3,
A display device wherein a thickness of the hole injection layer is smaller than a thickness of the first electrode. According to paragraph 1,
A display device wherein the thickness of the first hole transport layer is greater than the thickness of the first electron transport layer. According to paragraph 1,
A display device wherein the thickness of the second hole transport layer is greater than the thickness of the second organic light emitting layer. According to paragraph 1,
A display device wherein a thickness of the second hole transport layer is greater than a thickness of the second electrode. According to paragraph 1,
A display device wherein the thickness of the second hole transport layer is smaller than the thickness of the second electron transport layer. According to paragraph 1,
A display device wherein a thickness of the second electrode is smaller than a thickness of at least one of the layers included in the second light emitting unit. delete According to paragraph 1,
A display device wherein a thickness of the first hole control layer and the second hole control layer is smaller than a thickness of the first hole transport layer or the second hole transport layer. According to paragraph 1,
The HOMO energy level of the host and dopant of each of the first organic emission layer and the second organic emission layer is lower than the HOMO energy level of each of the first hole control layer and the second hole control layer. According to paragraph 1,
The LUMO energy level of the host and dopant of each of the first organic emission layer and the second organic emission layer is lower than the LUMO energy level of each of the first hole control layer and the second hole control layer. According to paragraph 1,
The triplet energy level (T1) of each of the first hole control layer and the second hole control 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. display device. According to paragraph 1,
The display device further includes a first charge generation layer and a second charge generation layer disposed between the first light emitting unit and the second light emitting unit. According to clause 16,
The first charge generation layer and the second charge generation layer have different thicknesses. According to paragraph 1,
The first sub-pixel area is a red sub-pixel area, the second sub-pixel area is a green sub-pixel area, and the third sub-pixel area is a blue sub-pixel area. According to clause 18,
The first organic light-emitting layer disposed in the red sub-pixel area is a first red light-emitting layer, and the second organic light-emitting layer disposed in the red sub-pixel area is a second red light-emitting layer,
The first organic emission layer disposed in the green sub-pixel area is a first green emission layer, and the second organic emission layer disposed in the green sub-pixel area is a second green emission layer,
The first organic light-emitting layer disposed in the blue sub-pixel area is a first blue light-emitting layer, and the second organic light-emitting layer disposed in the blue sub-pixel area is a second blue light-emitting layer. According to paragraph 1,
The first electrode has a structure in which a transparent conductive material layer and a reflective material layer are stacked. According to clause 20,
A display device, wherein the transparent conductive material layer includes ITO. According to clause 20,
A display device wherein the reflective material layer includes silver (Ag) or a silver alloy (Ag alloy). According to paragraph 1,
The display device wherein the second electrode includes an alloy of magnesium and silver (Mg:Ag). According to paragraph 1,
The display device further includes a capping layer disposed on the second electrode. According to paragraph 1,
A display device further comprising a thin film transistor connected to the first electrode.