KR102299481B1 - Organic light emitting device - Google Patents

Abstract

An organic light emitting device according to an embodiment of the present invention includes a first electrode and a second electrode, first and second light emitting units positioned between the first electrode and the second electrode, and a first and second light emitting unit positioned between the first and second light emitting units a second charge generating layer positioned between the first charge generating layer and the first and second light emitting units, and a second charge generating layer positioned on the first charge generating layer and a second hole transporting layer positioned on the second charge generating layer and a second charge generation layer comprising a first region and a second region, and a third hole transport layer positioned between the first region and the second region of the second charge generation layer. characterized in that

Description

Organic light emitting device {ORGANIC LIGHT EMITTING DEVICE}

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

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

The organic light emitting diode display includes a top emission type, a bottom emission type, a dual emission type, etc. depending on a direction in which light is emitted, and a passive matrix type according to a driving method. ) and active matrix type.

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

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

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

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

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

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

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

However, as the charge generation layer (CGL) is additionally applied in such a tandem structure, that is, a two-stack organic light emitting device structure using a stacking of a plurality of light emitting units, the first light emitting unit located below the charge generation layer (CGL) Bidirectional movement is required for electrons to move and holes to move to the second light emitting unit located on the charge generating layer CGL. In such a two-stack structure, the second charge generation layer (P-CGL), which is a p-type charge generation layer, should act as a hole injection layer (HIL), and thus, should be able to smoothly move holes.

In the conventional organic light emitting device, the second charge generation layer (p-CGL) is formed of a single layer, and the doping concentration of the p-type dopant doped in the second charge generation layer (p-CGL) is about 12 to about By controlling at the level of 15%, the efficiency and lifespan characteristics of the organic light emitting diode are secured.

However, as the doping concentration of the p-type dopant included in the second charge generation layer (P-CGL) is applied at a high level, hole mobility is increased and the first charge generation layer (n-CGL) and the second charge generation layer (n-CGL) A charge imbalance between the charge generation layers (p-CGL) is occurring.

That is, when the doping level of the second charge generating layer (p-CGL) positioned adjacent to the first charge generating layer (n-CGL) in the two-stack organic light emitting device structure is not at an appropriate level, in the charge generating layer In this case, charge generation may be disturbed, and accordingly, problems in efficiency and lifetime characteristics occur in organic light emitting diodes.

In addition, as the dopant doping concentration is applied at a high level to the second charge generating layer (p-CGL), the consumption of the dopant material increases. Accordingly, the material cost increases in terms of mass production of the product.

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

An object to be solved according to an embodiment of the present invention is to improve efficiency and lifespan by additionally forming a hole transport layer between regions of the second charge generating layer in which regions are separated and formed in an organic light emitting device using a stack of a plurality of light emitting units. An object of the present invention is to provide as possible an organic light emitting device.

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

In the organic light emitting device according to an embodiment of the present invention, an organic light emitting device capable of improving efficiency and lifespan is provided by additionally forming a third hole transport layer between the first region and the second region of the second charge generating layer.

An organic light emitting device according to an embodiment of the present invention includes a first electrode and a second electrode, first and second light emitting units positioned between the first electrode and the second electrode, and a first and second light emitting unit positioned between the first and second light emitting units a second charge generating layer positioned between the first charge generating layer and the first and second light emitting units, and a second charge generating layer positioned on the first charge generating layer and a second hole transporting layer positioned on the second charge generating layer and a second charge generation layer comprising a first region and a second region, and a third hole transport layer positioned between the first region and the second region of the second charge generation layer. characterized in that

The first region and the second region of the second charge generating layer may further include a p-type dopant, and a doping concentration of the p-type dopant in the first region and the second region may be 6 to 8%.

Doping concentrations of the p-type dopant in the first region and the second region of the second charge generation layer may be different from each other.

The p-type dopant of the first region and the second region of the second charge generation layer may be formed of any one _{of F 4 -TCNQ or NDP-9.}

A thickness of each of the first region and the second region of the second charge generating layer may be greater than or equal to the thickness of the third hole transport layer and less than or equal to the thickness of the second hole transport layer.

The thickness of the first region and the second region of the second charge generating layer may be different from each other.

A thickness of the third hole transport layer positioned between the first region and the second region of the second charge generating layer may be smaller than a thickness of the second hole transport layer positioned above the second charge generating layer.

A thickness of the third hole transport layer positioned between the first region and the second region of the second charge generation layer may be 100 Å or less.

The second hole transport layer positioned on the second charge generating layer and the third hole transport layer positioned between the first region and the second region of the second charge generating layer may include _{any one of HATCN, TBAHA, F 4} -TCNQ, and CuPc. can be made into one.

The second hole transport layer positioned on the second charge generating layer and the third hole transport layer positioned between the first and second regions of the second charge generating layer may be made of different materials.

In the organic light emitting device having a two-stack structure using a stack of a plurality of light emitting units according to an embodiment of the present invention, a second charge generating layer including a p-type dopant is formed to have a first region and a second region, and between the first and second regions. By additionally forming a third hole transport layer in the second charge generating layer to enable smooth charge generation in the second charge generating layer, the efficiency and lifespan of the organic light emitting diode can be improved.

In addition, by applying the third hole transport layer between the first region and the second region of the second charge generating layer, the concentration of the dopant doped in the first region and the second region of the second charge generating layer can be lowered, so that a high concentration of the dopant can be obtained. It is possible to improve mass productivity by reducing the material cost required according to the application of the dopant.

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

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

1 is a diagram schematically showing the structure of an organic light emitting device according to an embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating a structure of a second charge generating layer and an organic layer positioned adjacent to upper and lower portions of the second charge generating layer in the organic light emitting diode according to an embodiment of the present invention.
3 is a diagram illustrating conditions for evaluating a structure of a second charge generation layer in an organic light emitting diode according to an embodiment of the present invention.
4 is a view showing an electro-optical characteristic evaluation result of an organic light emitting diode according to an embodiment of the present invention.
5 is a view showing a result of evaluation of lifespan characteristics of an organic light emitting diode according to an embodiment of the present invention.

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

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

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

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

Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may 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 , the organic light emitting diode 1000 according to an embodiment of the present invention is disposed on a substrate in which a red sub-pixel region Rp, a green sub-pixel region Gp, and a blue sub-pixel region Bp are defined. The formed first electrode 110 (anode), the hole injection layer 120 (hole injection layer: HIL), the first hole transport layer 130 (1 ^st hole transporting layer: 1 ^st HTL), the first red light emitting layer 140, 1 ^st Red emission layer: 1 ^st Red EML), a first green emission layer (141, 1 ^st Green emission layer: 1 ^st Green EML), and a first blue emission layer (142, 1 ^st Blue emission layer: 1 ^st Blue EML) A first organic light emitting layer, a first electron transport layer (150, 1 ^st electron transporting layer: 1 ^st ETL), a first charge generation layer (160, 1 ^st charge generation layer: N-CGL), a second charge generation layer (165, 2 ^nd charge generation layer: P-CGL), a second hole transport layer (170, 2 ^nd hole transporting layer: 2 ^nd HTL), a second red emission layer (180, 2 ^nd Red emission layer: 2 ^nd Red EML), second A second organic emission layer including a green emission layer (181, 2 ^{nd Green emission layer: 2 nd} Green EML) and a second blue emission layer (182, 2 ^nd Blue emission layer: 2 ^nd Blue EML), and a second electron transport layer (190, 2) ^{It is configured to include an nd} electron transporting layer: 2 ^nd ETL), a second electrode 200 (cathode), and a capping layer 210 (capping layer: CPL).

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

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

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

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

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

The first electrode 110 is positioned on the substrate to correspond to all of the red sub-pixel region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp, and may be 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 reflection such as silver (Ag) or a 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 region Rp, the green sub-pixel region Gp, and the blue sub-pixel region Bp.

The hole injection layer 120 may serve to facilitate hole injection, and may include HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile) and CuPc (cupper phthalocyanine), PEDOT (poly(3) ,4)-ethylenedioxythiophene), PANI (polyaniline), and NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine) may be made of any one or more selected from the group consisting of, but is not limited thereto.

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

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

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

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

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

More specifically, the first green emission layer 141 and the second green emission layer 181 may include a host material 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).

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

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

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

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

The first electron transport layer 150 and the second electron transport layer 190 serve to facilitate electron transport, and Alq3 (tris(8-hydroxyquinolino)aluminum), PBD(2-(4-biphenylyl)-5- (4-tert-butylpheny)-1,3,4oxadiazole), TAZ, spiro-PBD, BAlq and SAlq may be made of any one or more selected from the group consisting of, but is not limited thereto.

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

The electron injection layer (EIL) is Alq3 (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 , and the second At least one of the electron transport layer 190 and the electron injection layer EIL may be omitted. In addition, at least one of the first hole transport layer 130 , the second hole transport layer 170 , the first electron transport layer 150 , the second electron transport layer 190 and the electron injection layer (EIL) is formed into two or more layers. It is also possible to form

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

Referring to FIG. 1 , the first charge generation layer 160 and the second charge generation layer 165 are positioned 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 of the first light emitting unit 1100 and the second light emitting unit 1200 .

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

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

The second charge generation layer 165 is disposed on the first charge generation layer 160 . The second charge generation layer 165 serves as a p-type charge generation layer (p-CGL) serving as 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, HATCN, TBAHA, F ₄ -TCNQ, and CuPc and the mixed layers, but may be of a doped p-type dopant (dopant) in the same organic material is not limited to this. In addition, the p-type dopant may be formed of any one of _{1) F 4 -TCNQ or 2) NDP-9 represented by the chemical structural formula shown below.}

One)

2)

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

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

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

The capping layer 210 is positioned on the second electrode 200 . The capping layer 210 is for increasing the light extraction effect in the organic light emitting device, and includes a first hole transport layer 130, a second hole transport layer 170 material, a first electron transport layer 150, and a second electron transport layer ( 190) materials, and 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) of the host material. Also, the capping layer 210 may be omitted.

FIG. 2 schematically illustrates the structure of a second charge generating layer 165 and an organic layer positioned adjacent to the upper and lower portions of the second charge generating layer 165 in the organic light emitting diode 1000 according to an embodiment of the present invention. It is a drawing showing

Referring to FIG. 2 , in the organic light emitting diode 1000 according to the embodiment of the present invention, the second charge generation layer 165 is formed by stacking the first region 166 and the third charge generation layer. and a hole transport layer 167 and a second region 168 of the second charge generation layer.

In the case of the conventional organic light emitting device, the second charge generation layer (p-CGL) is composed of a single layer in which regions are not divided. The charge generation layer 165 has a divided region of a first region 166 of the second charge generation layer and a second region 168 of the second charge generation layer, and also includes a first region ( 166) and a third hole transport layer 167 formed between the second region 168 of the second charge generation layer.

Also, as described above, the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer include an organic material and a p-type dopant that can serve as hole injection and transport. .

In the conventional organic light emitting device, the second charge generation layer (p-CGL) is formed of a single layer, and the doping concentration of the p-type dopant doped in the second charge generation layer (p-CGL) is about 12 to about Efficiency and lifespan characteristics are secured by controlling at the level of 15%.

However, in the case of the organic light emitting diode 1000 according to the embodiment of the present invention, the third hole transport layer 167 is interposed between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer. ) can be additionally formed to facilitate movement and transport of holes in the second charge generation layer 165 , and thus the first region 166 of the second charge generation layer and the second portion of the second charge generation layer It is possible to lower the doping concentration of the p-type dopant included in the region 168 to a level of 6 to 8%, which is lower than that of the conventional second charge generating layer.

In addition, the doping concentration of the p-type dopant in the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer takes the hole transport capability of the second charge generation layer 165 into consideration. Thus, it can be made different from each other in the range of 6 to 8%.

In addition, the p-type dopant included in the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer may be formed of any one _{of F 4 -TCNQ or NDP-9.}

In addition, in consideration of the hole injection characteristics of the second charge generation layer 165 , the thickness of each of the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer plays a role of hole transport. It may be greater than or equal to the thickness of the third hole transport layer 167 and may be less than or equal to the thickness of the second hole transport layer 170 . In addition, the thickness of the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer may be different from each other.

In addition, in the case of the third hole transport layer 167, when the thickness is formed to be thick, the movement of holes in the second charge generation layer 165 may be hindered, and thus the efficiency of charge generation may be lowered. The thickness of the third hole transport layer 167 positioned between the first region 166 and the second region 168 of the second charge generating layer of It may be formed to be smaller than the thickness of the transport layer 170 .

Therefore, the thickness of the third hole transport layer 167 positioned between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer can be formed to a thickness of 100 Å or less. and more preferably 20 to 70 Å.

Also located on the third hole transport layer 167 and the second charge generation layer 165 positioned between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer The second hole transport layer 170 may be formed of any one of 1) HATCN, 2) TBAHA, 3) F _{4 -TCNQ, and 4) CuPc represented by the chemical structural formula shown below.}

One)

2)

3)

4)

Also located on the third hole transport layer 167 and the second charge generation layer 165 positioned between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer The second hole transport layer 170 may be formed of different materials in consideration of hole transport characteristics.

3 is a diagram illustrating experimental conditions for evaluating the structure of the second charge generation layer 165 in the organic light emitting diode 1000 according to an embodiment of the present invention.

3 , the first charge generation layer 160 , the first region 166 of the second charge generation layer, the third hole transport layer 167 , the second region 168 of the second charge generation layer, and the second The structure of the other organic layers except for the hole transport layer 170 has the same structure as that of the organic light emitting device described with reference to FIG. 1 , and experiments were conducted by fabricating each blue organic light emitting device according to the conditions of FIG. 3 .

Referring to FIG. 3 , in the case of the comparative example, lithium (Li) is doped to a level of 2% in the charge generating layer host material as a first charge generating layer (n-CGL) as a structure according to a conventional organic light emitting device, and the thickness is 150 Å. and a first charge generation layer (n-CGL) having

In addition, the second charge generation layer (p-CGL) is composed of a single layer in which regions are not divided, the charge generation layer host material is doped with a p-type dopant at a level of 15%, and the second charge generation layer has a thickness of 50 Å. (p-CGL).

Also, the comparative example includes a second hole transport layer formed of a hole transport layer host material as a second hole transport layer on top of the second charge generating layer and having a thickness of 400 Å.

Also, referring to FIG. 3 , in the case of Example 1, as the structure of the organic light emitting device 1000 according to the embodiment of the present invention, lithium (Li) is 2 in the charge generating layer host material as the first charge generating layer 160 . and a first charge generation layer 160 doped to a level of % and having a thickness of 150 Å.

In addition, the second charge generation layer 165 has a region divided into a first region 166 and a second region 168 , and a third region formed between the first region 166 and the second region 168 . It further includes a hole transport layer 167 .

In Example 1 of the present invention, the first region 166 of the second charge generation layer is doped with a p-type dopant at a level of 8% in the charge generation layer host material and has a thickness of 100 Å, and the third hole The transport layer 167 is formed of a hole transport layer host material and has a thickness of 50 Å, and the second region 168 of the second charge generation layer is doped with a p-type dopant to a level of 8% in the charge generation layer host material and has a thickness of 100 Å. formed to have a thickness.

Also, in Example 1, the second hole transport layer 170 is formed of a hole transport layer host material as the second hole transport layer 170 on the second charge generating layer 165 and includes a second hole transport layer 170 having a thickness of 150 Å.

Also, referring to FIG. 3 , in the case of Example 2, as in Example 1, as the structure of the organic light emitting device 1000 according to the exemplary embodiment of the present invention, the first charge generation layer 160 is used as the charge generation layer host material as lithium. and a first charge generation layer 160 doped with (Li) to a level of 2% and having a thickness of 150 Å.

In addition, the second charge generation layer 165 has a region divided into a first region 166 and a second region 168 , and a third region formed between the first region 166 and the second region 168 . It further includes a hole transport layer 167 .

In Example 2 of the present invention, the first region 166 of the second charge generation layer is doped with a p-type dopant at a level of 6% in the charge generation layer host material to have a thickness of 100 Å, and the third hole The transport layer 167 is formed of a hole transport layer host material and has a thickness of 50 Å, and the second region 168 of the second charge generation layer is doped with a p-type dopant in the charge generation layer host material to a level of 6% and has a thickness of 100 Å. formed to have a thickness.

Also, in Example 2, the second hole transport layer 170 is formed of a hole transport layer host material as the second hole transport layer 170 on the second charge generating layer 165 and includes a second hole transport layer 170 having a thickness of 150 Å.

Each blue organic light emitting device according to the conditions of FIG. 3 was manufactured and the structure of the second charge generation layer was evaluated.

4 is a diagram illustrating an electro-optical characteristic evaluation result of the organic light-emitting device 1000 according to an exemplary embodiment of the present invention.

4 shows a comparative example according to a conventional organic light emitting device having a single-layered second charge generating layer structure as described with reference to FIG. 3 and an embodiment of the present invention having a new second charge generating layer 165 structure. It is a figure which shows the result of comparative evaluation of the electro-optical characteristic of the blue organic light emitting device according to Examples 1 and 2.

Referring to FIG. 4, comparing the driving voltage side of the blue organic light emitting device according to the comparative example and the embodiment of the present invention. In the comparative example, a driving voltage of 7.0V level was required to display a luminance of 498 nits, Example 1 In the same case, it can be seen that a driving voltage of 7.1V level is required to display a luminance of 498 nits, and a driving voltage of 7.2V level is required to display a luminance of 498 nits in Example 2.

That is, in Comparative Example and in Examples 1 and 2, a driving voltage of a similar level was required to exhibit the same luminance. Accordingly, in the case of the first and second embodiments of the present invention, that is, the third hole transport layer 167 is disposed between the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer. Including, the doping concentration of the p-type dopant included in the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer is 6% or 8%, which is lower than that of the prior art. It can be seen that even in this case, a driving voltage similar to that of the conventional structure is exhibited.

In addition, referring to FIG. 4 , comparing the current efficiency of the organic light emitting device according to the comparative example and the embodiment of the present invention, the comparative example showed a result of 5.4 Cd/A level. On the other hand, Example 1 showed a result of 6.1 Cd/A and Example 2 showed a level of 5.8 Cd/A, indicating that the efficiency was increased in Examples 1 and 2 compared to Comparative Examples.

That is, in comparison with the comparative example, the third hole transport layer 167 is applied between the first region 166 and the second region 168 of the second charge generating layer in Examples 1 and 2, and through this The doping concentration of the dopant in the first region 166 and the second region 168 of the second charge generation layer can be lowered compared to the prior art, and current efficiency is improved by enabling smooth charge generation in the second charge generation layer. It can be seen that the

In addition, referring to FIG. 5 , comparing the color coordinates of the organic light emitting diodes according to the comparative example and the embodiment, in the comparative example, CIE_x was 0.144 and CIE_y was 0.049. Also, in Example 1, CIE_x was 0.143 and CIE_y was 0.050, and in Example 2, CIE_x was 0.144 and CIE_y was 0.050.

Looking at the above results, when compared with the comparative example, the results of the color coordinate values of Examples 1 and 2 were shown at a similar level, which satisfies the desired color in Examples 1 and 2 when compared with the comparative example It can be seen that indicated

From the results of the above experiment, in the case of the organic light emitting diode 1000 according to the embodiment of the present invention, the space between the first region 166 and the second region 168 of the second charge generation layer including the p-type dopant is shown. By additionally applying the third hole transport layer 167 and thereby lowering the doping concentration of the dopant in the first region 166 and the second region 168 of the second charge generating layer, smoothness in the second charge generating layer 165 is By enabling charge generation, the efficiency of the organic light emitting diode may be improved.

Also, by applying a third hole transport layer 167 between the first region 166 and the second region 168 of the second charge generating layer, the first region 166 and the second region 168 of the second charge generating layer are ) can lower the concentration of dopant doped in, and it is possible to improve mass productivity by reducing the material cost required by applying a high concentration of dopant.

FIG. 5 is a view showing a result of evaluation of lifespan characteristics of the organic light emitting diode 1000 according to an exemplary embodiment of the present invention.

5 shows a comparative example according to a conventional blue organic light emitting device having a single-layered second charge generation layer structure and a new structure of the second charge generation layer 165 of the present invention, as described with reference to FIG. 3 above. It is a view showing the results of comparative evaluation of the lifespan characteristics of the blue organic light emitting diodes according to Examples 1 and 2.

As can be seen in FIG. 5 , in the case of the comparative example, the time until the emission luminance of 95% of the initial emission luminance level, that is, the 95% life time of the organic light emitting device showed a level of about 350 hours, but in Example In the case of 1, the 95% life time showed a level of about 440 hours, and in the case of Example 2, the 95% life time showed a level of about 390 hours. The lifespan of the organic light emitting diode was improved.

From the results of the above experiment, the organic light emitting diode 1000 according to the embodiment of the present invention has a third hole between the first region 166 and the second region 168 of the second charge generating layer including the p-type dopant. By additionally applying the transport layer 167 , the doping concentration of the dopant in the first region 166 and the second region 168 of the second charge generating layer can be lowered, and the smooth charge in the second charge generating layer 165 can be reduced. It can be seen that the efficiency of the organic light-emitting device is improved when compared with the conventional structure by enabling generation, and the result is more improved in terms of lifespan characteristics.

Summarizing the above results, in the case of the organic light emitting diode 1000 according to the embodiment of the present invention, between the first region 166 and the second region 168 of the second charge generating layer including the p-type dopant. By additionally forming the third hole transport layer 167 to enable smooth charge generation in the second charge generation layer 165 , the efficiency and lifespan of the organic light emitting diode may be improved.

In addition, by applying a third hole transport layer between the first region and the second region of the second charge generating layer, the concentration of dopants doped in the first region and the second region of the second charge generating layer can be lowered, and the high concentration of the dopant It is possible to improve mass productivity by reducing the material cost required depending on the application.

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 within the scope without departing from the technical spirit of the present invention. have. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

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

Claims (10)

a substrate having a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region defined therein;
a first electrode disposed on the substrate and a second electrode disposed to face the first electrode;
first and second light emitting units positioned between the first and second electrodes;
a first charge generation layer positioned between the first and second light emitting units;
a second charge generating layer positioned between the first and second light emitting units and positioned on the first charge generating layer; and
a second hole transport layer positioned on the second charge generation layer;
The second charge generation layer consists of a first region and a second region,
Further comprising a third hole transport layer positioned between the first region and the second region of the second charge generation layer,
the first light-emitting unit includes a first red light-emitting layer corresponding to the red sub-pixel area, a first green light-emitting layer corresponding to the green sub-pixel area, and a first blue light-emitting layer corresponding to the blue sub-pixel area;
the second light-emitting unit includes a second red light-emitting layer corresponding to the red sub-pixel area, a second green light-emitting layer corresponding to the green sub-pixel area, and a second blue light-emitting layer corresponding to the blue sub-pixel area;
The first region and the second region of the second charge generating layer, the second hole transport layer and the third hole transport layer are made of any one selected from HATCN, TBAHA, and CuPc, and the second hole transport layer and the third The hole transport layer is made of different materials,
The second charge generating layer may further include a p-type dopant. The method of claim 1,
A doping concentration of the p-type dopant in the first region and the second region of the second charge generation layer is 6 to 8%. 3. The method of claim 2,
Doping concentrations of the p-type dopant in the first region and the second region of the second charge generation layer are different from each other. 4. The method of claim 3,
The p-type dopant of the first region and the second region of the second charge generation layer is an organic light emitting diode comprising one _{of F 4 -TCNQ or NDP-9.} The method of claim 1,
The thickness of each of the first region and the second region of the second charge generating layer is greater than or equal to the thickness of the third hole transport layer and less than or equal to the thickness of the second hole transport layer. 6. The method of claim 5,
The thickness of the first region and the second region of the second charge generation layer are different from each other. The method of claim 1,
The thickness of the third hole transport layer positioned between the first region and the second region of the second charge generating layer is smaller than the thickness of the second hole transport layer positioned above the second charge generating layer. 8. The method of claim 7,
The thickness of the third hole transport layer positioned between the first region and the second region of the second charge generation layer is 100 Å or less. delete delete

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