KR20160061718A - Organic light emitting device - Google Patents

Abstract

According to an embodiment of the present invention, provided is an organic light emitting device of which the efficiency and durability are improved. The organic light emitting device includes first and second electrodes; first and second light emitting units disposed between the first and second electrodes; a first electric charge generating layer disposed between the first and second light emitting units; a second electric charge generating layer disposed between the first and second light emitting units and disposed on an upper portion of the first electric charge generating layer; and a second hole transfer layer disposed on an upper portion of the second electric charge generating layer. The second electric charge generating layer is composed of first and second areas, and includes a third hole transfer layer disposed between the first and second areas of the second electric charge generating layer.

Description

ORGANIC LIGHT EMITTING DEVICE

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device capable of improving efficiency and lifetime in an organic light emitting device.

The organic light emitting diode (OLED) is a self-luminous display device in which electrons and holes are injected into the light emitting layer from an anode for injecting electrons and an anode for injecting holes, And emits light when an exciton in which injected electrons and holes are coupled falls from an excited state to a ground state.

The organic light emitting display device includes a top emission type, a bottom emission type, and a dual emission type depending on a direction in which light is emitted, and a passive matrix type ) And active matrix (Active Matrix).

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

The number of pixels per unit area increases and a high luminance is required. However, since the unit area current (A) is limited by the light emitting structure of the organic light emitting display device, There is a problem that reliability is lowered and power consumption is increased.

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

Various organic light emitting device structures have been proposed for improving the efficiency, lifetime, and power consumption of the organic light emitting device in order to improve the quality and productivity of the organic light emitting display device.

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

However, merely laminating a plurality of light-emitting units simply does not increase the light-emitting effect, and it is necessary to obtain an effect similar to the effect that a plurality of light-emitting elements are connected in series in order to emit light from a plurality of light- do.

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 a plurality of light emitting devices as described above.

However, as the charge generation layer (CGL) is additionally applied in such a tandem structure, that is, in a two-stack organic light emitting device structure using a stack of a plurality of light emitting units, the first light emitting unit located below the charge generation layer Electrons move and bi-directional movement in which holes move to the second light emitting unit located above the charge generation layer (CGL) becomes necessary. In this two-stack structure, the second charge generation layer (P-CGL), which is a p-type charge generation layer, should serve as a hole injection layer (HIL)

In the conventional organic light emitting device, the second charge generation layer (p-CGL) has a doping concentration of a p-type dopant composed of a single layer and doped in the second charge generation layer (p-CGL) 15%, thereby securing the efficiency and lifetime characteristics of the organic light emitting device.

However, as the doping concentration of the p-type dopant contained in the second charge generating layer (P-CGL) is applied at a high level, the mobility of the holes increases and the first charge generating layer (n-CGL) Charge imbalance phenomenon occurs between the charge generation layer (p-CGL).

That is, when the doping level of the second charge generating layer (p-CGL) adjacent to the first charge generating layer (n-CGL) in the structure of the two-stack organic light emitting device does not become an appropriate level, The charge generation may be hindered in the organic light emitting device, resulting in problems of efficiency and lifetime characteristics of the organic light emitting device.

Also, the amount of dopant material consumed is increased while applying a dopant doping concentration to a high level in the second charge generating layer (p-CGL), thereby causing a problem of an increase in material cost in terms of mass production of the product.

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

A solution according to an embodiment of the present invention is to further improve efficiency and lifetime by additionally forming a hole transporting layer between second charge generating layer regions in which regions are separately formed in an organic light emitting element using a stack of a plurality of light emitting units It is an object of the present invention to provide a possible organic light emitting device.

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

In the organic light emitting device according to the embodiment of the present invention, a third hole transporting layer is additionally formed between the first region and the second region of the second charge generating layer, thereby improving the efficiency and lifetime.

An organic light emitting diode 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 second light emitting unit located between the first and second light emitting units A second charge generating layer located between the first charge generating layer and the first and second light emitting units and located above the first charge generating layer and a second hole transporting layer located above the second charge generating layer And the second charge generating layer comprises a first region and a second region, and a third hole transporting layer located between the first region and the second region of the second charge generating layer, .

The first and second regions of the second charge generating layer may further comprise a p-type dopant and the doping concentration of the p-type dopant in the first and second regions may be between 6 and 8%.

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

The p-type dopant in the first region and the second region of the second charge generating layer may be made of any one of F ₄ -TCNQ and NDP-9.

The thickness of each of the first and second regions of the second charge generating layer may be equal to or less than the thickness of the third hole transporting layer and may be less than or equal to the thickness of the second hole transporting layer.

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

The thickness of the third hole transporting layer located between the first region and the second region of the second charge generating layer may be smaller than the thickness of the second hole transporting layer located above the second charge generating layer.

The thickness of the third hole transporting layer located between the first region and the second region of the second charge generating layer may be 100 A or less.

The third hole transporting layer located between the first region and the second region of the second hole transporting layer and the second charge generating layer located above the second charge generating layer may be any of HATCN, TBAHA, F ₄ -TCNQ, and CuPc It can be done in one.

The second hole transport layer located on the second charge generation layer and the third hole transport layer located between the first region and the second region of the second charge generation layer may be made of different materials.

In the organic light emitting device having the two stack structure using the stacking of the plurality of light emitting units according to the embodiment of the present invention, the second charge generating layer including the p-type dopant is formed to have the first region and the second region, The third charge transport layer may be additionally formed in the second charge generation layer to enable smooth charge generation, thereby improving the efficiency and lifetime of the organic light emitting device.

Also, by applying a third hole transporting 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, The mass productivity can be improved by reducing the material cost required by dopant application.

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

The scope of the claims is not limited by the matters described in the contents of the invention, as the contents of the invention described in the problems, the solutions to the problems and the effects to be solved do not specify essential features of the claims.

1 is a schematic view illustrating a structure of an organic light emitting diode according to an embodiment of the present invention.
FIG. 2 is a schematic view illustrating the structure of an organic layer adjacent to an upper portion and a lower portion of the second charge generation layer and the second charge generation layer in the organic light emitting device according to the embodiment of the present invention.
3 is a view showing a condition for evaluating the structure of the second charge generating layer in the organic light emitting device according to the embodiment of the present invention.
4 is a graph showing the results of an electro-optical characteristic evaluation of an organic light emitting device according to an embodiment of the present invention.
FIG. 5 is a view showing a result of life characteristic evaluation of an organic light emitting device according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

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

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description. In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

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

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

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

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

1, an organic light emitting device 1000 according to an exemplary embodiment of the present invention includes a substrate on which a red subpixel region Rp, a green subpixel region Gp, and a blue subpixel region Bp are defined a first electrode (110, anode) formed with a hole injection layer (120, hole injection layer: HIL), a first hole transport layer (130, 1 ^st hole transporting layer: 1 ^st HTL), the first red light emitting layer (140, 1 consisting of 1 ^st blue EML): ^st Red emission layer: 1, ^st Red EML), a first green light-emitting layer ^{(141, 1 st green emission layer} : 1 st green EML) and the first blue light emitting layer (142, 1 ^st blue emission layer the first organic light emitting layer, a first electron transport layer (150, 1 ^st electron transporting layer: 1 ^st ETL), a first charge generating 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), the second red light emitting layer ^{(180, 2 nd red emission layer} : 2 nd red EML), a second green Gwangcheung ^{(181, 2 nd Green emission layer} : 2 nd Green EML) and the second blue light emitting layer ^{(182, 2 nd Blue emission layer} : 2 nd Blue EML) a second organic light emitting layer, a second electron transport layer (190, 2 ^nd consisting of is configured to include the CPL): electron transporting layer: 2 nd ETL), a second electrode (200, cathode) and capping layers (210, capping layer.

In addition, the first light emitting unit (1100, 1 ^st EL Unit) including a first organic light emitting layer between the organic light-emitting device 1000 includes a first electrode 110 and second electrode 200 according to an embodiment of the present invention 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 diode 1000 according to the 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 red light emitting layer 140, 1 green light emitting layer 141 and a first blue light emitting layer 142, and a first electron transporting layer 150. The first organic light emitting layer 141 and the first blue light emitting layer 142 may be formed of the same material.

The second light emitting unit 1200 may include a second hole transport layer 170, a second red light emitting layer 180, a second green light emitting layer 181, and a second blue light emitting layer 180. In the organic light emitting device 1000 according to an embodiment of the present invention, A second organic light emitting layer made of a light emitting layer 182, and a second electron transporting layer 190.

The organic light emitting device 1000 according to the 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, and a second charge generation layer 165 which is a p-type charge generation layer.

Although not shown, in an organic light emitting display device including an organic light emitting diode according to an exemplary embodiment of the present invention, a plurality of gate lines and data lines extending in parallel to any one of the gate lines and the data lines crossing each other and defining pixel regions A power supply wiring is located. In each pixel region, a switching thin film transistor connected to the gate wiring and the data wiring and a driving thin film transistor connected to the switching thin film transistor are disposed. A driving thin film transistor is connected to the first electrode 110 (anode).

The first electrode 110 is disposed on the substrate so as to correspond to both the red subpixel region Rp, the green subpixel region Gp, and the blue subpixel region Bp, and may be a reflective electrode.

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

The hole injection layer 120 is positioned on the first electrode 110 to correspond to both the red subpixel region Rp, the green subpixel region Gp, and the blue subpixel region Bp.

The hole injection layer 120 may function to smooth the injection of holes and may include HATCN (1,4,5,8,9,11-hexaazatriphenylene-hexanitrile), CuPc (cupper phthalocyanine), PEDOT (poly , 4) -ethylenedioxythiophene, PANI (polyaniline) and NPD (N, N-dinaphthyl-N, N'-diphenylbenzidine).

The first hole transport layer 130 and the second hole transport layer 170 are formed in the first hole transport layer (Rp) so as to correspond to both the red subpixel region Rp, the green subpixel region Gp, and the blue subpixel region Bp 130 are 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 transporting layer 130 and the second hole transporting layer 170 serve to smooth the transport of holes and may be made of NPD (N-dinaphthyl-N, N'-diphenylbenzidine), TPD (N, bis- (3-methylphenyl) -N, N'-bis- (phenyl) -benzidine, s-TAD and MTDATA (4,4 ' -triphenylamine), but the present invention is not limited thereto.

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 ). 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 phosphor 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) In 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) Or a phosphor containing PBT: Eu (DBM) 3 (Phen) 3 or perylene. Alternatively, the phosphorescent material is not limited thereto.

The first green light emitting layer 141 is located in the green sub pixel region Gp on the first hole transport layer 130 and the second green light emitting layer 181 is located in the green sub pixel region Gp ). 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 phosphor 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) And a fluorescent material including Alq3 (tris (8-hydroxyquinolino) aluminum). However, the present invention 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 ). 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 phosphor 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 may include a phosphorescent material containing a dopant material including (4,6-F2ppy) 2Irpic ≪ / RTI > The fluorescent material may include any one selected from the group consisting of spiro-DPVBi, spiro-6P, distyrylbenzene (DSB), distyrylarylene (DSA), PFO polymer and PPV polymer. It does not.

The first electron transporting layer 150 includes a first red light emitting layer 140 and a first green light emitting layer 141 so as to correspond to both the red subpixel region Rp, the green subpixel region Gp, and the blue subpixel region Bp. And the second electron transporting layer 190 is located on the first blue light emitting layer 142 and the second electron transporting layer 190 is located on the second subpixel region Rp, 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 as transport and injection electrons and the first electron transport layer 150 and the second electron transport layer 190 may have electron transport properties . ≪ / RTI >

The first electron transporting layer 150 and the second electron transporting layer 190 serve to smooth the transport of electrons and include Alq3 (tris (8-hydroxyquinolino) aluminum), PBD (2- (4-biphenylyl) (4-tert-butylpheny) -1,3,4oxadiazole), TAZ, spiro-PBD, BAlq, and SAlq. However, the present invention is not limited thereto.

Although not shown in FIG. 1, it is possible to additionally form an electron injection layer (EIL) on the second electron transport layer 190 separately.

The electron injection layer (EIL) is composed of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD (2- (4-biphenylyl) -5- , BAlq, or SAlq, but is not limited thereto.

Here, the structure is not limited according to the embodiment of the present invention, and the structure of the hole injection layer 120, the first hole transport layer 130, the second hole transport layer 170, the first electron transport layer 150, At least one of the electron transport layer 190 and the electron injection layer (EIL) may be omitted. 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) .

The first charge generating layer 160 is located on the first electron transporting layer 150 to correspond to both the red subpixel region Rp, the green subpixel region Gp and the blue subpixel region Bp, The charge generation layer 165 is located on the first charge generation layer 160 so as to correspond to both the red sub pixel region Rp, the green sub pixel region Gp and the blue sub pixel region Bp.

1, the first charge generating layer 160 and the second charge generating layer 165 are located between the first light emitting unit 1100 and the second light emitting unit 1200, and the first charge generating layer 160 and the second charge generating 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 generating layer 160 serves as an n-type charge generating layer (n-CGL) for injecting electrons into the first light emitting unit 1100 located below the first charge generating layer 160, The second charge generating layer 165 serves as a p-type charge generating layer (p-CGL) for injecting holes into the second light emitting unit 1200 located above the second charge generating 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, It is possible. The host material of the first charge generating layer 160 may be made of the same material as that of the first electron transporting layer 150 and the second electron transporting 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 generating layer 165 is located on the first charge generating layer 160. The second charge generating layer 165 serves as a p-type charge generating layer (p-CGL) serving as a hole injecting material. The host material of the second charge generating layer 165 serves as a first hole injecting layer 120, The first hole transporting layer 130 and the second hole transporting layer 170 may be formed of the same material. 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. The p-type dopant may be composed of any one of 1) F ₄ -TCNQ or 2) NDP-9 expressed by the following chemical structural formula.

One)

2)

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

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 serving as a reflective layer, The light is repeatedly reflected in the cavity between the light source and the light source, thereby increasing the light efficiency.

In addition, the first electrode 110 may be formed as a transmissive electrode, the second electrode 200 may be formed as a reflective electrode, and light from the organic emission layer may be displayed externally through the first electrode 110.

The capping layer 210 is located on the second electrode 200. The capping layer 210 is for increasing the light extracting effect in the organic light emitting device and includes a first hole transporting layer 130, a second hole transporting layer 170 material, a first electron transporting layer 150, a second electron transporting layer 190 and a first red light emitting layer 140, a second red light emitting layer 180, a first green light emitting layer 141, a second green light emitting layer 181, a first blue light emitting layer 142, 182). ≪ / RTI > Further, the capping layer 210 can be omitted.

2 schematically shows the structure of an organic layer positioned adjacent to upper and lower portions of a second charge generation layer 165 and a second charge generation layer 165 in the organic light emitting device 1000 according to an embodiment of the present invention. Fig.

Referring to FIG. 2, the second charge generation layer 165 of the organic light emitting device 1000 according to the embodiment of the present invention includes a first region 166 of the second charge generation layer, A hole transport layer 167 and a second region 168 of the second charge generating layer.

In the case of the conventional organic light emitting device, the second charge generation layer (p-CGL) is composed of a single layer not divided into regions. Alternatively, in the organic light emitting device 1000 according to the embodiment of the present invention, The charge generation layer 165 has a delimited 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 has a first region 166 of the second charge generation layer And a third hole transport layer 167 formed between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer.

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 capable of performing hole injection and transport and a p-type dopant .

In the conventional organic light emitting device, the second charge generation layer (p-CGL) has a doping concentration of a p-type dopant composed of a single layer and doped in the second charge generation layer (p-CGL) And 15%, respectively, to ensure efficiency and lifetime characteristics.

However, in the case of the organic light emitting device 1000 according to the embodiment of the present invention, the third hole transport layer 167 is formed between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer. It is possible to smoothly move and transport the holes in the second charge generation layer 165, so that the first region 166 of the second charge generation layer and the second region 166 of the second charge generation layer It is possible to reduce the doping concentration of the p-type dopant contained in the region 168 to a level of 6 to 8% which is lower than that of the conventional second charge generating layer.

The doping concentration of the p-type dopant in the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer is determined by considering the hole transporting ability of the second charge generating layer 165 To 6% and 8%, respectively.

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 may be any one of F ₄ -TCNQ and NDP-9.

Considering the hole injection characteristics of the second charge generating layer 165, the thickness of each of the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer is the role of hole transport And may be less than or equal to the thickness of the second hole transport layer 170. The thickness of the second hole transport layer 170 may be less than or equal to the thickness of the third hole transport layer 167, The thickness of the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer may be different from each other.

Further, in the case of the third hole transport layer 167, if the thickness of the third hole transport layer 167 is thick, the movement of holes may be disturbed in the second charge generation layer 165, The thickness of the third hole transport layer 167 located between the first region 166 of the first charge generation layer and the second region 168 of the second charge generation layer is set to be larger than the thickness of the second hole transport layer 167 located above the second charge generation layer 165 May be formed to be smaller than the thickness of the transport layer (170).

The thickness of the third hole transport layer 167 located between the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer may be less than 100 Å And more preferably from 20 to 70 angstroms.

The third hole transport layer 167 and the second charge generation layer 165 located 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 transporting layer 170 may be formed of any one of 1) HATCN, 2) TBAHA, 3) F ₄ -TCNQ and 4) CuPc, which are represented by the following chemical structural formulas.

One)

2)

3)

4)

The third hole transporting layer 167 and the second charge generating layer 165 located between the first region 166 of the second charge generating layer and the second region 168 of the second charge generating layer The second hole transporting layer 170 may be formed of different materials in consideration of the hole transporting property.

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

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

Referring to FIG. 3, in the comparative example, lithium (Li) was doped to a level of 2% in the charge generation layer host material by a first charge generation layer (n-CGL) (N-CGL) having a first charge generating layer and a second charge generating layer.

In addition, the second charge generating layer (p-CGL) is composed of a single layer of which the region is not separated, and the p-type dopant is doped to the charge generating layer host material at a level of 15% (p-CGL).

The comparative example also includes a second hole transport layer formed of a hole transport layer host material as a second hole transport layer on the second charge generation layer and having a thickness of 400 ANGSTROM.

Referring to FIG. 3, in the case of Embodiment 1, the structure of the organic light emitting device 1000 according to the embodiment of the present invention includes a first charge generation layer 160, % And a first charge generating layer 160 having a thickness of 150 ANGSTROM.

The second charge generating layer 165 has a region divided into a first region 166 and a second region 168 and has a third region 166 formed between the first region 166 and the second region 168, And further includes a hole transport layer 167.

In the first embodiment of the present invention, the first region 166 of the second charge generating layer is formed such that the p-type dopant is doped at a level of 8% and has a thickness of 100 Å in the charge generating layer host material, Transport layer 167 is formed of a hole transport layer host material and has a thickness of 50 ANGSTROM and a second region 168 of the second charge generating layer is doped with a p type dopant to a charge generation layer host material at a level of 8% Thickness.

In Example 1, the second hole transport layer 170 is formed on the second charge generation layer 165, and the second hole transport layer 170 is formed of a hole transport layer host material and has a thickness of 150 ANGSTROM.

Referring to FIG. 3, in the case of Embodiment 2, the structure of the organic light emitting device 1000 according to the embodiment of the present invention is similar to that of Embodiment 1 except that the first charge generating layer 160 is made of lithium (Li) is doped to a level of 2% and has a thickness of 150 ANGSTROM.

The second charge generating layer 165 has a region divided into a first region 166 and a second region 168 and has a third region 166 formed between the first region 166 and the second region 168, And further includes a hole transport layer 167.

In the second embodiment of the present invention, the first region 166 of the second charge generating layer is formed such that the p-type dopant is doped to the charge generating layer host material at a level of 6% and has a thickness of 100 ANGSTROM, Transport layer 167 is formed of a hole transport layer host material and has a thickness of 50 ANGSTROM and a second region 168 of the second charge generating layer is doped with a p-type dopant to a charge generation layer host material at a level of 6% Thickness.

In Example 2, a second hole transport layer 170 is formed on the second charge generation layer 165, and the second hole transport layer 170 is formed of a hole transport layer host material and has a thickness of 150 ANGSTROM.

Each of the blue organic light emitting devices according to the conditions of FIG. 3 was fabricated to evaluate the structure of the second charge generating layer.

4 is a diagram showing the result of the electro-optical characteristic evaluation of the organic light emitting diode 1000 according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a comparative example according to a conventional organic light emitting device having a second charge generating layer structure of a single layer as described above with reference to FIG. 3 and an embodiment of the present invention having a structure of a novel second charge generating layer 165 Optical characteristics of the blue organic light emitting device according to Examples 1 and 2.

Referring to FIG. 4, the driving voltage of the blue organic light emitting device according to the comparative example and the exemplary embodiment of the present invention is compared with that of the comparative example. In the comparative example, a driving voltage of about 7.0V is required to show a luminance of 498nit. It is found that the driving voltage of 7.2V is required to exhibit the luminance of 498nit and the luminance of 498nit in the case of the second embodiment.

That is, a similar level of driving voltage is required to show the same luminance in both the comparative example and the first and second embodiments. Therefore, in the case of Embodiment 1 and Embodiment 2 of the present invention, the third hole transport layer 167 is formed between the first region 166 of the second charge generation layer and the second region 168 of the second charge generation layer, And the doping concentration of the p-type dopant contained 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% It can be seen that the driving voltage is similar to that of the conventional structure.

Referring to FIG. 4, the current efficiency of the organic light emitting device according to the comparative example and the exemplary embodiment of the present invention is compared with that of the comparative example, and the result is shown to be 5.4Cd / A in the comparative example. On the other hand, in the case of Example 1, the result is 6.1Cd / A, and in Example 2, the result is 5.8Cd / A. As a result, the efficiency is improved in Examples 1 and 2 as compared with Comparative Example.

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 generation layer in Embodiments 1 and 2, 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 compared with the conventional method and smooth charge generation can be performed in the second charge generating layer, As shown in Fig.

Referring to FIG. 5, the color coordinate values of the organic light emitting device according to the comparative example and the exemplary embodiment of the present invention are compared. In the comparative example, CIE_x is 0.144 and CIE_y is 0.049. In the case of Example 1, CIE_x was 0.143 and CIE_y was 0.050. In Example 2, CIE_x was 0.144 and CIE_y was 0.050.

As a result of comparison with the comparative example, the results of color coordinate values similar to those of the first and second embodiments are shown. In comparison with the comparative example, the results satisfying the desired color are also satisfied in the first and second embodiments .

 It can be seen from the results of the above experiment that 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 generation layer including the p- The third hole transport layer 167 is additionally applied to reduce the doping concentration of the dopant in the first region 166 and the second region 168 of the second charge generation layer to thereby improve the smoothness of the second charge generation layer 165 Charge generation can be performed, and the efficiency of the organic light emitting device can be improved.

The third charge transport layer 167 is applied between the first region 166 and the second region 168 of the second charge generation layer to form the first region 166 and the second region 168 of the second charge generation layer ) Can be lowered and the mass productivity can be improved by reducing the material cost due to application of a high concentration of dopant.

FIG. 5 is a view showing the life characteristic evaluation result of the organic light emitting diode 1000 according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a comparative example according to a conventional blue organic light emitting device having a second charge generating layer structure of a single layer as described with reference to FIG. 3 and a comparative example according to the present invention having a structure of a novel second charge generating layer 165 Fig. 5 is a graph showing the results of comparative evaluation of lifetime characteristics of blue organic light emitting devices according to Example 1 and Example 2. Fig.

As can be seen from FIG. 5, in the comparative example, the time until the light emission luminance of 95% of the initial light emission luminance was exhibited, that is, the 95% lifetime of the organic light emitting device was about 350 hours, 1, the 95% lifetime showed a level of about 440 hours. In the case of Example 2, the 95% lifetime showed a level of about 390 hours. When compared with the comparative example, in Examples 1 and 2 The lifetime of the organic light emitting device is improved.

 As a result of the experiment, the organic light emitting diode 1000 according to the embodiment of the present invention has the third hole 163 between the first region 166 and the second region 168 of the second charge generation layer including the p- 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 through the additional application of the transport layer 167 and the smooth charge As a result, the efficiency of the organic light emitting device is improved as compared with the conventional structure. As a result, the lifetime of the organic light emitting diode is improved.

In the case of the organic light emitting diode 1000 according to the embodiment of the present invention, the first region 166 and the second region 168 of the second charge generation layer including the p- A third hole transport layer 167 may be additionally formed to enable smooth charge generation in the second charge generation layer 165 to improve the efficiency and lifetime of the organic light emitting device.

Also, by applying a third hole transporting layer between the first and second regions of the second charge generating layer, the concentration of the dopant doped in the first and second regions of the second charge generating layer can be lowered, It is possible to improve the mass productivity by reducing the material cost required by the application.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, have. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

1000: organic light emitting element
110: first electrode
120: Hole injection layer
130: First hole transport layer
140: first red light emitting layer
141: first green light emitting layer
142: first blue light emitting layer
150: first electron transporting layer
160: first charge generating layer
165: second charge generating layer
166: second charge generating layer first region
167: Third hole transport layer
168: second charge generating layer second region
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 first electrode and a second electrode;
First and second light emitting units positioned between the first electrode and the second electrode;
A first charge generation layer located between the first and second light emitting units;
A second charge generation layer located between the first and second light emitting units and located above the first charge generation layer; And
And a second hole transport layer located on the second charge generation layer,
Wherein the second charge generation layer comprises a first region and a second region,
And a third hole transporting layer located between the first region and the second region of the second charge generating layer. The method according to claim 1,
Wherein the first region and the second region of the second charge generation layer further comprise a p-type dopant, and the doping concentration of the p-type dopant in the first region and the second region is 6 to 8%. 3. The method of claim 2,
Wherein the doping concentration of the p-type dopant in the first region and the second region of the second charge generation layer is different. The method of claim 3,
And the p-type dopant in the first region and the second region of the second charge generation layer comprises any one of F ₄ -TCNQ and NDP-9. The method according to claim 1,
Wherein the thickness of each of the first region and the second region of the second charge generation 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,
And the thickness of the first region and the second region of the second charge generation layer are different from each other. The method according to claim 1,
The thickness of the third hole transporting layer located between the first region and the second region of the second charge generating layer is smaller than the thickness of the second hole transporting layer located above the second charge generating layer. 8. The method of claim 7,
Wherein the thickness of the third hole transporting layer located between the first region and the second region of the second charge generation layer is 100 ANGSTROM or less. 8. The method of claim 7,
The second hole transport layer located above the second charge generation layer and the third hole transport layer located between the first region and the second region of the second charge generation layer are HATCN, TBAHA, F ₄ -TCNQ And CuPc. 10. The method of claim 9,
The third hole transporting layer located between the first and second regions of the second charge transporting layer and the second charge transporting layer located above the second charge generating layer comprises an organic light emitting device.

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