KR20180062222A - Organic Light Emitting Device and Organic Light Emitting Display Apparatus using the same - Google Patents

Abstract

The present invention relates to an organic electroluminescent device comprising a first stack, a second stack, and a third stack provided between an anode and a cathode, wherein the second stack comprises a red light emitting layer and a green light emitting layer A light emitting device and an organic light emitting display using the same are provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED)

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 that emits white light.

The organic light emitting device has a structure in which a light emitting layer is formed between a cathode for injecting electrons and an anode for injecting holes, and electrons generated in the cathode and holes generated in the anode are injected into the light emitting layer When excited, excited electrons and holes are coupled to generate excitons, and the generated excitons emit light while falling from the excited state to the ground state.

Such an organic light emitting device can be applied not only to illumination but also to a thin light source or a display device of a liquid crystal display device. In particular, an organic light emitting device that emits white light can be applied to a full color display device in combination with a color filter.

Hereinafter, a conventional organic light emitting device will be described with reference to the drawings.

FIG. 1A is a schematic cross-sectional view of a conventional organic light emitting device, and FIG. 1B is a graph showing an emission spectrum of a conventional organic light emitting device.

1A, a conventional organic light emitting device includes an anode, a first stack, a charge generating layer (CGL), a second stack (second stack), and a cathode. .

The first stack is formed on the anode and includes a blue (B) emission layer (EML).

The charge generation layer CGL may be formed between the first stack and the second stack so that charge is generated between the first stack and the second stack Balanced control.

The second stack (2nd Stack) is formed between the charge generation layer (CGL) and the cathode and includes a yellow green (YG) emission layer (EML).

In such a conventional organic light emitting device, the blue light emitted from the blue (B) emission layer (EML) of the first stack and the yellow (YG) emission layer of the second stack EML) is mixed to emit white light.

However, the conventional organic light emitting device has a disadvantage that the color reproduction rate is low when an image is displayed by displaying an emission spectrum having two peak wavelengths.

1B, in the conventional case, one peak wavelength appears in the short wavelength band due to the blue (B) light emitted from the first stack and is emitted from the second stack (second stack) A single peak wavelength appears in the long wavelength band by the yellow green (YG) light. As described above, only one peak wavelength appears in the long wavelength band, which limits the color range that can be implemented and thus the color reproduction rate is deteriorated. Particularly, in the conventional case, green (G) and red (R) are realized through the yellow green (YG) emission layer (EML) of the second stack (2nd Stack). In this case, .

In order to solve the conventional problem of low color reproducibility, the inventors of the present invention have found that a red (R) emission layer is formed in addition to a yellow (YG) emission layer (EML) in a second stack The organic light emitting device was tested.

As a result, it was confirmed that the obtained organic light emitting device exhibited one peak wavelength in a short wavelength band and two peak wavelengths in a long wavelength band, resulting in three peak wavelengths, and also a light efficiency of red (R).

However, when the yellow (YG) emission layer (EML) and the red (R) emission layer are included in the second stack (2nd Stack), the light efficiency of green (G) is lowered, Respectively.

Accordingly, it is an object of the present invention to provide an organic light emitting device capable of improving the color reproduction ratio by improving both the red (R) and green (G) luminous efficiency, and an organic light emitting display using the same.

In order to achieve the above object, the present invention provides a light emitting device comprising a first stack, a second stack, and a third stack provided between an anode and a cathode, the second stack comprising a red light emitting layer and a green An organic light emitting device comprising a light emitting layer is provided.

The present invention also includes a thin film transistor layer provided on a substrate, and an organic light emitting element provided on the thin film transistor layer, wherein the organic light emitting element includes a first stack, a second stack, And a third stack, wherein the second stack includes a red light emitting layer and a green light emitting layer stacked in layers different from each other.

The present invention has the following effects.

According to an embodiment of the present invention, since the second stack provided between the first stack and the second stack includes a red (R) emission layer (EML) and a green (G) emission layer (EML) ) And green (G), the color reproduction rate can be improved.

According to another embodiment of the present invention, the second stack further includes an emission control layer (ECL) between the red (R) emission layer (EML) and the green (G) emission layer (EML) The color viewing angle characteristics can be improved.

FIG. 1A is a schematic cross-sectional view of a conventional organic light emitting device, and FIG. 1B is a graph showing an emission spectrum of a conventional organic light emitting device.
2 is a schematic cross-sectional view of an organic light emitting device according to an embodiment of the present invention.
3 is a schematic cross-sectional view of an organic light emitting device according to another embodiment of the present invention.
4 is a graph showing the intensity of light emitted by the organic light emitting device according to Example 1 and Example 2 of the present invention.
5 is a graph showing a color change ratio according to viewing angles of organic light emitting devices according to Example 1 and Example 2 of the present invention.
FIG. 6 is a graph showing a change in luminescence intensity by wavelength band as a result of application of the emission control layer having various compositions.
7 is a graph showing changes in color viewing angle characteristics according to the thickness of the emission control layer (ECL).
FIG. 8 is a graph showing luminescence intensities of the organic luminescent devices according to Comparative Examples, Examples 1 and 2 according to wavelengths.
FIG. 9 is a graph showing the color gamut of the organic luminescent device according to the comparative example, the first embodiment, and the second embodiment.
10 is a graph showing the rate of change of color according to viewing angles of organic light emitting devices according to Comparative Examples, Examples 1 and 2.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey 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. In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can 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.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

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, preferred embodiments of the present invention will be described in detail with reference to the drawings.

2 is a schematic cross-sectional view of an organic light emitting device according to an embodiment of the present invention.

2, an organic light emitting diode according to an exemplary embodiment of the present invention includes an anode, a first stack, a first charge generating layer (first CGL), a second stack (second stack) A second charge generating layer (2nd CGL), a third stack (third stack), and a cathode.

The anode may include a transparent conductive layer having a high work function. The transparent conductive layer may be formed of ITO (Indium Tin Oxide), IZO (indium zinc oxide), SnO ₂ or ZnO, but is not limited thereto.

The first stack (Stack) is formed on the anode to emit blue (B) light. The first stack may include a hole injection layer (HIL), a first hole transporting layer (HTL), a first emission layer (EML), and a first hole transport layer And a first electron transport layer (1st ETL).

The hole injecting layer HIL is formed on the anode and may be formed of MTDATA (4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine), CuPc (copper phthalocyanine) or PEDOT / PSS , 4-ethylenedioxythiophene, and polystyrene sulfonate). However, the present invention is not limited thereto. The hole injection layer (HIL) may be formed by doping a P-type dopant into the first hole transport layer .

The first HTL may be formed on the hole injection layer (HIL), and may be TPD (N, N'-diphenyl-N, N'-bis (3-methylphenyl) phenyl-4,4'-diamine, NPD (N, N-diphenyl benzidine), or NPB (N, N'- -benzidine), and the like, but the present invention is not limited thereto. The first HTL may be formed of the same material as that of the HIL except that the P type dopant is not included. In this case, in the same process equipment, (HIL) and a first hole transport layer (1st HTL).

The first emission layer (1st EML) is formed on the first HTL (1st HTL). The first emission layer (1st EML) is composed of a blue emission layer that emits blue (B) light.

The first EML may include an organic material capable of emitting blue light, for example, a blue light having a peak wavelength in the range of 440 nm to 480 nm, and specifically, an anthracene an anthracene derivative, a pyrene derivative, and a perylene derivative may be doped with at least one host material, but the present invention is not limited thereto.

The first electron transport layer (1st ETL) is formed on the first emission layer (1st EML), and includes carbazole, oxadiazole, triazole, phenanthroline, Benzoxazole, benzthiazole, and the like, but the present invention is not limited thereto.

The first charge generation layer (1st CGL) is formed between the first stack and the second stack and is disposed between the first stack and the second stack The charge is controlled in a balanced manner.

The first charge generation layer (1st CGL) includes an N-type charge generation layer formed on the first stack and positioned adjacent to the first stack, and an N-type charge generation layer formed on the N-type charge generation layer And a P-type charge generation layer formed adjacent to the second stack (second stack).

The N-type charge generation layer injects electrons into the first stack, and the P-type charge generation layer injects holes into the second stack. The N-type charge generation layer may be composed of an organic layer doped with an alkali metal such as Li, Na, K, or Cs, or an alkaline earth metal such as Mg, Sr, Ba, or Ra. The P-type charge generation layer may be doped with an organic material having a hole transporting ability.

The second stack may be formed on the first charge generation layer (1st CGL) to emit red (R) light and green (G) light.

The second stack (2nd Stack) includes a second HTL, a second EML, a third EML, and a second ETL.

The second hole transport layer (2nd HTL) is formed on the first charge generation layer (1st CGL), and TPD (N, N'-diphenyl-N, N'- -bi-phenyl-4,4'-diamine, NPD (N-dinaphthyl-N, N'-diphenyl benzidine), or NPB (naphthalen- '-diphenyl-benzidine), and the like, but the present invention is not limited thereto. The second HTL may be made of the same material as the first HTL, but may be made of a material different from the first HTL.

The second emission layer (2nd EML) is formed on the second HTL (2nd HTL).

The second emission layer (2nd EML) may include an organic material emitting red (R) light, for example, light having a peak wavelength in a range of 600 nm to 650 nm, and specifically, a host comprising a carbazole compound or a metal complex The material may be doped with a red dopant. The carbazole-based compound may include CBP (4,4-N, N'-dicarbazole-biphenyl), CBP derivative, mCP (N, N'-dicarbazolyl-3,5-benzene) The metal complex may include ZnPBO (phenyloxazole) metal complex or ZnPBT (phenylthiazole) metal complex.

The third emission layer (3rd EML) is formed on the second emission layer (2nd EML).

The third emission layer (3rd EML) may include an organic material that emits green (G) light, for example, light having a peak wavelength in the range of 510 nm to 550 nm. Specifically, a host comprising a carbazole compound or a metal complex The material may be doped with a green dopant.

The host material of the second emission layer (2nd EML) and the host material of the third emission layer (3rd EML) may be made of the same phosphorescent host material. In this case, the driving voltage of the device may be lowered. However, the host material of the second emission layer (2nd EML) and the host material of the third emission layer (3rd EML) may be made of different phosphorescent host materials.

As described above, according to an embodiment of the present invention, the second stack (2nd Stack) includes a second emission layer (2nd EML) emitting red (R) light and a third emission layer 3rd EML). Therefore, two peak wavelengths appear in the long wavelength band, and the luminous efficiency of red (R) and green (G) is improved and the color reproduction rate can be improved.

Further, the second light emitting layer (2nd EML) emitting a relatively long wavelength can be disposed close to the anode corresponding to the light emitting surface, thereby improving the microcavity effect.

The second electron transport layer (2nd ETL) is formed on the third emission layer (3rd EML) and is formed of carbazole, oxadiazole, triazole, phenanthroline, Benzoxazole, benzthiazole, and the like, but the present invention is not limited thereto.

The second electron transport layer (2nd ETL) may be made of the same material as the first electron transport layer (1st ETL), but is not limited thereto.

The second charge generation layer (2nd CGL) is formed between the second stack and the third stack and is connected between the second stack and the third stack The charge is controlled in a balanced manner.

The second charge generation layer (2nd CGL) may include an N-type charge generation layer formed on the second stack and positioned adjacent to the second stack, and a second charge generation layer formed on the N-type charge generation layer And a P-type charge generation layer formed adjacent to the third stack (3rd Stack).

The N-type charge generation layer injects electrons into the second stack, and the P-type charge generation layer injects holes into the third stack. The N-type charge generation layer may be composed of an organic layer doped with an alkali metal such as Li, Na, K, or Cs, or an alkaline earth metal such as Mg, Sr, Ba, or Ra. The P-type charge generation layer may be doped with an organic material having a hole transporting ability.

The second charge generating layer (2nd CGL) may be made of the same material as the first charge generating layer (1st CGL), but the present invention is not limited thereto.

The third stack (3rd Stack) may be formed between the second charge generation layer (2nd CGL) and the cathode to emit blue light.

The third stack includes a third hole transport layer (3rd HTL), a fourth emission layer (4th EML), a third electron transport layer (3rd ETL), and an electron injection layer (EIL).

The third hole transport layer (3rd HTL) is formed on the second charge generation layer (2nd CGL), and TPD (N, N'-diphenyl-N, N'- -bi-phenyl-4,4'-diamine, NPD (N-dinaphthyl-N, N'-diphenyl benzidine), or NPB (naphthalen- '-diphenyl-benzidine), and the like, but the present invention is not limited thereto. The third hole transport layer (3rd HTL) may be made of the same material as the first HTL or the second HTL, but may be made of a different material.

The fourth emission layer (4th EML) is formed on the third hole transport layer (3rd HTL). The fourth light emitting layer (4th EML) is composed of a blue light emitting layer for emitting blue (B) light.

The fourth emission layer (4th EML) may include an organic material capable of emitting blue (B) light, for example, a blue light in a peak wavelength range of 440 nm to 480 nm, and specifically, an anthracene an anthracene derivative, a pyrene derivative, and a perylene derivative may be doped with at least one host material, but the present invention is not limited thereto.

According to an embodiment of the present invention, since the first stack and the third stack each include a blue (B) emission layer (EML), the emission efficiency of blue (B) .

The third electron transport layer (3rd ETL) is formed on the fourth emission layer (4th EML) and includes carbazole, oxadiazole, triazole, phenanthroline, Benzoxazole, benzthiazole, and the like, but the present invention is not limited thereto.

The third electron transport layer (3rd ETL) may be made of the same material as the first electron transport layer (1st ETL) or the second electron transport layer (2nd ETL), but may be made of different materials as the case may be.

The electron injection layer (EIL) is formed on the third electron transport layer (3rd ETL), and may be formed of lithium fluoride (LiF) or lithium quinolate (LiQ), but is not limited thereto.

The cathode is formed on the third stack. The cathode may be made of a metal having a low work function such as aluminum (Al), silver (Ag), magnesium (Mg), lithium (Li), calcium (Ca) no.

In the organic light emitting diode according to an embodiment of the present invention, the blue light emitted from the first emission layer (1st EML) of the first stack (1st) and the fourth emission layer (4th EML) of the third stack (3rd) Light emitted from the second light emitting layer (2nd EML) of the second stack (2nd Stack) and the light of red (R) emitted from the third light emitting layer (3rd EML) of the second stack Green (G) light is mixed and white light is emitted.

In order to improve the efficiency of red (R) light, green (G) light and blue (B) light, the first EML, the second EML, EML), and the fourth light emitting layer (4th EML).

Considering that the efficiency of the fluorescent material that emits blue (B) light is lower than the efficiency of the phosphor that emits green (G) or red (R) light, first, Emitting layer (1st EML) and the fourth emitting layer (4th EML) are set and then the second emitting layer (2nd EML) emitting the red (R) And the stacking position of the light emitting layer (3rd EML) is set.

The stacking position of the second light emitting layer (2nd EML) and the third light emitting layer (3rd EML) is located at the third HTL in the second stack (2nd HTL) and the third HTL in the third stack The thickness of the hole transport layer (3rd HTL) can be adjusted and set. Specifically, the thickness of the third hole transport layer (3rd HTL) is made thicker than that of the second hole transport layer (2nd HTL), and the second emission layer (2nd EML) and the third emission layer It is possible to set an appropriate position between the anode and the cathode so as to improve the luminous efficiency of red (R) and green (G).

2, the second emission layer (2nd emission layer) emitting red (R) and the third emission layer (3rd emission layer) emitting green (G) are formed in contact with each other , There is a limitation in setting the stacking position of the second light emitting layer (2nd EML) and the third light emitting layer (3rd EML). If the stacking position of the second emission layer (2nd EML) and the third emission layer (3rd EML) is not optimized, the color change may increase according to the viewing angle, and the color viewing angle characteristic may be deteriorated.

Hereinafter, an organic light emitting device according to another embodiment of the present invention capable of improving the color viewing angle characteristics by reducing the color change according to the viewing angle will be described.

3 is a schematic cross-sectional view of an organic light emitting device according to another embodiment of the present invention. The organic light emitting device according to FIG. 3 includes a second emission layer (2nd EML) emitting red (R) in a second stack (2nd Stack) and a third emission layer (3rd EML) emitting green 2 is the same as that of the organic light emitting device of FIG. 2 except that an emission control layer (ECL) is additionally formed. Therefore, the following description will be focused on different structures.

3, an emission control layer (ECL) is additionally formed between a second emission layer (2nd emission layer) emitting red (R) and a third emission layer (3rd emission layer) emitting green (G) , The color change according to the viewing angle is reduced, and the color viewing angle characteristic can be improved.

That is, in the case of the organic light emitting device according to FIG. 3, the second emission layer (2nd EML) emitting the red (R) and the third emission layer (3rd EML The third light emitting layer (3rd EML) emitting the green G is positioned closer to the cathode than the anode so that the luminous efficiency of the green G is increased and the viewing angle Thereby reducing the color change caused by the color change.

The emission control layer (ECL) may include a material having electron transport properties such as materials of the first to third electron transport layers (1st to 3rd ETL) For example, a mixture of materials having hole transporting properties such as materials of the first to third hole transporting layers (1st to 3rd HTLs). The emission control layer (ECL) may also be a bipolar material having both electron transport and hole transport, that is, both electron transport and hole transport.

4 is a graph showing the intensity of light emitted by the organic light emitting device according to Example 1 and Example 2 of the present invention. In FIG. 4, Example 1 is the organic light emitting device according to the above-described FIG. 2, and the embodiment is the organic light emitting device according to FIG.

4, a second emission layer (2nd EML) emitting red (R) and a third emission layer (3rd EML) emitting green (G) The emission intensity of the green (G) wavelength band of about 520 nm is improved as compared with Example 1 in which the emission control layer (ECL) is not provided.

In addition, it can be seen that the color purity is improved by reducing the shoulder portion of the long wavelength band in Example 2 compared to Example 1. [

5 is a graph showing a color change ratio according to viewing angles of organic light emitting devices according to Example 1 and Example 2 of the present invention. In FIG. 5, Example 1 is the organic light emitting device according to the above-described FIG. 2, and the embodiment is the organic light emitting device according to FIG.

As shown in FIG. 5, in Example 2 (EML) having a light emission control layer (ECL) between a second emission layer (2nd emission layer) emitting red (R) and a third emission layer The color change ratio according to the viewing angle decreases compared to Example 1 in which the emission control layer (ECL) is not provided. Therefore, it can be seen that the color viewing angle characteristic of Example 2 having the emission control layer (ECL) is improved as compared with Example 1 having no emission control layer (ECL).

As described above, the emission control layer (ECL) may be a mixture of a material having an electron transporting property and a material having a hole transporting property, or a bipolar material. When the emission control layer (ECL) is made of a material having an electron transporting property and a mixture having a hole transporting property, the mixing ratio between the material having the electron transporting property and the material having the hole transporting property is 3 : 7 to 7: 3.

FIG. 6 is a graph showing changes in luminescence intensities according to wavelengths as the emission control layer having various compositions is applied, which is a result of applying the emission control layer having the composition according to Sample 1 to Sample 6 in Table 1 below.

Table 1 below shows the external quantum efficiency (EQE) for each of the first to sixth samples and the normalized intensity results of green and red.

ECL EQE
Normalized Intensity P-type E-type Green Red Sample 1 10 0 20.0 One 0.10 (non-luminous) Sample 2 7 3 19.6 One 0.36 Sample 3 5 5 20.4 One 0.48 Sample 4 3 7 19.4 0.71 One Sample 5 0 10 17.8 0.15 One Sample 6 Bipolar 19.5 One 0.46

In Table 1, Sample 1 uses an emission control layer (ECL) made of only a material having a hole transporting property (P-type), Sample 2 uses a material having a hole transporting property (P-type) (ECL) having a weight ratio of a material having a transport characteristic (E-type) of 7: 3 is used. Sample 3 has a material (P-type) having a hole transporting property and an electron transporting property (P-type) having a hole transporting property and a material (E (electron transporting material) having an electron transporting property) using a light emission control layer (ECL) -type) is 3: 7, Sample 5 is an emission control layer (ECL) made only of a material having an electron transporting property (E-type), and Sample 6 (ECL) composed of a bipolar material.

Referring to FIG. 6 and Table 1, Sample 2, Sample 3, Sample 4, and Sample 6 have excellent external quantum efficiency (EQE) and normalized luminescence intensity of green and red Normalized Intensity) is also excellent.

Therefore, the emission control layer (ECL) may be formed of a bipolar material, or a mixture of materials having electron transport properties and materials having hole transport properties in a range of 3: 7 to 7: 3 Is preferable.

Particularly, in Sample 2, Sample 3, and Sample 4, the case of Sample 3 has an external quantum efficiency (EQE) and a normalized luminescence intensity of Green (Green) and Red (Red) Normalized Intensity) is superior.

Therefore, when the emission control layer (ECL) is made of a mixture of a material having an electron transporting property and a material having a hole transporting property, a mixing ratio between a material having an electron transporting property and a material having a hole transporting property Is more preferably 5: 5.

7 is a graph showing changes in color viewing angle characteristics according to the thickness of the emission control layer (ECL).

FIG. 7 shows the color viewing angle characteristics of the organic light emitting device according to FIG. 3 as the thickness of the emission control layer (ECL) changes. As can be seen from FIG. 7, as the thickness of the emission control layer (ECL) increases to 50 A, 100 A and 200 A, the color change rate gradually decreases at a viewing angle of 60 deg., While the thickness of the emission control layer (ECL) It can be seen that the color change rate gradually increases at a viewing angle of 60 °.

Particularly, when the thickness of the emission control layer (ECL) is 300 ANGSTROM, the color change ratio is rather large at a viewing angle of 60 DEG in comparison with the case where the emission control layer (ECL) is not applied (ECL 0).

Therefore, the thickness of the emission control layer (ECL) is preferably set to less than 300 ANGSTROM.

FIG. 8 is a graph showing the luminescence intensities of the organic luminescent devices according to Comparative Examples, Examples 1 and 2, and FIG. 9 is a graph showing the luminescence intensity of the organic luminescent devices according to Comparative Examples, Examples 1 and 2 And FIG. 10 is a graph showing a color change ratio according to viewing angles of the organic light emitting diode according to the comparative example, the first embodiment, and the second embodiment.

Table 2 below shows the results of Figs. 8 to 10 for the organic luminescent device according to Comparative Example, Example 1 and Example 2. Fig.

The second stack
G efficiency
(%) G color coordinates R efficiency
(%) R color coordinates BT2020
Overlap ratio
Viewing angle
(? U'v ') x y x y Comparative Example R / YG 100 0.279 0.660 100 0.678 0.322 72.6 0.022 Example 1 R / G 107 0.217 0.706 90 0.692 0.307 83.8 0.030 Example 2 R / ECL / G 109 0.209 0.712 82 0.692 0.206 85.1 0.024

In Table 2, the comparative example uses a light emitting layer that emits yellow green (YG) instead of green (G) as the third emitting layer (3rd EML) in the organic light emitting device according to the aforementioned FIG. 2, FIG. 2 is an organic light emitting device, and FIG. 2 is an organic light emitting device according to the previously described FIG.

As can be seen from FIG. 8 and Table 2, the luminous efficiency of the red (R) light is lower than that of the comparative example in Examples 1 and 2, but the luminous efficiency of the green (G) light is improved. That is, as can be seen from FIG. 8, the peak wavelength of the green color layer (Green CL) agrees with the peak wavelength of the green wavelength band of the first and second embodiments.

Therefore, the color purity in Examples 1 and 2 can be improved as compared with Comparative Examples. Particularly, in the case of Example 2, the luminous efficiency of green (G) light is improved and the color purity is excellent as compared with Example 1.

As can be seen from FIG. 9 and Table 2, it can be seen that the color gamut of Example 1 and Example 2 is broader than that of Comparative Example, and thus the color gamut is improved. Particularly, in the case of the embodiment 2, the color range that can be expressed is wider than in the embodiment 1, and thus the color reproduction rate is improved.

10 and Table 2, it can be seen that the color change ratio is slightly larger in Example 1 and Example 2 at a viewing angle of 60 ° than the comparative example. However, in Example 2, the color change ratio is small at a viewing angle of 60 DEG in comparison with Example 1, and the difference from Comparative Example is not large. Therefore, it can be seen that the color viewing angle characteristics of Example 2 are improved compared to Example 1. [

FIG. 11 is a schematic cross-sectional view of an organic light emitting diode display according to an embodiment of the present invention, which is applied to the organic light emitting diode according to FIG. 2 or FIG.

11, the organic light emitting diode display according to an exemplary embodiment of the present invention includes a substrate 10, a thin film transistor layer 20, a planarization layer 30, a first electrode 40, a bank layer 50, , An organic layer (60), and a second electrode (70).

The substrate 10 may be made of glass, or a transparent plastic, such as polyimide, which is capable of bending or rolling, but is not limited thereto.

The thin film transistor layer 20 is formed on the substrate 10. The thin film transistor layer 20 includes a gate electrode 21, a gate insulating film 22, a semiconductor layer 23, a source electrode 24a, a drain electrode 24b, and a protective film 25.

The gate electrode 21 is patterned on the substrate 10 and the gate insulating film 22 is formed on the gate electrode 21 and the semiconductor layer 23 is formed on the gate insulating film 22 The source electrode 24a and the drain electrode 24b are patterned so as to face each other on the semiconductor layer 23 and the protective film 25 is patterned on the source electrode 24a and the source electrode 24a, And is formed on the drain electrode 24b.

Although the bottom gate structure in which the gate electrode 21 is formed under the semiconductor layer 23 is shown in the figure, the top gate structure in which the gate electrode 21 is formed on the semiconductor layer 23 .

The planarization layer 30 is formed on the thin film transistor layer 20 to planarize the substrate surface. The planarization layer 30 may be formed of an organic insulating film such as photo-acryl, but is not limited thereto.

The first electrode (40) is formed on the planarization layer (30). The first electrode 40 is connected to the drain electrode 24b or the source electrode 24a of the thin film transistor layer 20 through a contact hole formed in the protective layer 25 and the planarization layer 30 .

The first electrode 40 may be an anode of the various embodiments described above.

The bank layer 50 is formed on the first electrode 40 and the planarization layer 30 to define a pixel region. The bank layer 50 is formed in a matrix structure in a boundary region between a plurality of pixels, so that the pixel region is defined by the bank layer 50.

The organic layer 60 is formed on the first electrode 40. The organic layer 60 may also be formed on the bank layer 50. That is, the organic layer 60 may be connected to adjacent pixels without being separated for each pixel.

The organic layer 60 may include a first stack (first stack), a first charge generation layer (first CGL), a second stack (second stack), a second charge generation layer (second CGL) And a third stack (third stack). Accordingly, white light may be emitted from the organic layer 60.

The second electrode (70) is formed on the organic layer (60). The second electrode 70 may be a cathode of the various embodiments described above.

The stacked structure of the first electrode 30, the organic layer 60, and the second electrode 70 may be an organic light emitting device according to the above-described FIG. 2 or FIG.

Although not shown, individual pixels may further include a color filter for filtering the white light emitted from the organic layer 60 by wavelength. The color filter is formed on the movement path of light. That is, in the case of the so-called bottom emission type in which the light emitted from the organic layer 60 advances toward the lower substrate 10, the color filter is formed below the organic layer 60, In the case of the so-called top emission type in which the light emitted from the organic layer 60 advances toward the upper second electrode 70, the color filter is formed on the organic layer 60.

In the above description, the anode is a transparent electrode and the cathode is a reflective electrode. The first stack, the second stack, and the third stack The present invention is not necessarily limited to this. The anode may be a reflective electrode, and the cathode may be a cathode. In this case, And an upper light emitting organic light emitting device formed of a transparent electrode and emitting light emitted in the first stack, the second stack, and the third stack (third stack) in the direction of the cathode (cathode) .

In the case of the upper light emitting organic light emitting device, the second emission layer (2nd EML) emitting red (R), provided in the second stack (2nd Stack) And can be disposed closer to the cathode, which is a transparent electrode.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . 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 the same should be interpreted as being included in the scope of the present invention

10: substrate 20: thin film transistor layer
30: planarization layer 40: first electrode
50: bank layer 60: organic layer
70: Second electrode

Claims (11)

Anode and cathode;
A first stack, a second stack, and a third stack provided between the anode and the cathode;
A first charge generation layer provided between the first stack and the second stack, and a second charge generation layer provided between the second stack and the third stack,
Wherein the second stack includes a red light emitting layer and a green light emitting layer stacked in layers different from each other. The method according to claim 1,
Wherein the red light emitting layer and the green light emitting layer are spaced apart from each other. 3. The method of claim 2,
Wherein an emission control layer is additionally provided between the red emission layer and the green emission layer, and the red emission layer and the green emission layer are separated from each other by the emission control layer. The method of claim 3,
Wherein the emission control layer comprises a mixture of a material having an electron transporting property and a material having a hole transporting property. 5. The method of claim 4,
Wherein the mixing ratio between the material having the electron transporting property and the material having the hole transporting property is in the range of 3: 7 to 7: 3. The method of claim 3,
Wherein the emission control layer is made of a bipolar material having an electron transporting property and a hole transporting property. The method of claim 3,
Wherein the thickness of the emission control layer is less than 300 ANGSTROM. The method according to claim 1,
Wherein one of the anode and the cathode is a reflective electrode and the other is a transparent electrode,
Wherein the red light emitting layer is disposed close to the transparent electrode, and the green light emitting layer is disposed close to the reflective electrode. The method according to claim 1,
Wherein the first stack is disposed closest to the anode and the third stack is disposed closest to the cathode, wherein the first stack and the third stack each include a blue light emitting layer. The method according to claim 1,
Wherein the second stack and the third stack each comprise a hole transport layer,
Wherein the thickness of the hole transport layer of the third stack is thicker than the thickness of the hole transport layer of the second stack. Board;
A thin film transistor layer provided on the substrate; And
And an organic light emitting element provided on the thin film transistor layer,
Wherein the organic light emitting device comprises the organic light emitting device according to any one of claims 1 to 10.

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