KR20180062220A - Organic Light Emitting Device and Organic Light Emitting Display Apparatus using the same - Google Patents

Abstract

The present invention provides an organic light emitting element capable of lowering a drive voltage and an organic light emitting display device using the same. The organic light emitting element comprises a first stack comprising a first hole transporting layer, a first light emitting layer, and a first electron transporting layer; a second stack comprising a second hole transporting layer, a second light emitting layer, and a second electron transporting layer; and a third stack comprising a third hole transporting layer, a third light emitting layer, and a third electron transporting layer. The first electron transporting layer is thinner than the second hole transporting layer. The second electron transporting layer is thicker than the third hole transporting layer.

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.

1 is a schematic cross-sectional view of a conventional organic light emitting device.

1, 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 (Stack) is formed on the anode to emit blue (B) light. The first stack includes a hole injecting layer (HIL), a hole transporting layer (HTL), a blue (B) emission layer (EML), and an electron transporting layer Layer (ETL).

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) may be formed between the charge generation layer (CGL) and the cathode to emit yellow green (YG) light. The second stack includes a hole transport layer (HTL), a light emitting layer (EML) of yellowish green (YG), an electron transport layer (ETL), and an electron injection layer (EIL).

In the conventional organic light emitting device, the light of blue (B) emitted from the first stack (Stack) and the light of yellow (YG) emitted by the second stack (second stack) Lt; / RTI >

However, the conventional organic light emitting device has a drawback in that the driving voltage is high and the power consumption is increased. The present inventors have confirmed through various studies that the driving voltage of a device can not be optimized if the thickness of a plurality of organic layers can not be optimized and the thickness range of a plurality of organic layers for lowering the driving voltage is confirmed through various experiments to complete the present invention .

An object of the present invention is to provide an organic light emitting device capable of lowering a driving voltage and an organic light emitting display using the same.

In order to achieve the above-described object, the present invention provides a light emitting device comprising a first stack including a first hole transporting layer, a first light emitting layer, and a first electron transporting layer, a second hole transporting layer, a second light emitting layer, and a second electron transporting layer And a third stack comprising a third hole transporting layer, a third emitting layer and a third electron transporting layer, wherein the thickness of the third electron transporting layer is thicker than the thickness of the second electron transporting layer, And the thickness of the electron transporting layer is thicker than the thickness of the first electron transporting layer.

The present invention also provides a method of manufacturing a thin film transistor comprising 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 hole transport layer, a first light emitting layer and a first electron transport layer A second stack comprising a first stack, a second hole transport layer, a second light emitting layer and a second electron transport layer, and a third stack comprising a third hole transport layer, a third light emitting layer and a third electron transport layer, Wherein the thickness of the third electron transporting layer is greater than the thickness of the second electron transporting layer and the thickness of the second electron transporting layer is greater than the thickness of the first electron transporting layer.

The present invention has the following effects.

According to an embodiment of the present invention, the thickness T3 of the third electron transport layer (third ETL) is made thicker than the thickness T2 of the second electron transport layer (2nd ETL) (T2) of the first electron transport layer (ETL) is larger than the thickness of the first electron transport layer (1st ETL), the driving voltage of the organic light emitting element can be lowered.

1 is a schematic cross-sectional view 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 graph showing a driving voltage according to Comparative Example and Embodiments 1 to 3. Fig.
4 is a graph showing the driving voltage according to the comparative example and the example 5. Fig.
Fig. 5 is a graph showing the luminous efficiency according to the comparative example and the example 5. Fig.
6 is a schematic cross-sectional view of an OLED display 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 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, the organic light emitting diode according to an exemplary embodiment of the present invention includes a reflective layer, an anode, a first stack, a first charge generation layer (first CGL), a second stack A second stack, a second charge generating layer (2nd CGL), a third stack (third stack), a buffer layer, and a cathode.

The reflective layer is formed below the anode to emit light emitted from the first stack, the second stack, and the third stack, (Cathode) direction.

The anode may be formed on the reflective layer and 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.

The first EML may be formed by doping at least one host material selected from the group consisting of an anthracene derivative, a pyrene derivative and a perylene derivative with a blue dopant. However, But is not limited thereto.

The blue dopant included in the first emission layer (1st EML) may include a delayed fluorescence (TADF) dopant. The conventional fluorescent dopant has an internal quantum efficiency (IQE) of about 25%, whereas the retarded fluorescent dopant has an internal quantum efficiency (IQE) of about 40%. Therefore, when the blue dopant included in the first emission layer (1st EML) includes the retarded fluorescent dopant, the blue light emission efficiency can be improved.

The retarded fluorescent dopant is a dopant having a triplet-triplet annihilation (TTA) property. The smaller the exchange energy between the triplet and triplet of the retarded fluorescent dopant, the more the triplet to singlet The blue light emission efficiency can be improved. Likewise, the smaller the exchange energy between the singlet-triplets of the host material contained in the first EML is, the more easily the transition from a triplet to a singlet becomes, The efficiency can be improved.

The retarded fluorescent dopant may be an organic material including carbazole, acridine, or dibenzopyrazine, but is not limited thereto.

In order to improve the light emission efficiency of blue (B) light in the first emission layer (1st EML), a triplet exciton in the first emission layer (1st EML) is confined in the first emission layer (1st EML) There is a need. For this purpose, the triplet energy of the first HTL located under the first EML is lower than the triplet energy of the host material of the first EML, And a triplet energy of a first electron transport layer (first ETL) located above the first emission layer (1st EML) is higher than a triplet energy of a host material of the first emission layer (1st EML) energy.

The first ETL may be formed on the first EML and may include carbazole, oxadiazole, triazine, triazole, phenanthrol, Phenanthroline, benzoxazole or benzthiazole, but the present invention is not limited thereto.

In order to make the triplet energy of the first electron transport layer (first ETL) higher than the triplet energy of the host material of the first emission layer (1st EML), the first electron transport layer (1st The triplet energy of ETLs may be preferred above 2.9 eV.

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 (2nd Stack) may be formed on the first charge generation layer (1st CGL) to emit yellow-green (YG) light.

The second stack (2nd Stack) includes a second HTL, a second ETL, 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 yellowgreen (YG) light, for example, light having a peak wavelength in a range of 520 nm to 620 nm, and specifically, a carbazole-based compound or a metal complex The phosphorescent host material may be doped with a phosphorescent dopant of a yellow-green color. 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 second electron transport layer (2nd ETL) is formed on the third emission layer (3rd EML), and is formed of carbazole, oxadiazole, triazine, triazole, phenanthrol Phenanthroline, benzoxazole or benzthiazole, but the present invention is not limited thereto.

Since the second emission layer (2nd EML) in the second stack (2nd EML) includes a phosphor, the second ETL formed on the second emission layer (2nd EML) electron mobility) is preferable.

In the case of organic materials with a high electron mobility, the triplet energy has a range of 1.8 eV or less. Therefore, the triplet energy of the second electron transport layer (2nd ETL) may be preferably 1.8 eV or less.

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 on the second charge generation layer (2nd CGL) to emit blue light.

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

The third emission layer (3rd 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 a blue fluorescent dopant, 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 third emission layer (3rd EML), and is formed of carbazole, oxadiazole, triazine, triazole, phenanthrol Phenanthroline, benzoxazole or benzthiazole, but the present invention is not limited thereto.

The third electron transport layer (3rd ETL) must transport electrons that have passed through the buffer layer and the electron injection layer (EIL) to the third emission layer (3rd EML) mobility) is preferably made of a fast organic material. Considering the electron mobility, the triplet energy of the third electron transport layer (ETL) may preferably be 1.95 eV or less.

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 buffer layer is formed between the third stack and the cathode. The buffer layer prevents the electron injection layer (EIL) from being damaged during the process of forming the cathode. Such a buffer layer may be formed of an organic material such as hexaazatriphenylene hexanitrile (HATCN), but is not limited thereto.

The cathode is formed on the buffer layer. 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 device according to an embodiment of the present invention, light of blue (B) light emitted from the first stack (first stack) and the third stack (third stack) (YG) light emitted from the light emitting layer is mixed to emit white light.

In order to improve the efficiency of light emitted from the first stack, the second stack, and the third stack, the first stack, the second stack, The second stack and the third stack are stacked on the first stack and the first stack in the first stack and the second stack in the third stack, It is necessary to optimize the stacking positions of the second light emitting layer (2nd EML) in the third stack (3rd EML) and the third light emitting layer (3rd EML) in the third stack.

A distance D1 from the lower surface of the anode to the lower surface of the first emission layer (1st EML) is preferably set to a value in order to optimize the stacking position of the first emission layer (1st EML) in the first stack (1st Stack) (D1) of the thickness from the anode to the first HTL may be set in the range of 450 ANGSTROM to 550 ANGSTROM.

Next, in order to optimize the stacking position of the second emission layer (2nd EML) in the second stack (2nd Stack), the distance from the lower surface of the first emission layer (1st EML) to the lower surface of the second emission layer (D2) of thicknesses from the first emission layer (EML) to the second hole transport layer (2nd HTL) may range from 1450 Å to 1550 Å.

According to an embodiment of the present invention, the thickness (T1) of the first electron transport layer (first ETL) may preferably be in the range of 100 ANGSTROM to 150 ANGSTROM. If the thickness (T1) of the first electron transport layer (ETL) exceeds 150 ANGSTROM, the driving voltage of the device can be increased. When the thickness (T1) of the first ETL is less than 100 ANGSTROM, the electron transporting property is deteriorated. Hole that can not contribute to light emission in the first ETL may be generated, The same hole may adversely affect the N-type charge generation layer of the first charge generation layer (1st CGL), so that the lifetime and performance of the device may be deteriorated.

When the thickness T1 of the first ETL is in the range of 100 ANGSTROM to 150 ANGSTROM, it is preferable that the thickness of the second hole transport layer (2nd HTL) The thickness (H1) is preferably larger than the thickness (T1) of the first electron transport layer (1st ETL). In particular, it is preferable that the thickness H1 of the second HTL is at least three times the thickness T1 of the first ETL.

Next, in order to optimize the stacking position of the second emission layer (2nd EML) in the third stack (3rd Stack), the distance from the lower surface of the second emission layer (2nd EML) to the lower surface of the third emission layer (D3) of thicknesses from the second emission layer (2nd EML) to the third hole transport layer (3rd HTL) may be in a range of 850 Å to 950 Å.

According to an embodiment of the present invention, the thickness (T2) of the second electron transport layer (2st ETL) may be in the range of 110 to 160 ANGSTROM. If the thickness T2 of the second electron transport layer (2nd ETL) exceeds 160 ANGSTROM, the driving voltage of the device can be increased. When the thickness (T2) of the second ETL is less than 110 ANGSTROM, the electron transporting property is deteriorated, and a hole which can not contribute to light emission in the second EML is formed, The same hole may adversely affect the N-type charge generation layer of the second charge generation layer (2nd CGL), and the lifetime and performance of the device may be deteriorated.

When the thickness (T2) of the second ETL is in the range of 110 ANGSTROM to 160 ANGSTROM, it is preferable that the thickness of the third hole transport layer (3rd HTL) The thickness H2 may be thinner than the thickness T2 of the second electron transport layer (2nd ETL). However, the present invention is not limited thereto.

Next, in order to optimize the stacking position of the cathode, the distance D4 from the lower surface of the third emission layer (3rd EML) to the lower surface of the cathode (i.e., the third emission layer (3rd EML) And the thickness D4 from the buffer layer to the buffer layer may range from 750 to 850 ANGSTROM.

According to an embodiment of the present invention, the thickness (T3) of the third electron transport layer (3rd ETL) may be in the range of 200 ANGSTROM to 250 ANGSTROM. If the thickness (T3) of the third electron transport layer (3rd ETL) is less than 200 ANGSTROM, the electron transporting characteristics may deteriorate and the emission efficiency of the third emission layer (3rd EML) may be decreased. If the thickness (T3) of the third electron transport layer (3rd ETL) exceeds 250 ANGSTROM, the driving voltage of the device can be increased.

When the thickness (T3) of the third electron transport layer (3rd ETL) is in the range of 200 ANGSTROM to 250 ANGSTROM, the thickness H3 of the electron injection layer HIL, considering the stacking position of the cathode, Is preferably thicker than the thickness (T3) of the third electron transporting layer (3rd ETL).

As described above, according to an embodiment of the present invention, the thickness T3 of the third electron transport layer (3rd ETL) is made thicker than the thickness (T2) of the second electron transport layer (2nd ETL) The driving voltage of the organic light emitting element can be lowered by making the thickness (T2) of the second layer (ETL) larger than the thickness of the first electron transport layer (1st ETL).

In addition, if the thickness of the buffer layer is too large, electrons generated in the cathode may not easily move to the electron injection layer (EIL), which may cause a voltage increase. Therefore, it is preferable that the thickness H4 of the buffer layer is 100 angstroms or less.

Also, the thickness H5 of the cathode may range from 1250 Å to 1350 Å.

The distance D5 from the lower surface of the anode to the lower surface of the cathode, that is, the sum of the thicknesses from the anode to the buffer (D5 May range from 3700A to 3900A.

The present inventors measured the driving voltage for the organic light emitting device manufactured by changing the thicknesses of the organic layers, and the results are shown in Table 1 below.

Comparative Example Example 1 Example 2 Example 3 EIL (A) 250 350 250 250 3rd ETL (A) 300 200 300 300 3rd HTL (A) 135 135 90 135 2nd ETL (Å) 60 60 160 60 2nd HTL (A) 765 765 765 920 1st ETL (Å) 300 300 300 100 The driving voltage (V) 12.4 12.1 12.2 12.1

As can be seen from Table 1 above, the thickness of the third electron transport layer (3rd ETL) is thicker than the thickness of the electron injection layer (EIL) and the thickness of the third electron transport layer (3rd ETL) It can be seen that the driving voltage V is relatively low in the case of Embodiment 1 in which the thickness of the third electron transport layer (3rd ETL) is smaller than the thickness of the electron injection layer (EIL) and the thickness of the third electron transport layer (3rd ETL) is 200 ANGSTROM. In Table 1, the driving voltage V means a driving voltage at a current of 10 mA / cm ² .

The thickness of the second electron transport layer (2nd ETL) was smaller than that of the third hole transport layer (3rd HTL) and the thickness of the second electron transport layer (2nd ETL) It can be seen that the driving voltage V is relatively low in the case of Embodiment 2 in which the thickness is thicker than the thickness of the third hole transport layer (3rd HTL) and the thickness of the second electron transport layer (2nd ETL) is 160 ANGSTROM.

The thickness of the first electron transport layer (1st ETL) was smaller than that of the second hole transport layer (2nd HTL) and the thickness of the first electron transport layer (1st ETL) was 300 ANGSTROM. It can be seen that the driving voltage V is relatively low in the case of Embodiment 3 in which the thickness is smaller than the thickness of the second HTL and the thickness of the first ETL is 100 ANGSTROM.

The present inventors measured the luminous efficiency, the color viewing angle, and the driving voltage for the organic light emitting device manufactured by changing the thickness of the organic layers, and the results are shown in Table 2 below.

Comparative Example Example 4 Example 5 EIL (A) 250 350 350 3rd ETL (A) 300 200 200 3rd HTL (A) 135 90 90 2nd ETL (Å) 60 110 110 2nd HTL (A) 765 920 960 1st ETL (Å) 300 100 100 R efficiency (cd / A) 3.8 3.8 4.0 G efficiency (cd / A) 19.6 19.3 18.9 B efficiency (cd / A) 1.6 1.6 1.6 W Efficiency (cd / A) 47.9 47.3 47.2 The color viewing angle (? U'v ') 0.012 0.010 0.010 The driving voltage (V) 12.4 11.8 11.8

As can be seen from the above Table 2, in the case of Example 4 and Example 5, the luminous efficiency is almost similar to that in the comparative example, while the color viewing angle characteristic? U'v 'is improved and the driving voltage V ) Is low.

The color viewing angle characteristic (DELTA u'v ') in Table 2 indicates the rate of change of color at a viewing angle of 60 degrees. In Examples 4 and 5, the color change ratio is smaller than that of the Comparative Example, It can be seen that it is improved. In Table 2, the driving voltage V means a driving voltage at a current of 10 mA / cm ² .

3 is a graph showing a driving voltage according to Comparative Example and Embodiments 1 to 3. Fig.

3 and Examples 1 to 3 correspond to Comparative Examples and Examples 1 to 3 according to Table 1 described above. As can be seen from FIG. 3, it can be seen that the driving voltages V of Examples 1 to 3 are lower than those of Comparative Examples.

4 is a graph showing the driving voltage according to the comparative example and the example 5. Fig.

4 and 5 correspond to the comparative example and the example 5 according to the above-mentioned Table 2. [ As can be seen from FIG. 4, it can be seen that the driving voltage V of Example 5 is lower than that of the comparative example.

Fig. 5 is a graph showing the luminous efficiency according to the comparative example and the example 5. Fig.

5 and 5 correspond to the comparative example and the example 5 according to the above-mentioned Table 2. [ As can be seen from FIG. 5, it can be seen that Example 5 exhibits a luminous efficiency almost similar to that of the Comparative Example.

FIG. 6 is a schematic cross-sectional view of an organic light emitting diode display according to an embodiment of the present invention, in which the organic light emitting diode according to FIG. 2 is applied.

6, the OLED display 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 a reflector and an anode of FIG.

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) (3rd Stack), and a buffer layer (Buffer). 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 formed of the cathode shown in FIG.

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 aforementioned 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 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.

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 (14)

Anode and cathode;
A first stack including a first hole transporting layer, a first light emitting layer provided on the first hole transporting layer, and a first electron transporting layer provided on the first light emitting layer, the first stack being provided between the anode and the cathode;
A second stack disposed between the first stack and the cathode, the second stack including a second hole transport layer, a second light emitting layer provided on the second hole transport layer, and a second electron transport layer provided on the second light emitting layer; And
A third stack including a third hole transport layer, a third light emitting layer provided on the third hole transport layer, and a third electron transport layer provided on the third light emitting layer, the third stack being provided between the second stack and the cathode, , ≪ / RTI >
Wherein the thickness of the third electron transporting layer is thicker than the thickness of the second electron transporting layer and the thickness of the second electron transporting layer is thicker than the thickness of the first electron transporting layer. The method according to claim 1,
Wherein the third stack further comprises an electron injection layer provided on the third electron transport layer,
Wherein the thickness of the third electron transporting layer is thinner than the thickness of the electron injection layer. The method according to claim 1,
Wherein the thickness of the first electron transporting layer is in the range of 100 ANGSTROM to 150 ANGSTROM. The method according to claim 1,
And the thickness of the second electron transporting layer is in the range of 110 ANGSTROM to 160 ANGSTROM. The method according to claim 1,
And the thickness of the third electron transporting layer ranges from 200 ANGSTROM to 250 ANGSTROM. The method according to claim 1,
A buffer layer is further provided between the third stack and the cathode,
Wherein the thickness of the buffer layer is 100 angstroms or less. The method according to claim 1,
Wherein a distance from a lower surface of the anode to a lower surface of the first light emitting layer is in a range of 450 ANGSTROM to 550 ANGSTROM. The method according to claim 1,
Wherein a distance from a lower surface of the first light emitting layer to a lower surface of the second light emitting layer ranges from 1450 Å to 1550 Å. The method according to claim 1,
Wherein a distance from a lower surface of the second light emitting layer to a lower surface of the third light emitting layer ranges from 850 Å to 950 Å. The method according to claim 1,
Wherein a distance from a lower surface of the third light emitting layer to a lower surface of the cathode is in a range of 750 ANGSTROM to 850 ANGSTROM. The method according to claim 1,
Wherein the triplet energy of the first electron transport layer and the triplet energy of the first hole transport layer are higher than the triplet energy of the host material of the first light emitting layer. The method according to claim 1,
The triplet energy of the first electron transport layer is at least 2.9 eV,
The triplet energy of the second electron transport layer is 1.8 eV or less,
And the triplet energy of the third electron transporting layer is 1.95 eV or less. The method according to claim 1,
Wherein the first light emitting layer comprises a blue fluorescent retarding dopant,
Wherein the second light emitting layer comprises a phosphorescent dopant of yellow-green,
And the third light emitting layer comprises a blue fluorescent dopant. 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 13.

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