KR20140034686A - Organic light emitting display device - Google Patents

Organic light emitting display device Download PDF

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Publication number
KR20140034686A
KR20140034686A KR1020130095778A KR20130095778A KR20140034686A KR 20140034686 A KR20140034686 A KR 20140034686A KR 1020130095778 A KR1020130095778 A KR 1020130095778A KR 20130095778 A KR20130095778 A KR 20130095778A KR 20140034686 A KR20140034686 A KR 20140034686A
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South Korea
Prior art keywords
light emitting
host
layer
transport layer
stack
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KR1020130095778A
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Korean (ko)
Inventor
김신한
조귀정
감윤석
오혜민
김태식
전성수
송치율
김화경
최홍석
한미영
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엘지디스플레이 주식회사
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Priority to KR20120100935 priority
Application filed by 엘지디스플레이 주식회사 filed Critical 엘지디스플레이 주식회사
Priority claimed from CN201310412355.7A external-priority patent/CN103681760B/en
Publication of KR20140034686A publication Critical patent/KR20140034686A/en

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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/5004Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED]; characterised by the interrelation between parameters of constituting active layers, e.g. HOMO-LUMO relation
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/5012Electroluminescent [EL] layer
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/5012Electroluminescent [EL] layer
    • H01L51/5024Electroluminescent [EL] layer having a host comprising an emissive dopant and further additive materials, e.g. for improving the dispersability, for improving the stabilisation, for assisting energy transfer
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2251/00Indexing scheme relating to organic semiconductor devices covered by group H01L51/00
    • H01L2251/50Organic light emitting devices
    • H01L2251/55Organic light emitting devices characterised by parameters
    • H01L2251/552HOMO-LUMO-EF

Abstract

The present invention relates to an organic light emitting display device that can improve the light emission efficiency at a high current by improving a roll-off phenomenon and can increase panel efficiency. First and second electrodes opposed to each other, a hole injection layer, a hole transport layer, at least two first and second light emitting layers, and an electron transport layer are sequentially stacked between the first electrode and the second electrode, and Each of the at least two first and second light emitting layers may be formed of different hosts, and the same dopant may be doped in different proportions, or the first light emitting layer may include a first host and a second host, and the second light emitting layer may be formed of a first host. A first host and a second host different from the third host, wherein the first and second light emitting layers are each doped with the same phosphorescent yellow-green dopant in the same ratio.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device which can improve a light emitting efficiency at a high current by improving a roll-off phenomenon and can increase panel efficiency.

The image display device that realizes various information on the screen is a core technology of the information communication age and it is becoming thinner, lighter, more portable and higher performance. Accordingly, an organic light emitting device displaying an image by controlling the amount of emitted light of an organic light emitting layer is being spotlighted by a flat panel display capable of reducing weight and volume, which is a disadvantage of a cathode ray tube (CRT).

Organic Light Emitting Device (OLED) is a self-luminous device using a thin light emitting layer between electrodes and has the advantage of thinning like a paper. Specifically, the organic light emitting device includes an anode, a hole transport layer (HTL), a hole transport layer (HIL), a light emitting layer, an electron injection layer (EIL), an electron injection layer Transport Layer (ETL), and a cathode.

Among these, an organic light emitting display device is considered as a competitive application for not requiring a separate light source, compacting the device, and displaying clear color images.

Nowadays, an organic light emitting diode display is formed of a stack structure in which a first stack including a fluorescent blue light emitting layer and a second stack structure including a phosphorescent yellow-green light emitting layer are stacked. Use an element. In the white organic light emitting device, blue light emitted from the blue fluorescent light emitting layer and yellow light emitted from the fluorescent yellow-green light emitting layer are mixed with each other to realize white light.

At this time, the phosphorescent yellow-green light emitting layer has a triplet-triplet annihilation (TTA) as the high current increases, resulting in a roll-off phenomenon in which the luminous efficiency is lowered. Thus, the luminous efficiency at high current is reduced.

In addition, the phosphorescent yellow-green wavelength according to the conventional white organic light emitting device is a region including a green wavelength and a red wavelength. At this time, the area of the Full Width Half Maximum (FWHM) according to the conventional phosphorescent yellow-green wavelength band is small as shown in FIG. 1. In this case, the FWHM means the width of the intermediate point in the overall height of the wavelength. When the area of the FWHM decreases, the light intensity according to the green wavelength and the light intensity according to the red wavelength are reduced. That is, the light intensity is proportional to the area, and when the area is small, the light intensity is small. Therefore, since the area of the FWHM according to the conventional white organic light emitting device is small, the light intensity according to the green wavelength and the red wavelength is reduced, and thus the color reproduction rate is lowered, thereby reducing the panel efficiency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an organic light emitting display device capable of improving roll-off phenomenon to improve luminous efficiency at high current and increasing panel efficiency. There is a purpose.

According to an aspect of the present invention, an organic light emitting diode display includes: first and second electrodes facing each other on a substrate; And a hole injection layer, a hole transporting layer, at least two light emitting layers, and an electron transporting layer are sequentially stacked between the first electrode and the second electrode, wherein each of the at least two light emitting layers is formed of a different host, and the same dopant is formed. It is characterized by being doped in different proportions.

The at least two light emitting layers may include: a first light emitting layer having a first host and doped with a phosphorescent yellow-green dopant; The phosphorescent yellow-green dopant having a second host different from the first host and having the same phosphorous yellow-green dopant as the first light emitting layer may include a second light emitting layer doped at a different ratio from the first light emitting layer.

The first homo level of the first host is lower than or equal to the homo level of the hole transport layer, and the first homo level has a difference within -0.05 eV to -0.5 eV from the homo level of the hole transport layer. have.

The first homo level of the first host is -6.0 eV to -5.0 eV, the first lumo level of the first host is -2.5 eV to -2.3 eV, and the first host is 5.0 × 10 -5 cm 2 / Vs It is characterized by having a hole mobility of ˜1.0 × 10 −5 cm 2 / Vs.

The phosphorescent yellow-green dopant of the first light emitting layer may be doped with 1% to 10% of the first light emitting layer based on the volume of the first light emitting layer.

The second lumo level of the second light emitting layer has a lumo level that is higher than or equal to the lumo level of the electron transport layer, and the second lumo level has a difference within -0.05 eV to -0.5 eV from the lumo level of the electron transport layer. It is characterized by.

The second homo level of the second light emitting layer is -6.5eV ~ -5.0eV, the second lumo level of the second light emitting layer is -3.0eV ~ -2.0eV, the second host is 9.0 × 10 -5 cm 2 / It is characterized by having an electron mobility of Vs ˜1.0 × 10 −3 cm 2 / Vs.

The phosphorescent yellow-green dopant of the second light emitting layer may be doped with 10% to 20% of the second light emitting layer based on the volume of the second light emitting layer.

Triplet levels of the first and second hosts are characterized in that 2.0eV ~ 3.0eV.

The thickness from the first light emitting layer to just before the second electrode may be defined by Equation 1 below.

[Equation 1]

Figure pat00001

Where H 'is the thickness from the first light emitting layer to just before the second electrode, n is the refractive index, and λ is the PL peak wavelength of the dopant.

The thickness from the second light emitting layer to just before the second electrode may be defined by Equation 2 below.

&Quot; (2) "

Figure pat00002

Where H 'is the thickness from the second light emitting layer to just before the second electrode, n is the refractive index, and λ is the PL peak wavelength of the dopant.

On the other hand, the organic light emitting display device according to the present invention for achieving the above object, the first and second electrodes facing each other on the substrate; A first stack in which a hole injection layer, a third hole transport layer, a fourth hole transport layer, a third light emitting layer, and a second electron transport layer are sequentially stacked on the first electrode; A second stack in which a first hole transport layer, a second hole transport layer, at least two light emitting layers, and a first electron transport layer are sequentially stacked between the first stack and the second electrode; And a charge generating layer formed between the first stack and the second stack to control charge balance between the stacks, wherein each of the at least two light emitting layers is formed of different hosts, and the same yellow-green dopant is formed from each other. Another feature is that it is doped in different proportions.

In addition, the organic light emitting diode display according to the present invention for achieving the above object, the first and second electrodes facing each other on the substrate; A hole injection layer, a hole transporting layer, at least first and second light emitting layers, and an electron transporting layer are sequentially stacked between the first electrode and the second electrode, and the first light emitting layer includes a first host and a second host. The second light emitting layer includes a first host and a third host, and the first and second light emitting layers each have the same yellow-green dopant doped at the same ratio.

Here, the first lumo level of the first host is higher than or equal to the lumo level of the electron transport layer, and the first lumo level has a difference within +0.05 eV to +0.2 eV from the lumo level of the electron transport layer. There is a characteristic.

The first homo level of the first host is -6.0eV ~ -5.0eV, the first host has a hole mobility of 5.0 × 10 -5 cm 2 / Vs ~ 1.0 × 10 -5 cm 2 / Vs have.

The second homo level of the second host is lower than or equal to the homo level of the hole transport layer, and the second homo level has a difference within -0.05 eV to -0.5 eV from the homo level of the hole transport layer. have.

The second lumo level of the second host is -2.5eV ~ -2.3eV, and the second host has a hole mobility of 9.0 × 10 -4 cm 2 / Vs ~ 1.0 × 10 -3 cm 2 / Vs have.

The third homo level of the third host is lower than or equal to the homo level of the hole transport layer, and the third homo level has a difference within -0.05 eV to -0.5 eV from the homo level of the hole transport layer. have.

The third lumo level of the third host is -2.5eV ~ -2.3eV, the third host has a hole mobility of 9.0 × 10 -4 cm 2 / Vs ~ 1.0 × 10 -3 cm 2 / Vs have.

The hole mobility of the third host is faster than the hole mobility of the second host, and the triplet level of the first host, the second host, and the third host is 2.0 eV to 3.0 eV.

The phosphorescent yellow-green dopant of each of the first and second light emitting layers may be doped with 8% to 25% of each light emitting layer based on the volume of each light emitting layer.

In addition, the organic light emitting diode display according to the present invention for achieving the above object, the first and second electrodes facing each other on the substrate; A first stack in which a hole injection layer, a third hole transport layer, a fourth hole transport layer, a third light emitting layer, and a second electron transport layer are sequentially stacked on the first electrode; A second stack in which a first hole transport layer, a second hole transport layer, at least two first and second light emitting layers, and a first electron transport layer are sequentially stacked between the first stack and the second electrode; A first charge generation layer formed between the first stack and the second stack to control charge balance between the first and second stacks; A third stack in which a fifth hole transport layer, a fourth light emitting layer, and a third electron transport layer are sequentially stacked between the second stack and the second electrode; A second charge generation layer formed between the second stack and the third stack to adjust charge balance between the second and third stacks, the first light emitting layer having a first host and a second host, The second light emitting layer has a third host different from the first host and the second host, and the first and second light emitting layers each have the same phosphorescent yellow-green dopant doped at the same ratio.

Here, each of the third and fourth light emitting layers has a dopant of a blue fluorescent component in one host.

The organic light emitting diode display according to the present invention includes a white light emitting device having at least two phosphorescent light emitting layers, and each of the at least two light emitting layers is formed of the same dopant as a different host. In this case, the dopants of each of the at least two light emitting layers may be doped at different ratios, so that light emission efficiency at high current may be improved by improving a roll-off phenomenon in which the luminance of the light emitting layer decreases as the amount of current increases.

In addition, the organic light emitting diode display according to the present invention may include at least two light emitting layers of different hosts, thereby increasing the area of the FWHM. As such, as the area of the FWHM becomes wider, the light intensity according to the green wavelength and the red wavelength is increased, thereby improving color reproduction and panel efficiency according to the improvement of color reproduction.

The HOMO level of the light emitting layer adjacent to the hole transport layer among the at least two light emitting layers may be lower than or equal to the HOMO level of the hole transport layer, thereby facilitating the injection of holes.

In addition, the LUMO level of the light emitting layer adjacent to the electron transporting layer among the at least two light emitting layers may be higher than or equal to the LUMO level of the electron transporting layer so that electron injection may be smooth.

On the other hand, the organic light emitting diode display according to the present invention includes a white light emitting device having at least two phosphorescent light emitting layers, each of the at least two light emitting layer is made of the same dopant is mixed with the same host. In this case, the dopants of each of the at least two light emitting layers may be doped at the same ratio to each other so that light emission efficiency at high current may be improved by improving a roll-off phenomenon in which the luminance of the light emitting layer decreases as the amount of current increases.

In addition, the organic light emitting diode display according to the present invention may include at least two light emitting layers in which different hosts and the same host are mixed, thereby increasing the area of the FWHM. As such, as the area of the FWHM becomes wider, the light intensity according to the green wavelength and the red wavelength is increased, thereby improving color reproduction and panel efficiency according to the improvement of color reproduction.

As described above, the injection of holes and the injection of electrons are made smooth, so that the life of the device can be improved.

1 is a graph illustrating emission peak wavelengths of a conventional white organic light emitting diode.
2A through 2D are equivalent circuit diagrams of R, G, B, and W pixels of the organic light emitting diode display according to the present invention.
3 is a cross-sectional view of an organic light emitting diode display in accordance with the R, G, B, and W sub-pixel regions illustrated in FIGS. 2A to 2D.
4 is a perspective view illustrating a white organic light emitting diode according to a first embodiment of the present invention.
5 is a band diagram of a white organic light emitting diode according to a first embodiment of the present invention.
6 is a perspective view illustrating a white organic light emitting diode according to a second exemplary embodiment of the present invention.
FIG. 7A is a cross-sectional view illustrating a white organic light emitting diode having different positions of a light emitting layer, and FIG. 7B is a graph for describing peak emission wavelengths according to positions shown in FIG. 7A.
8 is a cross-sectional view for describing positions of the first light emitting layer and the second light emitting layer according to the first and second embodiments of the present invention.
9 illustrates emission peak wavelengths of the white organic light emitting diodes according to the first and second exemplary embodiments and emission peak wavelengths of the white organic light emitting diodes according to the comparative example.
10 is a band diagram of a white organic light emitting diode according to a third exemplary embodiment of the present invention.
11 is a perspective view showing a white organic light emitting element according to a fourth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Prior to the detailed description of the present invention, the same components will be denoted by the same reference numerals as much as possible even if shown on different drawings, and the known components will be omitted if it is determined that the subject matter of the present invention may obscure the gist of the present invention. do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2A to 8.

2A to 2D are equivalent circuit diagrams for R, G, B, and W pixels of the OLED display according to the present invention, and FIG. 3 is an R, G, B, and W sub pixel area shown in FIGS. 2A to 2D. Is a cross-sectional view of an organic light emitting display device. 4 is a perspective view illustrating a white organic light emitting diode according to an exemplary embodiment of the present invention, and FIG. 5 is a band diagram of the white organic light emitting diode illustrated in FIG. 4.

The organic light emitting diode display according to the present invention includes a substrate in which a display area is defined by a plurality of sub pixel areas formed in a matrix form and a sealing substrate for protecting sub pixels formed on the substrate from moisture or oxygen.

The plurality of sub-pixel areas are composed of an R sub pixel area, a G sub pixel area, a B sub pixel, and a W sub pixel area, and the R, G, B, and W sub pixel areas are arranged in a matrix to display an image. As shown in FIG. 2A, the plurality of sub pixel regions may be arranged in a row, four rows, and four rows of R, G, B, and W sub pixel regions in parallel with the gate line. In FIG. 2A, the R, G, B, and W sub pixel regions are arranged in order, but may be arranged in the order of R, B, G, and W sub pixel regions, or may be arranged in the order of the W, R, G, and B pixel regions. The order of arrangement is not limited and can be changed according to the needs of the user.

In addition, the R, B, G, and W sub pixel regions may be arranged in two rows by two columns, as shown in FIGS. 2B and 2C. For example, as illustrated in FIG. 2B, the R sub pixel area includes a second i (where i = 1 or more natural number) -first data line DL2i-1 and a second i-1th gate line GL2i-1. And the G sub pixel area is formed at the cross area of the second i-th data line DL2i and the second i-th gate line GL2i-1, and the B sub pixel area is the second i-first time. The W sub-pixel region is formed at the intersection of the data line DL2i-1 and the second i-th gate line GL2i, and the W sub-pixel region is formed at the intersection of the second i-th data line DL2i and the second i-th gate line GL2i. Can be arranged.

As illustrated in FIG. 2C, the R sub pixel area is formed at an intersection area of the second i-1 th data line DL2i-1 and the second i-1 th gate line GL2i-1, and the B sub pixel. The region is formed at the intersection of the second i-th data line DL2i and the second i-th gate line GL2i-1, and the G sub-pixel area is the second i-th data line DL2i-1 and the second ii. The W sub-pixel region may be formed in the intersection region of the second gate line GL2i, and the W sub pixel region may be formed and disposed in the intersection region of the second i-th data line DL2i and the second i-th gate line GL2i.

In addition, in the R, B, G, and W sub pixel regions, the same sub pixel regions may be disposed in each gate line direction as illustrated in FIG. 2D. That is, the R sub pixel regions are disposed in the first gate line, the G sub pixel regions are disposed in the second gate line, the B sub pixel regions are disposed in the third gate line, and the W sub pixel region is disposed in the fourth gate line. Can be arranged.

Each of the R, G, B, and W sub-pixel regions is provided with a cell driver 200 and a white organic light emitting element connected to the cell driver 200 as shown in FIGS. 2A to 2D.

The cell driver 200 includes a switch thin film transistor TS connected to the gate line GL and the data line DL, a switch thin film transistor TS and a power line PL and a first electrode of the organic electroluminescent device And a storage capacitor C connected between the power supply line PL and the drain electrode 110 of the switch thin film transistor TS. The sub-pixel regions may have a structure including a switch transistor, a driving transistor, a capacitor, and an organic light emitting element, or may have a structure in which a transistor and a capacitor are further added. Also, although the driving thin film transistor may be directly connected to the first electrode of the white organic light emitting device, another thin film transistor may be formed between the driving thin film transistor and the white organic light emitting device.

The gate electrode of the switch thin film transistor TS is connected to the gate line GL and the source electrode thereof is connected to the data line DL while the drain electrode is connected to the gate electrode of the driving thin film transistor TD and the storage capacitor C . The source electrode of the driving thin film transistor TD is connected to the power supply line PL and the drain electrode 110 is connected to the first electrode 122. [ The storage capacitor C is connected between the power supply line PL and the gate electrode of the driving thin film transistor TD.

The switch thin film transistor TS is turned on when a scan pulse is supplied to the gate line GL to supply the data signal supplied to the data line DL to the gate electrode of the storage capacitor C and the drive thin film transistor TD do. The driving thin film transistor TD controls the amount of light emitted from the organic electroluminescent device by controlling the current I supplied from the power supply line PL to the organic electroluminescent device in response to a data signal supplied to the gate electrode. Even if the switch thin film transistor TS is turned off, the driving thin film transistor TD supplies a constant current I until the data signal of the next frame is supplied by the voltage charged in the storage capacitor C, Thereby allowing the organic light emitting element to maintain luminescence.

As shown in FIG. 3, the driving thin film transistor TD is connected to the gate line GL, and includes a gate electrode 102 formed on the substrate 100 and a gate insulating film formed on the gate electrode 102. To prevent damage to the oxide semiconductor layer 114 and the oxide semiconductor layer 114 formed to overlap the gate electrode 102 with the gate insulating film 112 therebetween, and to protect it from the influence of oxygen. An etch stopper 106 formed on the oxide semiconductor layer 114, a source electrode 108 connected to the data line DL, and a drain electrode 110 formed to face the source electrode 108. Also, a first protective film 118 is formed on the driving thin film transistor TD.

The oxide semiconductor layer 114 is formed of an oxide containing at least one metal selected from Zn, Cd, Ga, In, Sn, Hf and Zr. Such a thin film transistor including the oxide semiconductor layer 114 has advantages of a higher charge mobility and a lower leakage current characteristic than a thin film transistor including a silicon semiconductor layer. In addition, since the thin film transistor including the silicon semiconductor layer is formed through a high temperature process and needs to be subjected to a crystallization process, uniformity in the crystallization process is deteriorated as the size of the thin film transistor is increased. On the other hand, the thin film transistor including the oxide semiconductor layer 114 can be subjected to a low temperature process, and it is advantageous to have a large area.

In the color filter, an R color filter 124R is formed on the passivation layer of the R sub pixel region to emit red (R), and a G color filter 124G is formed on the passivation layer of the G sub pixel region to form green (G). It emits light, and the B color filter 124B is formed on the passivation film of the B sub pixel region to emit blue (B). The color filter is not formed on the passivation film of the W sub pixel region, and emits white (W). In addition, a second passivation layer 126 is formed on each of the R, G, and B color filters 124R, 124G, and 124B.

The white organic light emitting diode includes a first electrode 240 connected to the drain electrode 110 of the driving thin film transistor TD, a second electrode 230 facing the first electrode 240, and a first electrode ( And a bank insulating layer 130 having a bank hole 132 exposing the 240, and a light emitting layer 250 stacked between the first electrode 240 and the second electrode 230.

3 illustrates a bottom emission method in which light emitted from the emission layer 250 is emitted downward, the organic light emitting device according to the exemplary embodiment of the present invention may emit light in a top emission method or a double-sided emission method. Therefore, it is not limited thereto.

The first electrode 240 is formed of a transparent conductive material such as transparent conductive oxide (TCO) as an anode and formed of indium tin oxide (ITO) or indium zinc oxide (IZO). do.

The second electrode 230 is a cathode and is formed of a reflective metal material, and the reflective metal material is aluminum (Al), gold (Au), molybdenum (MO), chromium (Cr), copper (Cu), LiF, or the like. Or formed of aluminum and a LiF alloy.

Hereinafter, the white organic light emitting diode will be described in detail.

[First Embodiment]

4 is a perspective view illustrating a white organic light emitting diode according to a first exemplary embodiment of the present invention, and FIG. 5 is a band diagram of the white organic light emitting diode illustrated in FIG. 4.

In the white organic light emitting diode according to the first exemplary embodiment of the present invention, as shown in FIG. 4, a hole injection layer 214 and a first hole are formed between the first electrode 240 and the second electrode 230. The transport layer 224a, the second hole transport layer 224b, at least two light emitting layers 226a and 226b, and the electron transport layer 228 are sequentially stacked. Each of the at least two light emitting layers 226a and 226b is made of the same dopant with different hosts, and the dopants of the at least two light emitting layers 226a and 226b are doped at different ratios. In this case, the at least two light emitting layers 226a and 226b will be described by taking an example of the first light emitting layer 226a and the second light emitting layer 226b.

The first emission layer 226a has a first host and a phosphorescent yellow-green dopant, and the second emission layer 226b has a second host and a phosphorescent yellow-green dopant. phosphorescence Yellow-phosphorescence Green). The first emission layer 226a and the second emission layer 226b are formed by co-deposition of the same dopant with different doping amounts to different first and second hosts 1Host and 2Host. The first host 1Host of the first light emitting layer 226a and the second host 2Host of the second light emitting layer 226b have different homogeneous homogeneous Molecular Orbital (HOMO) levels and a lumo (Lowest Unoccupied Molecular Orbital). Has a LUMO) level.

That is, as shown in FIG. 5, the first host 1Host has a first HOMO level and a first LUMO level, and a first HOMO level. Level has a HOMO level lower than or equal to the HOMO level (4 HTL HOMO Level) of the second hole transport layer 224b. In this case, the first HOMO level has a difference within -0.05eV to -0.5eV from the HOMO level (4 HTL HOMO Level) of the second hole transport layer 224b. Accordingly, the hole from the second hole transport layer 224b is preferably injected into the first host 1Host of the first light emitting layer 226a. To this end, the first HOMO level is -6.0eV to -5.0eV, and the first LUMO level is -2.5eV to -2.3eV. In addition, the first host 1Host has a fast hole mobility of 5.0 × 10 -5 cm 2 / Vs to 1.0 × 10 -5 cm 2 / Vs. The doping amount of the first light emitting layer 226a is doped with 1% to 10% of the first light emitting layer 226a based on the volume of the first light emitting layer 226a. The triplet level of the first host 1host is 2.0 eV to 3.0 eV.

The second host 2Host has a second HOMO level and a second LUMO level, and the second LUMO level is an LUMO of the electron transport layer 228. It has a LUMO level that is higher than or equal to 2ETL LUMO Level. In this case, the second LUMO level has a difference within -0.05 eV to -0.5 eV from the LUMO level of the electron transport layer 228. Accordingly, electrons from the electron transport layer 228 may be injected into the second host 2Host of the second emission layer 226b. To this end, the second HOMO level is -6.5eV to -5.0eV, and the second LUMO level is -3.0eV to -2.0eV. In addition, the second host 2Host has a fast electron mobility of 9.0 × 10 −5 cm 2 / Vs to 1.0 × 10 −3 cm 2 / Vs. The doping amount of the second light emitting layer 226b is doped to 10% to 20% of the second light emitting layer 226b based on the volume of the second light emitting layer 226b. The triplet level of the second host 2 is from 2.0 eV to 3.0 eV.

As such, the doping amount of the first light emitting layer 226a is smaller than the doping amount of the second light emitting layer 226b. In general, the relationship between the amount of current and the luminance (cd / A) of the light emitting layer is a roll-off phenomenon in which the luminance of the light emitting layer gradually decreases as the amount of current increases. By controlling the doping amount of the second light emitting layer 226b differently, the roll-off phenomenon in which the luminance of the light emitting layer decreases as the amount of current increases may be improved.

This improves the roll-off phenomenon by applying a doping amount optimized for changing a zone generated by an exciton of the light emitting layer according to the amount of current, based on the physical characteristics of the host.

[Second Embodiment]

Meanwhile, a white organic light emitting device having a multi-stack structure including the structure of the white organic light emitting device described with reference to FIG. 4 may be implemented.

FIG. 6 is a perspective view illustrating a white organic light emitting diode according to a second exemplary embodiment of the present invention, and illustrates a multi-stack structure including the structure of the white organic light emitting diode of FIG. 4.

As illustrated in FIG. 6, the white organic light emitting diode according to the second exemplary embodiment of the present invention includes a first stack 210, a charge generation layer 222, and a second stack 220. It has a multi-stack structure. The organic light emitting device having a multi-stack structure includes light emitting layers of different colors in each stack, and light emitted from the light emitting layers of each stack is mixed to realize white light. 6 illustrates a bottom emission method in which light emitted from the first, second, and third emission layers 218, 226a, and 226b is emitted downward, but the organic light emitting diode according to an exemplary embodiment of the present invention may be a top emission method. Light can be emitted by double-sided light emission. Therefore, it is not limited thereto.

The first electrode 240 is formed of a transparent conductive material such as transparent conductive oxide (TCO) as an anode and formed of indium tin oxide (ITO) or indium zinc oxide (IZO). do.

The second electrode 230 is a cathode and is formed of a reflective metal material, and the reflective metal material is aluminum (Al), gold (Au), molybdenum (MO), chromium (Cr), copper (Cu), LiF, or the like. Or formed of aluminum and a LiF alloy.

The first stack 210 includes a hole injection layer (HIL) 214 and a third hole transport layer (HTL) 216a between the first electrode 240 and the charge generation layer 222. ), A fourth hole transport layer 216b, a third emitting layer (ETL) 218, and a second electron transport layer (ETL) 212 are sequentially stacked. In this case, the third light emitting layer 218 emits blue light as a light emitting layer in which a dopant of a blue fluorescent component is included in one host.

The charge generation layer (CGL) 222 is formed between the stacks to control the charge balance between the stacks. The charge generation layer 222 is adjacent to the first stack 210 and adjacent to the N-type organic layer 222a and the second stack 220 which inject electrons into the first stack 210. It is made of a P-type organic layer 222b positioned to inject holes into the second stack 220.

The second stack 220 has the structure described with reference to FIG. 4. That is, a first hole transport layer 224a, a second hole transport layer 224b, at least two light emitting layers 226a and 226b, and a first electron transport layer between the charge generation layer 222 and the second electrode 230. 228 is sequentially stacked. Each of the at least two light emitting layers 226a and 226b is made of the same dopant with different hosts, and the dopants of the at least two light emitting layers 226a and 226b are doped at different ratios. In this case, the at least two light emitting layers of the second stack 220 are described as an example consisting of a first light emitting layer 226a and a second light emitting layer 226b, the configuration of the first and second light emitting layer is shown in FIG. As described in FIG. 5, the description thereof will be omitted.

In the white organic light emitting diode of the second embodiment of the present invention having the above configuration, the first light emitting layer 226a and the second light emitting layer 226b may adjust the light intensity according to the position. This will be described with reference to FIGS. 7A and 7B.

FIG. 7A is a cross-sectional view illustrating a white organic light emitting diode having different positions of a light emitting layer, and FIG. 7B is a graph for describing peak emission wavelengths according to positions shown in FIG. 7A.

The white organic light emitting device according to Case A has a multi-stack structure including a first stack having a fluorescent blue light emitting layer and a second stack having a phosphorescent yellow-green light emitting layer, and a phosphorescent yellow-green of a second stack. This is the case where the light emitting layer is formed at the first position P1.

The white organic light emitting device according to Case B has a multi-stack structure including a first stack having a fluorescent blue light emitting layer and a second stack having a phosphorescent yellow-green light emitting layer, and a phosphorescent yellow-green of a second stack. This is the case where the light emitting layer is formed at the second position P2 shifted leftward from the first position P1. This corresponds to the position of the first light emitting layer 226a of the second stack of the present invention.

The white organic light emitting device according to Case C has a multi-stack structure including a first stack having a fluorescent blue light emitting layer and a second stack having a phosphorescent yellow-green light emitting layer, and a phosphorescent yellow-green of a second stack. This is a case where the light emitting layer is formed at the third position P3 shifted to the right from the first position P1. This corresponds to the position of the second light emitting layer 226b of the second stack of the present invention.

As described above, the white organic light emitting diodes according to Cases A, B, and C have different positions of the phosphorescent yellow-green light emitting layer of the second stack. In the white organic light emitting diode, a position of an emission peak of the emission layer may vary according to the position of the emission layer. This will be described with reference to the graph of FIG. 7B.

FIG. 7B illustrates a graph of emission peak wavelengths according to the yellow-green emission layers of the second stack and omits the graphs of emission peak wavelengths according to the fluorescent blue emission layers of the first stack.

The first graph 28 is a graph of the emission peak wavelength of Case A illustrated in FIG. 7A, and represents the emission peak wavelength EM Peak when the emission layer of the second stack is positioned at the first position P1. The second graph 20 is a graph of the emission peak (EM Peak) wavelength of Case B illustrated in FIG. 7A, and the emission peak according to the case where the emission layer of the second stack is positioned at the second position P2 ( EM peak wavelength, and the third graph 22 is a graph of the EM peak wavelength of Case C shown in FIG. 7A, and the light emitting layer of the second stack is located at the third position P3. The emission peak (EM Peak) wavelength in some cases is shown.

Referring to this, the emission peak of the second graph 20 is located to the left shifted from the emission peak of the first graph 28, the emission peak of the third graph 20 is the emission peak of the first graph 28. It is in the shifted position to the right. As such, the position of the emission peak of the emission layer may vary according to the location of the emission layer.

Specifically, the emission peak wavelength of the white organic light emitting diode (EL peak) is the wavelength of the photoluminescence peak (PL peak) and the organic light emitting diode indicating a unique color of each light emitting layer material. It is determined by the product of the emission peak (hereinafter referred to as EM Peak) wavelength of the organic laminate within the structure.

The fourth graph 24 shows the emission peak wavelength of the white organic light emitting diode according to Case A. The first graph 28 and the phosphorescent yellow-green according to the emission peak wavelength of Case A are shown. It is a graph obtained by multiplying the peak wavelength of photoluminescence indicating the color of the light emitting layer.

The fifth graph 26 illustrates a graph in which the emission peak wavelength of the white organic light emitting diode according to Case B and the emission peak wavelength of the white organic light emitting diode according to Case C are summed. It is a graph obtained by multiplying the second graph 20 and the third graph 30 according to the emission peak of Case C by the wavelength of the peak of the photoluminescence indicating the color of the phosphorescent yellow-green emission layer.

Accordingly, when comparing the fourth graph 24 and the fifth graph 26, the fourth graph 24 is in the 556 nm wavelength band when compared with the fifth graph 26 as shown in FIG. 7B. Intensity of light is high, and the light intensity of 530 nm and 620 nm wavelength bands is decreasing. However, as illustrated in FIG. 7B, the fifth graph 26 has a lower intensity of light according to the 556 nm wavelength band and lower the intensity of the light in the 530 nm and 620 nm wavelength band as compared with the fourth graph 24. The century is rising.

That is, the wavelength band of 530nm is the wavelength band displaying green, and the wavelength band of 620nm is the wavelength band displaying red. Therefore, when the intensity of light of the 530nm wavelength band is good, the color of the blue color is high and the color reproducibility is high. When the light intensity is good, the red color can be displayed to increase the color reproducibility.

8 is a cross-sectional view for describing positions of the first light emitting layer and the second light emitting layer according to the first and second embodiments of the present invention.

As shown in FIG. 8, in the present invention, the position of the first light emitting layer of the second stack is defined by [Equation 1], and the position of the second light emitting layer of the second stack is defined by [Equation 2].

Figure pat00003

Figure pat00004

Here, H 'means the thickness from the first light emitting layer to just before the second electrode, and H means the thickness from the second light emitting layer to just before the second electrode. In addition, in [Equation 1] and [Equation 2], n is the refractive index, λ means the PL peak wavelength of the dopant.

9 illustrates emission wavelengths of the white organic light emitting diodes according to the first and second exemplary embodiments and peak emission wavelengths of the white organic light emitting diodes according to the comparative example.

In FIG. 9, the first graph 10 is an emission peak wavelength of a white organic light emitting diode according to a comparative example including a first stack having a fluorescent blue light emitting layer and a second stack having a phosphorescent yellow-green light emitting layer. .

The second graph 20 is a peak emission wavelength according to the white organic light emitting diode according to the present invention. The second graph 20 includes a first stack having a fluorescent blue light emitting layer, a first light emitting layer having a phosphorescent yellow-green dopant and a first host, and a phosphorescent light. Emission peak wavelength according to a white organic light emitting device including a second light emitting layer having a yellow-green dopant and a second host.

As illustrated in FIG. 9, the first graph 10 has a high intensity of light according to the 556 nm wavelength band, and a low intensity of light in the 525 nm to 530 nm and 610 nm to 625 nm wavelength bands.

However, as shown in FIG. 9, the second graph 12 has a low intensity of light according to the 556 nm wavelength band, and a high intensity of light in the 525 nm to 530 nm nm and 610 nm to 625 nm wavelength bands.

As described above, the wavelength band of 525 nm to 530 nm is a wavelength band displaying green, and the wavelength band of 610 nm to 625 nm is a wavelength band displaying red.

In addition, the luminous efficiency is proportional to the area of the FWHM position. 9, the area of the FWHM position of the second graph 12 is larger than the area of the FWHM position of the first graph 10. In this way, the light intensity is increased when the area of the FWHM is large. In other words, the area of the FWHM position is proportional to the light intensity. Therefore, when the area of the FWHM becomes wider, the area of the wavelength band of 525 nm to 530 nm and the area of the wavelength band of 610 nm to 625 nm become wider, thereby increasing the light intensity of the corresponding wavelength band.

Therefore, when the area of the FWHM becomes wider, the area of the wavelength band of 525 nm to 530 nm and the area of the wavelength band of 610 nm to 625 nm become wider, thereby increasing the light intensity of the corresponding wavelength band.

Therefore, as the area of the FWHM becomes wider, the area of the wavelength band of 525nm to 530nm becomes wider, and the intensity of light in the wavelength band of 525nm to 530nm is increased, so that the unique color of green can be displayed, thereby improving color reproduction. do. In addition, as the area of the FWHM becomes wider, the area of the wavelength range of 610 nm to 625 nm becomes wider, and the intensity of light in the wavelength range of 610 nm to 625 nm increases, so that the inherent color of red can be displayed, thereby improving color reproduction. do.

As described above, in the second graph according to the present invention, the intensity of light in the wavelength band displaying green and the wavelength band displaying red is high, thereby resulting in excellent color reproduction. The color reproducibility is improved, thereby improving the efficiency of the panel. That is, the panel efficiency of the display device using the white organic light emitting diode according to the present invention is 28.40, and the panel efficiency of the display device using the white organic light emitting diode according to the comparative example is 28.21. As described above, the panel efficiency of the display device using the white organic device according to the present invention is about 10% higher than the panel efficiency of the display device using the white organic device according to the comparative example.

Thus, color reproducibility and panel efficiency were improved by using the white organic light emitting element according to the present invention.

[Third Embodiment]

In the first embodiment of the present invention, the doping amount of the first light emitting layer 226a and the doping amount of the second light emitting layer 226b are adjusted differently so that the roll-off phenomenon in which the luminance of the light emitting layer decreases as the amount of current increases. It can be explained that can be improved.

However, the present invention is not limited thereto, and the first emission layer 226a mixes the first host and the second host, the second emission layer 226b mixes the first host and the third host, and the first and second emission layers By doping the same dopant in the same ratio, it is possible to improve the roll-off phenomenon that the luminance of the light emitting layer decreases as the amount of current increases.

10 is a band diagram of a white organic light emitting diode according to a third exemplary embodiment of the present invention.

4, a hole injection layer 214 and a first hole are formed between the first electrode 240 and the second electrode 230 as described with reference to FIG. 4. The transport layer 224a, the second hole transport layer 224b, at least two light emitting layers 226a and 226b, and the electron transport layer 228 are sequentially stacked. However, the white organic light emitting diode according to the third embodiment of the present invention differs from the first embodiment of the present invention in the host and dopant ratios of the at least two light emitting layers 226a and 226b.

That is, in the white organic light emitting diode according to the third exemplary embodiment of the present invention, each of the at least two light emitting layers 226a and 226b is formed of the same host, different hosts, and the same dopant, and each of the at least two light emitting layers 226a. Dopants of 226b are doped at the same ratio with each other. In this case, the at least two light emitting layers 226a and 226b will be described by taking an example of the first light emitting layer 226a and the second light emitting layer 226b.

As shown in FIG. 10, the first light emitting layer 226a has a first host Host A, a second host Host C, and a phosphorescent yellow-green dopant, and a second light emitting layer. 226b has a first host (Host A) and a third host (Host B) and a phosphorescent Yellow-Green dopant (phosphorescence Yellow-phosphorescence Green). The first light emitting layer 226a and the second light emitting layer 226b are formed by co-deposition of the same dopant with the same doping amount. The first to third hosts (Host A, Host B, and Host C) of the first light emitting layer 226a and the second light emitting layer have different homogeneous (highest occupied molecular orbital (HOMO)) levels and lumo (Lowest Unoccupied Molecular Orbital). Has a LUMO) level.

That is, as shown in FIG. 10, the LUMO level of the first host Host A has an LUMO level higher than or equal to the LUMO level of the electron transport layer 228, and the HOMO of the first host Host A. The level is -6.0 eV to -5.0 eV, and the first host Host A has a fast electron mobility of 5.0 × 10 -5 cm 2 / Vs to 1.0 × 10 -5 cm 2 / Vs. Here, the difference between the LUMO level of the first host Host A and the LUMO level of the electron transport layer 228 is within +0.05 eV to +0.2 eV.

The HOMO level of the second host Host C has a HOMO level lower than or equal to the HOMO level of the second hole transport layer 224b, and the LUMO level of the second host Host C is -2.5 eV to -2.3. eV, and the second host Host C has a fast hole mobility of 9.0 × 10 −4 cm 2 / Vs to 1.0 × 10 −3 cm 2 / Vs. Here, the difference between the HOMO level of the second host Host C and the HOMO level of the second hole transport layer 224b is within -0.05eV to -0.5eV.

HOMO level of the third host (Host B) has a HOMO level lower than or equal to the HOMO level of the second hole transport layer 224b, LUMO level of the second host (Host C) is -2.5eV ~ -2.3 eV, and the third host (Host B) has a fast hole mobility of 9.0 × 10 -4 cm 2 / Vs ~ 1.0 × 10 -3 cm 2 / Vs. Here, the difference between the HOMO level of the third host (Host B) and the HOMO level of the second hole transport layer 224b is within -0.05eV to -0.5eV.

Here, the hole mobility of the third host (Host B) should be faster than the hole mobility of the second host (Host C), and the third host (Host A, the second host (Host C) and the third host (Host) Triplet level (energy) of B) is 2.0eV ~ 3.0eV.

Dopant doping amounts of each of the first and second light emitting layers 226a and 226b are doped with 8% to 25% of each light emitting layer based on the volume of each light emitting layer.

[Fourth Embodiment]

Meanwhile, the white organic light emitting diode having a multi-stack structure including the structure of the white organic light emitting diode having the characteristics described with reference to FIG. 10 may be implemented.

FIG. 11 is a perspective view illustrating a white organic light emitting diode according to a fourth exemplary embodiment of the present invention, and illustrates a multi-stack structure including the structure of the white organic light emitting diode having the features described with reference to FIGS. 4 and 10.

As illustrated in FIG. 11, the white organic light emitting diode according to the fourth embodiment of the present invention includes a first stack 210, a first charge generation layer 222, a second stack 220, It has a multi-stack structure including a second charge generation layer 260 and a third stack 270. The organic light emitting device having a multi-stack structure includes light emitting layers of different colors in each stack, and light emitted from the light emitting layers of each stack is mixed to realize white light. 11 illustrates a bottom emission method in which light emitted from the first, second, third, and fourth light emitting layers 218, 226a, 226b, and 270b is emitted downward, but according to an exemplary embodiment of the present invention. The light may be emitted by a top emission method or a double-sided emission method. Therefore, it is not limited thereto.

The first electrode 240 is formed of a transparent conductive material such as transparent conductive oxide (TCO) as an anode and formed of indium tin oxide (ITO) or indium zinc oxide (IZO). do.

The second electrode 230 is a cathode and is formed of a reflective metal material, and the reflective metal material is aluminum (Al), gold (Au), molybdenum (MO), chromium (Cr), copper (Cu), LiF, or the like. Or formed of aluminum and a LiF alloy.

The first stack 210 includes a hole injection layer (HIL) 214 and a third hole transport layer (HTL) between the first electrode 240 and the first charge generation layer 222. 216a, a fourth hole transport layer 216b, a third emitting layer (ETL) 218, and a second electron transport layer (ETL) 212 are sequentially stacked. In this case, the third light emitting layer 218 emits blue light as a light emitting layer in which a dopant of a blue fluorescent component is included in one host.

The first and second charge generation layers (CGLs) 222 and 260 are formed between stacks to control charge balance between the stacks. The first charge generation layer 222 is positioned adjacent to the first stack 210 and serves to inject electrons into the first stack 210, and the N type organic layer 222a and the second stack 220. It is formed of a P-type organic layer 222b positioned adjacent to and injecting holes into the second stack 220.

The second stack 220 has the structure described with reference to FIG. 4. That is, a first hole transport layer 224a, a second hole transport layer 224b, at least two light emitting layers 226a, between the first charge generation layer 222 and the second charge generation layer CGL. 226b) and the first electron transporting layer 228 are sequentially stacked. Each of the at least two light emitting layers 226a and 226b is formed of the same host, different hosts, and the same dopant as described with reference to FIG. 10, and the dopants of the at least two light emitting layers 226a and 226b are each other. Doped at the same rate. Since the configurations of the first and second light emitting layers 226a and 226b are the same as those described with reference to FIGS. 4 and 10, the description thereof will be omitted.

The second charge generation layer (CGL) 260 is positioned adjacent to the second stack 220 to form an N-type organic layer 260a which serves to inject electrons into the second stack 220. The P type organic layer 260b is positioned adjacent to the third stack 270 to inject holes into the third stack 270.

In the third stack 270, a fifth hole transport layer 270a, a fourth light emitting layer 270b, and a third electron transport layer 270c are sequentially stacked between the charge generation layer 260 and the second electrode 230. Structure. In this case, the fourth light emitting layer 270b emits blue light as a light emitting layer including a dopant of a blue fluorescent component in one host.

The white organic light emitting diode according to the fourth exemplary embodiment of the present invention having the above configuration has similar characteristics as described with reference to FIGS. 7A to 7B and 8 to 9.

 The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

100: substrate 210: first stack
212, 228, and 270c: electron transport layer 214: hole injection layer
216a, 216b, 224a, 224b, and 270a: hole transport layer
218, 226a, 226b, and 270b: light emitting layer 220: second stack
222 and 260: charge generation layer 222a and 260a: N type charge generation layer
222b and 260b: P-type charge generating layer 230: second electrode
240: first electrode 250: light emitting layer
270: third stack

Claims (23)

  1. First and second electrodes opposed to each other on a substrate;
    A hole injection layer, a hole transport layer, at least two first and second light emitting layers, and an electron transport layer are sequentially stacked between the first electrode and the second electrode,
    And each of the at least two light emitting layers is formed of different hosts, and the same dopants are doped at different ratios.
  2. The method of claim 1,
    The at least two light emitting layers
    A first light emitting layer having a first host and doped with a phosphorescent Yellow-Green dopant;
    And a second light emitting layer having a second host different from the first host and having the same phosphorescent yellow-green dopant as the first light emitting layer doped at a different rate from that of the first light emitting layer.
  3. 3. The method of claim 2,
    The first homo level of the first host is lower than or equal to the homo level of the hole transport layer, and the first homo level has a difference within -0.05 eV to -0.5 eV from the homo level of the hole transport layer. Organic light emitting display device.
  4. 3. The method of claim 2,
    The first homo level of the first host is -6.0 eV to -5.0 eV, the first lumo level of the first host is -2.5 eV to -2.3 eV, and the first host is 5.0 × 10 -5 cm 2 / Vs An organic light emitting display device having a hole mobility of ˜1.0 × 10 −5 cm 2 / Vs.
  5. 3. The method of claim 2,
    The phosphorescent yellow-green dopant of the first emission layer is doped with the first emission layer by 1% to 10% based on the volume of the first emission layer.
  6. 3. The method of claim 2,
    The second lumo level of the second light emitting layer has a lumo level that is higher than or equal to the lumo level of the electron transport layer, and the second lumo level has a difference within -0.05 eV to -0.5 eV from the lumo level of the electron transport layer. An organic light emitting display device.
  7. 3. The method of claim 2,
    The second homo level of the second light emitting layer is -6.5eV ~ -5.0eV, the second lumo level of the second light emitting layer is -3.0eV ~ -2.0eV, the second host is 9.0 × 10 -5 cm 2 / An organic light emitting display device having an electron mobility of Vs to 1.0 × 10 −3 cm 2 / Vs.
  8. 3. The method of claim 2,
    The phosphorescent yellow-green dopant of the second emission layer is doped with the second emission layer by 10% to 20% based on the volume of the second emission layer.
  9. 3. The method of claim 2,
    The triplet level of the first and second hosts is 2.0 eV to 3.0 eV.
  10. The method of claim 1,
    The thickness from the first light emitting layer to just before the second electrode is defined by Equation 1 below.
    [Equation 1]
    Figure pat00005

    Where H 'is the thickness from the first light emitting layer to just before the second electrode, n is the refractive index, and λ is the PL peak wavelength of the dopant.
  11. The method of claim 1,
    The thickness from the second light emitting layer to just before the second electrode is defined by Equation 2 below.
    &Quot; (2) "
    Figure pat00006

    Where H 'is the thickness from the second light emitting layer to just before the second electrode, n is the refractive index, and λ is the PL peak wavelength of the dopant.
  12. First and second electrodes opposed to each other on a substrate;
    A first stack in which a hole injection layer, a third hole transport layer, a fourth hole transport layer, a third light emitting layer, and a second electron transport layer are sequentially stacked on the first electrode;
    A second stack in which a first hole transport layer, a second hole transport layer, at least two light emitting layers, and a first electron transport layer are sequentially stacked between the first stack and the second electrode;
    A charge generation layer formed between the first stack and the second stack to control charge balance between the stacks;
    And each of the at least two light emitting layers is formed of different hosts, and the same yellow-green dopants are doped at different ratios.
  13. First and second electrodes opposed to each other on a substrate;
    A hole injection layer, a hole transport layer, at least first and second light emitting layers, and an electron transport layer are sequentially stacked between the first electrode and the second electrode,
    The first light emitting layer includes a first host and a second host, the second light emitting layer includes a first host and a third host, and the first and second light emitting layers each have the same yellow-green dopant in the same ratio. An organic light emitting display device, characterized in that it is doped.
  14. 14. The method of claim 13,
    The first lumo level of the first host is higher than or equal to the lumo level of the electron transport layer, and the first lumo level has a difference within +0.05 eV to +0.2 eV from the lumo level of the electron transport layer. Organic light emitting display device.
  15. 14. The method of claim 13,
    The first homo level of the first host is -6.0eV ~ -5.0eV, the first host has a hole mobility of 5.0 × 10 -5 cm 2 / Vs ~ 1.0 × 10 -5 cm 2 / Vs Organic light emitting display device.
  16. 14. The method of claim 13,
    The second homo level of the second host is lower than or equal to the homo level of the hole transport layer, and the second homo level has a difference within -0.05 eV to -0.5 eV from the homo level of the hole transport layer. Organic light emitting display device.
  17. 17. The method of claim 16,
    The second lumo level of the second host is -2.5eV ~ -2.3eV, the second host has a hole mobility of 9.0 × 10 -4 cm 2 / Vs ~ 1.0 × 10 -3 cm 2 / Vs Organic light emitting display device.
  18. 14. The method of claim 13,
    The third homo level of the third host is lower than or equal to the homo level of the hole transport layer, and the third homo level has a difference within −0.05 eV to −0.5 eV from the homo level of the hole transport layer. Organic light emitting display device.
  19. The method of claim 18,
    The third lumo level of the third host is -2.5eV ~ -2.3eV, the third host has a hole mobility of 9.0 × 10 -4 cm 2 / Vs ~ 1.0 × 10 -3 cm 2 / Vs Organic light emitting display device.
  20. 14. The method of claim 13,
    The hole mobility of the third host is faster than the hole mobility of the second host, and the triplet level of the first host, the second host, and the third host is 2.0 eV to 3.0 eV. Display device.
  21. 14. The method of claim 13,
    The phosphorescent yellow-green dopant of each of the first and second light emitting layers is doped with each light emitting layer in an amount of 8% to 25% based on the volume of each light emitting layer.
  22. First and second electrodes opposed to each other on a substrate;
    A first stack in which a hole injection layer, a third hole transport layer, a fourth hole transport layer, a third light emitting layer, and a second electron transport layer are sequentially stacked on the first electrode;
    A second stack in which a first hole transport layer, a second hole transport layer, at least two first and second light emitting layers, and a first electron transport layer are sequentially stacked between the first stack and the second electrode;
    A first charge generation layer formed between the first stack and the second stack to control charge balance between the first and second stacks;
    A third stack in which a fifth hole transport layer, a fourth light emitting layer, and a third electron transport layer are sequentially stacked between the second stack and the second electrode;
    A second charge generation layer formed between the second stack and the third stack to control charge balance between the second and third stacks,
    The first light emitting layer has a first host and a second host, the second light emitting layer has a third host different from the first host and the second host, and the first and second light emitting layers are the same phosphorescent yellow-green, respectively. An organic light emitting display device wherein the dopants are doped in the same proportion to each other.
  23. 23. The method of claim 22,
    And each of the third and fourth light emitting layers includes a dopant of a blue fluorescent component in one host.
KR1020130095778A 2012-09-12 2013-08-13 Organic light emitting display device KR20140034686A (en)

Priority Applications (2)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160039111A (en) * 2014-09-30 2016-04-08 엘지디스플레이 주식회사 Organic light emitting display device and method for manufacturing of the same
WO2016068458A1 (en) * 2014-10-30 2016-05-06 주식회사 두산 Organic electroluminescent device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160039111A (en) * 2014-09-30 2016-04-08 엘지디스플레이 주식회사 Organic light emitting display device and method for manufacturing of the same
US9634293B2 (en) 2014-09-30 2017-04-25 Lg Display Co., Ltd. Organic light emitting display device having 2 stack structure and a metal oxide
US9911939B2 (en) 2014-09-30 2018-03-06 Lg Display Co., Ltd. Organic light emitting display device having 2 stack structure and a metal oxide
WO2016068458A1 (en) * 2014-10-30 2016-05-06 주식회사 두산 Organic electroluminescent device

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