KR20140079273A - White organic light emitting device - Google Patents

Abstract

The present invention discloses a white organic light emitting element. The disclosed white organic light emitting element includes a first and second electrodes facing each other on a substrate; a first stack sequentially laminating a hole injecting layer, a first hole transfer layer, a first light emitting layer, and a first electron transfer layer between the first and second electrodes; a second stack sequentially laminating a second hole transfer layer, a second light emitting layer, a third light emitting layer, a second electron transfer layer, and an electron injecting layer between the first stack and the second electrode; and a charge generating layer formed between the first and second stacks to control charge balance between the stacks. The first light emitting layer of the first stack is formed of a fluorescent blue light emitting layer having 1-peak of light emitting peak. The second light emitting layer and the third light emitting layer have 2-peak of light emitting peak and are formed by touching each other. One of the second and third light emitting layers is formed of a phosphorescent green light emitting layer or phosphorescent yellowish green light emitting layer and the other one is formed of a phosphorescent red light emitting layer. Therefore, according to the present invention, the white organic light emitting layer is formed to make a light emitting layer of the white organic light emitting element formed of the first and second stacks have a 3-peak of light emitting peak and uses a material of the hole transfer layer, as a host, in the light emitting layer of the second stack which is close to the hole transfer layer in order to ease the injection of holes. Doping concentration and thickness of the light emitting layer of the second stack are optimized in order to improve power consumption and improve panel efficiency and color re-productivity.

Description

[0001] The present invention relates to a white organic light emitting device,

The present invention relates to an organic light emitting device, and in particular, to provide a white organic light emitting device capable of improving characteristics of efficiency and color reproducibility and increasing power consumption.

In recent years, as the information age has come to a full-fledged information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, various flat panel display devices having excellent performance of thinning, light weight, Flat Display Device) has been developed to replace CRT (Cathode Ray Tube).

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display (FED) (Organic Light Emitting Device: OLED).

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.

In such an organic light emitting diode display, it is necessary to form an organic light emitting layer. In order to form an organic light emitting layer, a deposition method using a shadow mask has been used.

However, in the case of a large area of the shadow mask, due to the load, a fogging phenomenon occurs and it is difficult to use the shadow mask many times, and an alternative method is required because defects occur in the formation of an organic light emitting layer pattern.

As one of the various methods for replacing such a shadow mask, there is a white organic light emitting display.

Hereinafter, a white organic light emitting display will be described.

The white organic light emitting display device is characterized in that each layer between an anode and a cathode is deposited without a mask at the time of forming a light emitting diode, thereby sequentially depositing organic layers having different components including an organic light emitting layer in a vacuum state. Such a white organic light emitting display device is used for various purposes such as a thin light source, a backlight of a liquid crystal display device, or a full color display device employing a color filter.

Nowadays, a white organic light emitting display uses a pile light stack structure in which a first stack using a blue fluorescent element as a light emitting layer and a second stack structure using a yellow-green phosphor as a light emitting layer are stacked . The white organic light emitting device is realized by the mixing effect of the blue light emitted from the blue phosphor element and the yellow light emitted from the yellow phosphor element.

Such a white organic light emitting display device having a phosphor-type stack structure needs to improve the luminous efficiency and the color reproduction ratio in the case of white light emission and to improve the power consumption.

The present invention provides a white organic light emitting device in which a white organic light emitting device comprising a first stack and a second stack or a light emitting layer of a white organic light emitting device composed of a first stack to a third stack has a 3-peak emission peak It has its purpose.

Another object of the present invention is to provide a white organic light emitting device that facilitates injection of holes by using a material of the hole transport layer as a host in the light emitting layer of the second stack adjacent to the hole transport layer.

Another object of the present invention is to provide a white organic light emitting device which improves power consumption and improves panel efficiency and color reproducibility by optimizing the thickness and doping concentration of the light emitting layer of the second stack of the present invention.

The present invention provides a white organic light emitting device that increases the red luminance achievement rate and increases the color reproducibility by forming the light emitting layer of the second stack of the white organic light emitting device composed of the first stack to the third stack in a double light emitting layer structure There is another purpose.

According to an aspect of the present invention, there is provided a white organic light emitting device including: a first electrode and a second electrode opposing each other on a substrate; A first stack in which a hole injecting layer, a first hole transporting layer, a first light emitting layer, and a first electron transporting layer are sequentially stacked between the first electrode and the second electrode; A second stack in which a second hole transport layer, a second light emitting layer, a third light emitting layer, a second electron transport layer, and an electron injection layer are sequentially stacked between the first stack and the second electrode; And a charge generation layer formed between the first stack and the second stack to control charge balance between the respective stacks, wherein the first light emitting layer of the first stack is formed of a fluorescent blue light emitting layer having an emission peak of 1-Peak And the second light emitting layer and the third light emitting layer of the second stack have an emission peak in a contact with each other with a 2-peak, and any one of the second light emitting layer and the third light emitting layer is a phosphorescent green light emitting layer or a phosphorescent green light emitting layer And the other is formed of a phosphorescent red light emitting layer.

The white organic light emitting device according to the present invention includes a white organic light emitting device comprising a first stack and a second stack or a light emitting layer of a white organic light emitting device comprising a first stack to a third stack having a 3-peak emission peak There is a first effect.

In addition, the white organic light emitting device according to the present invention has the second effect of facilitating injection of holes by using the material of the hole transporting layer as a host in the light emitting layer of the second stack adjacent to the hole transporting layer.

Further, the white organic light emitting device according to the present invention has a third effect of improving power consumption, improving panel efficiency and color gamut by optimizing the thickness and doping concentration of the light emitting layer of the second stack.

In addition, the white organic light emitting device according to the present invention may be formed by forming the light emitting layer of the second stack of the white organic light emitting device composed of the first stack to the third stack into a double light emitting layer structure to increase the red luminance achievement rate, There is a fourth effect.

1 is a view illustrating a white organic light emitting device according to a first embodiment of the present invention.
FIG. 2 is a graph showing the results of a comparison between a conventional white organic light emitting device and a white organic light emitting device of the present invention.
3 is a graph showing the emission wavelength and intensity of the conventional white organic light emitting device and the white organic light emitting device of the present invention.
4 is a graph showing an experiment result according to the host ratio of the green light emitting layer of the second stack of the present invention.
FIG. 5 is a graph showing experimental results according to the host ratio of the red light emitting layer of the second stack of the present invention. FIG.
FIG. 6 is a graph showing the experimental results according to the doping ratio of the green light emitting layer of the second stack of the present invention.
7 is a view illustrating a white organic light emitting device according to a second embodiment of the present invention.
8 is a graph showing the emission wavelength and intensity of the conventional white organic light emitting device and the white organic light emitting device of the present invention.
9 is a graph showing the results of a comparison between a conventional white organic light emitting device and a white organic light emitting device of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a view illustrating a white organic light emitting device according to a first embodiment of the present invention.

Referring to FIG. 1, the white organic light emitting device of the present invention includes a first electrode 110 and a second electrode 130 which are opposed to each other on a substrate 100. A first stack 200, a charge generation layer 120 and a second stack 300 are formed on the first electrode 110 between the first electrode 110 and the second electrode 130, Are sequentially stacked. The first stack 200 and the second stack 300 include light emitting layers of different colors, and light of different colors emitted from the light emitting layers of each stack is mixed to realize white light.

The substrate 100 may include a thin film transistor formed on an insulating substrate, the insulating substrate may be formed of insulating glass, metal, plastic or polyimide (PI), and the thin film transistor may include a gate electrode, A source electrode and a drain electrode.

The first electrode 110 may be formed of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), or ZnO .

The second electrode 130 may be formed of a metal material such as Mg, Ca, Al, Al-alloy, Ag, Ag-alloy, Au, and Au- As shown in FIG.

The charge generation layer 120 is formed between the first stack 200 and the second stack 300 to supply electrons to the first stack 200 and holes to the second stack 300, And adjusts the charge balance between each stack. The charge generating layer 120 may be formed of a thin metal layer such as aluminum (Al) or a transparent electrode such as indium tin oxide (ITO) to have a single layer structure. In addition, it may be formed of a plurality of layers, which are the junction structures of organic layers by doping with impurities.

When formed in a plurality of layers, they are formed to be suitable for electron transport and hole transport, respectively, so that it is advantageous in improving the efficiency and prolonging the service life. At this time, the region of the charge generation layer 120 in contact with the first stack 200 may be N-type doped to facilitate electron supply. In addition, the region in contact with the second stack 300 may be formed by P-type doping to facilitate the supply of holes.

The first stack 200 includes a hole injection layer (HIL) 202, a first hole transport layer (HTL) 203, and a second hole transport layer (HTL) 203 between the first electrode 110 and the charge generating layer 120. , A first light emitting layer 204, and a first electron transport layer (ETL) 205 are sequentially stacked.

The hole injecting layer (HIL) may be made of a material having a high hole injecting capability, and may be doped with P-type dopant to facilitate hole injection.

The first light emitting layer 204 may be a fluorescent blue light emitting layer and may be formed as a single light emitting layer having an emission peak of 1-Peak. At this time, the first light emitting layer 204 may be formed by doping a fluorescent blue dopant in one host or doped with a fluorescent blue dopant in two hosts. The fluorescent blue dopant of the first light emitting layer 204 is formed of a dopant having a wavelength range of the emission peak in the range of 420 nm to 490 nm.

The second stack 300 includes a second hole transport layer (HTL) 302, a second light emitting layer 303, a third light emitting layer 304 (304) between the charge generation layer 120 and the second electrode 130, A second electron transport layer (ETL) 305, and an electron injection layer (EIL) 306 are stacked in this order.

The electron injection layer (EIL) may be made of a material having a high electron injection capability, and may be doped with N-type dopant to facilitate electron injection.

The second stack 300 is formed in contact with the second light emitting layer 303 and the third light emitting layer 304 without forming a charge generation layer or a buffer layer therebetween. The second light emitting layer 303 and the third light emitting layer 304 are stacked to form one second stack light emitting layer 301.

The second stacking luminescent layer 301 may be formed as a double luminescent layer having a phosphorescent red luminescent layer and a phosphorescent green luminescent layer stacked and having an emission peak of 2-Peak. In addition, the second stacking luminescent layer 301 may be formed by laminating a phosphorescent red luminescent layer and a phosphorescent green luminescent layer.

That is, when the second light emitting layer 303 is a phosphorescent red light emitting layer, the third light emitting layer 304 is formed of a phosphorescent green light emitting layer or a phosphorescent green light emitting layer. Alternatively, when the second light emitting layer 303 is a phosphorescent green light emitting layer or a phosphorescent green light emitting layer, the third light emitting layer 304 is formed as a phosphorescent red light emitting layer. Preferably, the second light emitting layer 303 is formed of a phosphorescent red light emitting layer, and the third light emitting layer 304 is formed of a phosphorescent green light emitting layer.

Wherein the phosphorescent green light emitting layer or the phosphorescent green light emitting layer is formed of a phosphorescent green dopant or a phosphorescent green dopant having an emission peak wavelength in the range of 500 nm to 580 nm and the phosphorescent red light emitting layer has a wavelength range of 580 nm to 680 nm Lt; RTI ID = 0.0 > red < / RTI > The doping ratio of the phosphorescent green light emitting layer or the phosphorescent green light emitting layer may be higher than the doping ratio of the phosphorescent red light emitting layer.

In addition, the phosphorescent green light emitting layer or the phosphorescent green light emitting layer may be thicker than the phosphorescent red light emitting layer. Preferably, the thickness of the phosphorescent green light emitting layer or the phosphorescent green light emitting layer is three times the thickness of the phosphorescent red light emitting layer.

The second light emitting layer 303 is formed in contact with and stacked on the second hole transporting layer 302. The second light emitting layer 303 is formed by laminating a phosphorescent dopant, a phosphorescent green dopant, a dopant may be doped. The two hosts may be composed of a hole type host and an electron type host. At this time, the hole host may be formed at 20 volume% to 80 volume% of the entire host, and the electronic host may be formed at 80 volume% to 20 volume% of the entire host.

In addition, the hole host may be formed of the same material as the second hole transport layer 302. When the host includes a hole host and the hole host is formed of the same material as the second hole transport layer 302, injection of holes into the light emitting layer can be facilitated.

The third light emitting layer 304 is formed on the second light emitting layer 303 and doped with phosphorescent green dopant, phosphorescent green dopant or phosphorescent dopant to two hosts, . At this time, the two hosts may be composed of a hole type host and an electron type host. At this time, the hole host may be formed at 20 volume% to 80 volume% of the entire host, and the electronic host may be formed at 80 volume% to 20 volume% of the entire host.

The third light emitting layer 304 may be formed by doping phosphorescent green dopant, phosphorescent green dopant or phosphorescent dopant to one host. At this time, the one host is formed as a bipolar host.

The first stack 200 may be formed as a fluorescent unit adjacent to the anode, and the second stack 300 may be formed as a phosphorescent unit adjacent to the cathode.

Further, in order to improve the power consumption and the panel efficiency of the white organic light emitting device, it is necessary to optimize the host ratio of the second light emitting layer and the third light emitting layer, the thickness of each light emitting layer, and the doping concentration.

FIG. 2 is a graph showing the results of a comparison between a conventional white organic light emitting device and a white organic light emitting device of the present invention.

3 is a graph showing the emission wavelength and intensity of the conventional white organic light emitting device and the white organic light emitting device of the present invention.

Referring to FIGS. 2 and 3, the panel efficiency and color reproduction ratio of the conventional 2-Peak including a blue light emitting layer in the first stack and including a yellow-green light emitting layer in the second stack, FIG. 3 is a graph illustrating the panel efficiency and color reproduction rate of a 3-Peak panel including a blue light emitting layer in a first stack according to the present invention and a red light emitting layer and a green light emitting layer in a second stack. 2 and 3, 3 Peak reddish has a larger intensity of red emission peak than 3 Peak greenish, 3 Peak greenish has a green emission peak intensity (A) than 3 Peak reddish intensity is large.

Comparing Experiment I, Experiment II and Experiment IV, it can be seen that the white organic light emitting device of the present invention has an excellent color reproducibility of 10% or more as compared with the conventional white organic light emitting device. In particular, 3 Peak greenish is characterized in that the color reproduction ratio can be improved without decreasing the panel efficiency. Comparing Experiment I and Experiment V, it can be seen that the white organic light emitting device of the present invention is characterized in that the panel efficiency is improved at the same color reproduction rate as that of the conventional white organic light emitting device, have.

That is, the present invention has the effect of improving the color reproduction rate or improving the panel efficiency and power consumption as compared with the conventional invention. In particular, it can be seen that the greater the intensity of the green emission peak A is formed, the larger the effect is formed.

Although not shown in the figure, the red emission peak B and the green emission peak A are formed to be higher as the thickness of the red emission layer or the green emission layer is thicker. As shown in FIG. 2, the larger the intensity of the green emission peak A is, the more the panel efficiency and the color reproducibility are improved. Therefore, the thickness of the green emission layer may be thicker than that of the red emission layer. More preferably, the thickness of the green light emitting layer may be three times the thickness of the red light emitting layer.

4 is a graph showing an experiment result according to the host ratio of the green light emitting layer of the second stack of the present invention.

Referring to FIG. 4, the green light emitting layer of the second stack is formed by doping an electron host and a hole host with a green dopant. 4 is a graph showing the green emission peak (A) and the red emission peak (B) of the second stack depending on the volume ratio of the electron host and the hole host of the green emission layer.

When the volume ratio of the hole host of the green light emitting layer is larger than that of the electron host, the intensity of the green light emission peak A is the highest and the intensity of the red light emission peak B is the lowest do. Further, it can be seen that the intensity of the green emission peak A is the lowest and the intensity of the red emission peak B is the highest when the volume ratio of the hole host is smaller than that of the electron host. As shown in FIG. 2, the larger the intensity of the green emission peak A is, the more the panel efficiency and the color reproduction rate are improved. Therefore, in order to include the improved effect as compared with the conventional art, the ratio of the hole host and the electron host is formed so that the intensity of the green emission peak A is formed to be high.

FIG. 5 is a graph showing an experiment result according to the ratio of the host of the red light emitting layer of the second stack of the present invention.

Referring to FIG. 5, the red light emitting layer of the second stack is formed by doping an electron host and a hole host with a red dopant. 5 is a graph showing the green emission peak (A) and the red emission peak (B) of the second stack depending on the volume ratio of the electron host and the hole host of the red emission layer.

When the volume ratio of the hole host of the red light emitting layer is larger than that of the electron host, the intensity of the green light emitting peak A is the highest and the intensity of the red light emitting peak B is the lowest do. Further, it can be seen that the intensity of the green emission peak A is the lowest and the intensity of the red emission peak B is the highest when the volume ratio of the hole host is smaller than that of the electron host. As shown in FIG. 2, the larger the intensity of the green emission peak A is, the more the panel efficiency and the color reproduction rate are improved. Therefore, in order to include the improved effect as compared with the conventional art, the ratio of the hole host and the electron host is formed so that the intensity of the green emission peak A is formed to be high.

FIG. 6 is a graph showing the experimental results according to the doping ratio of the green light emitting layer of the second stack of the present invention.

Referring to FIG. 6, the green light emitting layer of the second stack is formed by doping a host with a green dopant. 6 is a graph showing the green emission peak (A) and the red emission peak (B) of the second stack according to the doping ratio of the green dopant of the green emitting layer.

As shown in FIG. 6, the intensity of the green emission peak A increases as the doping ratio of the green dopant increases. Although not shown in the figure, the red emission layer of the second stack is formed such that the intensity of the red emission peak B increases as the doping ratio of the red dopant increases. Therefore, as shown in FIG. 2, as the intensity of the green luminescent peak (A) increases, the panel efficiency and the color reproducibility are further improved. Therefore, it is preferable that the doping ratio of the green dopant of the green luminescent layer is higher than that of the red dopant Lt; / RTI >

7 is a view illustrating a white organic light emitting device according to a second embodiment of the present invention.

Referring to FIG. 7, the white organic light emitting device of the present invention includes a first electrode 110 and a second electrode 130 formed on a substrate 100 facing each other. A first stack 400, a first charge generation layer 220, and a second stack 130 are formed on the first electrode 110 between the first electrode 110 and the second electrode 130, 500, a second charge generating layer 320, and a third stack 600 are sequentially stacked.

The first stack 400 and the third stack 600 may include a light emitting layer of the same color. In addition, the second stack 500 may include a light emitting layer of a different color from the first stack 400 and the third stack 600. At this time, light of different colors emitted from the light emitting layer of each stack is mixed to realize white light.

Preferably, the first stack 400 and the third stack 600 may emit blue light. The second stack 500 may include a light emitting layer that emits red and yellow green light, or may include a light emitting layer that emits red and green light. In addition, the first stack 400 and the third stack 600 may be formed as fluorescent units, and the second stack 500 may be formed as a phosphorescent unit.

The substrate 100 may include a thin film transistor formed on an insulating substrate, the insulating substrate may be formed of insulating glass, metal, plastic or polyimide (PI), and the thin film transistor may include a gate electrode, A source electrode and a drain electrode.

The first electrode 110 may be formed of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), or ZnO . The second electrode 130 may be formed of a metal material such as Mg, Ca, Al, Al-alloy, Ag, Ag-alloy, Au, and Au- As shown in FIG.

The first charge generation layer 220 is formed between the first stack 400 and the second stack 500 to supply electrons to the first stack 400 and supply holes to the second stack 500 Thereby adjusting the charge balance between each stack. The second charge generating layer 320 is formed between the second stack 500 and the third stack 600 to supply electrons to the second stack 500 and the third stack 600 includes holes To control the charge balance between each stack.

The first charge generation layer 220 and the second charge generation layer 320 may be formed of a thin metal layer such as aluminum or a transparent electrode such as indium tin oxide And can be easily formed. In addition, it may be formed of a plurality of layers, which are the junction structures of organic layers by doping with impurities.

In the case of forming a plurality of layers, it is advantageous for improving the efficiency and prolonging the life span by being formed so as to be suitable for electron transport and hole transport, respectively. At this time, a region of the first charge generation layer 220 in contact with the first stack 400 and a region of the second charge generation layer 320 in contact with the second stack 500, N-type doping can be performed. A region of the first charge generation layer 220 in contact with the second stack 500 and a region of the second charge generation layer 320 in contact with the third stack 600 may be formed in order to facilitate the supply of holes And may be formed by P-type doping.

The first stack 400 includes a hole injection layer (HIL) 402, a first hole transport layer (HTL) 402, and a hole transport layer (HTL) 402 between the first electrode 110 and the first charge generation layer 220. A first light emitting layer 403, a first light emitting layer 404, and a first electron transport layer (ETL) 405 are sequentially stacked. The hole injecting layer (HIL) 402 may be made of a material having excellent hole injecting capability and may be doped with P-type dopant to facilitate hole injection.

The first light emitting layer 404 may be a fluorescent blue light emitting layer and may be formed as a single light emitting layer having an emission peak of 1-Peak. In this case, the first light emitting layer 404 may be formed by doping a fluorescent blue dopant into one host or by doping a fluorescent blue dopant into two hosts. The fluorescent blue dopant of the first light emitting layer 204 is formed of a dopant having a wavelength range of the emission peak in the range of 420 nm to 490 nm.

The second stack 500 includes a second hole transport layer (HTL) 502, a second light emitting layer 503, a third light emitting layer 504 (hereinafter, referred to as a second light emitting layer) 504 between the first charge generating layer 220 and the second charge generating layer 320 And a second electron transport layer (ETL) 505 are stacked in this order. The second stack 300 is formed in such a manner that the second light emitting layer 503 and the third light emitting layer 504 are in contact with each other without a charge generation layer or a buffer layer between them. The second light emitting layer 503 and the third light emitting layer 504 are stacked to form one second stack light emitting layer 501.

The second stacking light emitting layer 501 may be formed as a double light emitting layer having a phosphorescent red light emitting layer and a phosphorescent green light emitting layer stacked and having an emission peak of 2-Peak. In addition, the second stacking luminescent layer 501 may be formed by laminating a phosphorescent red emitting layer and a phosphorescent green emitting layer.

That is, when the second light emitting layer 503 is a phosphorescent red light emitting layer, the third light emitting layer 504 is formed of a phosphorescent green light emitting layer or a phosphorescent green light emitting layer. Alternatively, when the second light emitting layer 503 is a phosphorescent green light emitting layer or a phosphorescent green light emitting layer, the third light emitting layer 504 is formed as a phosphorescent red light emitting layer. Preferably, the second light emitting layer 503 is formed of a phosphorescent red light emitting layer, and the third light emitting layer 504 may be formed of a phosphorescent green light emitting layer.

Wherein the phosphorescent green light emitting layer or the phosphorescent green light emitting layer is formed of a phosphorescent green or phosphorescent green dopant having an emission peak wavelength in the range of 500 nm to 580 nm and the phosphorescent red light emitting layer has a wavelength band of 580 nm Gt; to 680 nm. ≪ / RTI > The doping ratio of the phosphorescent green light emitting layer or the phosphorescent green light emitting layer may be higher than the doping ratio of the phosphorescent red light emitting layer.

In addition, the phosphorescent green light emitting layer or the phosphorescent green light emitting layer may be thicker than the phosphorescent light emitting layer. Preferably, the thickness of the phosphorescent green light emitting layer or the phosphorescent green light emitting layer is three times the thickness of the phosphorescent red light emitting layer.

The second light emitting layer 503 is formed in contact with and stacked on the second hole transporting layer 502. The second light emitting layer 503 is formed by laminating a phosphorescent dopant, a phosphorescent green dopant, a dopant may be doped. The two hosts may be composed of a hole type host and an electron type host.

At this time, the hole host may be formed at 20 volume% to 80 volume% of the entire host, and the electronic host may be formed at 80 volume% to 20 volume% of the entire host. In addition, the hole host may be formed of the same material as the second hole transport layer 502 to facilitate injection of holes.

The third light emitting layer 504 is formed on the second light emitting layer 503 and is doped with a phosphorescent green dopant, a phosphorescent green dopant or a phosphorescent dopant to two hosts. .

At this time, the two hosts may be composed of a hole type host and an electron type host. At this time, the hole host may be formed at 20 volume% to 80 volume% of the entire host, and the electronic host may be formed at 80 volume% to 20 volume% of the entire host.

The third light emitting layer 504 may be formed by doping a phosphorescent green dopant, a phosphorescent green dopant, or a phosphorescent dopant to one host. At this time, the one host is formed as a bipolar host.

The third stack 600 includes a third hole transport layer (HTL) 601, a fourth emission layer 602, a third electron transport layer (ETL) 602 between the second charge generation layer 320 and the second electrode 130, An electron injection layer 603 and an electron injection layer (EIL) 604 are sequentially stacked. The electron injection layer (EIL) may be made of a material having a high electron injection capability, and may be doped with N-type dopant to facilitate electron injection.

The fourth light emitting layer 602 may be a fluorescent blue light emitting layer and may be formed as a single light emitting layer having an emission peak of 1-Peak. At this time, the fourth light emitting layer 602 may be formed by doping a fluorescent blue dopant into one host or by doping a fluorescent blue dopant into two hosts. The fluorescent blue dopant of the fourth emitting layer 602 is formed of a dopant having a wavelength range of the emission peak in the range of 420 nm to 490 nm.

8 is a graph showing the emission wavelength and intensity of the conventional white organic light emitting device and the white organic light emitting device of the present invention.

Referring to FIG. 8, a conventional white organic light emitting device is a white organic light emitting device including a blue light emitting layer in a first stack and a third stack, and a yellow-green light emitting layer in a second stack. In addition, the white organic light emitting device of the present invention includes a blue light emitting layer in the first stack and a third stack, and a white organic light emitting layer including a red light emitting layer and a yellow- Emitting device.

The region shown in FIG. 8 is a red region, and in the conventional invention, only two peaks are present, so that no peak is formed in the red region. Also, in the present invention, it can be seen that the intensity of red is formed to be larger in the red region as compared with the conventional invention with a three-peak structure. The luminance achievement rate, panel efficiency, and color reproduction rate will be described in more detail as follows.

9 is a graph showing the results of a comparison between a conventional white organic light emitting device and a white organic light emitting device of the present invention.

Referring to FIG. 9, when the luminance target value is 100%, the red luminance achievement rate of the conventional invention is 88%, which means that the red luminance is insufficient. This is because there is no separate red light emitting layer in the prior art and no peak is formed in the red region.

Thus, the white organic light emitting device according to the present invention was formed by stacking a red light emitting layer and a sulfur green light emitting layer in a second stack to form a second stack light emitting layer. Thus, in the red wavelength region, the white organic light emitting device according to the present invention has stronger intensity than the conventional invention.

Comparing the luminance achievement ratios of the present invention and the conventional invention, the present invention increased by about 13% to 101%. It is also confirmed that the red luminance achieving rate of the present invention exceeds 100% which is the luminance target value. It can also be confirmed that the achievement rates of the green and blue luminance of the present invention exceed the luminance target value of 100%.

Also, it can be confirmed that the panel efficiency is equal to or improved from the conventional invention. As the intensity increases in the red wavelength region, the color reproduction rate also increases.

Accordingly, the white organic light emitting device according to the present invention is characterized in that the light emitting layer of the white organic light emitting device comprising the white organic light emitting device composed of the first stack and the second stack or the first stack to the third stack has the emission peak of 3-Peak . At this time, by using the material of the hole transporting layer as a host in the light emitting layer of the second stack adjacent to the hole transporting layer, injection of holes can be facilitated. By optimizing the thickness and the doping concentration of the light emitting layer of the second stack, it is possible to improve the power consumption and improve the panel efficiency and the color gamut. Further, by forming the light emitting layer of the second stack of the white organic light emitting device composed of the first stack to the third stack into the double light emitting layer structure, there is an effect of increasing the red luminance achievement rate and increasing the color gamut.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: substrate 205: first electron transporting layer
110: first electrode 300: second stack
120: charge generation layer 301: second stacking luminescent layer
130: second electrode 302: second hole transport layer
200: first stack 303: second light emitting layer
202: Hole injection layer 304: Third light emitting layer
203: first hole transport layer 305: second electron transport layer
204: first light emitting layer 306: electron injection layer

Claims (24)

A first electrode and a second electrode opposed to each other on a substrate;
A first stack in which a hole injecting layer, a first hole transporting layer, a first light emitting layer, and a first electron transporting layer are sequentially stacked between the first electrode and the second electrode;
A second stack in which a second hole transport layer, a second light emitting layer, a third light emitting layer, a second electron transport layer, and an electron injection layer are sequentially stacked between the first stack and the second electrode;
And a charge generation layer formed between the first stack and the second stack to control charge balance between the stacks,
Wherein the first light emitting layer of the first stack is formed of a fluorescent blue light emitting layer having an emission peak of 1-Peak,
The second light-emitting layer and the third light-emitting layer of the second stack have a 2-peak emission peak, are formed in contact with each other,
Wherein one of the second light emitting layer and the third light emitting layer is formed of a phosphorescent green light emitting layer or a phosphorescent green light emitting layer and the other is a phosphorescent red light emitting layer.
The method according to claim 1,
Wherein the second light emitting layer is a phosphorescent red light emitting layer, and the third light emitting layer is a phosphorescent green light emitting layer.
The method according to claim 1,
Wherein the second light emitting layer is a phosphorescent green light emitting layer, and the third light emitting layer is a phosphorescent red light emitting layer.
The method according to claim 1,
The second light emitting layer is formed in direct contact with the second hole transporting layer,
Wherein the second light emitting layer is formed by doping a hole host and an electron host with a dopant.
5. The method of claim 4,
And a hole host of the second light emitting layer is the same as the material of the second hole transporting layer.
5. The method of claim 4,
Wherein the hole host of the second light emitting layer is formed at 20 volume% to 80 volume% of the entire host.
The method according to claim 1,
Wherein the third light emitting layer is formed by doping a hole host and an electron host with a dopant.
8. The method of claim 7,
Wherein the hole host of the third light emitting layer is formed at 20 volume% to 80 volume% of the entire host.
The method according to claim 1,
Wherein the third light emitting layer is formed by doping a bipolar host with a dopant.
The method according to claim 1,
Wherein the thickness of the phosphorescent green light emitting layer is thicker than the thickness of the phosphorescent red light emitting layer.
11. The method of claim 10,
Wherein the thickness of the phosphorescent green light emitting layer is three times the thickness of the phosphorescent red light emitting layer.
The method according to claim 1,
Wherein the doping ratio of the phosphorescent green light emitting layer is higher than the doping ratio of the phosphorescent red light emitting layer.
A first electrode and a second electrode opposed to each other on a substrate;
A first stack in which a hole injecting layer, a first hole transporting layer, a first emitting layer, and a first electron transporting layer are sequentially stacked on the first electrode, between the first electrode and the second electrode;
A second stack, in which a second hole transport layer, a second light emitting layer, a third light emitting layer, and a second electron transport layer are sequentially stacked on the first stack, between the first stack and the second electrode;
A third stack in which a third hole transport layer, a fourth emission layer, a third electron transport layer, and an electron injection layer are sequentially stacked on the second stack, between the second stack and the second electrode;
And a charge generation layer formed between the first stack and the second stack and between the second stack and the third stack to control charge balance between the stacks,
The first emission layer and the fourth emission layer are formed of a fluorescent blue light-emitting layer having an emission peak of 1-Peak,
The second light-emitting layer and the third light-emitting layer of the second stack have a 2-peak emission peak, are formed in contact with each other,
Wherein one of the second light emitting layer and the third light emitting layer is formed of a phosphorescent green light emitting layer or a phosphorescent green light emitting layer and the other is a phosphorescent red light emitting layer.
14. The method of claim 13,
Wherein the second light emitting layer is a phosphorescent red light emitting layer and the third light emitting layer is a phosphorescent green light emitting layer.
14. The method of claim 13,
Wherein the second light emitting layer is a phosphorescent green light emitting layer, and the third light emitting layer is a phosphorescent red light emitting layer.
14. The method of claim 13,
The second light emitting layer is formed in direct contact with the second hole transporting layer,
Wherein the second light emitting layer is formed by doping a hole host and an electron host with a dopant.
17. The method of claim 16,
And a hole host of the second light emitting layer is the same as the material of the second hole transporting layer.
17. The method of claim 16,
Wherein the hole host of the second light emitting layer is formed at 20 volume% to 80 volume% of the entire host.
14. The method of claim 13,
Wherein the third light emitting layer is formed by doping a hole host and an electron host with a dopant.
20. The method of claim 19,
Wherein the hole host of the third light emitting layer is formed at 20 volume% to 80 volume% of the entire host.
14. The method of claim 13,
Wherein the third light emitting layer is formed by doping a bipolar host with a dopant.
14. The method of claim 13,
Wherein the thickness of the phosphorescent green light emitting layer is thicker than the thickness of the phosphorescent red light emitting layer.
23. The method of claim 22,
Wherein the thickness of the phosphorescent green light emitting layer is three times the thickness of the phosphorescent red light emitting layer.
14. The method of claim 13,
Wherein the doping ratio of the phosphorescent green light emitting layer is higher than the doping ratio of the phosphorescent red light emitting layer.

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