KR20180001826A - White Organic Lighting Emitting Device and Organic Lighting Display Device Using the Same - Google Patents

Abstract

The present invention relates to a white organic light emitting device which has two or more adjacent light emitting layers in one stack to improve color reproducibility, and an organic light emitting display using the same. In a tandem-type device where light emitting layers are formed on a plurality of stacks, respectively, the emission peak of each of the light emitting layers is limited to a certain range. A wavelength gap between emission peaks is determined to realize a color reproduction rate sufficient to display natural colors.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device in which two or more adjacent light emitting layers are stacked in one stack in order to improve the color reproducibility and an OLED display using the same.

Recently, the field of display that visually expresses electrical information signals has rapidly developed as the information age has come to a full-fledged information age. In response to this, various flat panel display devices (flat display devices) having excellent performance such as thinning, light- 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 is considered as a competitive application for not requiring a separate light source, compacting the device, and displaying a clear color image.

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

However, in the case of a large area of the shadow mask, a phenomenon of sagging occurs due to the load, which makes it difficult to use the shadow mask many times, and the formation of the pattern of the organic light emitting layer is defective.

A white organic light emitting device (hereinafter, referred to as a 'white organic light emitting device') of a tandem type is one of the various methods that have been proposed in place of such a shadow mask. Hereinafter, As follows.

The white organic light emitting device is formed by depositing each layer between an anode and a cathode without forming a mask when a light emitting diode is formed, and the organic layers including the organic light emitting layer are sequentially deposited in a vacuum state with different components. The white organic light emitting device includes different light emitting layers for emitting light of a plurality of colors between the anode and the cathode, and a charge generating layer is provided between each light emitting layer. Each light emitting layer has a basic structure, do.

This white organic light emitting device emits light at different positions in the device, rather than emitting light using one material, but a plurality of light emitting layers including light emitting materials having different PL peaks (wavelengths) White light is generated by combining light emission. For example, a stack including a fluorescent light-emitting layer and a stack including a phosphorescent light-emitting layer may be stacked to realize a white organic light-emitting device.

However, the stack structure known to date does not have sufficient efficiency as a white organic light emitting device, and there is a problem in that color characteristics are changed in long driving due to the difference in efficiency by color. In addition, there is a problem that a sufficient color reproduction rate can not be realized in the display.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a white organic light emitting device in which two or more adjacent light emitting layers are stacked in one stack in order to improve color reproducibility and an organic light emitting display using the same.

The white organic light emitting device of the present invention is a tandem type device having a light emitting layer in each of a plurality of stacks. The light emitting layer has a luminescent peak within a certain range and a sufficient Color reproduction ratio can be realized.

In one embodiment, the white organic light emitting device of the present invention has a first electrode, first through third stacks sequentially disposed on the first electrode, and a second electrode on the third stack, One of the first to third stacks comprises a green light emitting layer having a first emission peak at a wavelength of 520 nm to 540 nm and a red emission layer having a second emission peak at a wavelength of 610 nm to 640 nm in contact with the green light emitting layer, The remaining stacks each include a blue light emitting layer having a third emission peak at a wavelength of 446 nm to 466 nm.

The intensity of the third emission peak among the first to third emission peaks is the largest.

Here, the third emission peak and the first emission peak are generated at a distance of 60 nm to 80 nm, and the first emission peak and the second emission peak are generated with a wavelength of 90 nm to 110 nm apart from each other.

In addition, the green light emitting layer may be provided in a plurality of layers, and the red light emitting layer and the blue light emitting layer may be provided in a single layer in each stack. In this case, the first green luminescent layer in contact with the red luminescent layer, the second green luminescent layer spaced apart from the red luminescent layer, and the red luminescent layer may be doped in this order.

In addition, a first charge generation layer may be formed between the first and second stacks, and a second charge generation layer may be formed between the second stack and the third stack. The first charge generating layer may be in contact with the red light emitting layer.

In addition, at least one of the first to third stacks may further include a light emitting layer and an electrode, and a common layer between the light emitting layer and the charge generating layer. For example, the red light emitting layer and the green light emitting layer are located in the second stack, and the first and second stacks have first and second blue light emitting layers, respectively, and between the first blue light emitting layer and the first electrode, A second charge generation layer, between the second blue light emitting layer and the second electrode, between the red light emitting layer and the first charge generating layer, between the green light emitting layer and the second charge generating layer, between the first blue light emitting layer and the first charge generating layer, And a common layer may be further included in at least one of the generated layer and the second blue light emitting layer.

According to another aspect of the present invention, there is provided a white organic light emitting device comprising a first electrode, a first common layer in contact with the upper surface of the first electrode, a first blue light emitting layer in contact with an upper surface of the first common layer, A second common layer in contact with the upper surface of the first blue light emitting layer; a red light emitting layer in contact with the upper surface of the second common layer; a green light emitting layer in contact with the upper surface of the red light emitting layer; A second common electrode which is in contact with the upper surface of the third common layer, a second common electrode which is in contact with the upper surface of the second common electrode, and a second electrode which is in contact with the upper surface of the fourth common layer, 2 blue luminescent layer has a luminescent peak of a first intensity at a wavelength of 446 nm to 466 nm and the red luminescent layer has a luminescent peak of a second intensity at a wavelength of 610 nm to 640 nm and the green luminescent layer has a luminescent peak at a wavelength of 520 nm to 540 nm Luminosity of the century It may have the size.

The third emission peak and the first emission peak are generated at a distance of 60 nm to 80 nm, and the first emission peak and the second emission peak may be generated with a wavelength of 90 nm to 110 nm.

The green light emitting layer may include first and second green light emitting layers having different dopant contents.

Further, the first to fourth common layers may be a single layer or a plurality of layers.

The first to fourth common layers may be formed of a hole-transporting material or an electron-transporting material, or a mixture of a hole-transporting material and an electron-transporting material.

At least one of the first to fourth common layers may include the same material as the host of the closest light emitting layer.

According to another aspect of the present invention, there is provided an OLED display device including a substrate having a plurality of sub-pixels, a driving transistor provided on each sub-pixel and a driving transistor, An organic light emitting display comprising: a reflective electrode; a transparent electrode; and an organic light emitting diode including a plurality of stacks between the reflective electrode and the transparent electrode, wherein one of the stacks of the plurality of stacks has a first And a red emission layer having a second emission peak at a wavelength of 610 nm to 640 nm in contact with the green emission layer, the remaining stacks each having a blue emission layer having a third emission peak at a wavelength of 446 nm to 466 nm .

The white organic light emitting device of the present invention and the organic light emitting display using the organic light emitting device of the present invention can realize an excellent color gamut by causing the emission peak of each light emitting layer to occur within a specific wavelength range in a structure having a plurality of light emitting stack structures.

In particular, the field of display devices is increasingly demanding a display level close to that of natural colors. It has a constant wavelength spacing between emission peaks of adjacent emission colors, thereby ensuring a constant lifetime in addition to an increase in color reproduction rate, maintaining high efficiency It is possible to prevent an increase in power consumption.

1 is a cross-sectional view illustrating a white organic light emitting device according to a first embodiment of the present invention;
2 is a graph showing the intensities of the white organic light emitting devices according to the present invention and the comparative example,
3 is a cross-sectional view showing a modified example of the adjacent light emitting layer of the second stack in the white organic light emitting device of the present invention
4A to 4C are graphs showing the wavelength shift range of the light emitting layer of the second stack in the white organic light emitting device of the present invention
5 is a cross-sectional view illustrating a second stack of a comparative example compared to the white organic light emitting device of the present invention
6 is a graph showing the emission intensities of the white organic light emitting devices according to the present invention and the comparative example,
7 is a graph showing the color reproducibility of the white organic light emitting device of the present invention compared with the DCI and BT2020 standards
8 is a cross-sectional view illustrating a white organic light emitting device according to a second embodiment of the present invention
9 is a schematic block diagram when the white organic light emitting device of the present invention is applied to an organic light emitting display
Fig. 10 is a circuit diagram of each sub-pixel of Fig.
11 is a view schematically showing the layer arrangement of each sub-pixel in the organic light emitting diode display of the present invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, when it is determined that a detailed description of a technique or configuration related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. The component names used in the following description are selected in consideration of easiness of specification, and may be different from the parts names of actual products.

First, the white organic light emitting device of the present invention will be described. The white organic light emitting device of the present invention refers to a configuration in which light is emitted except for a driving circuit in an organic light emitting display device. When a plurality of sub pixels provided on a substrate are arranged as red, green and blue (RGBW) Among them, the organic light emitting display device may correspond to a white subpixel, or may include a white organic light emitting device common to all the subpixels on the substrate, and may include a color filter on the upper side to display color. May commonly correspond to a white organic light emitting element formed in all the sub-pixels.

FIG. 1 is a cross-sectional view illustrating a white organic light emitting device according to a first embodiment of the present invention, and FIG. 2 is a graph illustrating intensity of a white organic light emitting device according to the present invention.

1, a white organic light emitting device according to a first exemplary embodiment of the present invention includes a first electrode 110, first to third stacks 200 and 300 , 400 and a second electrode (120) on the third stack (400).

The second stack 300 of the first through third stacks 200, 300, and 400 includes a green light emitting layer 320 having a first emission peak at a wavelength of 520 nm to 540 nm, (200, 400 in the figure) comprises a blue light emitting layer 210 having a third emission peak at a wavelength of 446 nm to 466 nm, respectively, and a red light emitting layer 310 having a second light emitting peak at a wavelength of 610 nm to 640 nm, , 410). More preferably, the emission peaks of the blue light emitting layer, the green light emitting layer and the red light emitting layer may be 451 nm to 465 nm, 525 nm to 535 nm, and 617 nm to 633 nm, respectively.

The reason why the emission peak of the light emitting layers should be limited to the above-mentioned range is as follows.

First, the reason why the emission peak of the blue light emitting layer should be in the range of 446 nm to 466 nm is because when the emission peak of 466 nm or more has a blue emission peak, the color reproduction rate is lowered by the rise of By and the color temperature charge of the white organic light emitting device is generated, The temperature of the panel rises due to the rise of the current required for the blue light emission for the specific luminance and there is a danger that the temperature of the panel may exceed the safety standard temperature. In the case of having the blue light emission peak of 446 nm or less, But the lifetime is shortened, the efficiency is deteriorated, and the panel temperature and power consumption are increased.

The reason why the emission peak of the green light emitting layer should be in the range of 520 nm to 540 nm is that when the green emission peak is 540 nm or more, the color reproduction rate does not meet the standard due to the decrease in the efficiency of green light emission, This is because the color reproducibility decreases due to the rise of the blue color coordinate By, the power consumption increases due to the low efficiency, and the life is short.

The reason why the emission peak of the red light emitting layer should be in the range of 610 nm to 640 nm is because when the red emission peak of 640 nm or more is present, the color reproducibility is improved but the efficiency is greatly lowered, which causes increase in power consumption, , And when it has a red emission peak of 610 nm or less, it emits an orange color different from red, and the color reproduction rate remarkably drops.

The red light emitting layer 310 includes a red host and a red dopant. The red host has a bipolar property, and a hole transporting host having a strong hole characteristic is used. For example, the red host has a Lowest Unoccupied Molecular Orbital (LUMO) energy level of -1.0 to -3.0 eV and a HOMO (Highest Occupied Molecular Orbital) energy level of -4.9 eV to -6.0 eV.

Since the red light emitting layer 310 is positioned between the first charge generation layer 510 and the green light emitting layer 320, electrons leaked from the green light emitting layer 320 as a main light emitting layer are trapped to contribute to red light emission, Thereby contributing to an improvement in the color recall ratio and an improvement in brightness of the device.

The host material used for the red light emitting layer 310 includes an aryl group as a core, and the aryl group is substituted with a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group having 6 to 24 carbon atoms, a substituted or unsubstituted aryl group having 10 to 30 A substituted or unsubstituted heteroaryl group having 2 to 24 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted carbon number Substituted or unsubstituted C1-C24 alkoxy, substituted or unsubstituted C6-C24 aryloxy, substituted or unsubstituted C1-C24 alkylsilyl, substituted or unsubstituted C1- An unsubstituted arylsilyl group having 6 to 24 carbon atoms, a cyano group, a halogen group, deuterium, and hydrogen, and R to R14 may be selected from the group consisting of an adjacent substituent and an axial It may form a ring.

The constituent of the core is an aryl group and is preferably an aryl group selected from phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine, acridine, Pyridine, pyrazine, pyridine, pyrazole, imidazole, pyrrolyl, pyrrolidine, pyrazine, quinoline, indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole and pyrroly.

Examples of the host material of the red light emitting layer 310 include CBP, CDBP, mCP, BCP, BAlq, and TAZ, and one or more of these materials may be included.

The phosphorescent dopant may be Ir (piz) 3 (Tris (1-phenylisoquinoline) iridium (III), Ir (piq) (Acetylacetonate) iridium (III)), Ir (BT) 2 (acac) (bisacetyl) acetylacetonate iridium (III) (Bis (2-pheylbenzothazolato) (accetylacetonate) iridium (III), but the present invention is not limited thereto.

Examples of the fluorescent dopant that can be included in the red light emitting layer 310 include rubrene (5,6,11,12-tetraphenylnaphthacene), DCJTB (4- (dicyanlmethylene) -2-tert- 7,7, -tetramethyljuloidin-4-yl-viyl) -4H), and the like.

As an example of the green light emitting layer 320, the host of the green light emitting layer 320 may include C-545T (10- (2-benzothia-zylyl) -1,1,7,7-tetramethyl- 2, 3, 6, 7-tetrahydro-1H, 5H, 11H- [1] benzo-pyrano [6,7,8-ij] quinolizin-11-ne and its derivatives, quinacridone derivatives and carbazole derivatives . When Alq3 is used as a host, it can emit green light by itself, but it includes a green dopant for improving the efficiency of green light emission, and both phosphorescent and fluorescent dopants are available.

The green light emitting layer 320 emits light having a wavelength of 500 nm to 590 nm and the red light emitting layer 310 emits light having a wavelength of 590 nm to 660 nm at a wavelength of 420 nm to 500 nm. And has the emission peak of each light emitting layer in the wavelength range described above.

The blue light emitting layers 210 and 410 may include at least one blue host and at least one blue dopant. Specifically, at least one fluorescent host material selected from the group consisting of an anthracene derivative, a pyrene derivative, and a perylene derivative may be doped with a fluorescent blue dopant. If there is development of a stable phosphorescent blue material, substitution will be possible.

In the above description, the light emitting layers of different luminescent colors are described as examples in which the adjacent stacks are located in the intermediate stack, but the present invention is not limited to this example, and the stack including the plurality of light emitting layers may be located in another stack. Also, in a white organic light emitting device, the stack may have more stacks than the three stacks of the illustrated example, in which case multiple stack configurations may have the same light emitting layer.

Meanwhile, the luminescence peaks (BP, GP, RP) in the present invention mean the maximum luminescence intensity that appears for each luminescent layer. As can be seen from the graph of FIG. 2, the emission peak of the maximum emission intensity can be shifted to one side of the center of each emission color wavelength range. The blue emission peak and the green emission peak occur at positions shifted to the left rather than the center of the corresponding wavelength region.

The white organic light emitting device of the present invention is characterized in that the emission peak is in a specific range. Red light emission and green light emission are simultaneously emitted in one stack, and light is distributed in accordance with the visibility of a person for every wavelength, It is possible to obtain an improved color reproduction ratio.

The intensity of the luminescence peak of the blue luminescent layer in each luminescent layer is larger than the luminescent peaks of the two luminescent layers. This is due to the relatively low visibility and the low efficiency of the blue light emitting material, which has been developed so far, to increase the luminescence intensity compared to other light emitting layers for the realization of white light. For example, the light intensity of the wavelength at which the emission peak of the blue light emitting layer is generated is at least twice the light intensity of the wavelength at which the emission peak of the green light emitting layer or the red light emitting layer occurs. To this end, two stacks of the blue light emitting layer are provided in the white organic light emitting device in comparison with other light emitting layers.

However, if a blue light emitting material has the same level of efficiency as other luminescent colors, the dual stack of the first stack, in which the stack with the blue light emitting layer is formed as a single stack and the red light emitting layer and the green light emitting layer are in contact with each other, It will be possible.

Further, the intensity of the emission peak of the red light emission layer is larger than the emission peak of the green light emission layer, and the difference is small, and can be changed according to the usage amount or the height of the host and the dopant for each light emission layer. Through experiments, it was confirmed that when the emission intensity of the red light emitting layer is made larger than the emission intensity of the green light emitting layer, a sufficient color gamut can be obtained with the blue light.

Here, the emission peak of the green light-emitting layer adjacent to the emission peak of the blue light-emitting layer is generated with a wavelength of 60 to 80 nm apart from each other, and the emission peak of the green light-emitting layer and the emission peak of the red light- . Relatively green light emission covers a broader wavelength than blue light emission or red light emission. This is to improve the color reproduction rate by appropriately dispersing the intervals in which the colors of the red cyan are expressed through appropriate separation between the emission peaks (BP, GP, RP) of the respective emission colors.

1, the white organic light emitting device according to the first embodiment of the present invention includes a first charge generation layer 510 between the first stack 200 and the second stack 300, And may further include a second charge generating layer 520 between the stack 300 and the third stack 400. In this case, the second stack 300 may include a hole injection layer between the first charge generation layer 510 and the red light emitting layer 310, Transport layer is omitted and the red light emitting layer 310 includes a hole transporting host to emit red light of itself and to transport holes passed through the first charge generating layer 510 to form a hole in the green light emitting layer 320 .

In addition, the first to third stacks 200, 300, and 400 may further include a common layer between the light emitting layer and the electrode or the charge generating layer. For example, a first common layer 220 may be formed between the first electrode 110 and the first blue light emitting layer 210, and a second common layer may be formed between the first blue light emitting layer 210 and the first charge generating layer 510 A third common layer 340 is formed between the green light emitting layer 320 and the second charge generating layer 520 and a second common charge generating layer 520 is formed between the second charge generating layer 520 and the second charge generating layer 520. [ The fourth common layer 420 may be disposed between the second blue light emitting layer 410 and the fifth common layer 430 between the second blue light emitting layer 410 and the second electrode 120. Here, the common layer helps hole injection / transport from the adjacent electrode to the light emitting layer, assists electron injection / transport, or transfers holes and / or electrons to an adjacent stack.

The first and second charge generating layers 510 and 520 may include n-type charge generating layers 510a and 520a and p-type charge generating layers 510b and 520b, respectively. The n-type The charge generating layers 510a and 520a are in contact with the common layers 230 and 340 of the lower stack and the p type charge generating layers 510b and 520b are in contact with the red light emitting layer 310 or the common layer 420 of the upper stack.

Here, the common layer 330 is not separately provided between the first red light emitting layer 310 and the first charge generating layer 510, and the first red light emitting layer (not shown) is formed on the first charge generating layer 510 310 may be directly formed or a sixth common layer 330 may be further formed between the first charge generation layer 510 and the red light emitting layer 310. In the former case, it is preferable that the red light emitting layer 310 essentially include a hole transporting host.

In some cases, the red light emitting layer 310 and the green light emitting layer 320 may be arranged in a lower order and the red light emitting layer 310 may be located on the upper side. In this case, the red light emitting layer 310 may include an electron transporting host.

3 is a cross-sectional view showing a modified example of the adjacent light emitting layer of the second stack in the white organic light emitting device of the present invention.

As shown in FIG. 3, in the second stack, the green light emitting layer 320 is not limited to a single light emitting layer, but may be formed of a plurality of layers of two or more layers.

In this case, it is preferable that the red light emitting layer 310 and the blue light emitting layers 210 and 410 are provided in a single layer in each stack. In addition, the white organic light emitting device of the present invention shown in FIG. 3 is a modification of the first embodiment of the present invention. The structure of the first and second stacks 200 and 400, except for the second stack structure, .

3, the first green light emitting layer 320a is in contact with the red light emitting layer 310. The second green light emitting layer 320a is spaced apart from the red light emitting layer and is in contact with the first green light emitting layer 320a. The first green light emitting layer 320a, the second green light emitting layer 320b, and the red light emitting layer 310 may have a dopant content in the order of the green light emitting layer 320b. This is because the green light emission is made the main emission in the second stack 300, the dopant content of the first green light emitting layer 320a is made the largest and the resonance of the second stack 300 is determined accordingly, The stack 300 can obtain the effect of expanding the color expression region not only in green but also in blue and red.

In addition, the first green light emitting layer 320a is a light emitting layer that emits light in the second stack 300, and the resonance effect in the second stack is aligned with the first green light emitting layer 320a. The green light emitting layer 320b and the red light emitting layer 310 perform auxiliary light emission together with transport of electrons or holes.

On the other hand, the white organic light emitting device of the present invention defines an ideal wavelength difference between the emission peaks of the respective emission colors as well as the emission peaks of the adjacent wavelength band.

[Table 1]

4A to 4C are graphs showing the wavelength shift range of the light emitting layer of the second stack in the white organic light emitting device of the present invention. Table 1 shows the structure of a modification (FIG. 3) of the first embodiment of the present invention DCI characteristic, and BT2020 characteristic shown in Fig. 4A to Fig. 4C.

As shown in FIG. 4A and Table 1, when the green emission peak is shifted to the left and the wavelength separation between the blue emission peak and the green emission peak is less than 60 nm, the DCI overlap ratio and / BT2020 overlap ratio is decreased, which means that the color reproduction ratio is decreased.

As shown in Fig. 4B and Table 1, in the comparative example (b), when the main emission peak of green is shifted to the right and the wavelength distance between the blue emission peak and the green emission peak is greater than 80 nm and less than 90 nm, The Gx value is significantly increased and the color deviates from the green color. Accordingly, the BT2020 area ratio or the BT2020 overlap ratio is less than the standard.

As shown in FIG. 4C and Table 1, in Comparative Example (c), the red main emission peak was shifted to the left, and the overlap ratio and area ratio of the BT2020 were decreased under the condition that the green emission peak and the red emission peak had values of less than 90 nm Respectively.

On the other hand, in the above-mentioned experiment, the reason why the wavelength separation between the green emission peak and the red emission peak is only lower than the lower limit is because it is difficult to form a red dopant that exhibits a condition exceeding the upper limit between the green emission peak and the red emission peak, , The red emission of such a condition is excluded from the experimental conditions because it is difficult to satisfy the efficiency characteristic because the photon in the narrow band gap is likely to be transferred to the non-luminous energy.

Unlike the comparative examples (a), (b) and (c), the color coordinates of R, G and B are all in the DCI standard and the BT 2020 standard in the modification of the first embodiment of the present invention Overlapping ratio was more than 98%, BT2020 area ratio and overlapped ratio were more than 84.7%.

For reference, the color gamut (or color gamut) refers to the range of colors that an input and output device can reproduce, depending on how the color space is defined.

DCI is Digital Cinema Initiatives that can be expressed by digital cinema. BT2020 is a standard of 4K / UHD recommended by International Broadcasting Union (ITU) and it is called Rec.2020 to be. For reference, the HD color space is BT709. BT709, DCI, BT2020, more strict criteria are applied, and color representation area becomes bigger.

The increase in the respective values of the area ratio of the BT2020 standard and the area ratio of the DCI means that a greater variety of colors can be realized than in a large-area and high-resolution display, which means that there is an effect of providing a sharp image quality. The larger the overlap ratio of the BT2020 standard and the overlap ratio of the DCI, respectively, means that the area overlapping the standard standard is larger, which means that it conforms to the standard specification of the display.

Table 1 shows that the DCI overlap ratio and the area ratio / overlap ratio of the BT2020 are larger than those of the comparative examples (a), (b) and (c) in the embodiment of the present invention, Which means that it exhibits excellent color reproducibility when applied.

5 is a cross-sectional view showing a second stack of a comparative example compared with the white organic light emitting device of the present invention.

As shown in FIG. 5, the white organic light emitting device according to the comparative example has a structure in which first and second green and green light emitting layers are provided instead of the first and second green light emitting layers, as compared with the structure of FIG.

FIG. 6 is a graph showing the intensity of light emitted by a white organic light emitting device according to the present invention and a comparative example.

Table 2 shows the efficiency, color coordinates, Vpeak, DCI and BT2020 characteristics of the comparative example of Fig. 5 and the modified example of the first embodiment of the present invention of Fig.

 [Table 2]

As shown in Table 2 and FIG. 6, the most distinct differences caused by the constitutions of the present invention and the comparative example are the color recall ratio, the BT2020 area ratio and overlap ratio are 84.7% of the present invention and 73.0% It can be seen that the area and overlap ratio increase by more than 15% in the standard.

It can be seen that the Vpeak value is 15.1 V in the present invention, but 15.3 V in the comparative example, and the power consumption can also be lowered in the present invention by decreasing the peak voltage value.

In addition, it was found that the color coordinates of red and green represent the natural color of the present invention.

The efficiencies of the yellow green (YG) and the green (G) of the comparative example are 20.7 Cd / A and 14.7 Cd / A respectively and the efficiency values of the yellow green (YG) of the comparative example are relatively superior, Which means that the expression of green in the gamut deviates to the lower right, which means that it can deviate from the DCI and BT 2020 specifications.

That is, it was confirmed that the white organic light emitting device of the present invention is uniformly reproduced in all of red, green, and blue colors as shown in FIG. 6, thereby obtaining a BT2020 area ratio and overlap ratio characteristics improved by 15% as compared with the comparative example.

As described above, in order to increase color purity in the present invention, the positions of R, G, and B peak emission wavelengths are limited and three stacks are provided. One of the red emission layer and the green emission layer is adjacent to the stack.

7 is a graph showing the color reproducibility of the white organic light emitting device of the present invention compared with the DCI and BT2020 standards.

As shown in FIG. 7, the BT2020 standard is wider than the DCI standard, and at least green is not included in the DCI standard when the white organic light emitting device of the present invention is applied. However, in the BT2020 standard, Respectively. In other words, as can be seen from the color coordinates in Table 2, the green color coordinates of Gx and Gy are (0.274, 0.667) in the structure of the comparative example, so they are superposed only on the inner part of the area corresponding to the standard of BT2020. However, The green color coordinates Gx and Gy of the device are extended to the upper left (0.210, 0.693), and it is confirmed that the gamut expansion occurs.

8 is a cross-sectional view illustrating a white organic light emitting device according to a second embodiment of the present invention.

The white organic light emitting device according to the second embodiment of the present invention is the same as the light emitting layer arrangement in the first embodiment described above except that the charge generation layer and the common layer are shared in adjacent stacks.

8, the white organic light emitting device according to the second embodiment of the present invention includes a first electrode 110, a first common layer 610 in contact with the upper surface of the first electrode 110, A second common layer 620 in contact with the upper surface of the first blue light emitting layer 210 and a second common layer 620 in contact with the upper surface of the second common layer 620, A green light emitting layer 320 contacting the upper surface of the red light emitting layer 310, a third common layer 630 contacting the upper surface of the green light emitting layer 320, A fourth common layer 640 which is in contact with the upper surface of the second blue light emitting layer 410 and a second common electrode which is in contact with the upper surface of the fourth common layer 640, (120).

The first and second blue light emitting layers 210 and 410 have emission peaks of a first intensity at a wavelength of 446 nm to 466 nm and the red light emitting layers 310 have emission peaks at wavelengths of 610 nm to 640 nm that are smaller than the first intensity And the green light emitting layer 320 has an emission peak of a third intensity lower than the first and second intensities at a wavelength of 520 nm to 540 nm.

2, the emission peak of the first intensity and the emission peak of the third intensity are generated with a wavelength of 60 nm to 80 nm being spaced apart from each other, and the third organic electroluminescent device according to the second embodiment of the present invention The emission peak of the intensity and the emission peak of the second intensity can be generated at a wavelength of 90 nm to 110 nm.

3, the green light emitting layer 320 may include first and second green light emitting layers 320a and 320b having different dopant contents. Referring to FIG.

The first to fourth common layers 610, 620, 630, and 640 may be a single layer or a plurality of layers. For example, the common layer has a single layer adjacent to the electrode, and the layer including the charge generating layer has a plurality of layers including an electron transport layer (ETL), a charge generation layer (CGL), and a hole transport layer Layer configuration. However, the present invention is not limited to this example, and a single layer common layer may be provided between the first blue light emitting layer 210 and the red light emitting layer 310, and between the green light emitting layer 320 and the second blue light emitting layer 410.

In this case, the hole-transporting material or the electron-transporting material may be used, or the hole-transporting material and the electron-transporting material may be mixed.

In particular, the first common layer 610 includes a hole transport layer, and may further include a hole injection layer between the first electrode 110 and the hole transport layer.

In addition, the second and third common layers 620 and 630 may be formed by laminating an electron transport layer, a charge generation layer, and a hole transport layer sequentially from the bottom.

The fourth common layer 640 may include an electron transport layer and may further include an electron injection layer between the electron transport layer and the second electrode 120.

At least one of the first to fourth common layers 610, 620, 630, and 640 may include the same material as the host of the nearest light emitting layer. This is to lower the barrier voltage when holes or electrons are transferred from the common layer to the luminescent layer or from the luminescent layer to the common layer.

Meanwhile, the white organic light emitting device described above is connected to a driving thin film transistor for sub-driving, and the application of the organic light emitting display will be described below.

FIG. 9 is a schematic block diagram when the white organic light emitting device of the present invention is applied to an organic light emitting display device, FIG. 10 is a circuit diagram of each sub pixel of FIG. 9, FIG. 8 is a diagram schematically showing a layer arrangement of sub-pixels. FIG.

9, the OLED display of the present invention includes an image processing unit 115, a data conversion unit 114, a timing control unit 113, a data driving unit 112, a gate driving unit 111, and a display panel 1000, .

The image processing unit 115 performs various image processing such as setting a gamma voltage to realize the maximum luminance according to the average image level using the RGB data signals RGB, and then outputs RGB data signals RGB. The image processor 115 generates a driving signal including at least one of the RGB data signal RGB as well as the vertical synchronizing signal Vsync, the horizontal synchronizing signal Hsync, the data enable signal DES and the clock signal CLK Output.

The timing controller 113 receives one or more of the vertical synchronization signal Vsync, the horizontal synchronization signal Hsync, the data enable signal DES and the clock signal CLK from the image processing unit 115 or the data conversion unit 114 And is supplied with a drive signal. The timing control section 113 generates a gate timing control signal GCS for controlling the operation timing of the gate driving section 111 and a data timing control signal DCS for controlling the operation timing of the gate driving section 112, .

The timing controller 113 outputs the data signal DATA corresponding to the gate timing control signal GCS and the data timing control signal DCS.

The data driver 112 samples and latches the data signal DATA supplied from the timing controller 113 in response to the data timing control signal DCS supplied from the timing controller 113 and converts the sampled data signal into a gamma reference voltage . The data driver 112 outputs the converted data signal DATA through the data lines DL1 to DLm. The data driver 1112 is formed in the form of an IC (Integrated Circuit).

The gate driving unit 111 outputs the gate signal while shifting the level of the gate voltage in response to the gate timing control signal GCS supplied from the timing control unit 113. [ The gate driver 111 outputs a gate signal through the gate lines GL1 to GLn. The gate driver 111 may be formed in the form of an IC or a gate-in-panel type in the display panel 150.

The display panel 1100 includes, for example, a sub-pixel structure including a red sub-pixel SPr, a green sub-pixel SPg, and a blue sub-pixel SPb. That is, one pixel P is composed of red, green, and blue sub-pixels. In some cases, it may further include a white sub-pixel WPg.

As shown in FIG. 10, each sub-pixel has a basic structure of a 2T1C structure including a switching transistor, a driving transistor, a capacitor, and an organic light emitting diode, and further, a transistor and a capacitor may be additionally provided. This circuit configuration is provided between the gate line GL in the first direction and the data line DL and driving power supply line VDDL in the direction crossing the gate line GL in the first direction.

The organic light emitting display includes an organic light emitting diode that emits light to each individual sub-pixel, and may further include a compensation circuit CC for each individual sub-pixel to prevent deterioration thereof. In some cases, the compensation circuit may be omitted.

The switching transistor SW operates in response to a gate signal supplied through the gate line GL so that a data signal supplied through the data line DL is stored as a data voltage in the storage capacitor Cst.

The driving transistor DR operates so that a driving current flows between the driving power supply line VDDL and the ground line GND according to the data voltage stored in the storage capacitor Cst.

The compensation circuit CC compensates the threshold voltage of the driving transistor DR and the like. The compensation circuit CC may be composed of one or more transistors and capacitors. Since the configuration of the compensation circuit CC can be variously configured, a detailed description thereof will be omitted.

The organic light emitting display having the above-described sub-pixel structure may be implemented by a top emission type, a bottom emission type, or a full-emission type, depending on a direction in which light is emitted.

The organic light emitting display of the present invention may emit light in one direction among the emission modes, as shown in FIG. 11, or may be emitted in a top emission mode . The light emitting direction is determined depending on which one of the first electrode 110 and the second electrode 120 is to be a reflective electrode. When the reflective electrode is the first electrode 110, In the case of the second electrode 120, light is emitted in a lower light emitting manner. At this time, the electrode other than the reflective electrode is a transparent electrode.

As shown in FIG. 11, each sub-pixel includes a white organic light emitting element WOLED that emits white light of a thin film transistor (TFT) including a driving transistor DR, and emits white light, and emits white light to red, green, and blue sub- Color display can be performed by applying the corresponding color filters (CFr, CFg, CFb). As described above, the individual sub-pixels are provided with a circuit including a driving transistor (DR in FIG. 10) for driving the organic light emitting diode.

Here, the white organic light emitting device WOLED includes a substrate (corresponding to the display panel 1100 of FIG. 9) having a plurality of sub-pixels, a driving transistor DR provided in each sub- 1 and 2 including a plurality of stacks between the first and second electrodes 110 and 120 and a first electrode 110 and a second electrode 120 which are connected to each other and are opposed to each other in the transistor DR, Or the white organic light emitting device WOLED of FIG.

Here, the white organic light emitting device WOLED includes a green light emitting layer having a first emission peak at a wavelength of 520 nm to 540 nm and a second emission peak at a wavelength of 610 nm to 640 nm in contact with the green light emitting layer. And the remaining stack includes a blue light emitting layer having a third emission peak at a wavelength of 446 nm to 466 nm, respectively.

When a white organic light emitting device that emits white light is commonly provided in each sub pixel of the present invention, an organic material of the organic light emitting device is deposited on each sub pixel to form an organic light emitting device, It is not necessary to use a metal mask for deposition, which makes it easy to increase the size. In addition, since the organic light emitting element has uniform characteristics without distinguishing the regions, a white organic light emitting element having a combination of light emitting layers having a specific wavelength range including a specific dopant is provided in each sub pixel, A color filter is provided to obtain light emission of each sub pixel in the form that white light is transmitted through the color filter. Therefore, it is possible to display close to the natural color so as to conform to the standard specification of the color gamut which is required to widen gradually by expanding the color gamut.

The white organic light emitting device of the present invention has three distinctly separated peak wavelengths, has the maximum intensity at the shortest wavelength, and thereby improves the color reproduction rate in accordance with the gradually increasing gamut condition.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

110: first electrode 120: second electrode
200: first stack 210: first blue light emitting layer
220: first common layer 230: second common layer
300: Second stack 310: Red light emitting layer
320: green light emitting layer 330: sixth common layer
340: third common layer 400: third stack
410: second blue light emitting layer 420: fourth common layer
430: fifth common layer 510: first charge generating layer
520: second charge generating layer

Claims (15)

A white organic light emitting device having a first electrode, first through third stacks sequentially disposed on the first electrode, and a second electrode on the third stack,
The stack of any one of the first through third stacks may include a green light emitting layer having a first emission peak at a wavelength of 520 nm to 540 nm and a red light emitting layer having a second emission peak at a wavelength of 610 nm to 640 nm in contact with the green light emitting layer In addition,
And the remaining stacks each include a blue light emitting layer having a third emission peak at a wavelength of 446 nm to 466 nm. The method according to claim 1,
And the intensity of the third emission peak of the first to third emission peaks is the largest. 3. The method of claim 2,
Wherein the third emission peak and the first emission peak are generated with a wavelength of 60 nm to 80 nm,
Wherein the first emission peak and the second emission peak are generated with a wavelength of 90 nm to 110 nm apart from each other. The method according to claim 1,
Wherein the green light emitting layer is provided in a plurality of layers, and the red light emitting layer and the blue light emitting layer are provided as a single layer in each stack. 5. The method of claim 4,
A first green luminescent layer in contact with the red luminescent layer, a second green luminescent layer spaced apart from the red luminescent layer, and a red luminescent layer. The method according to claim 1,
A first charge generation layer between the first stack and the second stack,
And a second charge generation layer between the second stack and the third stack. The method according to claim 6,
Wherein the first charge generating layer is in contact with the red light emitting layer. The method according to claim 6,
The red light emitting layer and the green light emitting layer are located in the second stack,
The first and second stacks having first and second blue light emitting layers, respectively,
A first charge generation layer, a first charge generation layer, a second charge generation layer, a second charge generation layer, a second charge generation layer, a second charge generation layer, Wherein at least one of the first charge generation layer, the second charge generation layer, and the second charge generation layer further includes a common layer. A first electrode;
A first common layer in contact with an upper surface of the first electrode;
A first blue light-emitting layer in contact with an upper surface of the first common layer;
A second common layer in contact with an upper surface of the first blue light emitting layer;
A red light emitting layer in contact with an upper surface of the second common layer;
A green light emitting layer in contact with the upper surface of the red light emitting layer;
A third common layer in contact with the upper surface of the green light emitting layer;
A second blue light-emitting layer in contact with an upper surface of the third common layer;
A fourth common layer in contact with the upper surface of the second blue light emitting layer; And
And a second electrode in contact with the upper surface of the fourth common layer,
Wherein the first and second blue light emitting layers have emission peaks of a first intensity at a wavelength of 446 nm to 466 nm,
Wherein the red light emitting layer has an emission peak of a second intensity smaller than the first intensity at a wavelength of 610 nm to 640 nm,
Wherein the green light emitting layer has an emission peak of a third intensity lower than the first and second intensities at a wavelength of 520 nm to 540 nm. 10. The method of claim 9,
The emission peak of the third intensity and the emission peak of the first intensity are generated with a wavelength of 60 nm to 80 nm being spaced apart from each other,
Wherein the emission peak of the first intensity and the emission peak of the second intensity are generated with a wavelength of 90 to 110 nm apart. 10. The method of claim 9,
Wherein the green light emitting layer comprises first and second green light emitting layers having different dopant contents. 10. The method of claim 9,
Wherein the first to fourth common layers comprise
A white organic light-emitting device comprising a single layer or a plurality of layers. 10. The method of claim 9,
Wherein the first to fourth common layers comprise
A hole-transporting substance or an electron-transporting substance
Or a mixture of a hole transporting material and an electron transporting material. 14. The method of claim 13,
At least one of the first to fourth common layers
Wherein the organic material layer comprises the same material as the host of the closest light emitting layer. A substrate having a plurality of sub-pixels;
A driving transistor provided in each sub-pixel on the substrate; And
And an organic light emitting diode including an organic light emitting diode including a plurality of stacks between the first electrode and the second electrode, the first electrode and the second electrode being connected to the driving transistor,
Wherein one of the stacks of the plurality of layers includes a green light emitting layer having a first emission peak at a wavelength of 520 nm to 540 nm and a red light emission layer having a second emission peak at a wavelength of 610 nm to 640 nm in contact with the green light emitting layer,
And the remaining stacks each include a blue light emitting layer having a third emission peak at a wavelength of 446 nm to 466 nm.

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