KR102614067B1 - White Organic Light Emitting Element and Organic Light Emitting Display Device Using the Same - Google Patents

Abstract

The present invention relates to a white organic light-emitting device that improves color gamut and lifespan by changing the mobility characteristics of a long-wavelength light-emitting layer when two or more adjacent light-emitting layers are applied in a stack, and to an organic light-emitting display device using the same, for which different wavelengths are used. In a stack having a light-emitting layer in contact, the light-emitting layer with a relatively long wavelength is made to have specific transport properties.

Description

White organic light emitting element and organic light emitting display device using the same {White Organic Light Emitting Element and Organic Light Emitting Display Device Using the Same}

The present invention relates to an organic light emitting device, and in particular, to a white organic light emitting device that improves color gamut and lifespan by changing the mobility characteristics of the long wavelength light emitting layer when applying two or more adjacent light emitting layers in one stack, and to an organic light emitting display device to which the same is applied. It's about.

Recently, as we have entered a full-fledged information age, the field of displays that visually express electrical information signals has developed rapidly, and in response to this, various flat panel displays with excellent performance in thinness, lightness, and low power consumption have been developed. Display Device) has been developed and is rapidly replacing the existing cathode ray tube (CRT).

Specific examples of such flat panel displays include Liquid Crystal Display devices (LCD), Plasma Display Panel devices (PDP), Field Emission Display devices (FED), and organic light emitting display devices. (Organic Light Emitting Device: OLED), etc.

Among these, organic light emitting display devices are being considered as a competitive application because they do not require a separate light source, compact the device, and display vivid colors.

For such an organic light emitting display device, the formation of an organic light emitting layer is essential, and conventionally, a deposition method using a shadow mask was used to form the organic light emitting layer.

However, in the case of large-area shadow masks, sagging occurs due to load, which makes it difficult to use them multiple times and causes defects in forming organic light-emitting layer patterns, so an alternative is required.

One of several methods that have been proposed to replace such a shadow mask is a tandem organic light emitting device.

In this tandem organic light-emitting device, when forming a light-emitting diode, layers of organic components between the anode and cathode are deposited over the entire area without a mask. The formation of organic films, including the organic light-emitting layer, is carried out in a vacuum by sequentially varying the components. It is characterized by deposition.

This tandem organic light-emitting device does not emit light using one material, but rather combines multiple light-emitting layers containing light-emitting materials with different PL peaks (Photoluminescence Peaks) for each wavelength, emitting light at different positions within the device. Light is generated. As an example, there is an example of implementing a white organic light-emitting device by stacking a stack containing a fluorescent light-emitting layer and a stack containing a phosphorescent light-emitting layer.

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 change during long-term operation due to differences in efficiency for each color. Additionally, there is a problem in displaying a sufficient color gamut.

The present invention was developed to solve the above problems, and provides a white organic light emitting device that improves color gamut and lifespan by changing the mobility characteristics of the long wavelength light emitting layer when applying two or more adjacent light emitting layers in one stack, and an organic light emitting display using the same. The problem to be solved is to provide a device.

The organic light-emitting device of the present invention can improve color gamut and lifespan by the specific mobility characteristics of the long-wavelength light-emitting layer in a stack having a plurality of light-emitting layers adjacent to each other among the stacks, each having a light-emitting layer.

An organic light emitting device for this purpose may include, for example, a reflective electrode and a transparent electrode facing each other, a plurality of stacks between the reflective electrode and the transparent electrode, and a charge generation layer between the stacks. At least one of the stacks of layers includes first and second light-emitting layers that are in contact with each other and have different emission peaks, and of the first and second light-emitting layers, the light-emitting layer having a long-wavelength emission peak is a single bipolar material. may include hosts.

In addition, the first light-emitting layer is a light-emitting layer with a shorter wavelength emission peak than the second light-emitting layer, and is closer to the reflective electrode among the reflective electrode and the transparent electrode, and the single host of the second light-emitting layer has an electron mobility of 1.0x10 ^-6. cm ² /Vs to 5.0x10 ^-3 cm ² /Vs, and may be a bipolar material with electron mobility greater than hole mobility.

Alternatively, the first light-emitting layer is a light-emitting layer having an emission peak of a longer wavelength than the second light-emitting layer, is closer to the transparent electrode among the reflective electrode and the transparent electrode, and the single host of the first light-emitting layer has a hole mobility of 1.0x10 ^-6 cm. ² /Vs to 5.0x10 ^-3 cm ² /Vs, and may be a bipolar material in which hole mobility is greater than electron mobility.

Here, the first emission layer may have an emission peak of 600 nm to 650 nm, and the second emission layer may have an emission peak of 510 nm to 590 nm.

The dopant content of the second emitting layer may be greater than the dopant content of the first emitting layer.

In addition, the upper and lower stacks adjacent to the stack having the first and second light emitting layers may equally have a single light emitting layer of a third light emitting layer having a different light emission peak from the first and second stacks. Here, the third emitting layer may have an emission peak of a shorter wavelength than the first and second emitting layers.

Each stack may further include a first common layer in contact with each light-emitting layer and close to the transparent electrode, and a second common layer in contact with each light-emitting layer and close to the reflective electrode.

In addition, an organic light emitting display device of the present invention for achieving the same purpose includes a substrate having a plurality of subpixels, a driving transistor provided in each subpixel on the substrate, and a reflective electrode connected to one of the driving transistors. An organic light emitting diode including a transparent electrode, a plurality of stacks between the reflective electrode and the transparent electrode, and a charge generation layer between the stacks, and the organic light emitting diode may include the organic light emitting device configuration described above. there is.

The white organic light emitting device of the present invention and the organic light emitting display device using the same have the following effects.

In a structure without an auxiliary light-emitting layer, there is an advantage in that the main light-emitting layer can express pure colors of each of the main light-emitting layer and the auxiliary light-emitting layer, compared to the method where the main light-emitting layer contributes to dual color expression.

In addition, in a stack having light-emitting layers of different wavelengths in contact, the light-emitting layer with a relatively short wavelength is used as the main light-emitting layer, and the light-emitting layer with a relatively long wavelength is used as an auxiliary light-emitting layer, so that the light-emitting layer with a relatively long wavelength has a specific transport property, so that the auxiliary light-emitting layer has its own It can express its own luminous color and at the same time help transport excitons/electrons or holes to the adjacent main luminescent layer.

Therefore, in addition to the luminous efficiency of colors lacking in white by the emission of the auxiliary light emitting layer, the color reproduction rate of the display device can be increased by increasing the efficiency of the main light emitting layer and the efficiency of overall white light emission, thereby enabling display closer to natural colors. do. As a result, viewer satisfaction can be improved.

1 is a cross-sectional view showing the organic light-emitting device of the present invention.
Figure 2 is a cross-sectional view showing a second stack of organic light-emitting devices according to the first embodiment of the present invention.
Figure 3 is a cross-sectional view showing a white organic light-emitting device according to a first embodiment of the present invention.
Figure 4 is a cross-sectional view showing a second stack of an organic light-emitting device according to a second embodiment of the present invention.
Figure 5 is a cross-sectional view showing a white organic light-emitting device according to a second embodiment of the present invention.
Figure 6 is a diagram showing an example of light emission of an organic light emitting display device using the white organic light emitting device of the present invention.
Figure 7 is a circuit diagram of each sub-pixel in Figure 6
Figure 8 is an example of a cross-sectional view of each sub-pixel in Figure 6
Figure 9 is a graph showing the intensity by wavelength when driving the white organic light-emitting device of the present invention.
Figure 10 is a graph showing comparison of intensity at red wavelength of comparative examples and experimental examples.
11A to 11C are graphs showing the intensity of each color of white organic light-emitting device of the present invention for comparative examples and the present invention.
12A to 12C are graphs showing the lifespan of the white organic light-emitting device of the present invention by emission color.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of technology or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, the component names used in the following description were selected in consideration of the ease of writing specifications and may be different from the component names of the actual product.

The following description first describes the basic configuration of the organic light emitting display device and then explains the white organic light emitting device applied thereto.

1 is a cross-sectional view showing the organic light-emitting device of the present invention.

As shown in FIG. 1, the organic light emitting device of the present invention includes an anode 110 and a cathode 120 facing each other, and a plurality of stacks 200, 300, 400 between the anode 110 and the cathode 120, and It includes charge generation layers 510 and 520 between the stacks.

As shown, the plurality of stacks may be three stacks, but the stack is not limited to this, and may be two or more stacks. Additionally, the organic light-emitting device includes a plurality of stacks, each with a light-emitting layer, and the final light emission is achieved by mixing the light emitted from each light-emitting layer. Organic light-emitting devices can be used in display devices or lighting devices. In the case of display devices, the emission color of the light-emitting layer within each stack is adjusted for the purpose of emitting white light. In the case of lighting devices, it is not limited to white light, but blue light. The emission of light can be adjusted by emitting light or other specific colors. Control of the color of light emitted from such an organic light-emitting device is determined by the combination of the light-emitting colors of the light-emitting layers provided in each stack.

Hereinafter, the three-stack structure shown in FIG. 1 that emits white light will be described.

The organic light-emitting device of the present invention includes first and second light-emitting layers 310 and 320 that are in contact with each other and have different emission peaks in at least one of the plurality of stacks 200, 300, and 400, Among the first and second light emitting layers 310 and 320, the light emitting layer having a long wavelength light emission peak includes a host of a single bipolar material.

Here, the second stack 300 located in the middle is provided with first and second light emitting layers 310 and 320 that emit light of different wavelengths and have a longer wavelength than the light emitting layers of the first and third stacks 200 and 400. It can be provided.

As shown, when three stacks are provided in an organic light emitting device, the first stack 200 and the third stack 400 may include a single light emitting layer of the same short wavelength.

For example, the single light-emitting layer of the first and third stacks 200 and 400 is a blue light-emitting layer, and the first and second light-emitting layers 310 and 320 of the second stack 300 are a yellow-green light-emitting layer and a red light-emitting layer. can do. In this case, the first emission layer 310 and the second emission layer 320 are not limited to one specific emission peak, and the yellow-green emission layer, which is the first emission layer 310, has its emission peak in the range of 510 nm to 590 nm. It is sufficient for the red light emitting layer, which is the second light emitting layer 320, to have its light emission peak in the range of 600 nm to 650 nm.

Here, the reason why the single light-emitting layer of the first and third stacks 200 and 400 is a blue light-emitting layer having an emission peak in the range of 440 nm to 480 nm is because the materials of the blue light-emitting layer known to date have relatively low efficiency compared to light-emitting layers of other colors. Therefore, this is to compensate for this. In other words, two stacks are provided to ensure sufficient blue light emission even over time. In some cases, if it is possible to secure a level of efficiency equivalent to that of the yellow-green light-emitting first light-emitting layer 310 by developing a material for the blue light-emitting layer, the blue light-emitting layer may be provided in only one stack. In this case, the same effect of white light emission can be achieved with just two stacks: a stack with a single blue light-emitting layer and a stack with two different adjacent light-emitting layers with longer wavelengths than the blue light-emitting layer.

Here, one of the anode 110 and the cathode 120 is a reflective electrode and the other is a transparent electrode. If the anode 110 is a reflective electrode and the cathode 120 is a transparent electrode, light is emitted upward, and if the anode 110 is a transparent electrode and the cathode 120 is a reflective electrode, light is emitted downward. In addition, in the case of the electrode including a reflective electrode among the anode 110 and the cathode 120, the direction of light emission does not change, and a transparent auxiliary electrode can be further included inside the organic light emitting device, that is, inside the reflective electrode. In addition, in the organic light-emitting device of the present invention, the position of the first light-emitting layer 310, which has a shorter wavelength, of the second stack 300 is determined depending on the position of the reflective electrode, and the first light-emitting layer 310 is relatively It is characterized in that it is located closer to the reflective electrode than the second light emitting layer 320. This is to set the position of the first light-emitting layer 310, which has the main light-emitting characteristics of the second stack, at the optimal resonance position of the organic light-emitting device.

That is, the light coming from the light emitting layers of different wavelengths resonates differently, and the maximum intensity is achieved when the first light emitting layer 310, which has the main light emission of the second stack 300, resonates between the anode 110 and the cathode 120. The third light emitting layer of the first stack 200 or/and the third stack 400 adjacent to the second stack 300 is also provided at a position where there is maximum intensity upon resonance of light emission from the light emitting layer. . Here, when the first and third stacks 200 and 400 are provided together, these stacks are provided with light-emitting layers of the same light-emitting color, and light waves resonating from the light-emitting layers of different stacks match to amplify the light emission intensity. Through this, the blue light emission from the first and third stacks 200 and 400 is made to have a light intensity similar to the yellow-green light emission, which is the main light emission of the second stack 300, and the blue light emission and yellow-green light emission are maintained even over time. By making the efficiency change similar, the occurrence of color difference during long-term operation can be reduced or eliminated.

Hereinafter, the first and second embodiments will be specifically described separately according to the direction of light emission.

*First Embodiment*

FIG. 2 is a cross-sectional view showing a second stack of an organic light-emitting device according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a white organic light-emitting device according to a first embodiment of the present invention.

As shown in Figure 2, the organic light emitting device according to the first embodiment of the present invention is provided with a reflective electrode 130 on the lower side and a transparent electrode 140 on the upper side to emit upper light, of which the light emitting layer is In the adjacent stack, a yellow-green light-emitting layer (YG) with a shorter wavelength is provided adjacent to the reflective electrode 130 located at the bottom, and a red light-emitting layer (R) with a longer wavelength is provided adjacent to the transparent electrode 140 located at the top. An example is shown in which the first light emitting layer 310 and the second light emitting layer 320 are provided in contact with the lower and upper sides, respectively.

When the organic light-emitting device of FIG. 2 is implemented as a white organic light-emitting device 1000 as shown in FIG. 3, it is provided with a reflective electrode 130 on a substrate 100, and the first to second organic light-emitting devices 1000' of the organic material layer 1000' are sequentially formed. It has three stacks (200, 300, 400), a first charge generation layer 510 and a second charge generation layer 520 between each stack, and a transparent electrode ( 140).

The first stack 200 and the third stack 400 include first common layers 210 and 410 and second common layers 230 and 430 below and above the third light emitting layers 220 and 420, respectively. A third common layer 330 and a fourth common layer 335 are provided below the first light emitting layer 310 and above the second light emitting layer 320 of the second stack 300, respectively.

The reflective electrode 130 may function as an anode, and the transparent electrode 140 may function as a cathode. At this time, the first charge generation layer 510 and the second charge generation layer 520 may be provided as a single layer, but hole inflow from the lower stack to the upper stack and the upper stack to the lower stack may occur. For electron inflow, it may be composed of a double layer of n-type charge generation layers 510a and 520a and p-type charge generation layers 510b and 520b. In this case, the first common layer 210 adjacent to the reflective electrode 130 or the third common layer 330 and the first common layer 410 adjacent to the p-type charge generation layers 510b and 520b perform hole transport. The second common layer 430 adjacent to the transparent electrode 140 or the second common layer 230 and fourth common layer 335 adjacent to the n-type charge generation layers 510a and 520a are used to transport electrons. functions. And, in the white organic light emitting device according to the first embodiment of the present invention, the first light emitting layer 310 close to the reflective electrode 130 has a shorter wavelength than the second light emitting layer 320, and the second stack 300 emits the main light, and the second light-emitting layer 320, which is close to the transparent electrode 140, helps transport excitons to the first light-emitting layer 310, causing the main light emission to occur in the first light-emitting layer 310. It contains a single host of bipolar polarity.

Here, the first emission layer 310 has an emission peak of 510 nm to 590 nm, and the second emission layer 320 has an emission peak of 600 nm to 650 nm. In addition, since the dopant content of the first light-emitting layer 310 is greater than that of the second light-emitting layer 320, the second stack 300 mainly emits light in the color of the first light-emitting layer 310. At this time, the main light emission of the second stack 300 corresponds to yellow-green light emission, and sometimes shifts to greener light emission. In the second light-emitting layer 320, some of the excitons generated by combining introduced holes and electrons are converted to a ground state and are used to emit red light. In addition, since the second light-emitting layer 320 has a host with good electron transport properties inside, the remaining excitons that are not used for light emission are transferred to the first light-emitting layer 310, and the excitons that pass over are of the first light-emitting layer 310. It is used for light emission and helps the main light emission of the first light emitting layer 310.

In addition, the first light-emitting layer 310 is in contact with the third common layer 330 that functions as a hole transport on the lower side, and at this time, the second light-emitting layer 320 is in contact with the fourth common layer 355 that functions in electron transport. ) is made of a material whose single host has an electron mobility of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs and whose electron mobility is greater than the hole mobility, so that it performs an auxiliary electron transport function. In some cases, the fourth common layer 355 may be omitted from the second stack 300, and in this case, the second light-emitting layer 320 is in contact with the second charge generation layer 520 and the second In order to sufficiently transport the charges introduced from the charge generation layer 520 to the first light emitting layer 310, the single host is made of a material with good electron transport properties.

At this time, the excitons generated in the second light-emitting layer 320 are transferred to the first light-emitting layer 310, and the excitons transferred to the first light-emitting layer 310 and the excitons generated in the first light-emitting layer 310 are used for light emission. Preferably, the first light-emitting layer 310 includes a host whose electron mobility is higher than that of the second light-emitting layer 320. In this case, in the first light-emitting layer 310, in addition to the host having an electron mobility higher than the electron mobility of at least the single host included in the second light-emitting layer 320, there is additionally another host whose hole mobility is higher than the electron mobility. Additional hosts can be included.

Here, the first emission layer 310 is a yellow-green emission layer and may include at least one mixed host and at least one dopant. Specifically, a phosphorescent yellow-green dopant may be doped into a phosphorescent host material made of a carbazole-based compound or metal complex with good electron transport properties. Carbazole-based compounds may include CBP (4, 4'-bis(carbazole-9-yl)-biphenyl), CBP derivatives, mCP (N, N'-dicarbazolyl-3, 5-benzene), or mCP derivatives. , the metal complex may include a ZnPBO (phenyloxazole) metal complex or a ZnPBT (phenylthiazole) metal complex.

Examples of the single bipolar host material of the second light emitting layer 320 include CBP, CDBP, mCP, BCP, BAlq, and TAZ.

In addition, a dopant is included in the second light emitting layer 320 to emit red light. The phosphorescent dopant includes Ir(piz)3(Tris(1-phenylisoquinoline)iridium(III), Ir(piq)2(acac)( Bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), Ir(bip)2(acac)(Bis)2-benzolbithiophen-2-yl-pyridime)(acetylacetonate)iridium(III)), Ir(BT)2( acac)(Bis(2-pheylbenzothazolato)(accetylacetonate)iridium(III), etc., but is not limited thereto.

In addition, examples of fluorescent dopants that can be included in the second light-emitting layer 320 include Rubrene (5, 6, 11, 12-tetraphenylnaphthacene), DCJTB (4-(dicyanlmethylene)-2-tert-butyl-6-(1,1) ,7,7,-tetramethyljuloidin-4-yl-viyl)-4H), etc.

The first light-emitting layer 310 is the main light-emitting layer and may include yellow-green or green dopant at a concentration of 30% or less, and the second light-emitting layer 320 is a sub-light emitting layer and may contain a smaller content of 10% or less. Preferably, it may contain 5% or less of red dopant.

For reference, light-emitting materials are largely divided into host materials and guest materials in terms of functionality. In general, there are cases where light is emitted with only one host or guest material, but it is difficult to control the purity of light emission to a specific wavelength, so a host/guest system whose emission spectrum of the host matches the absorption spectrum of the guest is used to improve color purity and luminous efficiency. can increase.

Meanwhile, the above-described second light-emitting layer 320 has been described as an example of a red light-emitting layer, but a separate substituent may be added. The above-described materials are known and are not limited thereto, and if materials are developed, they may be changed to other red light-emitting materials if they combine the functions of the above-described auxiliary light-emitting layer and red light-emitting and electron transport functions.

The third light emitting layers 220 and 420 of the first stack 200 and the third stack 400 are blue light emitting layers. This blue light-emitting layer emits light with an emission peak in the range of 440 nm to 480 nm, and is made of a fluorescent or phosphorescent material.

Materials for the blue light-emitting layer may include at least one host and at least one dopant. Specifically, the fluorescent blue dopant may be doped into at least one fluorescent host material selected from the group consisting of anthracene derivatives, pyrene derivatives, and perylene derivatives. Alternatively, if a stable phosphorescent blue host material is developed, a replacement may be possible.

In some cases, in the first embodiment, the white organic light emitting device may reverse its function so that the reflective electrode 130 and the transparent electrode 140 become a cathode and an anode, respectively. In this case, the light emitting layer of each stack The position of is left as is, and contrary to the properties of each common layer described above, the common layer that functions as a hole transport is set to function as an electron transport, and the common layer that functions as an electron transport is set to function as a hole transport. In addition, the same light emission can be achieved by inverting the top and bottom of the n-type charge transport layer and the p-type charge transport layer of the charge transport layer as described above.

*Second Embodiment*

Below, the structure of the second embodiment will be described.

FIG. 4 is a cross-sectional view showing a second stack of an organic light-emitting device according to a second embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a white organic light-emitting device according to a second embodiment of the present invention.

As shown in Figure 4, the organic light emitting device according to the second embodiment of the present invention is provided with a reflective electrode 130 on the upper side and a transparent electrode 140 on the lower side to emit lower light, of which the light emitting layer is In the adjacent stack, a yellow-green light-emitting layer (YG) with a shorter wavelength is provided adjacent to the reflective electrode 130 located at the top, and a red light-emitting layer (R) with a longer wavelength is provided adjacent to the transparent electrode 140 located at the bottom. This shows an example in which the first light emitting layer 310 and the second light emitting layer 320 are provided vertically.

When the organic light emitting device of FIG. 4 is implemented as a white organic light emitting device 1000 as shown in FIG. 5, it is provided with a reflective electrode 130 on a substrate 100 and the first to third stacks 200 and 300 in that order. , 400), a first charge generation layer 510 and a second charge generation layer 520 between each stack, and a transparent electrode 140 on the third stack 400. It is formed by

The first stack 200 and the third stack 400 include first common layers 210 and 410 and second common layers 230 and 430 below and above the third light emitting layers 220 and 420, respectively. A third common layer 330 and a fourth common layer 335 are provided below the first light emitting layer 310 and above the second light emitting layer 320 of the second stack 300, respectively.

The transparent electrode 140 may function as an anode, and the reflective electrode 130 may function as a cathode. At this time, as described above, the first charge generation layer 510 and the second charge generation layer 520 are provided as a single layer or allow holes to flow from the lower stack to the upper stack and from the upper stack to the lower stack. For electron inflow into the stack, it may be composed of a double layer of n-type charge generation layers 510a and 520a and p-type charge generation layers 510b and 520b. In this case, the first common layer 210 adjacent to the transparent electrode 140 or the third common layer 330 and the first common layer 410 adjacent to the p-type charge generation layers 510b and 520b perform hole transport. The second common layer 430 adjacent to the reflective electrode 130 or the second common layer 230 and fourth common layer 335 adjacent to the n-type charge generation layers 510a and 520a perform electron transport. functions.

And, in the white organic light emitting device according to the second embodiment of the present invention, the first light emitting layer 310 on the upper side close to the reflective electrode 130 has a shorter wavelength than the second light emitting layer 320, and the second stack ( 300) emits the main light, and the second light-emitting layer 320 on the lower side close to the transparent electrode 140 helps transport excitons to the first light-emitting layer 310, thereby producing the main light emission in the first light-emitting layer 310. For this purpose, it contains a single bipolar host.

Here, the first emission layer 310 has an emission peak of 510 nm to 590 nm, and the second emission layer 320 has an emission peak of 600 nm to 650 nm. Also, since the dopant content of the first light-emitting layer 310 is greater than that of the second light-emitting layer 320, the second stack 300 mainly emits light in yellow-green, which is the light-emitting color of the first light-emitting layer 310. In the second light-emitting layer 320, some of the excitons generated by combining introduced holes and electrons are converted to a ground state and are used to emit red light. In addition, because the second light-emitting layer 320 has a host with good hole transport inside, the remaining excitons that are not used for light emission are transferred to the first light-emitting layer 310, and the excitons that have passed over are of the first light-emitting layer 310. It is used for light emission and is used for light emission of the first light emitting layer 310. That is, the luminous efficiency of the first light-emitting layer 310 increases due to excitons generated by itself and excitons transferred from the second light-emitting layer 320, and a voltage is applied to the transparent electrode 140 and the reflective electrode 130. When current is generated in the low-white organic light-emitting device 1000, the first light-emitting layer 310 relatively emits main light in the second stack 300, and the second light-emitting layer 320 emits auxiliary light.

Here, the second emitting layer 320 is in contact with the third common layer 330 that functions as a hole transport, and at this time, the first emitting layer 310 is in contact with the fourth common layer 340 that functions in electron transport. there is. Here, the second light-emitting layer 320 has an auxiliary hole transport function to the adjacent first light-emitting layer 310, and the single host has a hole mobility of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs. It is made of a material whose hole mobility is greater than electron mobility.

At this time, the second light-emitting layer 320 combines some of the holes introduced from the lower third common layer 330 with electrons in the second light-emitting layer 320 and uses them for internal red light emission, and the remaining light is not used for light emission. The remaining holes are transferred to the first light emitting layer 310. Accordingly, holes that have passed into the first light-emitting layer 310 combine with electrons in the first light-emitting layer 310 to generate excitons, and the generated excitons are used for light emission. In this case, the first light-emitting layer 310 has a hole mobility higher than that of the second light-emitting layer 320 to help transport holes from the second light-emitting layer 320 to the first light-emitting layer 310. Be sure to include the host. In this case, the first light-emitting layer 310 further includes another host with excellent electron mobility in addition to the host having a hole mobility higher than that of at least the single host included in the second light-emitting layer 320. It may be desirable to do so. At this time, the first light emitting layer 310 includes two types of hosts: a first host with high hole mobility and a second host with high electron mobility.

In addition, the second light-emitting layer 320, which functions as the auxiliary light-emitting layer, also functions as a hole transport layer, and in this case, the third common layer 330 can be omitted from the second stack 300. In some cases, as shown, the second light-emitting layer 320 is located on top of the third common layer 330, which functions as a hole transport layer, and functions as a second hole transport layer, and can also function to emit red light. . To this end, the second light-emitting layer 320 includes at least one host and at least one dopant containing the same material as that of the adjacent lower third common layer 330 or having a similar energy level.

The red host included in the second light-emitting layer 320 has bipolar characteristics, and a hole-transporting host with strong hole characteristics is used. For example, this red host has a LUMO (Lowest Unoccupied Molecular Orbital) 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 second light-emitting layer 320 omits the third common layer 330 and is located between the first charge generation layer 510 and the first light-emitting layer 310, the first light-emitting layer 310 is the main light-emitting layer. ) by trapping electrons leaking from the device to contribute to red light emission, thereby increasing red efficiency and contributing to improving the color gamut and brightness of the device. Here, the emission peak of the second emission layer 320 is in the range of 600 nm to 650 nm.

The host material used in the second light-emitting layer 320 has an aryl group as its core, and the aryl group, a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a substituted or unsubstituted heteroaryl group, and a substituted or unsubstituted heteroaryl group having 10 to 24 carbon atoms. Condensed aryl group of 30, substituted or unsubstituted heteroaryl group of 2 to 24 carbon atoms, substituted or unsubstituted alkyl group of 1 to 24 carbon atoms, substituted or unsubstituted heteroalkyl group of 1 to 24 carbon atoms, substituted or unsubstituted Cycloalkyl group with 3 to 24 carbon atoms, substituted or unsubstituted alkoxyl group with 1 to 24 carbon atoms, substituted or unsubstituted aryloxy group with 6 to 24 carbon atoms, substituted or unsubstituted alkylsilyl group with 1 to 24 carbon atoms, substituted Alternatively, it may be selected from the group consisting of an unsubstituted aryl silyl group having 6 to 24 carbon atoms, a cyano group, a halogen group, deuterium, and hydrogen, and R to R14 may form a condensation ring with an adjacent substituent.

And, the core component is an aryl group, such as phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine, acridine, cynoline, quinazoline, quinoxaline, naphthitrine, and phthalazine. , quinolazane, indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole.

In addition, a dopant is included in the second light emitting layer 320 to emit red light. The phosphorescent dopant includes Ir(piz)3(Tris(1-phenylisoquinoline)iridium(III), Ir(piq)2(acac)( Bis(1-phenylisoquinoline)(acetylacetonate)iridium(III), Ir(bip)2(acac)(Bis)2-benzolbithiophen-2-yl-pyridime)(acetylacetonate)iridium(III)), Ir(BT)2( acac)(Bis(2-pheylbenzothazolato)(accetylacetonate)iridium(III), etc., but is not limited thereto.

In addition, examples of fluorescent dopants that can be included in the second light-emitting layer 320 include Rubrene (5, 6, 11, 12-tetraphenylnaphthacene), DCJTB (4-(dicyanlmethylene)-2-tert-butyl-6-(1,1) ,7,7,-tetramethyljuloidin-4-yl-viyl)-4H), etc.

The first light-emitting layer 310 is the main light-emitting layer and may include yellow-green or green dopants at a concentration of 30% or less, and the second light-emitting layer 320 is a sub-light emitting layer and may contain a smaller content of a dopant of 10% or less. Preferably, the red dopant may be included at a concentration of 5% or less.

Meanwhile, the above-described second light-emitting layer 320 has been described as an example of a red light-emitting layer, but a separate substituent may be added. The above-described materials are known and are not limited thereto, and if materials are developed, they may be changed to other red light-emitting materials if they combine the functions of the above-described auxiliary light-emitting layer and red light-emitting and hole transport functions.

Meanwhile, in the organic light emitting devices of the first and second embodiments described above, the optimal position of the light emitting layer of each stack can be adjusted by adjusting the thickness of each common layer. In the second stack that emits two lights, the thickness of each common layer is determined to fit the first light-emitting layer with a relatively short wavelength to the optimal position, and the second light-emitting layer with a relatively long wavelength is positioned in contact with the first light-emitting layer. Its thickness and included host and dopant content can be defined to function as electron and exciton transport or hole transport.

FIG. 6 is a diagram showing an example of light emission of an organic light emitting display device using the white organic light emitting device of the present invention, FIG. 7 is a circuit diagram of each sub-pixel of FIG. 6, and FIG. 8 is an example of a cross-sectional view of each sub-pixel of FIG. 6. am.

The organic light emitting display device of the present invention emits light in one of the light emission directions, and each sub-pixel commonly uses a white organic light emitting device (WOLED) 1000 that emits white light as shown in Figure 3 or Figure 5. In addition, white light emission can be achieved by applying color filters (CFr, CFg, CFb) of the corresponding colors to the red, green, and blue subpixels, respectively. Additionally, each subpixel is provided with a circuit including a driving transistor (TFT), as shown in FIG. 7, to drive the organic light emitting diode.

When a white organic light-emitting device that commonly emits white light is provided in each sub-pixel of the present invention, an organic material for a white organic light-emitting device (WOLED) is deposited compared to the method of providing red, green, and blue organic light-emitting devices for each sub-pixel. As there is no need to separate areas, there is no need to use a metal mask for deposition, and for this reason, it is easy to enlarge. In addition, since white organic light emitting devices (WOLEDs) have uniform characteristics without distinguishing regions, in a structure that divides sub-pixels for each color including specific dopants and applies a light emitting layer of each color, when driven for a certain period of time, each color By solving problems showing different deterioration characteristics, there is an advantage in that lifespan is improved and power consumption can be reduced.

Additionally, in some cases, a white sub-pixel including only a white organic light emitting element and a TFT without a separate color filter may be provided in addition to the R, G, and B sub-pixels.

Meanwhile, as shown in FIG. 7, each sub-pixel has a basic 2T1C structure including a switching transistor (SW), a driving transistor (DR), a capacitor (Cst), and the white organic light emitting device (WOLED) described above, and additionally a transistor And a capacitor may be added. And, this circuit configuration is provided between the gate line GL in the first direction and the data line DL and driving power line VDDL in the direction crossing the gate line GL.

The organic light emitting display device includes the white organic light emitting diode (WOLED) that emits light in each individual sub-pixel, and may further include a compensation circuit (not shown) for each individual sub-pixel to prevent its deterioration.

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

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

The compensation circuit compensates for the threshold voltage of the driving transistor (DR). The compensation circuit may be composed of one or more transistors and capacitors. Since the compensation circuit can be configured in various ways, specific examples and descriptions thereof will be omitted.

The organic light emitting display device having the above sub-pixel structure can be implemented as a top emission type as shown in FIG. 3 or a bottom emission type as shown in FIG. 5 depending on the direction in which light is emitted. there is.

The cross-sectional view of the organic light emitting display device in FIG. 8 shows a bottom emission method in which light is emitted in the direction of the substrate where the subpixels are arranged, but the display is not limited thereto. In other words, it can also be applied to a top-emission organic light emitting display device in which light is emitted in the opposite direction to the substrate on which the sub-pixels are arranged.

And, Figure 8 shows an organic light emitting display device using a coplanar structure thin film transistor as an example, but is not limited thereto. Thin film transistors with a staggered structure can also be applied.

As shown in Figure 8, the organic light emitting display device of the present invention includes a transistor (TFT - the transistor shown is a driving transistor) formed on a substrate 100 in one sub-pixel, a white organic light emitting diode (WOLED), and a color filter (CF). may be included.

First, the transistor (TFT) includes a semiconductor layer 1124, a gate electrode 1121, a source electrode 1122, and a drain electrode 1123.

The semiconductor layer 1124 is formed on the substrate 100 made of an insulating material such as transparent plastic or polymer film.

The semiconductor layer 1124 may be made of an amorphous silicon film, a polycrystalline silicon film obtained by crystallizing amorphous silicon, an oxide semiconductor, or an organic semiconductor.

At this time, a buffer layer is further formed between the substrate 100 and the semiconductor layer 1124 to protect the transistor (TFT) formed in a subsequent process from impurities such as alkali ions leaking from the substrate 100.

A gate insulating film 1115a made of a silicon nitride film or a silicon oxide film is formed on the semiconductor layer 1124. Then, a gate line GL including a gate electrode 1121 and a first storage electrode (not shown) are formed thereon.

The gate electrode 1121, the gate line, and the first storage electrode are a single material made of a first metal material with low resistance characteristics, for example, aluminum, copper, molybdenum, chromium, gold, titanium, nickel, neodymium, or an alloy thereof. It may be formed in layers or multiple layers.

An interlayer insulating film 1115b made of a silicon nitride film or a silicon oxide film is formed on the gate electrode 1121, the gate line, and the first sustain electrode. Then, a data line DL, a driving voltage line VDDL, source/drain electrodes 1122 and 1123, and a second sustain electrode (not shown) are formed thereon.

The source electrode 1122 and the drain electrode 1123 are formed at a predetermined interval and are electrically connected to the semiconductor layer 1124. More specifically, a semiconductor layer contact hole exposing the semiconductor layer 1124 is formed in the gate insulating film 1115a and the interlayer insulating film 1115b, and the source/drain electrodes 1122 and 1123 are formed through the semiconductor layer contact hole. It is electrically connected to the semiconductor layer 1124.

At this time, the second storage electrode (not shown) overlaps a portion of the first storage electrode below the interlayer insulating film 1115b to form a storage capacitor Cst.

The data line, driving voltage line, source/drain electrodes 1122 and 1123, and the second sustain electrode are made of a second metal material with low resistance characteristics, such as aluminum, copper, molybdenum, chromium, gold, titanium, nickel, and neon. It may be formed as a single layer or multiple layers made of dium or an alloy thereof.

A protective film 1115c is formed on the substrate 100 on which the data lines, driving voltage lines, source/drain electrodes 1122 and 1123, and the second sustain electrode are formed.

Then, a color filter 2000 is formed on the protective film 1115c. The color filter is a color conversion material that converts white light emitted from the upper white organic light emitting device (WOLED) 1000 into red, green, and blue.

An overcoat layer 1115d is formed on the protective film 1115c, covering the color filter 2000 (CF) and exposing a portion of the drain electrode 1123. The overcoat layer 1115d may be formed of an organic material, but is not limited to this and may also be formed of an inorganic material or an organic-inorganic mixture material.

Then, patterned transparent electrodes 140 are separately formed in each sub-pixel, and a bank 1115e that opens the light emitting portion of the sub-pixel is formed.

Subsequently, a white organic light emitting device (WOLED) including the transparent electrode 140 as in the above-described embodiment may be formed.

The white organic light emitting device (WOLED) is electrically composed of an anode 110, a light emitting part, and a cathode 120, of which the transparent electrode 140 of FIG. 5 described above is used as the anode 110 and the reflective electrode 130 is used as the anode 110. It can be positioned as the cathode 120, or, conversely, as shown in FIG. 3, the reflective electrode 130 can be positioned as the anode 110 and the transparent electrode 140 can be positioned as the cathode 120. Here, in the former, a transparent electrode patterned for each sub-pixel functions as an anode, and in the latter, a reflective electrode patterned for each sub-pixel functions as an anode. And, in the meantime, the light emitting unit may correspond to a plurality of stacks between the two electrodes described above.

In the following experiment, light intensity and lifespan are examined when implementing an organic light emitting display device using the white organic light emitting device of the present invention.

In an embodiment of the present invention, a stack forming a white organic light emitting device (WOLED) is used by arranging a single light-emitting layer of a blue light-emitting layer in the first stack and a red light-emitting layer and a yellow-green light-emitting layer in the second stack, arranged adjacently, The third stack uses a single blue emitting layer.

In the comparative example compared to this, the first and third stacks were used in the same manner as in the example, and a single yellow-green light emitting layer was used in the second stack.

Figure 9 is a graph showing the intensity by wavelength when driving the white organic light emitting device of the present invention.

As shown in FIG. 9, when the organic light emitting display device according to the first and second embodiments of the present invention is implemented, in addition to the main blue emission and yellow-green emission in the entire visible light range, the light emission intensity has a peak characteristic in the red region. You can have

The color gamut evaluation of these comparative examples and Examples 1 and 2 is examined in Table 1.

In the following experimental and comparative examples, the experiment was based on three stacks, and the stack adjacent to the anode and cathode was identically equipped with a single blue light-emitting layer, and the middle stack had a different light-emitting layer composition. That is, in the comparative examples, only the yellow-green light-emitting layer was applied to the middle stack, and in the experimental examples, the red light-emitting layer and the yellow-green light-emitting layer were in contact with each other. At this time, the comparative example was tested using the bottom emission method, and Experiments 1 to 3 were conducted using the bottom emission method, but the red emission layer was configured below the yellow-green emission layer, corresponding to the first embodiment of the present invention described above. However, the experiment was conducted by reducing the hole mobility of the single host included in the red emission layer to 8.0x10 ^-4 cm ² /Vs, 2.0x10 ^-4 cm ² /Vs, and 5.0x10 ^{-5 cm 2} /Vs, respectively.

In the following experiment, in the bottom light emitting method, when the red light emitting layer is provided below the yellow green light emitting layer, the red light emitting layer emits red light and also has a hole transport function, so a material with hole mobility greater than electron mobility is used as the host for the red light emitting layer. It was used as. In addition, if the hole transport characteristics of the red light-emitting layer are too large for its own red light-emitting above a certain level, the tendency is to transport holes to the yellow-green light-emitting layer, and the coupling rate of holes and electrons in the red light-emitting layer decreases. To prevent this, the hole mobility is adjusted. The upper limit is set to 5.0x10 ^-3 cm ² /Vs. In other words, the hole transport characteristic does not simply function to emit red light, but causes the main light to be emitted from the yellow-green light-emitting layer, so red light must be auxiliary light-emitted, so the hole mobility of the host of the red light-emitting layer is 1.0x10 ^-6. It must be more than cm ² /Vs to ensure a certain amount of hole transport into the yellow-green light emitting layer. In Experimental Examples 1 to 3 below, the hole mobility range of the host of the red light-emitting layer is set within the range of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs, and in this range, the red efficiency is at least It was confirmed that more than 6.7cd/A was secured. In addition, the color gamut of Experimental Examples 1 to 3 shows an improvement of more than 3 in the DCI overlap ratio characteristic and an improvement of 3 or more in the BT709 characteristic compared to the color gamut of the comparative example.

Additionally, Experimental Example 5 uses a top emission method, but the red emission layer is configured on the upper side of the yellow-green emission layer, which corresponds to the second embodiment of the present invention described above. In this case, the red light-emitting layer located above the yellow-green light-emitting layer functions as an electron transport in addition to red light-emitting, so a material with electron mobility greater than hole mobility was used as a host for the red light-emitting layer. That is, even in the case corresponding to the second example, the red luminance increased from 4.8 cd/A in the comparative example to 6.5 cd/A, and the color gamut also increased to a similar level as the first example described above. was able to confirm.

Meanwhile, in Experimental Example 4, compared to Experimental Example 5, the light emission direction was reversed to downward emission, which indicates that the longer wavelength red light-emitting layer was configured closer to the reflective electrode. In this case, the red efficiency increases compared to the comparative example without a red light-emitting layer, but even if the host of the red light-emitting layer has the same electron mobility characteristics, the resonance characteristics of the light-emitting layers between the transparent electrode and the reflective electrode are not optimized, so the relative This indicates that both red efficiency and color gamut are lowered compared to Experimental Example 5. This shows that both efficiency and color gamut tend to increase when the light emitting layer with a longer wavelength is moved away from the reflective electrode in both the top and bottom light emission methods.

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

Among the color gamut in the table above, BT709 refers to the color gamut that is satisfied by the conditions of sampling LUMA 74.25 MHz and sampling Chroma 6.75 MHz (4:2:2) in HDTV, and DCI refers to the satisfaction of the color gamut that can be expressed in digital cinema (Digital Cinema Initiatives). Increasing each value means that there is an effect of providing clearer picture quality than on a large-area TV. In addition, Table 1 above shows that the experimental examples have a wider BT709 or DCI overlap ratio than the comparative examples, showing excellent color gamut when applying the embodiments of the present invention.

Figure 10 is a graph showing a comparison of the intensity at the red wavelength of comparative examples and experimental examples.

Referring to the graph of FIG. 10 for the actual efficiency of red in the experiments in Table 1 described above, when the red light-emitting layer is provided in contact with the yellow-green light-emitting layer compared to the comparative example without the red light-emitting layer (Experimental Examples 1 to 5) It was confirmed that the intensity of red light emission increased in all cases. In addition, as in the first embodiment, when applying the bottom light-emitting structure and providing it below the yellow-green light-emitting layer, as shown in Experimental Examples 1 to 3, the hole mobility of the host of the red light-emitting layer, where hole transport is higher than electron transport, is It was confirmed that when gradually lowered from 8.0x10 ^-4 cm ² /Vs to 5.0x10 ^-5 cm ² /Vs, the red intensity tended to increase.

As in the second embodiment, in the case of applying the upper light-emitting structure and providing it on the upper side of the yellow-green light-emitting layer, the electron mobility of the host of the red light-emitting layer, where electron transport is higher than hole transport, is 6.0x10 ^-5 , as shown in Experimental Example 5. When cm ² /Vs, it was shown that the red intensity was approximately between Experimental Example 1 and Experimental Example 2.

This is because, in the structure of arranging adjacent light-emitting layers in the structure of the first and second embodiments of the present invention, the light-emitting layer with a shorter wavelength is placed closer to the reflective electrode and the light-emitting layer with a longer wavelength is placed closer to the transparent electrode, thereby improving the luminous efficiency of the adjacent light-emitting layers. It can be seen that all are raised to the optimal level.

Figures 11A to 11C are graphs showing the intensity of each color of white organic light emitting device of the present invention in comparative examples and examples of the present invention.

As shown in Table 2 and Figure 5, the white organic light emitting device of the present invention can be confirmed to have increased efficiency in all red, blue, and white colors when the yellow-green light-emitting layer and the red light-emitting layer are placed in contact with each other in at least one of the plurality of stacks. There is a slight decrease in efficiency in green, but the decrease in intensity in green emission is almost insignificant, and it was confirmed that the efficiency increase is significant in the remaining emission colors.

division R(cd/A) G(cd/A) B(cd/A) W(cd/A) Comparative example (B/YG/B) 4.8 20.6 2.7 72.4 Example (B/R+YG/B) 6.7 20.3 2.8 76.3

In addition, when checking the intensity of the emission color of each color, it can be seen that at the emission peak of red emission, the intensity increases by more than 50% from approximately 0.04 to 0.065 in the Example compared to the Comparative Example, as shown in FIG. 11a. In addition, as shown in Figure 11b, at the green emission peak, there is an intensity decrease of less than 10% from 0.82 to 0.75, but as shown in Table 2, in green emission, which has relatively high efficiency compared to other color emission, this intensity decrease is different for each emission color. Due to the difference in efficiency, it is possible to reduce the color difference between light emission colors that occurs when the white organic light emitting device is driven for a long time, thereby reducing the difference in viewing perception from the perspective of the display device.

And, as shown in Figure 11c, the blue emission peak increases from 0.17 to 0.18 in the example compared to the comparative example, showing that the efficiency increases even in the blue emission peak when the white organic light emitting device of the present invention is applied. .

Figures 12A to 12C are graphs showing the lifespan of the white organic light emitting device of the present invention for each emission color.

Table 3 and FIGS. 12A to 12C show that the material composition of the second light-emitting layer 320, which is the red light-emitting layer of the second stack, is different from the structure of the white organic light-emitting device according to the second embodiment of the present invention as shown in FIG. 5. The experiment was conducted with the remaining layer structures and materials remaining the same. In this case, in Comparative Example 2, the second light-emitting layer 320 was composed of two hosts and one dopant, and the hosts used were different hosts, a hole-transporting host and an electron-transporting host. Separately from this, in Experimental Examples 1 to 3 of the present invention, the second light-emitting layer 320 is composed of a single host and a single dopant, and is located below the first light-emitting layer 310, and the single host is The material had a hole mobility of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs, and the hole mobility was greater than the electron mobility. In addition, in Experimental Example 5 of the present invention, the second light-emitting layer 320 is composed of a single host and a single dopant, and is located on the upper side of the first light-emitting layer 310, and the single host has an electron mobility of It was made of a material whose electron mobility was greater than the hole mobility and was 6.0x10 ^-5 cm ² /Vs.

division red life green life blue life Comparative Example 2 (B/R+YG/B)
R: 2 hosts 1 dopant 100% 100% 100% Experimental Example 1 (B/R+YG/B)_bottom
R: 1 host 1 dopant 140% 101% 100% Experimental Example 2
(B/R+YG/B)_bottom
R: 1 host 1 dopant 144%
- - Experimental Example 3
(B/R+YG/B)_bottom
R: 1 host 1 dopant 170% - - Experimental Example 5
(B/YG+R/B)_top
R: 1 host 1 dopant 120% - -

In this case, assuming that the lifespan of each luminous color in Comparative Example 2 is 100%, in Experimental Example 1 of the present invention, the red lifespan is significantly improved to 140% as shown in Figure 11a, and the green lifespan is also 101% as shown in Figure 11b. There was a slight improvement, and as shown in Figure 11c, it was confirmed that the blue lifespan was at the same level as Comparative Example 2.

In Table 3, Experimental Example 1 was conducted with the hole mobility of the host included in the red light-emitting layer being 8.0x10 ^-4 cm ² /Vs, and in the same batch, the hole mobility of the host was 2.0x10 ^-4 cm ² /Vs, respectively. Experimental Examples 2 and 3 were performed while reducing the temperature to 5.0x10 ^-5 cm ² /Vs. Through Experimental Examples 1 to 3, it was found that the red lifetime increases as the hole mobility of the host of the red light-emitting layer in the bottom emission method gradually decreases in the range of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs. Could know.

Even in the case of the top emission method, an increase in lifespan was confirmed compared to the comparative example (when the red emission layer was composed of 2 hosts and 1 dopant).

That is, through the above experimental examples, when the white organic light emitting device of the present invention is applied, the red lifespan is significantly increased, which can be expected to significantly improve the red color gamut and lifespan, which is expected to be achieved in an organic light emitting display device that performs various color displays. This means that a display that can meet the needs of viewers is possible.

Meanwhile, the present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It will be clear to a person with ordinary knowledge.

100: substrate 110: anode
120: cathode 130: reflective electrode
140: transparent electrode 200: first stack
210: first common layer 220: third emitting layer
230: second common layer 300: second stack
310: first emitting layer 320: second emitting layer
330: third common layer 335: fourth common layer
400: third stack 410: first common layer
420: third light emitting layer 430: second common layer
510: first charge generation layer 520: second charge generation layer

Claims (11)

a cathode located on the anode;
A plurality of stacks positioned between the anode and the cathode; and
At least one charge generation layer located between the plurality of stacks,
At least one of the plurality of stacks has a stacked structure of a first light-emitting layer and a second light-emitting layer in contact with the first light-emitting layer,
The anode is a reflective electrode having a higher reflectance than the cathode,
The first light-emitting layer located between the anode and the second light-emitting layer emits light having an emission peak of a shorter wavelength than the second light-emitting layer,
The second light-emitting layer includes a single bipolar host whose electron mobility is greater than hole mobility,
The first light-emitting layer is a white organic light-emitting device comprising a host having higher electron mobility than the second light-emitting layer. According to clause 1,
The first light-emitting layer emits light with an emission peak of 510 nm to 590 nm,
The second light emitting layer is a white organic light emitting device that emits light with an emission peak of 600 nm to 650 nm. According to clause 1,
A white organic light emitting device wherein the dopant content of the first emitting layer is greater than the dopant content of the second emitting layer. According to clause 1,
The plurality of stacks have a stacked structure of a first stack, a second stack, and a third stack,
The second stack includes the first light-emitting layer and the second light-emitting layer,
The first stack and the third stack include a third light-emitting layer that emits light having an emission peak of a shorter wavelength than that of the first light-emitting layer and the second light-emitting layer. According to clause 4,
A white organic light emitting device in which the single host of the second light emitting layer has an electron mobility of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs. a cathode located on the anode;
A plurality of stacks positioned between the anode and the cathode; and
At least one charge generation layer located between the plurality of stacks,
At least one of the plurality of stacks has a stacked structure of a first light-emitting layer and a second light-emitting layer in contact with the first light-emitting layer,
The cathode is a reflective electrode having a higher reflectivity than the anode,
The first light-emitting layer located between the cathode and the second light-emitting layer emits light having an emission peak of a shorter wavelength than the second light-emitting layer,
The second light-emitting layer includes a single bipolar host whose hole mobility is greater than electron mobility,
The first light-emitting layer is a white organic light-emitting device comprising a first host having a higher hole mobility than the second light-emitting layer. According to clause 6,
A white organic light emitting device wherein the single host of the second light emitting layer has a hole mobility of 1.0x10 ^-6 cm ² /Vs to 5.0x10 ^-3 cm ² /Vs. According to clause 6,
The first light emitting layer further includes a second host having electron mobility higher than hole mobility. A substrate having subpixels;
a driving transistor provided in the sub-pixel of the substrate; and
Includes an organic light emitting diode connected to the driving transistor,
The organic light emitting diode includes a plurality of stacks positioned between a reflective electrode and a transparent electrode and at least one charge generation layer positioned between the plurality of stacks,
At least one of the plurality of stacks has a stacked structure of a first light-emitting layer and a second light-emitting layer in contact with the first light-emitting layer,
The first light-emitting layer located between the reflective electrode and the second light-emitting layer emits light having an emission peak of a shorter wavelength than the second light-emitting layer,
The second light-emitting layer includes a single bipolar host whose electron mobility is greater than hole mobility,
The first light emitting layer includes a first host having a higher electron mobility than the second light emitting layer and a second host having a hole mobility higher than the electron mobility. A substrate having subpixels;
a driving transistor provided in the sub-pixel of the substrate;
a reflective electrode connected to the driving transistor;
a first stack located on the reflective electrode and including a first light emitting layer;
a first charge generation layer located on the first stack;
a second stack located on the first charge generation layer and including a second light-emitting layer and a third light-emitting layer located on the second light-emitting layer;
a second charge generation layer located on the second stack;
a third stack located on the second charge generation layer and including a fourth light emitting layer; and
Includes a transparent electrode located on the third stack,
The second light-emitting layer located between the first light-emitting layer and the second charge generation layer is in contact with the first light-emitting layer, and the first light-emitting layer emits light having an emission peak of a shorter wavelength than the second light-emitting layer,
The second light-emitting layer has an electron mobility of 1.0x10-6 cm2/Vs to 5.0x10-3 cm2/Vs and includes a single bipolar host whose electron mobility is greater than the hole mobility,
The first emission layer includes a host having a higher electron mobility than the second emission layer. A substrate having subpixels;
a driving transistor provided in the sub-pixel of the substrate;
a transparent electrode connected to the driving transistor;
a first stack located on the transparent electrode and including a first light emitting layer;
a first charge generation layer located on the first stack;
a second stack located on the first charge generation layer and including a second light emitting layer and a third light emitting layer located on the second light emitting layer;
a second charge generation layer located on the second stack;
a third stack located on the second charge generation layer and including a fourth light emitting layer; and
Including a reflective electrode located on the third stack,
The second light-emitting layer located between the first light-emitting layer and the second charge generation layer emits light having an emission peak of a shorter wavelength than the first light-emitting layer,
The first light-emitting layer has a hole mobility of 1.0x10-6 cm2/Vs to 5.0x10-3 cm2/Vs and includes a single bipolar host whose hole mobility is greater than electron mobility,
The second light emitting layer includes a host having higher hole mobility than the first light emitting layer.