KR102543974B1 - White organic light emitting display device - Google Patents

Abstract

The white organic light emitting display device of the present invention is a white organic light emitting display device having an n(≥2) stack structure, wherein a red light emitting layer including a hole transport type host is positioned between the charge generation layer and the yellow-green light emitting layer. characterized by
According to this, since the red light emitting layer serves as a hole transport layer and an electron blocking layer other than the light emitting layer, it is possible to improve luminance, color gamut and color viewing angle.
In addition, the white organic light emitting display device of the present invention reduces quenching of excitons between the charge generation layer and the red light emitting layer by additionally inserting an auxiliary layer made of a hole transport type host between the charge generation layer and the red light emitting layer. It is characterized in that the efficiency of the red light emitting layer can be further improved.

Description

White organic light emitting display device {WHITE ORGANIC LIGHT EMITTING DISPLAY DEVICE}

The present invention relates to a white organic light emitting display device, and more particularly, to a white organic light emitting display device having an n(≥2) stack structure.

Recently, as interest in information displays has increased and demands for using portable information media have increased, research and commercialization of lightweight thin display devices have been focused.

In the field of such display devices, a liquid crystal display device (LCD) is one of the display devices that is attracting attention because of its light weight and low power consumption.

As another display device, since the organic light emitting display device is a self-emission type, it is superior to the liquid crystal display device in terms of viewing angle and contrast ratio. In addition, since a backlight is not required, it is possible to be lightweight and thin, and is advantageous in terms of power consumption. In addition, there are advantages in that DC low voltage driving is possible and response speed is fast.

Hereinafter, the basic structure and operating characteristics of the organic light emitting display will be described in detail with reference to the drawings.

1 is a diagram illustrating a light emitting principle of a general organic light emitting diode.

An organic light emitting display device generally includes an organic light emitting diode having the structure shown in FIG. 1 .

Referring to FIG. 1, an organic light emitting diode includes an anode 30f as a pixel electrode, a cathode 30g as a common electrode, and organic layers 30a, 30b, 30c, 30d, and 30e formed therebetween. do.

At this time, the organic layers 30a, 30b, 30c, 30d, and 30e include a hole transport layer (HTL) 30b and an electron transport layer (ETL) 30d and a hole transport layer 30b and an electron transport layer ( 30d) includes an emission layer (EML) 30c interposed therebetween.

At this time, in order to improve the luminous efficiency, a hole injection layer (HIL) 30a is interposed between the anode 30f and the hole transport layer 30b, and electrons are interposed between the cathode 30g and the electron transport layer 30d. An Electron Injection Layer (EIL) 30e is interposed therebetween.

In the organic light emitting diode configured as described above, when positive (+) and negative (-) voltages are applied to the anode 30f and the cathode 30g, respectively, holes passing through the hole transporting layer 30b pass through the electron transporting layer 30d. One electron moves to the light emitting layer 30c to form an exciton. In addition, when the exciton transitions from an excited state to a ground state, that is, a stable state, light of a predetermined wavelength is generated.

An organic light emitting display device displays an image by arranging sub-pixels on which organic light emitting diodes having the above-described structure are formed in a matrix form and selectively controlling the sub-pixels with a data voltage and a scan voltage.

At this time, the organic light emitting display device is divided into a passive matrix type and an active matrix type using a thin film transistor as a switching element. Among them, the active matrix method selects a sub-pixel by selectively turning on a thin film transistor, which is an active element, and maintains light emission of the sub-pixel with a voltage maintained in a storage capacitor.

In addition, organic light emitting display devices include a white organic light emitting display device that emits white light using at least two light emitting layers. Since the organic light emitting layer emits white light, the white organic light emitting display device includes a color filter to convert the white light into red, green, and blue light.

An organic light emitting display device emitting white light may have a structure including two light emitting layers in a complementary color relationship. In this structure, when white light passes through the color filter, there is a difference between the wavelength region of the emission peak of each light emitting layer and the transmission region of the color filter, so the range of colors that can be expressed is narrowed, making it difficult to realize a desired color reproduction rate.

For example, in the case of an organic light emitting display device including a blue light emitting layer and a yellow-green light emitting layer that emits white light, white light is emitted while emission peak wavelengths are formed in a blue wavelength region and a yellow-green wavelength region. However, when such white light passes through the red, green, and blue color filters, the transmittance of the blue wavelength region is lowered than that of the red or green wavelength region, resulting in lower luminous efficiency and color reproduction rate. In addition, the blue light emitting layer is made of a fluorescent light emitting material and the yellow light emitting layer is made of a phosphorescent light emitting material. The luminous efficiency of the yellow phosphorescent light emitting layer is relatively higher than that of the blue fluorescent light emitting layer, resulting in a difference in efficiency between the yellow phosphorescent light emitting layer and the blue fluorescent light emitting layer. As a result, the luminous efficiency and color gamut are reduced.

The present invention is to solve the above problems, and an object of the present invention is to provide a white organic light emitting display device having an n(≥2) stack structure with improved luminance, color gamut and color viewing angle. there is

Other objects and features of the present invention will be described in the following constitution of the invention and claims.

In order to achieve the above object, a white organic light emitting display device according to an embodiment of the present invention is a white organic light emitting display device having an n(≥2) stack structure, is positioned on a first electrode, and has a blue light emitting layer. A first light emitting unit including a first light emitting unit, a first charge generation layer positioned on the first light emitting unit, a red light emitting layer and a yellow-green light emitting layer contacting the first charge generation layer on the first charge generation layer A second light emitting unit including a It may be configured to include a second electrode positioned on the second light emitting unit.

A white organic light emitting display device according to an embodiment of the present invention is characterized in that a red light emitting layer is positioned on the first charge generation layer without a hole transport layer.

In the white organic light emitting display device according to an embodiment of the present invention, the red light emitting layer includes at least one hole transport type host having hole transport characteristics, and the hole transport type host constitutes a hole transport functional layer.

A white organic light emitting display device according to an exemplary embodiment of the present invention may further include a third light emitting part disposed on the second light emitting part and including a blue light emitting layer.

The white organic light emitting display device according to an exemplary embodiment of the present invention may further include a second charge generation layer positioned between the second light emitting part and the third light emitting part.

The first light emitting unit may include a first hole transport layer positioned between the first electrode and the blue light emitting layer, and a first electron transport layer positioned between the blue light emitting layer and the first charge generation layer.

The second light emitting unit may include a second electron transport layer positioned between the yellow-green light emitting layer and the second electrode.

An auxiliary layer positioned between the first charge generation layer and the red light emitting layer and having hole transport characteristics may be further included.

The auxiliary layer may be made of a hole transport type host.

The red emission layer may include a red dopant having a doping concentration of 0.5 to 10%.

The red light emitting layer may include a hole transport type host and at least one other host and one or more dopants.

The thickness of the hole transport type host and at least one other host may have a ratio of 0:1 to 1:0.

A white organic light emitting display device according to another embodiment of the present invention is positioned on a first electrode, and includes a first hole transport layer, a first light emitting layer, and a first electron transport layer, and a first light emitting portion positioned on the first light emitting portion. A second light emitting layer having a hole transport function and a second light emitting unit including a second electron transport layer, and a third light emitting unit located on the second light emitting unit and including a second hole transport layer, a third light emitting layer, and a third electron transport layer. and a second electrode positioned on the third light emitting unit.

The second light emitting layer may include two light emitting layers of a red light emitting layer and a yellow-green light emitting layer.

The red light emitting layer has a hole transport function, and the second light emitting unit may not have a hole transport layer.

The red light emitting layer includes at least two hosts and one dopant, and one of the at least two hosts may be a hole transport type host having a hole transport function.

A first charge generation layer positioned between the first light emitting unit and the second light emitting unit may be further included.

A second light emitting layer may be positioned on the first charge generation layer.

It is located between the first charge generation layer and the second light emitting layer and may further include an auxiliary layer having hole transport characteristics.

The auxiliary layer may be made of a hole transport type host.

As described above, in the white organic light emitting display device according to an exemplary embodiment of the present invention, the red light emitting layer simultaneously serves as a hole transport layer that transfers holes to the yellow-green light emitting layer in addition to serving as the light emitting layer. Accordingly, luminance, color gamut, and color viewing angle may be improved.

In addition, in the white organic light emitting display device according to an embodiment of the present invention, the dopant included in the red light emitting layer traps electrons leaking from the yellow-green light emitting layer, thereby contributing to electron-hole light emission, thereby contributing to yellow-green light emission. Rather, by emitting red light, the efficiency of red light is increased, contributing to the improvement of the luminance of the panel.

In addition, in the white organic light emitting display device according to another embodiment of the present invention, when an auxiliary layer made of a hole transport type host is additionally formed between the charge generation layer and the red light emitting layer, holes are transferred to the yellow-green light emitting layer, thereby increasing efficiency. It is possible to further improve the efficiency of the red color by reducing the probability of quenching between the P-type charge generation layer and the red light emitting layer.

1 is a diagram illustrating the light emitting principle of a general organic light emitting diode;
2 is an exemplary view schematically showing the structure of an organic light emitting diode according to an embodiment of the present invention.
3 is a graph showing light intensity according to wavelength in a white organic light emitting display device according to an embodiment of the present invention, as an example;
4 is a block diagram schematically showing a white organic light emitting display device according to an embodiment of the present invention.
5 is an exemplary diagram showing a circuit configuration for a sub-pixel of an organic light emitting display device;
6 is an exemplary view showing a schematic structure of sub-pixels in the white organic light emitting display device according to the embodiment of the present invention shown in FIG. 4;
7 is a schematic cross-sectional view of a portion of sub-pixels of a white organic light emitting display device according to an embodiment of the present invention.
8 is an exemplary view schematically showing the structure of an organic light emitting diode in the white organic light emitting display device according to the embodiment of the present invention shown in FIG. 7;
9 is a diagram schematically showing a band diagram of an organic light emitting diode according to an embodiment of the present invention.
10A, 10B, and 10C are views schematically showing color coordinate changes when the viewing angle changes from 0° to 60°.
11a, 11b, and 11c are photographs showing color coordinate changes when the viewing angle changes from 0° to 60°.
12 is a graph showing a change in color coordinates according to a change in viewing angle.
13a and 13b are graphs showing light intensity according to wavelength.
14a and 14b are graphs showing changes in light intensity over time.
15 is another graph showing a change in color coordinates according to a change in viewing angle.
16a and 16b are other graphs showing light intensity according to wavelength.
17 is an exemplary view schematically showing the structure of an organic light emitting diode in a white organic light emitting display device according to another embodiment of the present invention.
18 is a diagram schematically showing a band diagram of an organic light emitting diode according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a white organic light emitting display device according to the present invention will be described in detail so that those skilled in the art can easily implement it.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various forms different from each other, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification. The sizes and relative sizes of layers and regions in the drawings may be exaggerated for clarity of explanation.

When an element or layer is referred to as “on” or “on” another element or layer, it includes both cases where another element or layer is intervening as well as directly on another element or layer. do. On the other hand, when an element is referred to as “directly on” or “directly on”, it indicates that no other element or layer is intervening.

The spatially relative terms "below, beneath", "lower", "above", "upper", etc., refer to one element or component as shown in the drawing. It can be used to easily describe the correlation between and other elements or components. Spatially relative terms should be understood as encompassing different orientations of elements in use or operation in addition to the orientations shown in the figures. For example, when flipping elements shown in the figures, elements described as “below” or “beneath” other elements may be placed “above” the other elements. Thus, the exemplary term “below” may include directions of both below and above.

Terminology used herein is for describing the embodiments, and therefore is not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprise" and/or "comprising" means that a stated component, step, operation, and/or element is the presence of one or more other components, steps, operations, and/or elements. or do not rule out additions.

2 is an exemplary view schematically showing the structure of an organic light emitting diode according to an embodiment of the present invention.

At this time, FIG. 2 shows an organic light emitting diode having a 2-stack 2-peak structure as an example.

3 is a graph showing light intensity according to wavelength in a white organic light emitting display device according to an embodiment of the present invention, as an example.

2, it is located between the first electrode 18 and the second electrode 28 and the first electrode 18 and the second electrode 28, and the first light emitting part 31 and the second light emitting part (32).

Also, an N-type charge generation layer 35a and a P-type charge generation layer 35b are positioned between the first light emitting part 31 and the second light emitting part 32 . In this way, when two light emitting units are configured, the charge generation layers 35a and 35b control the balance of charges between the first light emitting unit 31 and the second light emitting unit 32 .

At this time, a plurality of transport layers and buffer layers may be provided in the first light emitting unit 31 and the second light emitting unit 32 to improve efficiency and lifespan.

That is, the first light emitting unit 31 includes a first hole transport layer 31b, a blue light emitting layer 31c, and a first electron transport layer 31d.

The second light emitting unit 32 includes a second hole transport layer 32b, a yellow-green light emitting layer 32c, and a second electron transport layer 32d.

Such a white organic light emitting diode may have poor efficiency and color gamut because it does not have a red light emitting layer. That is, the above-described white organic light emitting display device emits white light using blue peak light and yellow-green peak light, and implements a display by passing the white light through red, green, and blue color filters. There may be insufficient red efficiency.

As shown in FIG. 3, the blue light emitting layer exhibits light intensity in a wavelength range of 440 nm to 480 nm, and the yellow-green light emitting layer exhibits light intensity in a wavelength range of 510 nm to 590 nm. It can be seen that no light intensity appears at 600 nm to 650 nm corresponding to the wavelength range of red. Therefore, it can be seen that the red efficiency is insufficient.

Accordingly, a high current is required to produce high luminance, and as a result, power consumption increases. In addition, when another layer is added to improve efficiency, a process is added, resulting in an increase in cost.

Therefore, the inventors of the present invention conducted several experiments to improve red efficiency. The inventors of the present invention invented an organic light emitting display device having a new structure with improved efficiency and color reproducibility through various experiments. This will be described with reference to the following examples.

4 is a schematic block diagram of a white organic light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 4 , a white organic light emitting display device according to an embodiment of the present invention includes an image processing unit 115, a data conversion unit 114, a timing control unit 113, a data driver 112, and a gate driver 111. and a display panel 110 .

The image processing unit 115 performs various image processing such as setting a gamma voltage to achieve maximum luminance according to the average image level using the RGB data signal RGB, and then outputs the RGB data signal RGB. The image processing unit 115 generates a driving signal including at least one of a vertical sync signal (Vsync), a horizontal sync signal (Hsync), a data enable signal (DES), and a clock signal (CLK) as well as an RGB data signal (RGB). print out

The timing control unit 113 receives at least one of a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a data enable signal (DES), and a clock signal (CLK) from the image processing unit 115 or the data conversion unit 114. Receives a driving signal including The timing control unit 113 generates a gate timing control signal (GCS) for controlling the operation timing of the gate driver 111 and a data timing control signal (DCS) for controlling the operation timing of the data driver 112 based on the driving signal. outputs

The timing control unit 113 outputs a 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 it into a gamma reference voltage. and output The data driver 112 outputs the converted data signal DATA through the data lines DL1 to DLm. The data driver 112 is formed in the form of an integrated circuit (IC).

The gate driver 111 shifts the level of the gate voltage in response to the gate timing control signal GCS supplied from the timing controller 113 and outputs a gate signal. The gate driver 111 outputs a gate signal through the gate lines GL1 to GLn. The gate driver 111 is formed in the form of an IC or formed in the display panel 150 in a gate-in-panel (GIP) method.

For example, the display panel 110 may be implemented as 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 RGB sub-pixels SPr, SPg, and SPb. However, the present invention is not limited thereto, and may additionally include a white sub-pixel.

5 is an exemplary diagram showing a circuit configuration of a sub-pixel of an organic light emitting display device.

At this time, a case in which the sub-pixel shown in FIG. 5 is composed of a 2T (Transistor) 1C (Capacitor) structure including a switching transistor, a driving transistor, a capacitor, and an organic light emitting diode is taken as an example. However, the present invention is not limited thereto, and when a compensation circuit is added, various configurations such as 3T1C, 4T2C, and 5T2C may be used.

Referring to FIG. 5 , the organic light emitting display device includes gate lines GL arranged in a first direction, data lines DL and a driving power supply line VDDL arranged spaced apart from each other in a second direction crossing the first direction. ) defines a sub-pixel area.

One sub-pixel may include a switching transistor (SW), a driving transistor (DR), a capacitor (Cst), a compensation circuit (CC), and an organic light emitting diode (OLED).

The organic light emitting diode (OLED) operates to emit light according to a driving current formed by the driving transistor DR.

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

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

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

An organic light emitting display device having a sub-pixel structure as described above may be implemented in a top emission method, a bottom emission method, or a dual emission method according to a direction in which light is emitted.

FIG. 6 is an exemplary view showing a schematic structure of sub-pixels in the white organic light emitting display device according to the embodiment of the present invention shown in FIG. 4 .

Referring to FIG. 6 , RGB sub-pixels (SPr, SPg, SPb) are realized by using a white organic light emitting diode (WOLED) and color filters (CFr, CFg, CFb), or emitted light included in the organic light emitting diode. It may be implemented in a manner of forming a material by dividing it into red, green, and blue colors.

A method of using a white organic light emitting diode (WOLED) and color filters (CFr, CFg, CFb) is as follows.

The RGB sub-pixels SPr, SPg, and SPb include a transistor TFT, RGB color filters CFr, CFg, and CFb, and a white organic light emitting diode (WOLED).

That is, the RGB sub-pixels SPr, SPg, and SPb include RGB color filters CFr, CFg, and CFb to convert white light emitted from the white organic light emitting diode (WOLED) into red, green, and blue. .

The method using a white organic light emitting diode (WOLED) and color filters (CFr, CFg, CFb) is different from the method in which red, green, and blue light emitting materials are independently deposited on each sub-pixel. This is a method of equally depositing a light emitting material on all sub-pixels. Therefore, this method can be large-sized without using a fine metal mask (FMM), life can be improved, and power consumption can be reduced.

7 is a schematic cross-sectional view of a portion of sub-pixels of a white organic light emitting display device according to an exemplary embodiment of the present invention.

At this time, the organic light emitting display device shown in FIG. 7 is an example of a back emission type organic light emitting display device in which light is emitted toward a substrate on which pixels are arranged. However, the present invention is not limited thereto, and can be applied not only to a top emission type organic light emitting display device in which light is emitted in the opposite direction to a substrate on which pixels are arranged, but also to a double side emission type organic light emitting display device.

7 illustrates an organic light emitting display using a thin film transistor having a coplanar structure as an example. However, the present invention is not limited to the thin film transistor of the coplanar structure. It is also possible to apply it to a thin film transistor of a staggered structure.

8 is an exemplary view schematically showing the structure of an organic light emitting diode in the white organic light emitting display device according to the embodiment of the present invention shown in FIG. 7 .

Referring to FIG. 7 , in a white organic light emitting display device according to an embodiment of the present invention, one sub-pixel includes a transistor (TFT) formed on a substrate 101, a white organic light emitting diode (WOLED), and a color filter ( CF) may be included.

First, driving the transistor (TFT) The thin film transistor includes a semiconductor layer 124, a gate electrode 121, a source electrode 122 and a drain electrode 123.

The semiconductor layer 124 is formed on the substrate 101 made of an insulating material such as transparent plastic or polymer film.

The semiconductor layer 124 may be formed of an amorphous silicon film, a polycrystalline silicon film obtained by crystallizing amorphous silicon, an oxide semiconductor, or an organic semiconductor.

In this case, a buffer layer (not shown) may be further formed between the substrate 101 and the semiconductor layer 124 . The buffer layer may be formed to protect the transistor TFT formed in a subsequent process from impurities such as alkali ions flowing out of the substrate 101 .

A gate insulating layer 115a made of a silicon nitride layer (SiNx) or a silicon oxide layer (SiO ₂ ) is formed on the semiconductor layer 124 . Then, a gate line including a gate electrode 121 and a first storage electrode are formed thereon.

The gate electrode 121, the gate line, and the first storage electrode are formed of a first metal material having low resistance, for example, aluminum (Al), copper (Cu), molybdenum (Mo), chromium (Cr), or gold (Au). ), titanium (Ti), nickel (Ni), neodymium (Nd), or alloys thereof.

An inter insulation layer 115b made of a silicon nitride layer or a silicon oxide layer is formed on the gate electrode 121, the gate line, and the first storage electrode. Then, a data line, a driving voltage line, source/drain electrodes 122 and 123, and a second storage electrode (not shown) are formed thereon.

The source electrode 122 and the drain electrode 123 are spaced apart from each other at a predetermined interval and electrically connected to the semiconductor layer 124 . More specifically, a semiconductor layer contact hole exposing the semiconductor layer 124 is formed in the gate insulating layer 115a and the interlayer insulating layer 115b, and the source/drain electrodes 122 and 123 are formed through the semiconductor layer contact hole. It is electrically connected to the semiconductor layer 124 .

In this case, the second storage electrode overlaps a part of the first storage electrode below the interlayer insulating layer 115b to form a storage capacitor.

The data line, the driving voltage line, the source/drain electrodes 122 and 123, and the second storage electrode are formed of a second metal material having low resistance, for example, aluminum (Al), copper (Cu), molybdenum (Mo), It may be formed of a single layer or multiple layers made of chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), or an alloy thereof.

A protective film (or planarization film) 115c is formed on the substrate 101 on which the data lines, driving voltage lines, source/drain electrodes 122 and 123, and the second storage electrode are formed.

A color filter CF is formed on the passivation layer 115c. The color filter CF is a color conversion material that converts white light emitted from the white organic light emitting diode (WOLED) into red, green, and blue.

An overcoat layer 115d covering the color filter CF and exposing a part of the drain electrode 123 is formed on the passivation layer 115c. The overcoat layer 115d may be formed of an organic material, but may also be formed of an inorganic material or an organic/inorganic mixture.

Next, the white organic light emitting diode (WOLED) may include a first electrode 118 , a light emitting unit 130 and a second electrode 128 .

At this time, the light emitting unit 130 according to an embodiment of the present invention has an n(≥2) stack structure including at least one blue light emitting layer and a yellow-green light emitting layer, and is characterized in that it has a 3-peak. . This will be described in detail later.

This white organic light emitting diode (WOLED) is electrically connected to the driving thin film transistor. More specifically, a drain contact hole exposing the drain electrode 123 of the driving thin film transistor is formed in the passivation layer 115c and the overcoat layer 115d formed on the driving thin film transistor. The white organic light emitting diode (WOLED) is electrically connected to the drain electrode 123 of the driving thin film transistor through a drain contact hole.

That is, the first electrode 118 is formed on the overcoat layer 115d and is electrically connected to the drain electrode 123 of the driving thin film transistor through the drain contact hole.

The first electrode 118 supplies current (or voltage) to the light emitting unit 130 .

In addition, the first electrode 118 serves as an anode. Accordingly, the first electrode 118 is made of a transparent conductive material having a relatively high work function, and for example, indium-tin-oxide (ITO) or indium-zinc-oxide (Indium Zinc Oxide). ; IZO). However, the present invention is not limited thereto.

A bank 115e is formed on the substrate 101 on which the first electrode 118 is formed. At this time, the bank 115e surrounds the periphery of the first electrode 118 like a dam to define an opening and may be made of an organic insulating material.

The bank 115e may also be made of a photoresist containing a black pigment. In this case, the bank 115e serves as a light blocking member.

A light emitting part 130 and a second electrode 128 are formed on the substrate 101 on which the bank 115e is formed.

That is, the light emitting part 130 is formed between the first electrode 118 and the second electrode 128 . The light emitting unit 130 emits light by combining holes supplied from the first electrode 118 and electrons supplied from the second electrode 128 .

The light emitting unit 130 may have a multi-layered structure including a plurality of organic layers to improve light emitting efficiency of the light emitting layer in addition to the light emitting layer that emits light.

The reason why organic light-emitting diodes are manufactured in a multi-layered thin film structure is that hole and electron mobility differ greatly in the case of organic materials, so holes and electrons can be effectively transferred to the light emitting layer by using a hole transport layer and an electron transport layer. This is because the luminous efficiency is high when the density of holes and electrons is balanced. In addition, electrons injected into the light emitting layer from the second electrode 128 are confined to the light emitting layer by an energy barrier existing at the interface between the hole transport layer and the light emitting layer, so that the recombination probability of electrons and holes increases, thereby improving efficiency.

The light emitting unit 130 may be formed as a single layer connected to all pixels. In this case, it is preferable to include an organic light emitting material that generates white light. In this case, a color filter CF is formed for each sub-pixel to express various colors.

As another example, the light emitting unit 130 may be formed separately for each sub-pixel. In particular, in this case, each sub-pixel may include an organic light-emitting material that emits light of any one color among red, green, and blue.

The second electrode 128 is formed on the light emitting part 130 to provide electrons to the light emitting part 130 .

The second electrode 128 may be formed to cover the entire substrate 101 . That is, while the first electrode 118 has a divided form for each sub-pixel, the second electrode 128 may be formed as a single layer connected across all pixels. However, the present invention is not limited thereto.

At this time, the white organic light emitting display according to the embodiment of the present invention is characterized in that it has an n(≥2) stack structure, for example, a 3-stack, 3-peak structure in which the second light emitting part and the third light emitting part are located on the first light emitting part. to be However, the present invention is not limited to the three-stack structure described below.

In addition, the white organic light emitting display device according to an embodiment of the present invention is characterized in that a red light emitting layer including a hole transport type host is located in the second light emitting unit, specifically between the charge generation layer and the yellow-green light emitting layer. .

Referring to FIG. 8 , an organic light emitting diode having a 3-stack, 3-peak structure according to an embodiment of the present invention includes a first electrode 118, a second electrode 128, and a first electrode 118 and a second electrode 128. It includes a light emitting part positioned between them.

The light emitting unit may include a first light emitting unit 131 , a second light emitting unit 132 , and a third light emitting unit 133 .

In this case, a first N-type charge generation layer 135a' and a first P-type charge generation layer 135b' may be positioned between the first light emitting unit 131 and the second light emitting unit 132 . A second N-type charge generation layer 135a" and a second P-type charge generation layer 135b" may be positioned between the second light emitting unit 132 and the third light emitting unit 133.

At this time, the first N-type charge generation layer 135a' serves to inject electrons into the first light emitting part 131, and the first P-type charge generation layer 135b' serves to inject electrons into the second light emitting part 132. It serves to inject holes. In addition, the second N-type charge generation layer 135a" serves to inject electrons into the second light emitting part 132, and the second P-type charge generation layer 135b" injects holes into the third light emitting part 133. It serves as an injector.

The charge generation layers 135a', 135a", 135b', and 135b" may use various organic materials having strong electron donor and electron acceptor characteristics.

For example, the P-type charge generation layers 135b' and 135b" are hexaazatriphenylene-hexacarbonitrile (HAT-CN) (Dipyrazino[2,3-f:2',3'-h]quinoxaline- 2,3,6,7,10,11-hexacarbonitrile) or P-doped structure.

In addition, the charge generation layers 135a' and 135a" and 135b' and 135b" may be formed of a single layer such as HAT-CN.

In this way, when the light emitting unit is composed of three, the first charge generation layers 135a' and 135b' adjust the balance of electric charge between the first light emitting unit 131 and the second light emitting unit 132, and the second charge generation layer 135a', 135b' The generation layers 135a" and 135b" adjust the balance of electric charges between the second light emitting part 132 and the third light emitting part 133. However, as described above, the present invention is not limited to three light emitting units.

The first light emitting part 131 may include a first hole transport layer 131b, a blue light emitting layer 131c, and a first electron transport layer 131d. Each layer included in the first light emitting part 131 is positioned on the first electrode 118 .

The blue light emitting layer 131c emits blue light to a light emitting layer including a blue dopant and a host.

Also, a deep blue light emitting layer or a sky blue light emitting layer may be used instead of the blue light emitting layer 131c. A wavelength region corresponding to the blue light emitting layer 131c may be in the range of 440 nm to 480 nm.

The blue light emitting layer 131c may emit light with fluorescence, but may also emit light with phosphorescence.

The blue light emitting layer 131c may include at least one mixed host and at least one dopant. Specifically, at least one fluorescent host material selected from the group consisting of anthracene derivatives, pyrene derivatives and perylene derivatives may be doped with a fluorescent blue dopant, but is not necessarily limited thereto. .

Depending on the configuration of the device, a first hole injection layer may be added between the first electrode 118 and the first hole transport layer 131b. In addition, a first electron injection layer may be added between the first electron transport layer 131d and the first charge generation layers 135a' and 135b'.

The first hole transport layer 131b may be composed of a single layer or two layers.

The second light emitting unit 132 includes a red light emitting layer 134, a yellow-green light emitting layer 132c, and a second electron transport layer 132d. Each layer included in the second light emitting unit 132 is positioned on the first charge generation layers 135a' and 135b'.

The yellow-green light emitting layer 132c 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 a metal complex. Carbazole-based compounds may include CBP (4,4'-bis (carbozol-9-yl) -biphenyl), CBP derivatives, mCP (N, N'-dicarbazolyl-3,5-benzene) or mCP derivatives, and the like. , The metal complex may include a ZnPBO (phenyloxazole) metal complex or a ZnPBT (phenylthiazole) metal complex. A wavelength range corresponding to the yellow-green light emitting layer 132c may be in the range of 510 nm to 590 nm. The yellow-green light emitting layer 132c is a light emitting layer including at least one dopant including a yellow-green dopant and at least one host, and emits yellow-green light.

Depending on the configuration of the device, a second electron injection layer may be added between the second electron transport layer 132d and the second charge generation layers 135a" and 135b".

The third light emitting part 133 may include a third hole transport layer 133b, a blue light emitting layer 133c, and a third electron transport layer 133d. Each layer included in the third light emitting part 133 is located on the second charge generation layer 135a", 135b".

Depending on the configuration of the device, a third hole injection layer may be added between the second charge generation layers 135a" and 135b" and the third hole transport layer 133b, and the third electron transport layer 133d and the second electrode ( 128), a third electron injection layer may be added.

The third hole transport layer 133b may be composed of a single layer or two layers.

Also, a deep blue light emitting layer or a sky blue light emitting layer may be used instead of the blue light emitting layer 133c. A wavelength range corresponding to the blue light emitting layer 133c may be in the range of 440 nm to 480 nm.

The blue light emitting layer 133c may emit fluorescence or phosphorescence.

The blue light emitting layer 133c may include at least one mixed host and at least one dopant. Specifically, at least one fluorescent host material selected from the group consisting of anthracene derivatives, pyrene derivatives and perylene derivatives may be doped with a fluorescent blue dopant, but is not necessarily limited thereto. .

Accordingly, white light may be realized by mixing the blue light of the blue light emitting layers 131c and 133c and the yellow-green light of the yellow-green light emitting layer 132c. In particular, in the case of the present invention, in addition to the blue light emitting layers 131c and 133c and the yellow-green light emitting layer 132c, the red light emitting layer 134 is additionally provided in the second light emitting unit 132 to fill the insufficient red efficiency to produce complete white light. can be implemented That is, since the red light emitting layer 134 of the present invention has a spectral wavelength band of 600 to 650 nm, white light realized through the white organic light emitting diode of the present invention implements white light having a wide wavelength range of 440 to 650 nm.

In addition, the present invention has a 3-peak structure having three emission peaks by the red emission layer 134 . The three emission peaks may be 440 to 480 nm corresponding to a blue region, 510 to 590 nm corresponding to a yellow-green region, and 600 to 650 nm corresponding to a red region. Accordingly, it is possible to provide an organic light emitting display device with improved red efficiency and improved color gamut and color viewing angle.

In addition, since the yellow-green light emitting layer 132c has high luminous properties, the luminous properties of white light implemented by the white organic light emitting diode of the present invention can be improved.

For reference, the blue light emitting layers 131c and 133c, the red light emitting layer 134, and the yellow-green light emitting layer 132c may be formed through a vacuum thermal evaporation process. In the vacuum thermal evaporation process, an organic material having a desired color is placed on a deposition source having a discharge port, and then the deposition source is heated in a vacuum-maintained chamber to discharge the evaporated organic material through the discharge port, thereby forming an organic material on a substrate. method of deposition.

As described above, the white organic light emitting display device according to the exemplary embodiment of the present invention includes three light emitting units 131, 132, and 133. In addition, charge generation layers 135a', 135a", 135b', and 135b" are formed between the three light emitting units 131, 132, and 133.

However, the present invention is not limited thereto, and as described above, the present invention can be applied to a 2-stack or 4-stack n-stack structure in addition to the 3-stack structure.

In particular, the white organic light emitting display device according to the embodiment of the present invention includes a second hole transport layer between the first charge generation layers 135a' and 135b' and the yellow-green light emitting layer 132c of the second light emitting unit 132. It is characterized in that the red light emitting layer 134 is located without a buffer layer.

That is, the red light emitting layer 134 of the present invention is not included in the additional light emitting part, but is provided in the second light emitting part 132 having the yellow-green light emitting layer 132c.

In addition, the red light emitting layer 134 according to an embodiment of the present invention may replace the second hole transport layer. That is, the red light emitting layer 134 according to an embodiment of the present invention simultaneously serves as a second hole transport layer that transfers holes to the upper yellow-green light emitting layer 132c in addition to serving as a red light emitting layer. To this end, the red light emitting layer 134 according to an embodiment of the present invention includes at least one host (hereinafter referred to as a first red host) having the same or similar energy level as the second hole transport layer and at least one dopant ( It is characterized in that it consists of dopant).

For reference, the light emitting material is largely divided into a host material and a guest material in terms of functionality. In general, when only one material for host or guest is applied, light can be emitted, but color purity and luminous efficiency are poor. can increase efficiency.

The first red host refers to a hole transport type (or hole transfer type) host having relatively strong hole characteristics. For example, the first red host may have 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 to 6.0 eV.

In this case, the red light emitting layer 134 according to an embodiment of the present invention may further include a second red host.

The second red host means an electron transport type (or electron transfer type) host having relatively strong electron characteristics. For example, the second red host may have a LUMO energy level of 2.0 to 3.0 eV and a HOMO energy level of 5.0 to 6.5 eV.

For example, in the red light emitting layer 134 according to an embodiment of the present invention, the ratio of the first red host and the second red host may be 1:9 to 9:1.

In this case, when there is a dopant in the red light emitting layer 134, holes may be transferred to the yellow-green light emitting layer 132c that is bonded or separated by movement of the first red host.

In addition, as the red light-emitting layer 134 exists between the first charge generation layers 135a' and 135b' and the yellow-green light-emitting layer 132c, electrons leaking from the yellow-green light-emitting layer 132c are trapped and By contributing to red light emission, the efficiency of red light is increased, contributing to the improvement of the luminance of the panel.

The first red host having an energy level similar to that of the second hole transport layer may be formed of a hole transport layer material represented by the following formula, but is not limited thereto.

로 이루어질 수 있다.At this time, A, B =

can be made with

Rn (n = 1 to 12) of A or B is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a substituted or unsubstituted condensed aryl group having 10 to 30 carbon atoms, or a substituted or unsubstituted aryl group having 2 to 24 carbon atoms. Heteroaryl group, substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, substituted or unsubstituted heteroalkyl group having 1 to 24 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 24 carbon atoms, substituted or unsubstituted 1 to 24 carbon atoms 24 alkoxy groups, substituted or unsubstituted aryloxy groups having 6 to 24 carbon atoms, substituted or unsubstituted alkylsilyl groups having 1 to 24 carbon atoms, substituted or unsubstituted arylsilyl groups having 6 to 24 carbon atoms, cyano groups, It may be selected from the group consisting of a halogen group, deuterium and hydrogen, and R to R12 may form a condensed ring with a neighboring substituent.

L is an aryl group, phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine, acridine , cinnoline, quinazoline, quinoxaline, naphthydrine, phtalazine, quinolizine, indole, indazole, It may be selected from the group consisting of pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole.

The first red host may include materials of the following chemical formula.

,

,

,

,

(CBP)

(CDBP)

(mCP)

(BCP)

The red emission layer 134 may include one or more hosts, that is, a first red host, and may include one or more dopants.

Another host of the red light emitting layer 134, that is, a second red host may include a phosphorescent host, but is not limited thereto.

The second red host may include materials of the following chemical formula.

,

,

,

,

(BAlq)

(TAZ)

The phosphorescent host substituent may include a substituent having the structure described above, and Rn (n = 1 to 12) of the substituent is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, or a substituted or unsubstituted aryl group having 10 to 30 carbon atoms. A condensed aryl group, 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 A cycloalkyl group having 3 to 24 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 24 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 24 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 24 carbon atoms, a substituted or It may be selected from the group consisting of an unsubstituted arylsilyl group having 6 to 24 carbon atoms, a cyano group, a halogen group, deuterium, and hydrogen, and R1 to R12 may form a condensed ring with adjacent substituents.

The substituent is substituted or unsubstituted, and the fused or unfused aryl group is phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine (phenanthridine), acridine, cinnoline, quinazoline, quinoxaline, naphthydrine, phthalazine, quinolizine, indole Consists of indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole It consists of 1 to 5 overlapping substitutions or non-overlapping substitutions in the central structure.

The phosphorescent dopant material may be formed of a metal compound that forms a 3-coordinate with N—N or N—O, O—O around the iridium (Ir) metal.

The red light emitting layer 134 may have a thickness of 5 to 300 Å, preferably 50 to 150 Å.

The red light emitting layer 134 may emit fluorescence or phosphorescence.

Phosphorescent dopants included in the red light emitting layer 134 are Ir(piq) ₃ (Tris(1-phenylisoquinoline)iridium(III)), Ir(piq) ₂ (acac)(Bis(1-phenylisoquinoline)(acetylacetonate)iridium(III) )), Ir(btp) ₂ (acac)(Bis)2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III)), Ir(BT) ₂ (acac)(Bis(2- phenylbenzothazolato) (acetylacetonate) iridium (III)), etc., but is not limited thereto.

In addition, the fluorescent dopant included in the red light emitting layer 134 is Rubrene (5,6,11,12-tetraphenylnaphthacene), DCJTB (4-(dicyanlmethylene)-2-tert-butyl-6-(1,1,7,7 -tetramethyljuloidin-4-yl-vinyl) -4H pyran), etc., but is not limited thereto.

The red dopant of the red emission layer 134 may have a doping concentration of 0.1 to 10%, preferably 0.5 to 3%. Hereinafter, the doping concentration of the dopant means the concentration for the host.

9 is a diagram schematically showing a band diagram of an organic light emitting diode according to an embodiment of the present invention.

In this case, FIG. 9 illustrates an example in which the red light emitting layer R EML includes a first red host R HOST1 , a second red host R HOST2 , and a red dopant RD.

However, the present invention is not limited thereto, and the red light emitting layer R EML may include at least one host and at least one dopant.

9, in the red light emitting layer (R EML) according to an embodiment of the present invention, the LUMO (Lowest Unoccupied Molecular Orbital) energy level and HOMO (Highest Occupied Molecular Orbital) energy level of the first red host (R HOST1) It can be seen that is 2.2 eV and 5.4 eV, respectively, the same range as that of the second hole transport layer. Here, the first red host R HOST1 is a hole transport type host and may be configured as a host having higher (faster) ability to transport holes than electrons. Accordingly, the LUMO energy level of the first red host R HOST1 may be 1.0 to 3.0 eV, and the HOMO energy level may be 4.9 to 6.0 eV. Also, the LUMO energy level of the second red host R HOST2 may be 2.0 to 3.0 eV, and the HOMO energy level may be 5.0 to 6.5 eV. As shown in FIG. 9 , it can be seen that the LUMO energy level of the first P-type charge generation layer P-CGL adjacent to the first red host R HOST1 is 5.2 eV and the HOMO energy level is 8.3 eV. In addition, it can be seen that the LUMO energy level of the red dopant (RD) is 3.0 eV and the HOMO energy level is 5.0 eV. In FIG. 9 , ITO denotes the first electrode and AL denotes the second electrode.

In addition, the red light emitting layer (R EML) according to an embodiment of the present invention may replace the function of the second hole transport layer. That is, since the red light-emitting layer (R EML) is inserted between the first P-type charge generation layer (P-CGL) and the yellow-green light-emitting layer (YG EML), holes can be transferred to the yellow-green light-emitting layer (YG EML), so that yellow - Efficiency of the green light emitting layer (YG EML) can be improved, and red efficiency can be improved.

In the present invention, in the second light emitting unit, the yellow-green light emitting layer (YG EML) is a main light emitting layer, and the red light emitting layer (R EML) is a secondary light emitting layer that emits red light and serves as a second hole transport layer, and has luminance, color gamut and Color vision can be improved.

That is, the red light emitting layer (R EML) serves to fill the red efficiency lacking only with the blue light emitting layer and the yellow-green light emitting layer (YG EML). In addition, the first red host R HOST1 of the red light emitting layer R EML has the same energy level as that of the second hole transport layer, and is formed by the movement of the first red host R HOST1, which is a hole transport type host. It may also serve as a second hole transport layer that transfers holes to the green light emitting layer (YG EML). Accordingly, luminance, color gamut, and color viewing angle may be improved compared to the prior art without additional processes.

In addition, the red dopant RD of the red light emitting layer R EML traps electrons leaking from the yellow-green light emitting layer YG EML, thereby protecting the first P-type charge generation layer P-CGL. . In addition, as the red light emitting layer (R EML) exists between the first P-type charge generation layer (P-CGL) and the yellow-green light emitting layer (YG EML), electrons leaking from the yellow-green light emitting layer (YG EML) are trapped ( trapping) to contribute to red light emission, thereby increasing the efficiency of red light and contributing to the improvement of panel luminance.

10A, 10B, and 10C are diagrams schematically illustrating a change in color coordination when a viewing angle changes from 0° to 60°.

11a, 11b, and 11c are photographs showing color coordinate changes when the viewing angle changes from 0° to 60°.

At this time, FIGS. 10A and 11A show, as an example, a color coordinate change according to a viewing angle in an organic light emitting diode (comparative example) having a 3-stack structure without a red light emitting layer. In Comparative Example, for example, the thickness of the hole transport layer was measured as 60 Å. The red light emitting layers of Experimental Examples 1 and 2 were composed of one host and one dopant.

10B, 11B, 10C, and 11C illustrate a color coordinate change according to a viewing angle in an organic light emitting diode having a three-stack structure according to an embodiment of the present invention having a red light emitting layer as an example. At this time, FIGS. 10B and 11B illustrate a case where the red dopant of the red light emitting layer has a doping concentration of 1% (Experimental Example 1), and FIGS. A case (experimental example 2) is given as an example. They all contain one host, the first red host, with a thickness of about 100 Å.

12 is a graph showing a change in color coordinates according to a change in viewing angle.

The CIE 1931 color coordinate change (Δu'v') in the viewing angle direction from 0° to 60° of light emitted from the organic light emitting display device is set to be 0.02. At this time, the color coordinate change (Δu'v') is the initial color coordinate (u ₀ ', v ₀ ') based on the CIE 1931 color coordinate system (u', v') and the color coordinate after a predetermined time t (u _t ' , v _t ') is defined as the color coordinate difference between The color coordinate change Δu'v' may be referred to as a color viewing angle change rate or a color coordinate change rate according to a viewing angle.

When the color coordinate change (Δu'v') is less than 0.020, the user does not significantly recognize the color change phenomenon according to the viewing angle.

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.

There is a very big difference between displaying the main properties of color on a 2D plane and displaying them on a 3D space. And, even in the most basic RGB color space displayed in the same 3D space, its form varies depending on how the concept is defined.

And, even in the same two-dimensional flat space, the shape of the space is different depending on how the color properties are defined.

In the case of the CIE xy color space, which has been used since 1931, the difference between the visual color difference and the numerical color difference was severe, and research was continued to compensate for this, and in 1960, the CIE uv color space was adopted as a new standard. And, through additional research, the CIE u'v' color space was adopted as a standard in 1976. This CIE u'v' is simply a degree of change in the ratio as u'=u and v'=3/2v in CIE uv.

Referring to FIGS. 10A, 11A, and 12 , it can be seen that the color coordinate change (Δu'v') when the viewing angle changes from 0° to 60° in the comparative example is about 0.015.

On the other hand, referring to FIGS. 10B, 11B, and 12 , in the case of Experimental Example 1, it can be seen that the color coordinate change (Δu'v') when the viewing angle changes from 0° to 60° is about 0.010.

Referring to FIGS. 10C, 11C, and 12 , in the case of Experimental Example 2, it can be seen that the color coordinate change (Δu'v') when the viewing angle changes from 0° to 60° is about 0.011.

Therefore, it can be seen that in Experimental Examples 1 and 2, compared to Comparative Example, the color viewing angle and color gamut are improved with the addition of the red light emitting layer. And, the DCI coverage of Comparative Example was 91.3%, and Experimental Example 1 and Experimental Example 2 were measured as 94.7%. The DCI overlap ratio may be referred to as DCI color gamut satisfaction. Therefore, it can be seen that Experimental Example 1 and Experimental Example 2 have improved color reproducibility compared to Comparative Example. In addition, since the DCI (Digital Cinema Initiatives) overlapping ratio is widened, there is an effect of providing clearer picture quality in a large-area TV.

And, looking at the red efficiency, Comparative Example was measured as (0.666, 0.330), Experimental Example 1 and Experimental Example 2 were measured as (0.671, 0.325). Therefore, it can be seen that Experimental Example 1 and Experimental Example 2 have improved red efficiency compared to Comparative Example. At this time, when the doping concentration of the red dopant is small, it can be seen that the color coordinate change is small.

13A and 13B are graphs showing light intensity according to wavelength.

At this time, FIG. 13a shows the light intensity according to all wavelengths from 380 nm to 780 nm, and FIG. 13b shows the light intensity (ie, emission spectrum) according to the wavelength in the red wavelength band from 600 nm to 650 nm.

The ElectroLuminescence Spectrum is determined by multiplying the PhotoLuminescence Peak (PL Peak), which displays the unique color of the light emitting layer, and the Emittance Peak (EM Peak) of the organic layers constituting the organic light emitting device. do.

In particular, FIG. 13B shows the light intensity (emission spectrum) according to the wavelength after passing through the color filter.

At this time, as described above, in the comparative example, an organic light emitting diode having a 2-stack (or 3-stack) structure without a red light emitting layer is taken as an example.

Further, in Experimental Example 1, in an organic light emitting diode having a three-stack structure according to an embodiment of the present invention having a red light emitting layer, a case in which a red dopant in the red light emitting layer has a doping concentration of 1% is taken as an example. Experimental Example 2 illustrates an example in which a red dopant in a red light emitting layer has a doping concentration of 3% in an organic light emitting diode having a three-stack structure according to an embodiment of the present invention having a red light emitting layer.

At this time, for convenience, Comparative Example is shown as a solid line, and Experimental Example 1 and Experimental Example 2 are shown as a dotted line and a dotted line, respectively.

Referring to FIG. 13A , it can be seen that in Experimental Example 2, compared to Comparative Example, a light peak appears at a red wavelength (600 to 650 nm) and the light intensity slightly increases.

And, it can be seen that the light intensity increases in the blue wavelength (440 ~ 480 nm) in the case of Experimental Example 2 compared to the Comparative Example. In addition, it can be seen that the light intensities of Comparative Example and Experimental Examples 1 and 2 are similar at the yellow-green wavelength (510 to 590 nm).

In addition, referring to FIG. 13B , it can be seen that the efficiency of red color increased in the red wavelength (600 to 650 nm) in the case of Experimental Example 2 compared to the Comparative Example. Compared to Comparative Example, Experimental Example 2 shows a peak in the red wavelength region, which is a long wavelength region, and thus the color reproduction rate can be improved. For reference, efficiency can be obtained from the area of the graph.

On the other hand, when a red light emitting layer is added as in the present invention, since red is located in a long wavelength region compared to the comparative example, the color reproduction rate can be improved.

Overall luminance is expected to be 207, 262, and 240 for Comparative Example, Experimental Example 1, and Experimental Example 2, respectively, at 8.5A. Therefore, it can be seen that the luminance increased by about 27% and 16% in Experimental Examples 1 and 2 compared to the Comparative Example.

14A and 14B are graphs showing changes in light intensity over time.

At this time, FIG. 14a shows a change in light intensity with time for the blue light emitting layer. 14B shows the change in light intensity with time for the yellow-green light emitting layer.

Referring to FIG. 14A , it can be seen that in Experimental Examples 1 and 2, the time for the light intensity of the blue light emitting layer to reach 95% is equal to or greater than that of Comparative Example. Therefore, it can be seen that the lifespan of the blue light emitting layer is improved in Experimental Examples 1 and 2 compared to Comparative Example.

Referring to FIG. 14B , it can be seen that the lifespan of the yellow-green light emitting layer is also improved in Experimental Examples 1 and 2 compared to Comparative Example.

On the other hand, as described above, the red light emitting layer may include one or more hosts, and as an example, color coordinate change and efficiency in the case of a mixed host in which two hosts, that is, a first red host and a second red host are mixed. Take a look at The at least one host includes a hole transport type host having the same or similar energy level as the hole transport layer described above.

15 is another graph showing a change in color coordinates according to a change in viewing angle.

At this time, as described above, in the comparative example, an organic light emitting diode having a 3-stack structure without a red light emitting layer is taken as an example. In Comparative Example, for example, the thickness of the hole transport layer was measured as 60 Å.

Experimental Example 3 illustrates an example in which a first red host and a second red host each have a thickness of 50 Å in an organic light emitting diode having a three-stack structure according to an embodiment of the present invention having a red light emitting layer. In Experimental Example 4, in the organic light emitting diode having a three-stack structure according to an embodiment of the present invention having a red light emitting layer, the first red host and the second red host have thicknesses of 70 Å and 30 Å, respectively, as an example. there is. Here, the first red host is a hole transport type host having the same or similar energy level as the hole transport layer described above.

In Experimental Examples 3 and 4, the red dopant of the red light emitting layer had a doping concentration of 1%.

Referring to FIG. 15 , in the case of Experimental Examples 3 and 4, it can be seen that the color coordinate change (Δu'v') when the viewing angle changes from 0° to 60° is about 0.011.

Therefore, it can be seen that in Experimental Examples 3 and 4, compared to Comparative Example, the color viewing angle and color gamut were improved due to the addition of the red light emitting layer. In addition, the DCI coverage of Comparative Example was 91.3%, Experimental Example 3 was 94.2%, and Experimental Example 4 was 94.6%. The DCI overlap ratio may be referred to as DCI color gamut satisfaction. Therefore, it can be seen that the color reproducibility of Experimental Examples 3 and 4 was improved compared to Comparative Example. and. Since the DCI (Digital Cinema Initiatives) overlapping ratio is widened, there is an effect of providing a clearer picture quality on a large-area TV.

16A and 16B are other graphs showing light intensity according to wavelength.

At this time, Figure 16a shows the light intensity according to the entire wavelength from 380nm to 780nm, Figure 16b shows the light intensity according to the wavelength in the red wavelength band from 600nm to 650nm.

In particular, FIG. 16B shows the light intensity (ie, emission spectrum) according to the wavelength after passing through the color filter.

At this time, for convenience, Comparative Example is shown with a solid line, and Experimental Example 3 and Experimental Example 4 are shown with a dotted line and a dotted line, respectively.

Referring to FIG. 16A , it can be seen that the light intensity slightly increased in the red wavelength (600 to 650 nm) in Experimental Examples 3 and 4 compared to the Comparative Example. And, it can be seen that the light intensity increased in the blue wavelength (440 ~ 480 nm) in Experimental Examples 3 and 4 compared to the Comparative Example. It can be seen that the light intensities of Experimental Examples 3 and 4 are similar to those of Comparative Example at the yellow-green wavelength (510 to 590 nm).

In addition, referring to FIG. 16B , it can be seen that the red efficiency increased in Experimental Examples 3 and 4 compared to Comparative Example.

In the case of adding a red light emitting layer as in the present invention, since red is located in a long wavelength region compared to the comparative example, the color gamut can be improved.

The overall luminance is expected to be 207, 245, and 248 for Comparative Example, Experimental Example 3, and Experimental Example 4, respectively, at 8.5A. Therefore, it can be seen that the luminance increased by about 18% and 20% in Experimental Examples 3 and 4 compared to the Comparative Example. From this, when the thickness of the first red host and the second red host is 5:5 to 7:3, it can be seen that the luminance and red efficiency are increased compared to the comparative example.

Meanwhile, the present invention does not exclude additionally inserting an auxiliary layer made of a hole transport type host between the charge generation layer and the red light emitting layer, and this will be described in detail through other embodiments below.

17 is an exemplary view schematically showing the structure of an organic light emitting diode in a white organic light emitting display device according to another embodiment of the present invention.

At this time, the organic light emitting diode according to another embodiment of the present invention shown in FIG. 17 is the same as shown in FIG. 8 except that an auxiliary layer made of a hole transport type host is inserted between the charge generation layer and the red light emitting layer. It has substantially the same structure as that of the organic light emitting diode according to the embodiment of the present invention.

Referring to FIG. 17, an organic light emitting diode having a three-stack, three-peak structure according to another embodiment of the present invention includes a first electrode 218, a second electrode 228, and a first electrode 218 and a second electrode 228. ) includes a light emitting unit located between.

The light emitting unit may include a first light emitting unit 231 , a second light emitting unit 232 , and a third light emitting unit 233 .

In this case, the first N-type charge generation layer 235a' and the first P-type charge generation layer 235b' may be positioned between the first light emitting part 231 and the second light emitting part 232 . A second N-type charge generation layer 235a" and a second P-type charge generation layer 235b" may be positioned between the second light emitting unit 232 and the third light emitting unit 233.

At this time, the first N-type charge generation layer 235a' serves to inject electrons into the first light emitting part 231, and the first P-type charge generation layer 235b' serves to inject electrons into the second light emitting part 232. It serves to inject holes. In addition, the second N-type charge generation layer 235a" serves to inject electrons into the second light emitting part 232, and the second P-type charge generation layer 235b" injects holes into the third light emitting part 233. It serves as an injector.

As described above, the charge generation layers 235a', 235a", 235b', and 235b" may use various organic materials having strong electron donor and electron acceptor characteristics.

For example, the P-type charge generation layers 235b' and 235b" are hexaazatriphenylene-hexacarbonitrile (HAT-CN) (Dipyrazino[2,3-f:2',3'-h]quinoxaline- 2,3,6,7,10,11-hexacarbonitrile) or P-doped structure.

In addition, the charge generation layers 235a', 235a", 235b', 235b" may be formed of a single layer such as HAT-CN.

In this way, when the light emitting unit is configured as three stacks, the first charge generation layers 235a' and 235b' adjust the balance of charges between the first light emitting unit 231 and the second light emitting unit 232, and The second charge generation layers 235a" and 235b" adjust the balance of charges between the second light emitting part 232 and the third light emitting part 233. However, the present invention is not limited to the 3-stack structure.

The first light emitting part 231 may include a first hole transport layer 231b, a blue light emitting layer 231c, and a first electron transport layer 231d. Each layer included in the first light emitting part 231 is positioned on the first electrode 218 .

The blue light emitting layer 231c emits blue light to the light emitting layer including the blue dopant and the host.

Also, a dark blue light emitting layer or a sky blue light emitting layer may be used instead of the blue light emitting layer 231c. A wavelength region corresponding to the blue light emitting layer 231c may be in the range of 440 nm to 480 nm.

The blue light emitting layer 231c may emit light with fluorescence, but may also emit light with phosphorescence.

As described above, the blue light emitting layer 231c may include at least one host and at least one dopant. Specifically, at least one fluorescent host material selected from the group consisting of anthracene derivatives, pyrene derivatives and perylene derivatives may be doped with a fluorescent blue dopant, but is not necessarily limited thereto. .

Depending on the configuration of the device, a first hole injection layer may be added between the first electrode 218 and the first hole transport layer 231b. In addition, a first electron injection layer may be added between the first electron transport layer 231d and the first charge generation layers 235a' and 235b'.

The first hole transport layer 231b may be composed of a single layer or two layers.

The second light emitting unit 232 includes a red light emitting layer 234, a yellow-green light emitting layer 232c and a second electron transport layer 232d. Each layer included in the second light emitting unit 232 is positioned on the first charge generation layers 235a' and 235b'. At this time, the second light emitting unit 232 according to another embodiment of the present invention further includes one or more auxiliary layers 236 interposed between the first charge generation layers 235a' and 235b' and the red light emitting layer 234. It is characterized by including.

The yellow-green light emitting layer 232c may include at least one 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 a metal complex. Carbazole-based compounds may include CBP (4,4'-bis (carbozol-9-yl) -biphenyl), CBP derivatives, mCP (N, N'-dicarbazolyl-3,5-benzene) or mCP derivatives, and the like. , The metal complex may include a ZnPBO (phenyloxazole) metal complex or a ZnPBT (phenylthiazole) metal complex. A wavelength region corresponding to the yellow-green emission layer 232c may be in the range of 510 nm to 590 nm. The yellow-green light emitting layer 232c is a light emitting layer including a yellow-green dopant and a host and emits yellow-green light.

Depending on the configuration of the device, a second electron injection layer may be added between the second electron transport layer 232d and the second charge generation layers 235a" and 235b".

The third light emitting part 233 may include a third hole transport layer 233b, a blue light emitting layer 233c, and a third electron transport layer 233d. Each layer included in the third light emitting part 233 is located on the second charge generation layer 235a", 235b".

Depending on the configuration of the device, a third hole injection layer may be added between the second charge generation layers 235a" and 235b" and the third hole transport layer 233b, and the third electron transport layer 233d and the second electrode ( 228), a third electron injection layer may be added.

The third hole transport layer 233b may be composed of a single layer or two layers.

Also, a deep blue light emitting layer or a sky blue light emitting layer may be used instead of the blue light emitting layer 233c. A wavelength region corresponding to the blue light emitting layer 233c may be in the range of 440 nm to 480 nm.

The blue light emitting layer 233c may emit fluorescence or phosphorescence.

The blue light emitting layer 233c may include at least one host and at least one dopant. Specifically, at least one fluorescent host material selected from the group consisting of anthracene derivatives, pyrene derivatives and perylene derivatives may be doped with a fluorescent blue dopant, but is not necessarily limited thereto. .

Accordingly, white light may be implemented by mixing the blue light of the blue light emitting layers 231c and 233c and the orange light of the yellow-green light emitting layer 232c. In particular, as described above, in the case of the present invention, the red light emitting layer 234 is additionally provided in the second light emitting unit 232 in addition to the blue light emitting layers 231c and 233c and the yellow-green light emitting layer 232c, thereby filling the insufficient red efficiency. A perfect white light can be realized. That is, since the red light emitting layer 234 of the present invention has a spectral wavelength band of 600 to 650 nm, white light realized through the white organic light emitting diode of the present invention implements white light having a wide wavelength band of 440 to 650 nm.

In addition, the present invention has a 3-peak structure having three emission peaks by the red emission layer 234 . The three emission peaks may be 440 to 480 nm corresponding to a blue region, 510 to 590 nm corresponding to a yellow-green region, and 600 to 650 nm corresponding to a red region. Accordingly, it is possible to provide an organic light emitting display device with improved red efficiency and improved color gamut and color viewing angle. In addition, since the red light emitting layer 234 is included, an organic light emitting display device with improved red efficiency and improved color gamut and color viewing angle can be provided.

In addition, since the yellow-green light emitting layer 232c has high luminous properties, the luminous properties of white light implemented by the white organic light emitting diode of the present invention can be improved.

As described above, the white organic light emitting display device according to another embodiment of the present invention has a three-stack structure composed of three light emitting units 231, 232, and 233, substantially the same as the white organic light emitting display device according to the above-described embodiment. Consists of In addition, charge generation layers 235a', 235a", 235b', and 235b" are formed between the three light emitting units 231, 232, and 233.

However, the present invention is not limited thereto, and as described above, the present invention can be applied to a 2-stack or 4-stack n-stack structure in addition to the 3-stack structure.

In particular, in the white organic light emitting display device according to another embodiment of the present invention, the hole transport type is disposed between the first charge generation layers 235a' and 235b' and the yellow-green light emitting layer 232c of the second light emitting unit 232. It is characterized in that an auxiliary layer 236 made of a host and a red light emitting layer 234 including a hole transport type host are positioned.

That is, the red light emitting layer 234 of the present invention is not provided in the additional light emitting part, but is characterized in that it is provided in the second light emitting part 232 having the yellow-green light emitting layer 232c.

In addition, the red light emitting layer 234 according to another embodiment of the present invention may replace the second hole transport layer. That is, the red light emitting layer 234 according to another embodiment of the present invention simultaneously serves as a second hole transport layer that transfers holes to the upper yellow-green light emitting layer 232c in addition to serving as a red light emitting layer. To this end, the red light emitting layer 234 according to another embodiment of the present invention is characterized in that it consists of at least one host having the same or similar energy level as the second hole transport layer, that is, the first red host and at least one dopant.

As described above, the first red host refers to a hole transport type (or hole transfer type) host having relatively strong hole characteristics. For example, the first red host may have a LUMO energy level of 1.0 to 3.0 eV and a HOMO energy level of 4.9 to 6.0 eV.

In this case, the red emission layer 234 according to another embodiment of the present invention may further include a second red host.

The second red host means an electron transport type (or electron transfer type) host having relatively strong electron characteristics. For example, the second red host may have a LUMO energy level of 2.0 to 3.0 eV and a HOMO energy level of 5.0 to 6.5 eV.

For example, in the red emission layer 234 according to another embodiment of the present invention, the ratio of the first red host and the second red host may be 1.9 to 9:1.

In this case, when the dopant is minimally doped in the red light emitting layer 234, holes may be transferred to the yellow-green light emitting layer 232c that is joined or separated by movement of the first red host.

In addition, the second light emitting unit 232 according to another embodiment of the present invention not only has a red light emitting layer 234 between the first charge generation layers 235a' and 235b' and the yellow-green light emitting layer 232c, As the auxiliary layer 236 made of a hole transport type host exists between the charge generation layers 235a' and 235b' and the red light emitting layer 234, electrons leaking from the yellow-green light emitting layer 232c are trapped. By contributing to red light emission, the red efficiency is further increased. Thus, the luminance is further improved.

The first red host having an energy level similar to that of the second hole transport layer may be formed of a hole transport layer material represented by the following formula, but is not limited thereto.

로 이루어질 수 있다.At this time, A, B =

can be made with

Rn (n = 1 to 12) of A or B is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a substituted or unsubstituted condensed aryl group having 10 to 30 carbon atoms, or a substituted or unsubstituted aryl group having 2 to 24 carbon atoms. Heteroaryl group, substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, substituted or unsubstituted heteroalkyl group having 1 to 24 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 24 carbon atoms, substituted or unsubstituted 1 to 24 carbon atoms 24 alkoxy groups, substituted or unsubstituted aryloxy groups having 6 to 24 carbon atoms, substituted or unsubstituted alkylsilyl groups having 1 to 24 carbon atoms, substituted or unsubstituted arylsilyl groups having 6 to 24 carbon atoms, cyano groups, It may be selected from the group consisting of a halogen group, deuterium and hydrogen, and R1 to R12 may form a condensed ring with adjacent substituents.

L is an aryl group, phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine, acridine , cinnoline, quinazoline, quinoxaline, naphthydrine, phtalazine, quinolizine, indole, indazole, It may be selected from the group consisting of pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole.

The first red host may include materials of the following chemical formula.

,

,

,

,

(CBP)

(CDBP)

(mCP)

(BCP)

The red emission layer 234 may include one or more hosts, that is, a first red host, and may include one or more dopants.

Another host of the red emission layer 234, that is, the second red host may include a phosphorescent host, but is not limited thereto.

The second red host may include materials of the following chemical formula.

,

,

,

,

(BAlq)

(TAZ)

The phosphorescent host substituent may include a substituent having the structure described above, and Rn (n = 1 to 12) of the substituent is a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, or a substituted or unsubstituted aryl group having 10 to 30 carbon atoms. A condensed aryl group, 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 A cycloalkyl group having 3 to 24 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 24 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 24 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 24 carbon atoms, a substituted or It may be selected from the group consisting of an unsubstituted arylsilyl group having 6 to 24 carbon atoms, a cyano group, a halogen group, deuterium, and hydrogen, and R1 to R12 may form a condensed ring with adjacent substituents.

The substituent is substituted or unsubstituted, and the fused or unfused aryl group is phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine (phenanthridine), acridine, cinnoline, quinazoline, quinoxaline, naphthydrine, phthalazine, quinolizine, indole Consists of indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole It consists of 1 to 5 overlapping substitutions or non-overlapping substitutions in the central structure.

The phosphorescent dopant material may be formed of a metal compound that forms a 3-coordinate with N—N or N—O, O—O around the iridium (Ir) metal.

The red light emitting layer 234 may have a thickness of 5 to 300 Å, preferably 50 to 150 Å.

The red light emitting layer 234 may emit fluorescence or phosphorescence.

The red dopant of the red emission layer 234 may have a doping concentration of 0.1 to 10%, preferably 0.5 to 3%.

The auxiliary layer 236 is positioned between the first P-type charge generation layer 235b' and the red light-emitting layer 234 to form a cavity between the first P-type charge generation layer 235b' and the red light-emitting layer 234. Not only does it play a role in regulating the quenching of excitons, but it also plays a role in contributing to almost 100% luminescence by reducing the quenching probability of excitons.

The auxiliary layer 236 may be formed together with the red light emitting layer 234 or may be formed separately.

The auxiliary layer 236 may be formed of the same hole transport type host as the first red host of the red light emitting layer 234 . That is, a structure including a group selected from the above-described structure of the first red host may be formed in a symmetrical or asymmetrical structure, but the present invention is not limited thereto.

The auxiliary layer 236 may have a thickness of 10 to 300 Å, preferably 10 to 150 Å.

18 is a diagram schematically showing a band diagram of an organic light emitting diode according to another embodiment of the present invention.

In this case, FIG. 18 illustrates an example in which the red light emitting layer R EML includes a first red host R HOST1 , a second red host R HOST2 , and a red dopant RD.

However, the present invention is not limited thereto, and the red light emitting layer R EML may include at least one host and at least one dopant.

Referring to FIG. 18, in the red light emitting layer (R EML) according to another embodiment of the present invention, the LUMO energy level and the HOMO energy level of the first red host (R HOST1) and the auxiliary layer (HOST1') are 2.2 eV, respectively. and 5.4 eV, which is the same range as that of the second hole transport layer. However, the present invention is not limited thereto. Here, the first red host R HOST1 is a hole transport type host and can be regarded as a host having higher (faster) ability to transport holes than electrons. Accordingly, the LUMO energy level of the first red host R HOST1 may be 1.0 to 3.0 eV, and the HOMO energy level may be 4.9 to 6.0 eV. Also, the LUMO energy level of the second red host R HOST2 may be 2.0 to 3.0 eV, and the HOMO energy level may be 5.0 to 6.5 eV. Also, the auxiliary layer HOST1' may have a LUMO energy level of 1.0 to 3.0 eV and a HOMO energy level of 4.9 to 6.0 eV. As shown in FIG. 18, it can be seen that the LUMO energy level of the first P-type charge generation layer P-CGL adjacent to the first red host R HOST1 is 5.2 eV and the HOMO energy level is 8.3 eV. In addition, it can be seen that the LUMO energy level of the red dopant (RD) is 3.0 eV and the HOMO energy level is 5.0 eV. In FIG. 18, ITO denotes the first electrode and AL denotes the second electrode.

In addition, the red light emitting layer (R EML) according to another embodiment of the present invention may replace the function of the second hole transport layer. That is, since the red light-emitting layer (R EML) is inserted between the first P-type charge generation layer (P-CGL) and the yellow-green light-emitting layer (YG EML), holes can be transferred to the yellow-green light-emitting layer (YG EML), so that yellow - Efficiency of the green light emitting layer can be improved, and red efficiency can be improved.

As described above, in the present invention, in the second light emitting unit, the yellow-green light emitting layer (YG EML) is the main light emitting layer, and the red light emitting layer (R EML) is a secondary light emitting layer that emits red light and serves as the second hole transport layer. and color gamut and color viewing angle can be improved.

That is, the red light emitting layer (R EML) serves to fill the red efficiency lacking only with the blue light emitting layer and the yellow-green light emitting layer (YG EML). In addition, the first red host (R HOST1) and the auxiliary layer (HOST1') of the red light emitting layer (R EML) have the same energy level as the second hole transport layer, and the first red host (R HOST1), which is a hole transport type host, The auxiliary layer HOST1' may also serve as a second hole transport layer that transfers holes to the upper yellow-green light emitting layer YG EML. Accordingly, luminance, color gamut and color viewing angle can be further improved.

In addition, the red dopant RD of the red light emitting layer R EML and the auxiliary layer HOST1' trap electrons leaking from the yellow-green light emitting layer YG EML, so that the first P-type charge generation layer P- CGL) can be further protected. In addition, since the auxiliary layer HOST1' and the red light emitting layer (R EML) are present between the first P-type charge generation layer (P-CGL) and the yellow-green light emitting layer (YG EML), the yellow-green light emitting layer (YG EML) By trapping electrons leaking from and contributing to red light emission, the efficiency of red light is increased and the luminance of the panel is improved.

As an example, as described above, the comparative example takes an organic light emitting diode having a 3-stack structure without a red light emitting layer as an example.

Experimental Example 5 illustrates an example in which a first red host and a second red host each have a thickness of 50 Å in a three-stack organic light emitting diode having a red light emitting layer according to another embodiment of the present invention. Here, the first red host is a hole transport type host having the same or similar energy level as the hole transport layer described above.

In Experimental Example 5, a case in which the red dopant of the red emission layer has a doping concentration of 1% and an auxiliary layer made of the above-described first red host is provided as an example.

In the case of Experimental Example 5, it can be seen that the color viewing angle change rate (Δu'v') when the viewing angle changes from 0° to 60° is about 0.008. And, the DCI coverage was measured to be 98%. The DCI overlap ratio may be referred to as DCI color gamut satisfaction. Since the DCI (Digital Cinema Initiatives) overlapping ratio is widened, there is an effect of providing clearer picture quality on a large-area TV. It can be seen that the addition of the layer further improved the color viewing angle and color gamut. In addition, it can be seen that the red efficiency is further improved in the case of Experimental Example 5 compared to the Comparative Example or Experimental Examples 1 to 4. Experimental Example 6 is an example of a three-stack organic light emitting diode having a red light emitting layer according to another embodiment of the present invention, in which the first red host and the second red host have thicknesses of 70 Å and 50 Å, respectively. . Here, the first red host is a hole transport type host having the same or similar energy level as the hole transport layer described above.

In Experimental Example 6, a case in which the red dopant of the red light emitting layer has a doping concentration of 1% and an auxiliary layer made of the first red host described above is provided as an example.

In the case of Experimental Example 6, it can be seen that the color viewing angle change rate (Δu'v') when the viewing angle changes from 0° to 60° is about 0.014. And, the DCI coverage was measured to be 99%. The DCI overlap ratio may be referred to as DCI color gamut satisfaction. Since the DCI (Digital Cinema Initiatives) overlapping ratio is widened, there is an effect of providing a clearer picture quality on a large-area TV. Therefore, it can be seen that the color viewing angle and color gamut were further improved in Experimental Example 6 compared to Comparative Example or Experimental Examples 1 to 4 by adding the auxiliary layer as well as the red light emitting layer. And, it can be seen that the red efficiency is further improved in the case of Experimental Example 6 compared to Comparative Example or Experimental Examples 1 to 4.

Although many details have been specifically described in the above description, this should be interpreted as an example of a preferred embodiment rather than limiting the scope of the invention. Therefore, the invention should not be defined according to the described examples, but should be defined according to the scope of the claims and the scope of the claims.

118,218: first electrode 128,228: second electrode
130, 131,231, 132,232, 133,233: light emitting part
131c, 231c, 133c, 233c: blue light emitting layer
132c, 232c: yellow-green light emitting layer 134, 234: red light emitting layer
135a', 235a', 135a", 235a": N-type charge generation layer
135b', 235b', 135b", 235b": P-type charge generation layer
236: auxiliary layer

Claims (19)

first electrode;
a first light emitting unit including a first hole transport layer disposed on the first electrode, a blue light emitting layer disposed on the first hole transport layer, and a first electron transport layer disposed on the blue light emitting layer;
a first charge generation layer positioned on the first light emitting part;
a second light emitting unit including a second hole transport layer disposed on the first charge generation layer, a yellow-green light emitting layer disposed on the second hole transport layer, and a second electron transport layer disposed on the yellow-green light emitting layer; and
And a second electrode positioned on the second light emitting part,
The second hole transport layer includes at least one hole transport type host having a hole-accepting property and in contact with the upper surface of the first charge generation layer to transport holes to the yellow-green light emitting layer;
The white organic light emitting display device, characterized in that the second hole transport layer is a red light emitting layer that emits red light. delete The white organic light emitting display device according to claim 1 , further comprising a third light emitting part disposed on the second light emitting part and including a blue light emitting layer. 4. The white organic light emitting display device according to claim 3, further comprising a second charge generation layer positioned between the second light emitting part and the third light emitting part. delete delete delete delete The white organic light emitting display device according to claim 1, wherein the red light emitting layer includes a red dopant having a doping concentration of 0.5 to 10%. The white organic light emitting display device according to claim 1, wherein the red light emitting layer includes at least one host different from the hole transport type host and one or more dopants. 11. The white organic light emitting display device according to claim 10, wherein the hole transport type host and at least one other host have a thickness ratio of 1:9 to 9:1. delete delete delete delete delete delete delete delete

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