KR20160080077A - Organic light emitting diode and organic light emitting display device having the same, and method of fabricating the same - Google Patents

Abstract

According to the present invention, an organic light emitting diode, an organic light emitting display device with the same, and a manufacturing method of the organic light emitting diode disperse quantum dots (QDs) in a hole injection layer to inadvertently absorb blue light generated from red and green light emitting layers. According to the present invention, color purity can be improved and be maintained like first purity even after light emission for a long time.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED), an organic light emitting diode (OLED) display having the organic light emitting diode, a method of manufacturing the organic light emitting diode,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode and an organic light emitting display having the organic light emitting diode. More particularly, the present invention relates to an organic light emitting diode manufactured using a soluble process, To a method of manufacturing a diode.

In recent years, there has been a growing interest in information display and a demand for a portable information medium has increased, and a lightweight flat panel display (FPD) that replaces a cathode ray tube (CRT) And research and commercialization are being carried out.

In the field of flat panel displays, a liquid crystal display device (LCD), which is light and consumes less power, has attracted the greatest attention, but a liquid crystal display device is not a light emitting device but a light receiving device. ) And a viewing angle. Therefore, a new display device capable of overcoming such drawbacks is actively developed.

Since the organic light emitting display device, which is one of the new display devices, is self-emitting type, the viewing angle and the contrast ratio are superior to the liquid crystal display device. In addition, since a backlight is not required, it is possible to make a light-weight thin type, and it is also advantageous in terms of power consumption. It has the advantage of being able to drive DC low voltage and has a fast response speed.

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 for explaining the principle of light emission of a general organic light emitting diode.

In general, an organic light emitting display device includes an organic light emitting diode as shown in FIG.

The organic light emitting diode includes an anode 18 as a pixel electrode, a cathode 28 as a common electrode, and organic layers 30a, 30b, 30c, 30d and 30e formed therebetween.

The organic layers 30a, 30b, 30c, 30d and 30e are formed of a hole transport layer (HTL) 30b, an electron transport layer (ETL) 30d, a hole transport layer 30b and an electron transport layer And an emission layer (EML) 30c interposed between the emission layers 30a and 30d.

In this case, a hole injection layer (HIL) 30a is interposed between the anode 18 and the hole transport layer 30b to enhance the emission efficiency, and electrons are injected between the cathode 28 and the electron transport layer 30d. An electron injection layer (EIL) 30e is interposed.

When the positive and negative voltages are applied to the anode 18 and the cathode 28, the organic light emitting diode having the above structure passes through the hole transporting layer 30b and the electron transporting layer 30d One electron is moved to the light emitting layer 30c to form an exciton, and light is generated when the exciton transitions from an excited state to a ground state, that is, a stable state.

An organic light emitting display displays an image by arranging sub-pixels having organic light emitting diodes of the above-described structure 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 an active matrix method using a passive matrix or a thin film transistor as a switching element. The active matrix method selectively turns on the thin film transistor, which is an active element, to select a sub-pixel and maintain the emission of the sub-pixel with the voltage held in the storage capacitor.

Such organic light emitting diodes generally use vacuum deposition for each layer. This is a method of vaporizing the material of the layer to be formed in a vacuum chamber and depositing the material on the substrate.

However, when the vacuum chamber is used, the size of the chamber must be at least larger than the size of the substrate on which the vacuum deposition is performed. Further, it is necessary to secure a sufficient space for the inflow of the substrate in the chamber, and there is a limit to the increase in size.

In a general organic light emitting diode, blue light may emit light in the red light emitting layer depending on the position where the hole / electron recombination zone is formed. That is, when the hole / electron coupling region is formed close to the hole transporting layer or the electron transporting layer, undesired blue light may be emitted. This phenomenon may occur even after the organic light emitting diode emits light for a long time.

2 is a graph showing an example of a radiant power according to a wavelength in a general organic light emitting diode.

At this time, FIG. 2 shows an example of the radiation flux according to the wavelength of the green light emitting layer.

Referring to FIG. 2, it can be seen that a blue peak appears at a wavelength band corresponding to blue light (440 nm to 480 nm).

An object of the present invention is to provide an organic light emitting diode manufactured using a solution process, an organic light emitting display having the organic light emitting diode, and a method of manufacturing the organic light emitting diode.

Another object of the present invention is to provide an organic light emitting diode having improved color purity, an organic light emitting display having the same, and a method of manufacturing an organic light emitting diode.

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

According to an embodiment of the present invention, an organic light emitting diode and an organic light emitting display including the organic light emitting diode may have a structure in which quantum dots are dispersed in a hole injection layer or an encapsulation layer, And absorbs the blue light which has not occurred.

For this, an organic light emitting diode and an organic light emitting display including the organic light emitting diode according to an embodiment of the present invention are sequentially disposed on a first electrode and a first electrode, and sequentially form a hole injection layer, a hole transport layer, a light emitting layer, And a second electrode located above the light emitting portion.

At this time, the light emitting portion is divided into red, green, and blue sub-pixels, and the phosphor is injected into the hole injection layer of the red, green, and blue sub-pixels or the encapsulation layer corresponding to the red, Lt; / RTI >

These phosphors may be quantum dots that emit red or green light by absorbing blue light emitted from the light emitting portion of red and green sub-pixels.

On the other hand, the phosphor may be dispersed in the encapsulation layer corresponding to the light emitting portion of the blue sub-pixel.

In addition, a method of manufacturing an organic light emitting diode according to an exemplary embodiment of the present invention includes forming a hole injection layer of a blue sub-pixel on a first electrode, forming a hole injection layer of red, green, and blue sub- And forming a hole transport layer and a light emitting layer on the hole injection layer of red, green, and blue sub-pixels, respectively.

At this time, the hole injecting layer, the hole transporting layer, and the light emitting layer can be formed through a solution process.

The hole injection layer can be formed using a solvent in which quantum dots are dispersed.

As described above, according to the organic light emitting diode and the organic light emitting display having the organic light emitting diode according to the embodiment of the present invention, the light efficiency and color purity are improved, and the color purity is improved even after long- It has a sustainable effect.

In addition, according to the organic light emitting display device according to another embodiment of the present invention, the viewing angle can be improved by scattering light.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a principle of light emission of a general organic light emitting diode. FIG.
2 is a graph showing an example of a radiant power according to wavelengths in a general organic light emitting diode.
3 is a block diagram schematically illustrating an organic light emitting display according to an embodiment of the present invention.
4 is an exemplary diagram showing a circuit configuration for a sub-pixel of an organic light emitting display device.
5 is a schematic cross-sectional view of an organic light emitting display according to a first embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating an example of one sub-pixel in the organic light emitting display according to the first embodiment of the present invention shown in FIG.
FIG. 7 is an exemplary view schematically showing the structure of an organic light emitting diode in an organic light emitting display according to a first embodiment of the present invention shown in FIG. 5;
8A and 8B are exemplary views showing an example of a solution process.
FIGS. 9A and 9B are graphs showing an example of a radiation flux according to a wavelength. FIG.
10 is a cross-sectional view illustrating an example of one sub-pixel in the organic light emitting display according to the second embodiment of the present invention.
FIG. 11 is an exemplary view schematically showing the structure of an organic light emitting diode in an organic light emitting display according to a second embodiment of the present invention shown in FIG. 10; FIG.
12 is a plan view schematically showing an organic light emitting display device according to a second embodiment of the present invention.
FIG. 13 is a graph illustrating an example of the intensity of light emitted from a green sub-pixel according to wavelengths.

An organic light emitting diode and an organic light emitting display device having the same according to an embodiment of the present invention are characterized in that proton dots are dispersed in a hole injection layer to absorb blue light unintentionally generated from red and green light emitting layers .

For this, an organic light emitting diode and an organic light emitting display including the organic light emitting diode according to an embodiment of the present invention are sequentially disposed on a first electrode and a first electrode, and sequentially form a hole injection layer, a hole transport layer, a light emitting layer, And a second electrode located above the light emitting portion.

At this time, the light emitting portion is divided into red, green and blue sub-pixels, and the phosphor may be dispersed in the hole injection layer of the red, green and blue sub-pixels.

These phosphors can be made of quantum dots.

The quantum dots can absorb the blue light emitted from the light emitting portion of the red sub-pixel.

Quantum dots absorb blue light and can emit red or green light.

In addition, a method of manufacturing an organic light emitting diode according to an exemplary embodiment of the present invention includes forming a hole injection layer of a blue sub-pixel on a first electrode, forming a hole injection layer of red, green, and blue sub- And forming a hole transport layer and a light emitting layer on the hole injection layer of red, green, and blue sub-pixels, respectively.

At this time, the hole injecting layer, the hole transporting layer, and the light emitting layer can be formed through a solution process.

The hole injection layer can be formed using a solvent in which quantum dots are dispersed.

According to another aspect of the present invention, there is provided an organic light emitting display including a transistor provided on a substrate, a first electrode provided on the transistor, a first electrode sequentially disposed on the first electrode, And an encapsulation layer disposed on the second electrode, wherein the light emitting portion is divided into red, green, and blue sub-pixel light emitting portions, The encapsulation layer corresponding to the light emitting portion of the red, green sub-pixel includes a phosphor.

Wherein the encapsulation layer comprises first, second and third portions respectively corresponding to light emitting portions of the red, green and blue sub-pixels, the first, second and third portions of the encapsulation layer Second, and third phosphors, respectively.

The size of the second phosphor may be smaller than that of the first phosphor and larger than that of the third phosphor.

The first, second, and third phosphors may be quantum dots that absorb blue light and emit light of longer wavelength than the blue light.

The light emitting layer of the red sub-pixel includes a red light emitting layer and a blue common light emitting layer, and the light emitting layer of the green sub-pixel includes a green light emitting layer and a blue common light emitting layer, .

Hereinafter, preferred embodiments of the organic light emitting diode and the organic light emitting display including the organic light emitting diode and the organic light emitting diode according to the present invention will be described with reference to the accompanying drawings, Will be described in detail so as to be easily carried out.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of the layers and regions in the figures may be exaggerated for clarity of illustration.

It will be understood that when an element or layer is referred to as being another element or "on" or "on ", it includes both intervening layers or other elements in the middle, do. On the other hand, when a device is referred to as "directly on" or "directly above ", it does not intervene another device or layer in the middle.

The terms spatially relative, "below," "lower," "above," "upper," and the like, And may be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprise "and / or" comprising ", as used in the specification, means that the presence of stated elements, Or additions.

3 is a block diagram schematically showing an organic light emitting display device according to an embodiment of the present invention.

3, an organic light emitting display according to an exemplary embodiment of the present invention includes an image processor 115, a data converter 114, a timing controller 113, a data driver 112, a gate driver 111, A display panel 110 may be included.

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

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

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

The data driver 112 samples and latches the data signal DATA supplied from the timing controller 113 in response to the data timing control signal DCS supplied from the timing controller 113, And outputs it. 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 IC (Integrated Circuit).

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

The display panel 110 may be implemented in a sub-pixel structure including, for example, 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, SPb. However, the present invention is not limited thereto, and may further include a white sub-pixel.

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

In this case, the sub-pixel shown in FIG. 4 is configured as a 2T (Transistor) 1C (Capacitor) structure including a switching transistor, a driving transistor, a capacitor, and an organic light emitting diode. However, the present invention is not limited to this, and when a compensation circuit is added, it can be configured in various ways such as 3T1C, 4T2C, 5T2C, and the like.

4, the organic light emitting display includes a gate line GL arranged in a first direction and a data line DL spaced apart from each other in a second direction crossing the first direction and a driving power line VDDL Sub-pixel region is defined by the sub-pixel region.

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 in accordance with the driving current generated by the driving transistor DR.

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

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

The compensation circuit CC compensates the threshold voltage of the driving transistor DR and the like. The compensation circuit CC may consist of one or more transistors and capacitors. The configuration of the compensation circuit (CC) is very various, and a detailed illustration and description thereof are omitted.

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

FIG. 5 is a schematic cross-sectional view of an organic light emitting display according to a first embodiment of the present invention. Referring to FIG.

At this time, FIG. 5 illustrates one pixel made up of red, green and blue sub-pixels, that is, RGB sub-pixels. The RGB sub-pixels may be formed by dividing the light emitting material included in each organic light emitting diode into RGB colors.

FIG. 6 is a cross-sectional view illustrating an example of a sub-pixel in the organic light emitting display according to the first embodiment of the present invention shown in FIG. 5, in which a green sub-pixel is taken as an example.

5 and 6 illustrate an organic light emitting display device of a back light emission type in which light is emitted in the direction of a substrate on which pixels are arranged. However, the present invention is not limited thereto. The present invention can be applied to an organic light emitting display device of a both-side emission type as well as a top emission type organic light emitting display device in which light is emitted in a direction opposite to a substrate on which pixels are arranged.

5 and 6 illustrate an organic light emitting display device using a thin film transistor having a coplanar structure. However, the present invention is not limited to a thin film transistor having a coplanar structure.

FIG. 7 is a schematic view showing the structure of an organic light emitting diode in the organic light emitting display according to the first embodiment of the present invention shown in FIG.

5 to 7, the organic light emitting display device according to the first embodiment of the present invention may include a transistor (TFT) formed on a substrate 101 and an organic light emitting diode (OLED).

In this case, for example, the substrate 101 may be divided into red, green and blue sub-pixels R, G and B, and red, green and blue sub-pixels R, G and B may be regularly repeated . This regularity can be line-by-line or diagonal.

First, the driving thin film transistor as a transistor (TFT) 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 a transparent plastic or a polymer film.

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

At this time, 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 a transistor (TFT) formed in a subsequent process from an impurity such as alkali ions flowing out from the substrate 101. [

A gate insulating film 125a made of a silicon nitride film (SiNx) or a silicon oxide film (SiO2) is formed on the semiconductor layer 124. A gate line (not shown) including the gate electrode 121, An electrode (not shown) is formed.

The gate electrode 121 and the gate line and the first sustain electrode may be formed of a first metal material having low resistance characteristics such as aluminum (Al), copper (Cu), molybdenum (Mo), chrome (Cr) ), Titanium (Ti), nickel (Ni), neodymium (Nd), or alloys thereof.

An inter insulation layer 125b made of a silicon nitride film, a silicon oxide film or the like is formed on the gate electrode 121, the gate line and the first sustain electrode, and a data line (not shown), a driving voltage line (Not shown), source / drain electrodes 122 and 123, and a second sustain electrode (not shown).

The source electrode 122 and the drain electrode 123 are spaced apart from each other by a predetermined distance and are electrically connected to the semiconductor layer 124. More specifically, the gate insulating film 125a and the interlayer insulating film 125b are provided with a semiconductor layer contact hole exposing the semiconductor layer 124. Source / drain electrodes 122 and 123 are formed through the semiconductor layer contact holes. And is electrically connected to the semiconductor layer 124.

At this time, the second sustain electrode overlaps with a part of the first sustain electrode below the interlayer insulating film 125b to form a storage capacitor.

The data line, the driving voltage line, the source / drain electrodes 122 and 123 and the second sustain electrode may be formed of a second metal material having low resistance characteristics such as aluminum (Al), copper (Cu), molybdenum (Mo) And may be formed of a single layer or multiple layers of chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd)

A protective film (or a planarization film) 125c is formed on the substrate 101 on which the data lines, the driving voltage lines, the source / drain electrodes 122 and 123 and the second sustain electrodes are formed.

An overcoat layer 125d exposing a part of the drain electrode 123 is formed on the protective film 125c. The overcoat layer 125d may be formed of an organic material, but may be formed of an inorganic material or a mixture of organic and inorganic materials. At this time, if the protective film 125c serves as the overcoat layer 125d, the overcoat layer 125d may not be formed.

Next, the organic light emitting diode OLED may include a first electrode 118, a light emitting portion 130, and a second electrode 128.

The organic light emitting diode OLED is electrically connected to the driving thin film transistor TFT. More specifically, in the protective film 125c and the overcoat layer 125d formed on the driving thin film transistor TFT, a drain contact hole exposing the drain electrode 123 of the driving thin film transistor TFT is formed. The organic light emitting diode OLED is electrically connected to the drain electrode 123 of the driving thin film transistor TFT through the drain contact hole.

That is, the first electrode 118 is formed on the overcoat layer 125d and is electrically connected to the drain electrode 123 of the driving thin film transistor TFT through the drain contact hole.

The first electrode 118 supplies current (or voltage) to the light emitting unit 130, and defines a light emitting region having a predetermined area.

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 large work function. For example, indium tin oxide (ITO) or indium zinc oxide (IZO) . However, the present invention is not limited thereto.

A bank 125e is formed on the substrate 101 on which the first electrode 118 is formed. At this time, the bank 125e surrounds the edge of the first electrode 118 to define an opening, and is made of an organic insulating material.

The bank 125e may also be made of a photosensitizer containing a black pigment, in which case the bank 125e serves as a light shielding member.

The light emitting portion 130 and the second electrode 128 are sequentially formed on the substrate 101 on which the bank 125e is formed.

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

The light emitting unit 130 may have a multilayer structure including auxiliary layers 130a, 130b, and 130d for improving luminous efficiency of the light emitting layer 130c in addition to the light emitting layer 130c. That is, the light emitting unit 130 includes a hole transport layer 130b, an electron transport layer 130d, and a light emitting layer 130c interposed between the hole transport layer 130b and the electron transport layer 130d.

A hole injection layer 130a is interposed between the first electrode 118 and the hole transport layer 130b and an electron injection layer 130b is formed between the second electrode 128 and the electron transport layer 130d. Not shown) may be interposed.

The light emitting unit 130 may be divided into red, green, and blue sub-pixels R, G, and B to be formed through a soluble process. Which can be formed by selectively coating a solution-processable material of low molecular weight or high molecular weight on the first electrode 118.

The light emitting layer 130c, the hole injecting layer 130a and the hole transporting layer 130b can be usually formed by a solution process. In some cases, the hole injecting layer 130a may be omitted, or the hole injecting layer 130a and the hole transporting layer 130b may be formed as one layer by mixing materials. In addition, the hole injection layer 130a and the hole transport layer 130b may be formed by dividing into two or more layers.

The electron transporting layer 130d may be formed entirely without dividing into regions, and may be formed by a vacuum deposition method. In some cases, an electron injection layer may be additionally formed on the electron transport layer 130d.

Here, the material forming the light emitting layer 130c of the red, green and blue sub-pixels R, G and B formed by the solution process may be a fluorescent light emitting material or a phosphorescent light emitting material, respectively. These light emitting layers 130c may include one or more dopants capable of expressing luminescent color in one or more hosts.

The solution process can be selected from inkjet printing, nozzle printing, transferring process, thermal jet printing, or spin coating.

Such a solution process may proceed without a separate mask or chamber. Therefore, the solution process has a simpler process and a lower process cost than the deposition process, thereby reducing the processing time and manufacturing cost of the organic light emitting diode (OLED).

Hereinafter, a method of a solution process applied to manufacture the light emitting layer 130c, the hole injection layer 130a, and the hole transport layer 130b according to the first embodiment of the present invention will be described as an example.

8A and 8B are illustrations showing an example of a solution process.

Fig. 8A relates to inkjet printing, in which printing is performed through a head 140 having a jetting port capable of dropping ink 145 on a substrate 101. Fig.

In this case, the head 140 or the substrate 101 moves during printing. In this case, fine control for each area is easy. That is, selective coating of each sub-pixel of the organic light emitting display device can be easily performed.

In addition to inkjet printing, nozzle printing is a process of preparing a slit-shaped nozzle and printing on the substrate 101. [ A plurality of such nozzles may be provided. It is relatively easy to print a pattern distributed over a wider area than the ink-jet printing method. For example, in the case of an organic light emitting display device in which a bank is formed on a substrate 101, when a predetermined layer is formed by the front nozzle printing method, it is possible to divide the organic light emitting display device by the bank.

FIG. 8B relates to roll printing, in which a main roller 150 on which a pattern 155 is formed is rotated to form a print pattern on the substrate 101. FIG. In this case, the sub-roller 151 is connected to the head to which the printing solution is supplied, thereby guiding the printing solution from the head to be continuously supplied onto the pattern 155 of the main roller 150. In some cases, when the pattern 155 is not formed on the main roller 150, the entire substrate 101 can be coated.

Additional examples of such solution processes include transferring processes, gravure printing and thermal jet printing.

However, the above-mentioned examples are limited to the solution process, and may be performed by solution process of other equipment or other process depending on development of equipment and the like.

5 to 7, the light emitting unit 130 of the red, green sub-pixels R and G according to the first embodiment of the present invention includes a phosphor layer formed on the hole injection layer 130a, (135) are dispersed. The phosphor 135 is made of a water-absorbing material and absorbs light having a short wavelength, that is, blue light (refer to an arrow A shown in FIG. 6) to emit light of a desired color, thereby increasing color purity. In addition, it is possible to shift to a desired wavelength of light by emitting light of the phosphor 135 by absorbing light of a short wavelength generated as the luminescent region moves over time.

As described above, when the hole / electron coupling region is formed close to the hole transporting layer 130b or the electron transporting layer 130d depending on the position where the hole / electron coupling region is formed in the light emitting layer 130c, unwanted blue light leaks It comes out. Due to the blue color mixture, a color phenomenon may occur in red and green sub-pixels (R, G). Such a dark color may occur even after long-time light emission of the organic light emitting diode (OLED).

Therefore, the present invention is characterized in that a phosphor 135 made of a water-soluble material capable of absorbing blue light is added to the hole injection layer 130a of the red and green sub-pixels R and G.

The color may be adjusted according to the type of the phosphor 135 added to the hole injection layer 130a.

For example, a process may be performed by forming a layer by adding a phosphor 135 to a solution of the hole injection layer 130a.

Such a fluorescent material 135 may be a quantum dot (QD) having a small size so as to be well dispersed in a solution without changing the characteristics of the hole injection layer 130a.

For reference, the quantum dots may include core nanocrystals and shell nanocrystals surrounding core nanocrystals. In addition, the quantum dots may include organic ligands bound to the shell nanocrystals. The quantum dots may also include an organic coating layer surrounding the shell nanocrystals.

The shell nanocrystals can be formed in two or more layers. The shell nanocrystals are formed on the surface of the core nanocrystals. The quantum dots can convert wavelengths of light incident on the core nanocrystals to longer wavelengths through the shell nanocrystals forming the shell layer and increase the efficiency of light.

The quantum dots may include at least one of a group II compound semiconductor, a group III compound semiconductor, a group V compound semiconductor, and a group VI compound semiconductor. More specifically, the core nanocrystals may include Cdse, InGaP, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The shell nanocrystals may also include CuZnS, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The diameter of the quantum dots may be in the range of 1 nm to 10 nm.

The wavelength of light emitted from the quantum dots can be controlled by the size of the quantum dots or the molar ratio of the molecular cluster compound and the nanoparticle precursor in the synthesis process. The organic ligand may include pyridine, mercapto alcohol, thiol, phosphine and phosphine oxide, and the like. Organic ligands stabilize unstable quantum dots after synthesis. After synthesis, a dangling bond is formed on the outer surface, and the dangling bonds may cause the quantum dots to become unstable. However, one end of the organic ligand is in an unbonded state, and one end of the unbound organic ligand can bond with the dangling bond to stabilize the quantum dots.

When the quantum dot is smaller than the Bohr radius of the exciton formed by the electrons and holes excited by light or electricity, the quantum confinement effect is generated to have a staggering energy level, and the energy gap size . In addition, the charge is localized within the quantum dots, so that it has high luminous efficiency.

Unlike general fluorescent dyes, these quantum dots vary in fluorescence wavelength depending on the particle size. That is, as the size of the particle becomes smaller, it emits light having a shorter wavelength, and the particle size can be adjusted to produce fluorescence in a visible light region of a desired wavelength.

The quantum dots can be synthesized by a chemical wet process. Here, the chemical wet method is a method of growing particles by adding a precursor material to an organic solvent, and quantum dots can be synthesized by a chemical wet method.

Next, the second electrode 128 is formed on the light emitting portion 130 to provide electrons to the light emitting portion 130.

The second electrode 128 may be formed to cover the entire substrate 101. That is, the first electrode 118 is divided into sub-pixels, while the second electrode 128 may be formed as one layer connected to all the pixels.

Hereinafter, characteristics of the organic light emitting diode according to the first embodiment of the present invention will be described with reference to the drawings.

9A and 9B are graphs showing an example of radiation flux according to wavelengths.

Here, FIG. 9A shows the radiation flux according to the wavelength of the green light emitting layer, and FIG. 9B shows the radiation flux according to the wavelength of the red light emitting layer.

Referring to FIGS. 9A and 9B, it can be seen that in the case of the comparative example, a blue peak appears at a wavelength band corresponding to blue light (440 nm to 480 nm).

However, in the case of the first embodiment of the present invention, it can be seen that the blue peak disappears in the wavelength band corresponding to the blue light. This is because the phosphor dispersed in the hole injection layer absorbs blue light unintentionally generated from the red light emitting layer. Therefore, it is possible to prevent the color development in the red and green light emitting layers due to the blue color mixture.

Accordingly, according to the first embodiment of the present invention, the color purity is improved and the color purity can be maintained at the same time even after the long-time light emission.

In the case of the red and green light emitting layers according to the first embodiment of the present invention, red and green peaks appear more strongly in the wavelength range (600 nm to 650 nm, 500 nm to 550 nm) corresponding to red and green light, respectively have. This is because the blue light absorbed by the phosphor is converted into the red light and the green light.

FIG. 10 is a cross-sectional view illustrating an example of a sub-pixel in the organic light emitting display according to the second embodiment of the present invention, and shows a green sub-pixel as an example.

In this case, the organic light emitting display shown in FIG. 10 exemplifies a top emission type organic light emitting display in which light is emitted in a direction opposite to that of the substrate on which the pixels are arranged. However, the present invention is not limited thereto, and the present invention is also applicable to an organic light emitting display device of a double-sided emission type.

10 illustrates an organic light emitting display device using a thin film transistor having a coplanar structure. However, the present invention is not limited to a thin film transistor having a coplanar structure.

11 is a schematic view illustrating the structure of an organic light emitting diode in an organic light emitting display according to a second embodiment of the present invention shown in FIG.

Referring to FIGS. 10 and 11, the organic light emitting display according to the second embodiment of the present invention may include a TFT formed on a substrate 201 and an organic light emitting diode (OLED).

In this case, for example, the substrate 201 may be divided into red, green and blue sub-pixels Pr, Pg and Pb, and red, green and blue sub-pixels Pr, Pg and Pb may be regularly repeated . This regularity can be line-by-line or diagonal.

First, the driving thin film transistor as a transistor (TFT) includes a semiconductor layer 224, a gate electrode 221, a source electrode 222, and a drain electrode 223.

The semiconductor layer 224 is formed on a substrate 201 made of an insulating material such as a transparent plastic or a polymer film.

The semiconductor layer 224 may be formed of an amorphous silicon film, a polycrystalline silicon film obtained by crystallizing amorphous silicon, an oxide semiconductor, an organic semiconductor, or the like.

At this time, a buffer layer (not shown) may be further formed between the substrate 201 and the semiconductor layer 224. The buffer layer may be formed to protect a transistor (TFT) formed in a subsequent process from impurities such as alkali ions flowing out from the substrate 201. [

A gate insulating film 225a made of a silicon nitride film (SiNx) or a silicon oxide film (SiO2) is formed on the semiconductor layer 224. A gate line (not shown) including a gate electrode 221, An electrode (not shown) is formed.

The gate electrode 221 and the gate line and the first sustain electrode may be formed of a first metal material having low resistance characteristics such as aluminum (Al), copper (Cu), molybdenum (Mo), chrome (Cr) ), Titanium (Ti), nickel (Ni), neodymium (Nd), or alloys thereof.

An inter insulation layer 225b made of a silicon nitride film, a silicon oxide film, or the like is formed on the gate electrode 221, the gate line, and the first sustain electrode, and a data line (not shown) (Not shown), source / drain electrodes 222 and 223, and a second sustain electrode (not shown).

The source electrode 222 and the drain electrode 223 are spaced apart from each other by a predetermined distance and are electrically connected to the semiconductor layer 224. More specifically, a semiconductor layer contact hole exposing the semiconductor layer 224 is formed in the gate insulating film 225a and the interlayer insulating film 225b, and the source / drain electrodes 222 and 223 are formed through the semiconductor layer contact holes. And is electrically connected to the semiconductor layer 224.

At this time, the second sustain electrode overlaps with a part of the first sustain electrode below the interlayer insulating film 225b to form a storage capacitor.

The data line, the driving voltage line, the source / drain electrodes 222 and 223 and the second sustain electrode may be formed of a second metal material having low resistance characteristics such as aluminum (Al), copper (Cu), molybdenum (Mo) And may be formed of a single layer or multiple layers of chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd)

A protective film (or a flattening film) 225c is formed on the substrate 201 on which the data lines, the driving voltage lines, the source / drain electrodes 222 and 223 and the second sustain electrodes are formed.

An overcoat layer 225d exposing a part of the drain electrode 223 is formed on the protective film 225c. The overcoat layer 225d may be formed of an organic material, but may be formed of an inorganic material or a mixture of organic and inorganic materials. At this time, if the protective film 225c serves as the overcoat layer 225d, the overcoat layer 225d may not be formed.

Next, the organic light emitting diode OLED may include a first electrode 218, a light emitting portion 230, and a second electrode 228.

The organic light emitting diode OLED is electrically connected to the driving thin film transistor TFT. More specifically, in the protective film 225c and the overcoat layer 225d formed on the driving thin film transistor TFT, a drain contact hole exposing the drain electrode 223 of the driving thin film transistor TFT is formed. The organic light emitting diode OLED is electrically connected to the drain electrode 223 of the driving thin film transistor TFT through the drain contact hole.

That is, the first electrode 218 is formed on the overcoat layer 225d and is electrically connected to the drain electrode 223 of the driving thin film transistor TFT through the drain contact hole.

The first electrode 218 supplies current (or voltage) to the light emitting unit 230, and defines a light emitting region having a predetermined area.

Also, the first electrode 218 serves as an anode. Accordingly, the first electrode 218 is made of a transparent conductive material having a relatively large work function. For example, the first electrode 218 may be formed of indium tin oxide (ITO) or indium zinc oxide (IZO) . However, the present invention is not limited thereto.

A bank 225e is formed on the substrate 201 on which the first electrode 218 is formed. At this time, the bank 225e surrounds the periphery of the first electrode 218 to define an opening, and is made of an organic insulating material.

The bank 225e may also be made of a photosensitizer containing a black pigment, in which case the bank 225e serves as a light shielding member.

A light emitting portion 230 and a second electrode 228 are sequentially formed on the substrate 201 on which the bank 225e is formed.

That is, the light emitting portion 230 is formed between the first electrode 218 and the second electrode 228. The light emitting unit 230 emits light by the combination of the holes supplied from the first electrode 218 and the electrons supplied from the second electrode 228.

The light emitting portion 230 may have a multilayer structure including auxiliary layers 232, 234, and 238 for improving light emission efficiency of the light emitting layer 236 in addition to the light emitting layer 236. That is, the light emitting portion 230 includes a hole transport layer 234, an electron transport layer 238, and a light emitting layer 236 interposed between the hole transport layer 234 and the electron transport layer 238.

A hole injection layer 232 is interposed between the first electrode 218 and the hole transport layer 234 and an electron injection layer 232 is interposed between the second electrode 228 and the electron transport layer 238. [ Not shown) may be interposed.

The light emitting unit 230 may be divided into red, green, and blue sub-pixels Pr, Pg, and Pb and may be formed through a soluble process. Which can be formed by selectively coating a solution-processable material of low molecular weight or high molecular weight on the first electrode 218.

The red and green light emitting layers 236a and 236b, the hole injecting layer 232, and the hole transporting layer 234 can be formed by a solution process. In some cases, the hole injection layer 232 may be omitted, or the hole injection layer 232 and the hole transport layer 234 may be formed as a single layer by mixing materials. Further, the hole injection layer 232 and the hole transport layer 234 may be formed by dividing into two or more layers.

The blue common light emitting layer 236c and the electron transporting layer 238 may be formed entirely without distinguishing the regions, and may be formed by a vacuum deposition method. In some cases, an additional electron injection layer may be further formed on the electron transport layer 238.

Accordingly, the light emitting portion 230 of the red sub-pixel Pr includes the hole injection layer 232, the hole transporting layer 234, the red light emitting layer 236a, the blue common light emitting layer 236c, and the electron transporting layer 238 And the light emitting portion 230 of the green sub-pixel Pg includes a hole injection layer 232, a hole transporting layer 234, a green light emitting layer 236b, a blue common light emitting layer 236c, and an electron transporting layer 238 And the light emitting portion 230 of the blue sub-pixel Pb includes a hole injection layer 232, a hole transporting layer 234, a blue common light emitting layer 236c, and an electron transporting layer 238. The blue common light emitting layer 236c of the red and green sub-pixels Pr and Pg serves as a hole blocking layer.

Here, the material constituting the light emitting layer 236 of the red, green and blue sub-pixels Pr, Pg and Pb formed by the solution process or the vacuum deposition process may be a fluorescent light emitting material or a phosphorescent light emitting material, respectively. The light emitting layer 236 may include one or more dopants capable of expressing luminescent color in one or more hosts.

The solution process can be selected from inkjet printing, nozzle printing, transferring process, thermal jet printing, or spin coating.

Such a solution process may proceed without a separate mask or chamber. Therefore, the solution process has a simpler process and a lower process cost than the deposition process, thereby reducing the processing time and manufacturing cost of the organic light emitting diode (OLED).

Next, the second electrode 228 is formed on the light emitting portion 230 to provide electrons to the light emitting portion 230.

The second electrode 228 may be formed to cover the entire substrate 201. That is, the first electrode 218 is divided into sub-pixels Pr, Pg, and Pb, but the second electrode 228 may be formed as one layer connected to all the pixels.

A capping layer 240 is formed on the second electrode 228 and the capping layer 240 may cover the entire substrate 201 in the same manner as the second electrode 228. The capping layer 240 may be made of an organic material having a high refractive index and may be formed by amplifying the wavelength of light traveling along the capping layer 240 by surface plasma resonance, thereby increasing the light extraction efficiency in the top emission type organic light emitting diode display device.

Next, an encapsulation layer 250 is formed on the capping layer 240. The encapsulation layer 250 may be formed of a polymer that protects the organic light emitting diode OLED by blocking water or oxygen introduced from the outside and functions as a moisture absorbing or buffering layer.

Here, between the capping layer 240 and the encapsulation layer 250, a single-layer thin film of an inorganic film or a multilayer thin film of an inorganic film and an organic film may be further formed.

The organic light emitting display according to the second embodiment of the present invention is characterized in that a phosphor 252 is dispersed in an encapsulation layer 250. The phosphor 252 is made of a water-absorbing material and absorbs light having a short wavelength, that is, blue light (L11) to emit light of a desired color (L12), thereby increasing color purity and improving light efficiency. In addition, it is possible to shift the wavelength of desired light by emitting light of the phosphor 252 by absorbing light of a short wavelength generated as the luminescent region moves over time.

As described above, when the hole / electron coupling region is formed close to the hole transporting layer 234 or the electron transporting layer 238 according to the position where the hole / electron coupling region is formed in the light emitting layer 236, unwanted blue light It leaks out. Due to the blue color mixture, toning may occur in red and green sub-pixels Pr and Pg. Such a dark color may occur even after long-time light emission of the organic light emitting diode (OLED).

Accordingly, in the present invention, the first and second portions 250a and 250b of the encapsulation layer 250 of red, green and blue sub-pixels Pr and Pg are made of a water- 1 and the second phosphors 252a and 252b, respectively. In addition, in the present invention, a third phosphor 252c made of a water-absorbing material capable of absorbing blue light is added to the third portion 250c of the encapsulation layer 250 of the blue sub-pixel Pb, To a desired wavelength band.

Meanwhile, the first, second, and third phosphors 252a, 252b, and 252c scatter light to emit light in a direction other than the front direction, thereby improving the viewing angle.

For example, the encapsulation layer 250 of the present invention may be formed by printing an adhesive polymer comprising a phosphor 252 in liquid form or by laminating a film comprising the phosphor 252 have.

The fluorescent material 252 added to the encapsulation layer 250 may use a small quantum dot (QD). Unlike general fluorescent dyes, these quantum dots vary in fluorescence wavelength depending on the particle size. That is, as the size of the particle becomes smaller, it emits light having a shorter wavelength, and the particle size can be adjusted to produce fluorescence in a visible light region of a desired wavelength.

Therefore, the size of the second phosphor 252b of the green sub-pixel Pg is smaller than that of the first phosphor 252a of the red sub-pixel Pr and the size of the third phosphor 252c of the blue sub- .

For reference, the quantum dots may include core nanocrystals and shell nanocrystals surrounding core nanocrystals. In addition, the quantum dots may include organic ligands bound to the shell nanocrystals. The quantum dots may also include an organic coating layer surrounding the shell nanocrystals.

The shell nanocrystals can be formed in two or more layers. The shell nanocrystals are formed on the surface of the core nanocrystals. The quantum dots can convert wavelengths of light incident on the core nanocrystals to longer wavelengths through the shell nanocrystals forming the shell layer and increase the efficiency of light.

The quantum dots may include at least one of a group II compound semiconductor, a group III compound semiconductor, a group V compound semiconductor, and a group VI compound semiconductor. More specifically, the core nanocrystals may include Cdse, InGaP, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The shell nanocrystals may also include CuZnS, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe or HgS. The diameter of the quantum dots may be in the range of 1 nm to 10 nm.

The wavelength of light emitted from the quantum dots can be controlled by the size of the quantum dots or the molar ratio of the molecular cluster compound and the nanoparticle precursor in the synthesis process. The organic ligand may include pyridine, mercapto alcohol, thiol, phosphine and phosphine oxide, and the like. Organic ligands stabilize unstable quantum dots after synthesis. After synthesis, a dangling bond is formed on the outer surface, and the dangling bonds may cause the quantum dots to become unstable. However, one end of the organic ligand is in an unbonded state, and one end of the unbound organic ligand can bond with the dangling bond to stabilize the quantum dots.

When the quantum dot is smaller than the Bohr radius of the exciton formed by the electrons and holes excited by light or electricity, the quantum confinement effect is generated to have a staggering energy level, and the energy gap size . In addition, the charge is localized within the quantum dots, so that it has high luminous efficiency.

The quantum dots can be synthesized by a chemical wet process. Here, the chemical wet method is a method of growing particles by adding a precursor material to an organic solvent, and quantum dots can be synthesized by a chemical wet method.

FIG. 12 is a plan view schematically showing an organic light emitting display according to a second embodiment of the present invention, which shows an encapsulation layer and red, green and blue sub-pixels.

Pixels Pr, Pg, and Pb of the same color are arranged on the substrate 201 along the first direction and red, green, and blue sub-pixels Pr, Pg, Pb) are alternately arranged. The organic light emitting diode OLED is disposed in each of red, green and blue sub-pixels Pr, Pg and Pb.

The encapsulation layer 250 overlying the organic light emitting diode OLED includes first, second, and third portions 250a, 250b, and 250c. The first portion 250a of the encapsulation layer 250 is positioned corresponding to the red sub-pixel Pr arranged along the first direction and the second portion 250b of the encapsulation layer 250 Pixel Pg arranged in one direction and the third portion 250c of the encapsulation layer 250 corresponds to the blue sub-pixel Pb arranged in the first direction Respectively.

As mentioned above, the encapsulation layer 250 includes a phosphor (252 in FIG. 11), and the first, second, and third portions 250a, 250b, and 250c are first and second 2, and a third phosphor (252a, 252b, and 252c in FIG. 11), respectively. The size of the second phosphor (252b in Fig. 11) in the second portion 250b is smaller than the size of the first phosphor (252a in Fig. 11) in the first portion 250a and the size of the third phosphor (252c in Fig. 11).

FIG. 13 is a graph showing the intensity of light emitted from a green sub-pixel according to a wavelength as normalized. Here, as a comparative example, the intensity of light emitted from a green sub-pixel that does not include a phosphor is also shown.

Referring to FIG. 13, it can be seen that in the case of the comparative example, a blue peak appears at a wavelength band (440 nm to 480 nm) corresponding to blue light.

However, in the case of the second embodiment of the present invention, it can be seen that the blue peak disappears in the wavelength band corresponding to the blue light. This is because the phosphor in the encapsulation layer absorbs the blue light which is unintentionally generated in the red, green sub-pixel. Therefore, it is possible to prevent the color development in the red and green sub-pixels due to the blue color mixture.

Thus, according to the second embodiment of the present invention, the color purity is improved and the color purity can be maintained at the same time even after long-time light emission.

In addition, according to the second embodiment of the present invention, the phosphor scatters light and emits light in a direction other than the front direction, thereby improving the viewing angle.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

118: first electrode 128: second electrode
130: light emitting portion 130a: hole injection layer
130b: Hole transport layer 130c: Light emitting layer
130d: Electron transport layer 135: Phosphor

Claims (16)

A first electrode;
A light emitting portion sequentially disposed on the first electrode, the light emitting portion including a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer; And
And a second electrode located on the light emitting portion,
The light emitting unit is divided into red, green, and blue sub-pixels,
Wherein the phosphor is dispersed in the hole injection layer of the light emitting portion of the green sub-pixel.
The method according to claim 1,
Wherein the phosphor is a quantum dot.
3. The method of claim 2,
And the quantum dots absorb blue light emitted from the light emitting portion of the red sub-pixel.
The method of claim 3,
And the quantum dots absorb the blue light to emit red or green light.
A transistor provided on a substrate;
A first electrode disposed on the transistor;
A light emitting portion sequentially disposed on the first electrode, the light emitting portion including a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer; And
And a second electrode located on the light emitting portion,
The light emitting unit is divided into red, green, and blue sub-pixels,
And the phosphor is dispersed in the hole injection layer of the light emitting portion of the red sub-pixel.
6. The method of claim 5,
Wherein the phosphor comprises quantum dots.
The method according to claim 6,
And the quantum dots absorb blue light emitted from the light emitting portion of the red sub-pixel.
8. The method of claim 7,
And the quantum dots absorb the blue light to emit red or green light.
Forming a first electrode on the substrate;
Forming a hole injection layer of a blue sub-pixel on the first electrode, and forming a hole injection layer of red and green sub-pixels using a solvent in which the phosphor is dispersed;
Forming a hole transport layer and a light emitting layer on the hole injection layer of the red, green and blue sub-pixels; And
And forming a second electrode on the light emitting layer,
Wherein the hole injection layer, the hole transport layer, and the light emitting layer are formed through a solution process.
10. The method of claim 9,
And forming an electron transport layer on the light emitting layer.
10. The method of claim 9,
Wherein the hole injection layer is formed using a solvent in which quantum dots are dispersed.
A transistor provided on a substrate;
A first electrode disposed on the transistor;
A light emitting portion sequentially disposed on the first electrode, the light emitting portion including a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer;
A second electrode located on the light emitting portion;
An encapsulation layer disposed over the second electrode,
/ RTI >
The light emitting unit is divided into red, green, and blue sub-pixels,
Wherein the encapsulation layer corresponding to the light emitting portion of the red, green sub-pixel includes a phosphor.
13. The method of claim 12,
Wherein the encapsulation layer comprises first, second and third portions respectively corresponding to light emitting portions of the red, green and blue sub-pixels, the first, second and third portions of the encapsulation layer And the first, second, and third phosphors, respectively.
14. The method of claim 13,
The size of the second phosphor is smaller than that of the first phosphor and larger than that of the third phosphor.
14. The method of claim 13,
Wherein the first, second, and third phosphors absorb blue light and emit light of a longer wavelength than the blue light.
13. The method of claim 12,
The light emitting layer of the red sub-pixel includes a red light emitting layer and a blue common light emitting layer, and the light emitting layer of the green sub-pixel includes a green light emitting layer and a blue common light emitting layer, Organic electroluminescence display device.

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