KR102596337B1 - Organic light emitting display device - Google Patents

Abstract

The organic light emitting display device according to an embodiment of the present invention includes a light emitting part between an anode and a cathode, and constitutes a bank in a part of the anode, a planarization layer under the anode, and a charge blocking layer adjacent to the planarization layer, thereby blocking external light. By blocking charges caused by outgassing in the planarization layer, the lifespan of the organic light emitting display device can be improved.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY DEVICE}

The present invention relates to an organic light emitting display device, and more specifically, to an organic light emitting display device that can minimize degradation of lifespan due to external light.

Recently, as we have entered the information age, the field of displays that visually express electrical information signals has developed rapidly, and in response to this, a variety of display devices with excellent performance such as thinner, lighter, and lower power consumption have been developed. is being developed.

Specific examples of such display devices include Liquid Crystal Display device (LCD), Plasma Display Panel device (PDP), Field Emission Display device (FED), and organic light emitting display device ( Organic Light Emitting Display Device (OLED), etc. may be mentioned.

In particular, organic light emitting display devices are attracting widespread attention because they are self-emitting devices and have the advantages of fast response speed, luminous efficiency, brightness, and viewing angle compared to other display devices. In addition, due to the recent development of organic light emitting display devices capable of emitting white light, their application fields, such as backlights or lighting, are extensive, and they are recognized as one of the most important displays.

[Prior art literature]

[Patent Document]

[White organic light emitting device] (Patent Application No. 10-2007-0053472)

When an organic light emitting display device including an organic light emitting element is continuously exposed to an external environment, the organic light emitting element is damaged and its lifespan is reduced. In particular, when an organic light emitting display device is exposed to UV (UltraViolet), which is external light, for a long time, the lifespan of the organic light emitting display device decreases.

Accordingly, the inventor of the present invention recognized the above-mentioned problems and conducted several experiments to prevent the lifespan of the organic light emitting display device from being reduced by external light. Accordingly, the inventor of the present invention, through various experiments, invented an organic light emitting display device with a new structure that can minimize the decline in lifespan.

The problem to be solved according to embodiments of the present invention is to provide an organic light emitting display device with improved lifespan by minimizing damage to the organic light emitting device due to external environments such as UV.

Problems to be solved according to embodiments of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

The organic light emitting display device according to an embodiment of the present invention has a structure between the anode and the cathode.

It includes a light emitting part, a bank in a part of the anode, a planarization layer in the lower part of the anode, and

It includes a charge blocking layer adjacent to the planarization layer.

An organic light emitting display device according to an embodiment of the present invention includes a light emitting portion disposed on an anode and a cathode disposed on the light emitting portion, and provides protection against outgassing generated in a planarization layer in contact with the anode due to external light. A charge blocking layer is formed adjacent to the planarization layer to prevent the lifespan from being reduced.

Specific details of other embodiments are included in the detailed description and drawings.

The present invention constructs a charge blocking layer that blocks charges generated by outgassing in the planarization layer due to external light, thereby reducing the problem of damage to the organic light emitting device due to charges generated by outgassing due to external light moving to the light emitting unit. there is.

In addition, the present invention forms a charge blocking layer that blocks charges generated by outgassing in the planarization layer due to external light, thereby reducing damage to the organic light emitting device due to outgassing, thereby improving the lifespan of the organic light emitting display device. You can do it.

In addition, the present invention configures a charge blocking layer that blocks charges caused by external light adjacent to the planarization layer, so that charges moving to the light emitting part can be trapped by the charge blocking layer, so the recombination region of the light emitting layer is maintained and the organic light emitting display is displayed. The lifespan of the device can be improved.

In addition, the present invention configures a charge blocking layer that blocks charges caused by external light adjacent to the planarization layer, so that the charge moving to the light emitting part is blocked by the charge blocking layer, and thus the charges moving to the light emitting part can be reduced, thereby reducing the organic Damage to the light emitting device can be reduced and the lifespan of the organic light emitting display device can be improved.

The effects of the present invention are not limited to the effects mentioned above, and are not limited to those not mentioned above.

Other effects will become clear to those skilled in the art from the description below.

Since the content of the invention described in the problem to be solved, the means for solving the problem, and the effect described above do not specify the essential features of the claim, the scope of the claim is not limited by the matters described in the content of the invention.

Figure 1 is a diagram for explaining the decrease in lifespan of an organic light emitting display device due to UV exposure according to an embodiment of the present invention.
Figure 2 is a diagram showing the relationship between voltage and current density according to an embodiment of the present invention.
FIG. 3A is a diagram showing an organic light emitting display device according to another embodiment of the present invention.
Figure 3b is a diagram showing an organic light emitting device according to another embodiment of the present invention.
FIG. 4 is a diagram illustrating the movement of charges due to UV exposure in an organic light emitting display device according to another embodiment of the present invention.
Figure 5 is a diagram showing the relationship between voltage and current density according to another embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. These embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is not limited. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship of two parts is described as 'on top', 'on the top', 'on the bottom', 'next to', etc., 'immediately' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

In the case of a description of a temporal relationship, for example, if a temporal relationship is described as 'after', 'successfully after', 'after', 'before', etc., 'immediately' or 'directly' Unless used, non-consecutive cases may also be included.

Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Each feature of the various embodiments of the present invention can be combined or combined with each other, partially or entirely, and various technological interconnections and operations are possible, and each embodiment can be implemented independently of each other or together in a related relationship. It may be possible.

Hereinafter, embodiments of the present invention will be examined in detail through the attached drawings and examples.

Figure 1 is a diagram for explaining the decrease in lifespan of an organic light emitting display device due to UV exposure according to an embodiment of the present invention.

Referring to FIG. 1, the organic light emitting display device includes a planarization layer 34 that planarizes the upper part of the substrate, an anode 40 that supplies holes, a light emitting part 50 including a light emitting layer, and a cathode 60 that supplies electrons. They are stacked sequentially. Additionally, the organic light emitting display device includes a bank 35 that can distinguish sub-pixel areas. Additionally, the light emitting unit 50 may include a hole injection layer and an electron transport layer.

When an organic light emitting display device is exposed to an external environment such as UV for a long period of time, the light emitting portion 50 is damaged due to outgassing of the organic layer adjacent to the light emitting portion 50 or the anode 40. . To be more specific, the planarization layer 34 disposed under the anode 40 adjacent to the light emitting portion 50 is made of an organic material such as polyimide (PI) or acryl. In addition, polyimide or acrylic resin forms a partially negatively charged gas compound (70) such as NMP (N-Methyl-2-Pyrrolidone) or hexanitrile by UV. For example, the nitrile group (-CN) of hexanenitrile has a charge distribution in which the positive charge is blocked by carbon atoms and the negative charge protrudes to the outside. Due to this outgassing, the negatively charged gas compound 70 is discharged out from the planarization layer 34, that is, through the bank 35 in the direction of the arrow 45, and in this process, the organic layer constituting the light emitting portion 50 and react. That is, the gas compound 70 reacts with a positively charged compound constituting the hole injection layer, which is an organic layer disposed at the bottom of the light emitting unit 50. Accordingly, the materials forming the hole injection layer lose their positive charge, making it impossible to smoothly inject holes into the light emitting layer.

In addition, if charges due to outgassing remain in the organic layer, it causes deterioration of the organic light-emitting elements that make up the organic light-emitting display device and causes pixel shrinkage, which causes the size of the organic light-emitting elements to decrease over time. It accelerates.

Therefore, when strong UV is irradiated to the organic light emitting display device or the organic light emitting display device is exposed to UV for a long time, the hole injection performance of the hole injection layer deteriorates and the organic light emitting device deteriorates, thereby shortening the life of the organic light emitting display device. Problems with deterioration arise.

This is explained in detail as follows.

An organic light emitting display device emits light by recombining holes and electrons in the light emitting layer to form an exciton. The area where holes and electrons recombine to form excitons can be called a recombination zone.

However, when strong UV is irradiated to the organic light emitting display device or the organic light emitting device is exposed to UV for a long time, the hole injection layer adjacent to the planarization layer is damaged due to outgassing of the planarization layer, which is an organic material layer, and holes are transmitted to the light emitting layer. Injection performance deteriorates.

Therefore, since the injection of holes into the light-emitting layer is not smooth, the number of holes moving into the light-emitting layer decreases, and the recombination area changes from before UV irradiation or before UV exposure. That is, the recombination region is not formed in the light-emitting layer, but rather is formed in the hole injection layer. In this case, compared to the excitons formed in the light-emitting layer, the excitons formed in the hole injection layer annihilate more quickly and the lifespan is reduced. In particular, in the case of a phosphorescent material emitting layer, triplet-triplet annihilation (TTA) due to exciton collision progresses rapidly and deteriorates. Due to collisions between excessively fast excitons, the number of excited excitons that can emit light at the same driving voltage is significantly reduced, thereby reducing the lifespan of the organic light emitting display device.

Additionally, changes in current density when the organic light emitting display device is irradiated with strong UV or continuously exposed to UV will be described with reference to FIG. 2 .

Figure 2 is a diagram showing the relationship between voltage and current density according to an embodiment of the present invention.

In Figure 2, the horizontal axis represents voltage (unit: V), and the vertical axis represents current density (unit: mA/cm ² ). And, A is a graph before UV irradiation or exposure to UV, and B is a graph after UV irradiation or exposure to UV.

As shown in Figure 2, there is almost no difference in current density between A and B until the voltage reaches 3.5V. There is a difference in current density between A and B after the voltage is 4V. For example, at a voltage of 5V, the current density of A is about 28mA/cm ² and the current density of B is 7.5mA/cm ² . Therefore, in the case of the same voltage of 5V, it can be seen that the current density of B after being irradiated with UV or exposed to UV decreases sharply compared to A. In other words, it can be seen that the luminance of the organic light emitting display device decreases when irradiated with UV or exposed to UV.

Accordingly, the inventor of the present invention conducted several experiments to block charges by outgassing in order to improve the lifespan of the organic light emitting display device. In other words, a new organic light emitting display device was invented in which a charge blocking layer adjacent to the planarization layer is constructed to block the path through which charges generated in the planarization layer move to the light emitting layer. This will be explained with reference to FIGS. 3 to 5.

FIG. 3A is a schematic cross-sectional view illustrating an organic light emitting display device according to another embodiment of the present invention. Figure 3b is a diagram showing an organic light emitting device according to another embodiment of the present invention. Referring to FIGS. 3A and 3B , the organic light emitting display device 200 includes a substrate 210, a thin film transistor 220, an anode 240, a light emitting unit 250, and a cathode 260.

The organic light emitting display device 200 includes a plurality of pixels. Each pixel includes a plurality of sub pixels. A sub-pixel is an element for displaying one color and refers to the minimum unit area where light is actually emitted. Additionally, a plurality of sub-pixels can be gathered to form the smallest group capable of expressing white light. For example, three sub-pixels may form one group, including a red sub-pixel (R), a green sub-pixel (G), and a blue sub-pixel (B). Additionally, the organic light emitting display device 200 may further include a white sub-pixel in addition to the red sub-pixel (R), green sub-pixel (G), and blue sub-pixel (B). However, it is not limited to this, and various sub-pixel designs are possible. In FIG. 3A , for convenience of explanation, only one sub-pixel among the plurality of sub-pixels of the organic light emitting display device 200 is shown.

The substrate 210 is made of an insulating material to support various components of the organic light emitting display device 200. For example, the substrate 210 may be made of a material with flexibility, such as glass or plastic. If the organic light emitting display device 200 is a flexible organic light emitting display device 200, it may be made of a flexible material such as plastic. In addition, when flexible organic light emitting devices that are easy to implement are applied to vehicle lighting devices or vehicle display devices, the degree of freedom in designing and designing vehicle lighting devices or vehicle display devices according to the structure or exterior shape of the vehicle is increased. can be secured.

In addition, the organic light emitting display device 200 according to another embodiment of the present invention is used for TVs, mobiles, tablet PCs, monitors, laptop computers, and vehicle displays. It can be applied to display devices, etc. Alternatively, it may be applied to wearable display devices, foldable display devices, and rollable display devices.

A buffer layer 231 is formed on the substrate 210 to protect various components of the organic light emitting display device 200 from penetration of moisture (H ₂ O) or oxygen (O ₂ ) from outside the substrate 210. do. The substrate 210 may be removed during the manufacturing process of the organic light emitting display device 200. Additionally, whether or not the buffer layer 231 is configured is determined based on the type of substrate 210 or the type of thin film transistor 220 applied to the organic light emitting display device 200.

A thin film transistor 220 including an active layer 222, a gate electrode 221, a source electrode 223, and a drain electrode 224 is formed on the buffer layer 231.

Specifically explained, it is as follows. An active layer 222 is formed on the substrate 210. The active layer 222 may be formed of amorphous silicon (a-Si), polycrystalline silicon (poly-Si), an oxide semiconductor, or an organic semiconductor. When the active layer 222 is formed of an oxide semiconductor, it may be formed of ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), IGZO (Indium Gallium Zinc Oxide), or ITZO (Indium Tin Zinc Oxide). It is not limited.

A gate insulating layer 232 is formed on the active layer 222 to insulate the active layer 222 and the gate electrode 221. The gate electrode 221 serves as a switch of the thin film transistor 220, and may be made of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo), or an alloy thereof, but is limited thereto. It doesn't work.

The gate insulating layer 232 prevents the current flowing in the active layer 222 from flowing to the gate electrode 221. The gate insulating layer 232 may be composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

An interlayer insulating layer 233 is formed to insulate the gate electrode 221, the source electrode 223, and the drain electrode 224. The interlayer insulating layer 233 may be composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

A source electrode 223 and a drain electrode 224 respectively contacting the active layer 222 are formed on the interlayer insulating layer 233. The source electrode 223 and the drain electrode 224 are electrically connected to the active layer 222. The source electrode 223 and the drain electrode 224 may be made of a conductive metal such as copper (Cu), aluminum (Al), molybdenum (Mo) or an alloy thereof, but are not limited thereto. no.

In this specification, for convenience of explanation, only the driving thin film transistor 220 connected to the anode 240 is shown among various thin film transistors that can be included in the organic light emitting display device 200. Each sub-pixel may further include a switching thin film transistor or capacitor. Additionally, in this specification, the thin film transistor 220 is described as having a coplanar structure, but a thin film transistor with an inverted staggered structure may also be used.

A protective layer 270 and a planarization layer 234 are formed on the thin film transistor 220. The protective layer 270 may be made of an inorganic material. For example, the protective layer 270 may be made of a silicon oxide film (SiOx) or a silicon nitride film (SiNx), but is not limited thereto.

And, the planarization layer 234 functions to planarize the upper part of the substrate 210. The planarization layer 234 may be composed of a single layer or multiple layers, and may be made of an organic material. For example, the planarization layer 234 may be made of polyimide or acryl. The protective layer 270 and the planarization layer 234 include contact holes for electrically connecting the thin film transistor 220 and the anode 240 in each sub-pixel.

Anode 240 is disposed on planarization layer 234. The anode 240 is an electrode configured to supply holes to the light-emitting layer constituting the light-emitting portion 250. The anode 240 is electrically connected to the thin film transistor 220 through a contact hole in the protective layer 270 and the planarization layer 234, and is electrically connected, for example, to the source electrode 223 of the thin film transistor 220. can be connected In the drawing, the anode 240 is shown as connected to the source electrode 223 of the thin film transistor 220, but depending on the design, the anode 240 may be connected to the drain electrode 224 of the thin film transistor 220.

The anodes 240 are arranged to be spaced apart for each sub-pixel. The anode 240 may be made of a transparent conductive material with a high work function. Transparent conductive materials may include, for example, indium tin oxide (ITO), indium zinc oxide (IZO), etc.

When the organic light emitting display device 200 according to another embodiment of the present invention is a top emission type, the anode 240 reflects the light emitted from the light emitting layer 250 to the anode 240 and flows upward more smoothly. It may further include a reflective layer so that it can be emitted. For example, the anode 240 may have a two-layer structure in which a transparent conductive layer made of a transparent conductive material and a reflective layer are sequentially stacked, or it may have a three-layer structure in which a transparent conductive layer, a reflective layer, and a transparent conductive layer are sequentially stacked. The reflective layer may be silver (Ag) or an alloy containing silver, for example, silver or APC (Ag/Pd/Cu). Here, the anode 240 may be referred to as a pixel electrode.

A bank 235 is formed in a portion of the anode 240. Specifically, the bank 235 is arranged to cover at least a portion of the edge of the anode 240 and exposes a portion of the upper surface of the anode 240. Bank 235 divides sub-pixel areas. That is, the bank 235 may distinguish a pixel area composed of a plurality of sub-pixel areas. At this time, the bank 235 is in contact with the light emitting unit 250. Bank 235 may be made of organic material. For example, the bank 235 may be made of polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto.

And, a charge blocking layer 271 is formed on the protective layer 270. The charge blocking layer 271 blocks charges from moving to the light emitting unit 250 due to outgassing in the planarization layer 234 made of organic material due to external light. That is, the charge blocking layer 271 is formed adjacent to the planarization layer 234 so that the lifespan is not reduced due to outgassing that occurs in the planarization layer 234 in contact with the anode 230 due to external light.

Accordingly, by trapping charges resulting from outgassing of the planarization layer 234 by the charge blocking layer 271 closest to the planarization layer 234, the charges can be blocked from moving to the light emitting unit 250. In other words, the charge blocking layer 271 can reduce or block the movement of charges to the light emitting unit 250, thereby preventing damage to the light emitting unit 250 and improving the lifespan of the organic light emitting display device 200. there is. This will be described in more detail later with reference to FIG. 4 .

Cathode 260 is disposed on anode 240. The cathode 260 supplies electrons to the light-emitting layer of the light-emitting unit 250. Since the cathode 260 must supply electrons, it is made of a conductive material with a low work function. More specifically, the cathode 260 may be a metal material such as magnesium (Mg), silver-magnesium (Ag:Mg), etc. Here, the cathode 260 may also be referred to as a common electrode.

In addition, when the organic light emitting display device 200 according to another embodiment of the present invention is a top emission type, the cathode 260 is made of indium tin oxide (ITO) or indium zinc oxide (IZO). ), Indium Tin Zinc Oxide (ITZO), Zinc Oxide (ZnO), and Tin Oxide (TiO) series of transparent conductive oxides.

A light emitting unit 250 is disposed between the anode 240 and the cathode 260. The light emitting unit 250 may include various organic layers as needed. The anode 240, the light emitting unit 250, and the cathode 260 constitute an organic light emitting device (ED; Emitting Diode).

The organic light emitting device (ED) will be described with reference to FIG. 3B. Figure 3b is a diagram showing an organic light emitting device according to another embodiment of the present invention.

Referring to Figure 3b, an organic light emitting device (ED) according to another embodiment of the present invention includes an anode 240, a common hole injection layer 251, a first hole transport layer 252a, and a second hole transport layer 252b. , a first organic emission layer (253a), a second organic emission layer (253b), a third organic emission layer (253c), an electron transport layer (254), and a cathode (260).

As shown in FIG. 3B, an organic light emitting display device including an organic light emitting element (ED) according to another embodiment of the present invention has a first sub-pixel (R) and a second sub-pixel (R) as an area for displaying one color. It includes a pixel (G) and a third sub-pixel (B). Each of the first sub-pixel (R), the second sub-pixel (G), and the third sub-pixel (B) may emit light of different colors. For example, the first sub-pixel (R) may emit red light, the second sub-pixel (G) may emit green light, and the third sub-pixel (B) may emit blue light.

Also, depending on the design, the organic light emitting display device 200 may have a patterned emission layer structure. An organic light emitting display device with a patterned light emitting layer structure has a structure in which light emitting layers that emit different colors are separated for each pixel. For example, a red light-emitting layer for emitting red light, a light-emitting layer for emitting green light, and a blue light-emitting layer for emitting blue light are respectively a red sub-pixel (R), a green sub-pixel (G), and It can be configured separately in the blue sub-pixel (B). In each of the red organic emission layer, green organic emission layer, and blue organic emission layer, holes and electrons supplied through the anode 240 and cathode 260 combine with each other to emit light. Each organic light emitting layer may be deposited in a pattern on each sub-pixel (R, G, B) using a mask with openings for each sub-pixel, for example, a fine metal mask (FMM).

A hole injection layer (HIL) 251 is disposed on the anode 240. The hole injection layer 251 is an organic layer that facilitates injection of holes from the anode 240 into the first organic light-emitting layer 253a, the second organic light-emitting layer 253b, and the third organic light-emitting layer 253c. The hole injection layer 251 is, for example, HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine) , F4-TCNQ(2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane), and NPD(N,N'-bis(naphthalene-1-yl)-N,N'- It may consist of one or more of bis(phenyl)-2,2'-dimethylbenzidine), but is not limited thereto.

The first hole transport layer (HTL) 252a is disposed on the hole injection layer 251 of the first sub-pixel (R). And, the second hole transport layer 252b is disposed on the hole injection layer 251 of the second sub-pixel (G). The first hole transport layer 252a and the second hole transport layer 252b are organic layers that smoothly transfer holes from the hole injection layer 251 to the first organic light-emitting layer 253a and the second organic light-emitting layer 253b.

In addition, the thickness of each of the first hole transport layer 252a and the second hole transport layer 252b may form the optical distance of the microcavity. Specifically, the thickness of each of the first hole transport layer 252a and the second hole transport layer 252b is such that the first organic light-emitting layer 253a forms a microcavity structure between the anode 240 and the cathode 260, and 2 The organic light emitting layer 253b may be determined to form a microcavity structure between the anode 240 and the cathode 260.

In Figure 3b, it is assumed that the first organic light-emitting layer 253a is a red light-emitting layer and the second organic light-emitting layer 253b is a green light-emitting layer, and the thickness of the first hole transport layer 252a is thicker than the thickness of the second hole transport layer 252b. expressed. However, it is not limited to this.

Accordingly, the first hole transport layer 252a and the second hole transport layer 252b form the optical distance between the microcavities of the first sub-pixel (R) and the second sub-pixel (G) of the organic light emitting display device 200. Efficiency can be improved.

The first hole transport layer 252a and the second hole transport layer 252b are, for example, NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2' -dimethylbenzidine), TPD(N,N'-bis-(3-methylphenyl)-N,N'-bis(phenyl)-benzidine), s-TAD(2,2',7,7'-tetrakis(N, It may consist of one or more of N-dimethylamino)-9,9-spirofluorene) and MTDATA (4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), but is limited to these. It doesn't work.

Here, the hole injection layer 251, the first hole transport layer 252a, and the second hole transport layer 252b can be referred to as hole transport layers. The hole transport layer can be said to be a layer that transfers and injects holes into the light emitting layer.

The first organic emitting layer (EML) 253a, the second organic emitting layer 253b, and the third organic emitting layer 253c may include a material that can emit light of a specific color. For example, the first organic light-emitting layer 253a, the second organic light-emitting layer 253b, and the third organic light-emitting layer 253c include a light-emitting material capable of emitting red light, green light, blue light, or yellow-green light. can do. However, it is not limited thereto and may include a light-emitting material capable of emitting light of different colors. At this time, the light-emitting material can be formed using a phosphorescent material or a fluorescent material. Additionally, the first organic emission layer 253a, the second organic emission layer 253b, and the third organic emission layer 253c may be composed of at least one host and at least one dopant. In addition, the first organic emission layer 253a, the second organic emission layer 253b, and the third organic emission layer 253c may be composed of a mixed host in which at least one host is mixed and at least one dopant. . When composed of a mixed host, there is an effect that the host can be deposited uniformly within the organic light-emitting layer.

The first organic light-emitting layer 253a is disposed on the first hole transport layer 252a. The first organic emission layer 253a is disposed in the first sub-pixel (R) and may emit red light. When emitting red light, CBP(4,4'-bis(carbazol-9-yl)biphenyl), mCP(1,3-bis(carbazol-9-yl)benzene), NPD(N,N'-bis( naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine), and at least one host material such as Be complex and Ir(btp) ₂ (acac)(bis(2-benzo) [b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III)), Ir(piq) ₂ (acac)(bis(1-phenylisoquinoline)(acetylacetonate)iridium(III)), Ir(piq) ₃ ( It may be made of a phosphorescent material containing a dopant such as tris(1-phenylquinoline)iridium(III)) or Pt(TPBP)(5,10,15,20-tetraphenyltetrabenzoporphyrin platinum complex). Additionally, it may be made of a fluorescent material containing perylene, but is not limited thereto.

And, the second organic light-emitting layer 253b is disposed on the second hole transport layer 252b. The second organic emission layer 253b is disposed in the second sub-pixel (G) and may emit green light. In the case of green emission, at least one host material such as CBP, mCP, NPD, and Be complex, and Ir(ppy) ₃ (tris(2-phenylpyridine)iridium(III)) or Ir(ppy) ₂ (acaa) (It may be made of a phosphorescent material containing a dopant material such as an iridium complex (Ir complex) containing bis(2-phenylpyridine)(acetylacetonate)iridium(III). Additionally, Alq ₃ (tris(8-hydroxyquinolino)aluminium) It may be made of a fluorescent material containing, but is not limited to this.

And, the third organic light-emitting layer 253c is disposed on the hole injection layer 251. The third organic emission layer 253c is disposed in the third sub-pixel (B) and may emit blue light. In the case of blue emission, at least one host material including CBP, mCP, and ADN (9,10-di(naphth-2-yl)anthracene) and FIrPic(bis(3,5,-difluoro-2- It may be made of a phosphorescent material containing a dopant material such as (2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III)). Additionally, DPVBi(4,4'-bis[4-di-p-tolylamino) stryl)biphenyl), DSA (1-4-di-[4-(N,N-di-phenyl)amino]styryl-benzene), PFO (polyfluorene)-based polymer, and PPV (polyphenylenevinylene)-based polymer. It may be made of a fluorescent material, but is not limited thereto.

The electron transport layer (ETL) 254 is disposed on the first organic light-emitting layer (253a), the second organic light-emitting layer (253b), and the third organic light-emitting layer (253c), and receives electrons from the cathode 260. It is an organic layer that is transmitted to the organic light-emitting layer 253. The electron transport layer 254 is, for example, Liq (8-hydroxyquinolinolato-lithium), PBD (2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), TAZ ( 3-(4-biphenyl)4-phenyl-5-tert-butylphenyl-1,2,4-triazole), BCP(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline) and BAlq(bis It may be made of one or more of (2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium), but is not limited thereto. The electron transport layer 254 may be omitted depending on the structure or characteristics of the organic light emitting display device 200.

An electron injection layer (EIL) is disposed on the electron transport layer 254. The electron injection layer is an organic layer that facilitates the injection of electrons from the cathode 260 to the light emitting layer 253. The electron injection layer may be a metal inorganic compound such as BaF ₂ , LiF, NaCl, CsF, Li ₂ O, and BaO. Additionally, the electron injection layer includes HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine), and NPD (N ,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine), but is not limited thereto. The electron injection layer may be omitted depending on the structure or characteristics of the organic light emitting display device 200.

Here, the electron transport layer 254 and the electron injection layer can be referred to as an electron transport layer. The electron transport layer can be said to be a layer that transfers and injects electrons into the light emitting layer.

A capping layer may be further formed on the cathode 260. The capping layer may be omitted depending on the structure or characteristics of the organic light emitting display device 200.

As described in FIG. 3A, the planarization layer 234 is formed of an organic material. When this organic material is exposed to external light for a long period of time, the lifespan of the organic light emitting display device is reduced due to outgassing of the organic material. Therefore, a charge blocking layer 271 is formed adjacent to the planarization layer 234 to block the movement of charges due to outgassing or to trap charges. This will be explained with reference to FIG. 4 .

FIG. 4 is a diagram illustrating the movement of charge due to UV exposure in an organic light emitting display device according to another embodiment of the present invention. Specifically, Figure 4 is a diagram to explain how the charge blocking layer of the present invention blocks the movement of charges generated by outgassing or traps the charges.

As shown in FIG. 4, the charge blocking layer 271 is formed below the planarization layer 234. The polyimide or acrylic resin constituting the planarization layer 234 forms a partially negatively charged gas compound 170 such as NMP (N-Methyl-2-Pyrrolidone) or hexanitrile by UV, which is external light. do. The negatively charged gas compound 170 caused by outgassing reacts with the hole injection layer constituting the light emitting part 250, damaging the light emitting part 250. Therefore, when negative charges caused by outgassing of the planarization layer 234 due to external light move to the light emitting unit 250, the light emitting unit 250 is damaged, so it is important to block the path through which the negative charges move. That is, in order to block negative charges caused by outgassing of the planarization layer 234 by external light from moving to the light emitting unit 250, the charge blocking layer 271 is formed on the layer closest to the planarization layer 234. Therefore, the charge blocking layer 271 can block negative charges from moving to the light emitting unit 250.

This is because the charge blocking layer 271 is formed under the planarization layer 234 to trap negative charges caused by outgassing of the planarization layer 234 by external light (indicated by arrow 145). That is, by constructing the charge blocking layer 271, which has a positive charge that can react with negative charges, adjacent to the planarization layer 234, the negative charge moving to the light emitting unit 250 can be reduced or minimized. Therefore, in order to react with negative charges and trap negative charges, the charge blocking layer 271 may be made of a positively charged material. That is, the charge blocking layer 271 is formed on the protective layer 270 adjacent to the planarization layer 234, and may be made of a p+ layer. Alternatively, the charge blocking layer 271 may be formed by doping the protective layer 270 with boron (B), a p-type material. In this case, the process can be simplified because the protective layer 270 can be formed by doping a p-type material when depositing the protective layer 270.

Therefore, the charge blocking layer 271 prevents the inflow of negative charges into the light emitting unit 250, so it does not react with the positively charged compound constituting the hole injection layer, which is an organic layer disposed at the bottom of the light emitting unit 250. . In other words, the materials that make up the hole injection layer may not lose positive charges that react with negative charges, so holes can be smoothly injected into the light emitting layer. Accordingly, damage to the light emitting layer can be reduced, thereby improving the lifespan of the organic light emitting display device.

In addition, since the holes of the hole injection layer are smoothly injected into the light emitting layer by the charge blocking layer 271, the recombination area of holes and electrons is located closer to the electron transport layer than the hole injection layer compared to the configuration without the charge blocking layer. You can. Accordingly, the recombination region of the light emitting layer can be maintained by the charge blocking layer 271, thereby improving the lifespan of the organic light emitting display device. Here, the hole injection layer can be called a hole transport layer, and the electron transport layer can be called an electron transport layer.

Additionally, the light emitting layer constituting the light emitting unit 250 may be composed of a phosphorescent light emitting layer or a fluorescent light emitting layer. In the case of a phosphorescent light-emitting layer, negative charges due to outgassing can be blocked by the charge blocking layer of the present invention, thereby preventing deterioration of the light-emitting part and further reducing the lifespan of the organic light-emitting display device.

Additionally, changes in current density when the organic light emitting display device is irradiated with strong UV or continuously exposed to UV will be described with reference to FIG. 5 .

Figure 5 is a diagram showing the relationship between voltage and current density according to another embodiment of the present invention.

In Figure 5, the horizontal axis represents voltage (unit: V), and the vertical axis represents current density (unit: mA/cm ² ). And, A is a graph before UV irradiation or exposure to UV, and C is a graph after UV irradiation or exposure to UV.

As shown in Figure 5, it can be seen that as the voltage increases, there is no difference in the current densities of A and C. In other words, it can be seen that by configuring the charge blocking layer of the present invention, the luminance of the organic light emitting display device does not change even when UV is irradiated or exposed to the organic light emitting display device.

Organic light emitting display devices according to embodiments of the present invention can be described as follows.

The organic light emitting display device according to an embodiment of the present invention includes a light emitting portion between an anode and a cathode, a bank located in a portion of the anode, a planarization layer below the anode, and a charge blocking layer adjacent to the planarization layer, thereby preventing exposure to external light. This can reduce the problem of damage to the organic light emitting device due to the charge generated by outgassing moving to the light emitting unit.

According to another feature of the present invention, the charge blocking layer can block charges from moving to the light emitting unit due to outgassing of the planarization layer due to external light.

According to another feature of the present invention, the charge blocking layer can trap charges caused by outgassing of the planarization layer by external light.

According to another feature of the present invention, a protective layer is further included below the planarization layer, and the charge blocking layer is on the protective layer and may be made of a p+ layer.

According to another feature of the present invention, a protective layer is further included below the planarization layer, and the charge blocking layer may be formed by doping the protective layer with a p-type material.

According to another feature of the present invention, the light emitting unit may include at least one hole transport layer, at least one electron transport layer, and a light emitting layer.

According to another feature of the present invention, the light emitting layer may include a phosphorescent light emitting layer or a fluorescent light emitting layer.

According to another feature of the present invention, the charge blocking layer can block charges from moving to the hole transport layer due to outgassing of the planarization layer by external light.

An organic light emitting display device according to an embodiment of the present invention includes a light emitting portion disposed on an anode and a cathode disposed on the light emitting portion, and its lifespan is not reduced by outgassing occurring in the planarization layer in contact with the anode due to external light. By forming a charge blocking layer adjacent to the planarization layer, the lifespan of the organic light emitting display device can be improved.

According to another feature of the present invention, a protective layer is further included below the planarization layer, and the charge blocking layer is on the protective layer and may be made of a p+ layer.

According to another feature of the present invention, a protective layer is further included below the planarization layer, and the charge blocking layer may be formed by doping the protective layer with a p-type material.

According to another feature of the present invention, the light emitting unit may include at least one hole transport layer, at least one electron transport layer, and a light emitting layer.

According to another feature of the present invention, the recombination region formed by the movement of holes in the hole transport layer and electrons in the electron transport layer to the light emitting layer may be configured to be closer to the electron transport layer than to the hole transport layer.

Although embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit of the present invention. . Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. The scope of protection of the present invention should be interpreted in accordance with the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of the present invention.

200: Organic light emitting display device
220: Thin film transistor
234: Flattening layer
270: protective layer
271: Charge blocking layer
235: bank
240: anode
251: Hole injection layer
252a, 252b: hole transport layer
253a, 253b, 253c: light emitting layer
254: Electron transport layer
260: cathode

Claims (13)

In an organic light emitting display device including a light emitting portion between an anode and a cathode,
a bank in a portion of the anode;
A planarization layer below the anode; and
Comprising a charge blocking layer adjacent to the planarization layer,
An organic light emitting display device, wherein the charge blocking layer is made of a positively charged material. According to claim 1,
The charge blocking layer blocks the transfer of charges caused by outgassing of the planarization layer by external light to the light emitting unit. According to claim 1,
The charge blocking layer traps charges caused by outgassing of the planarization layer by external light. According to claim 1,
Further comprising a protective layer below the planarization layer,
The charge blocking layer is on the protective layer and is made of a p+ layer. According to claim 1,
Further comprising a protective layer below the planarization layer,
An organic light emitting display device, wherein the charge blocking layer is formed by doping the protective layer with a p-type material. According to claim 1,
An organic light emitting display device, wherein the light emitting unit includes at least one hole transport layer, an electron transport layer, and a light emitting layer. According to claim 6,
An organic light emitting display device, wherein the light emitting layer includes a phosphorescent light emitting layer or a fluorescent light emitting layer. According to claim 6,
The charge blocking layer blocks the transfer of charges caused by outgassing of the planarization layer by external light to the hole transport layer. A light emitting portion disposed on the anode; and
It includes a cathode disposed on the light emitting unit,
Outgassing that occurs in the flattening layer in contact with the anode due to external light
A charge blocking layer is formed adjacent to the planarization layer so that the lifespan is not reduced by this,
An organic light emitting display device, wherein the charge blocking layer is made of a positively charged material. According to clause 9,
Further comprising a protective layer below the planarization layer,
The charge blocking layer is on the protective layer and is made of a p+ layer. According to clause 9,
Further comprising a protective layer below the planarization layer,
An organic light emitting display device, wherein the charge blocking layer is formed by doping the protective layer with a p-type material. According to clause 9,
An organic light emitting display device, wherein the light emitting unit includes at least one hole transport layer, an electron transport layer, and a light emitting layer. According to claim 12,
The organic light emitting display device wherein the recombination region formed by the movement of holes in the hole transport layer and electrons in the electron transport layer to the light emitting layer is configured to be closer to the electron transport layer than the hole transport layer.

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