KR102599469B1 - Organic light emitting display device - Google Patents

Abstract

An organic light emitting display device according to an embodiment of the present invention includes a substrate having a pixel area, an anode on the substrate, a light emitting portion on the anode and including a hole injection layer, a light emitting layer, and an electron transport layer, and a light emitting portion on the light emitting portion. By forming a cathode, a bank in contact with the anode, and a charge blocking layer on the bank and in contact with the hole injection layer, the light emission performance and 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 the lifespan and performance of the display device due to UV (Ultra Violet) irradiation.

Organic light emitting display devices are self-emitting displays, and unlike liquid crystal displays, they do not require a separate light source and can be manufactured in a lightweight and thin form. In addition, organic light emitting display devices are not only advantageous in terms of power consumption due to low voltage operation, but also have excellent color reproduction, response speed, viewing angle, and contrast ratio (CR), so they are being developed as large-area, high-definition next-generation displays. there is.

In an organic light emitting display device, an emissive layer (EML) made of organic material is placed between two electrodes consisting of an anode and a cathode, holes are injected from the anode to the emitting layer, and electrons are injected into the light emitting layer. ) is injected from the cathode into the light-emitting layer, the injected electrons and holes recombine with each other to form excitons, generating light.

The emission layer of an organic light emitting display device contains a host material and a dopant material, and light is emitted through the interaction of the two materials. At this time, the host serves to generate excitons from electrons and holes and transfer energy to the dopant. A dopant is a dye-like organic substance added to the host in small amounts, and its function is to receive energy from the host and convert it into light.

Generally, the light emitting part of an organic light emitting display device includes a hole transport layer (HTL) between the anode and the light emitting layer and an electron transport layer (ETL) between the cathode and the light emitting layer, so that holes and cathodes are transmitted from the anode and the cathode to the light emitting layer. Allows electrons to be injected and moved smoothly.

[Prior art literature]

[Patent Document]

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

When using a conventional organic light emitting display device for a long period of time, the light emitting performance and lifespan deteriorate. There are various reasons for this decrease in luminous performance and lifespan. Among them, continuous exposure of organic light emitting display devices to external light such as sunlight reduces luminous performance and lifespan. In particular, UV (Ultra Violet) contained in external light such as sunlight has a fatal effect on organic light emitting display devices. .

When strong UV is irradiated to an organic light emitting display device or the organic light emitting display device is exposed to UV for a long time, an outgassing phenomenon occurs inside the organic light emitting display device. The flattening layer formed of polyimide or photoacryl forms a gas compound with a negative charge (-) such as Nmethylpyrrolidone (NMP) or hexanitrile by UV irradiation. As these negatively charged gas compounds are discharged to the outside, they react with the light-emitting portion adjacent to the planarization layer and formed of organic materials.

In particular, the negative charge (-) generated by the outgassing phenomenon reacts with the positively charged (+) material constituting the hole injection layer disposed on the outermost side of the light emitting part, and the characteristics of the hole injection layer deteriorate, resulting in hole injection. This makes it impossible to smoothly inject holes into the light-emitting layer.

In this way, if the injection of holes is not smooth and the number of holes moving to the light emitting layer decreases, the area of the recombination area of holes and electrons becomes smaller than the recombination area before UV irradiation. As the area of the recombination region decreases, the density of excitons increases, and at this time, compared to the existing large-area recombination region, triplet-triplet exciton collision annihilation (TTA) progresses faster, causing the light-emitting layer to It deteriorates. In other words, due to excessively fast collisions between excitons, the number of excitons capable of emitting light at the same driving voltage is significantly reduced, thereby reducing the lifespan of the organic light emitting display device.

In this way, when the organic light emitting display device is irradiated with strong UV from the outside 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, thereby reducing the light emission performance and lifespan of the organic light emitting display device. Problems arise.

Accordingly, the inventors of the present invention recognized the above-mentioned problems and invented a new organic light emitting display device through various experiments to improve the light emitting performance and lifespan of the organic light emitting display device.

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.

An organic light emitting display device according to an embodiment of the present invention includes a substrate having a pixel area, an anode on the substrate, a light emitting portion on the anode and including a hole injection layer, a light emitting layer, and an electron transport layer, a cathode on the light emitting portion, It includes a bank in contact with the anode and a charge blocking layer on the bank and in contact with the hole injection layer.

The organic light emitting display device according to an embodiment of the present invention is on a bank, an anode, and a bank that contacts the anode and partitions the first pixel area, the second pixel area, and the third pixel area. and a hole injection layer disposed in the third pixel region, a first hole transport layer, a second hole transport layer, and a third hole disposed on the hole injection layer and disposed in the first pixel region, the second pixel region, and the third pixel region, respectively. The first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are on each of the transport layer, the first hole transport layer, the second hole transport layer, and the third hole transport layer, and are disposed in the first pixel area, the second pixel area, and the third pixel area, respectively. , It is on the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer, and the electron transport layer and electron transport layer disposed in the first pixel area, the second pixel area, and the third pixel area, and the first pixel area and the second pixel. It includes a cathode disposed in the region and the third pixel region, and a charge blocking layer located on the bank and in contact with the hole injection layer.

An organic light emitting display device according to an embodiment of the present invention includes a substrate having a pixel area, a planarization layer on the substrate, an anode on the planarization layer, and a light emitting part on the anode and including a hole injection layer, a light emitting layer, and an electron transport layer. , a cathode on the light emitting unit, a bank disposed in contact with the anode on the planarization layer, and a charge blocking layer on the bank that is in contact with the hole injection layer to prevent light emission performance and lifespan from being reduced by outgassing occurring in the planarization layer. .

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

An organic light emitting display device including a charge blocking layer according to an embodiment of the present invention blocks the effects of outgassing caused by strong UV irradiation from the outside of the organic light emitting display device or exposure of the organic light emitting display device to UV for a long time. By minimizing the layer, luminous performance and lifespan can be improved.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Since the content of the invention described above in the problem to be solved, the means for solving the problem, and the effect 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.

1 is a schematic cross-sectional view illustrating an organic light emitting display device according to an embodiment of the present invention.
Figure 2 is a cross-sectional view to explain a phenomenon that occurs when UV is irradiated to an organic light emitting display device according to an embodiment of the present invention.
Figure 3 is a cross-sectional view for explaining the pixel area of an organic light emitting display device according to an embodiment of the present invention.
Figure 4 is a cross-sectional view illustrating a bank area of an organic light emitting display device according to an embodiment of the present invention.
FIGS. 5A and 5B are diagrams illustrating the lifespan of a conventional organic light emitting display device and an organic light emitting display device according to an embodiment of the present invention measured before and after UV irradiation.

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. The present 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.

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.

1 is a schematic cross-sectional view illustrating an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 1 , the organic light emitting display device 100 may include a substrate 110, a thin film transistor 120, an anode 140, a light emitting unit 150, and a cathode 160.

The substrate 110 may be a glass or plastic substrate with flexible characteristics, and allows components to be easily formed on the top of the substrate 110.

A buffer layer 131 may be disposed on the substrate 110 to prevent moisture (H ₂ O) from penetrating from outside the substrate 110. However, the buffer layer 131 may be omitted depending on the structure or characteristics of the organic light emitting display device 100.

The thin film transistor 120 may include a gate electrode 121, a source electrode 124, a drain electrode 123, and a semiconductor layer 122.

The semiconductor layer 122 is made of amorphous silicon, polycrystalline silicon with better mobility than amorphous silicon, or ZnO or IGZO (Indium-Gallium-Zinc Oxide) with excellent mobility and uniformity characteristics. It can be composed of the same oxide semiconductor, but is not limited to this.

The gate electrode 121 functions as a switch of the thin film transistor 120. The gate electrode 121 may be made of a conductive metal, such as copper (Cu), aluminum (Al), molybdenum (Mo), or an alloy thereof, but is not limited thereto.

The gate insulating layer 132 prevents the current flowing in the semiconductor layer 122 from flowing to the gate electrode 121. The gate insulating layer 132 may be an insulating film composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx).

The source electrode 124 and the drain electrode 123 serve to transmit an external electrical signal from the thin film transistor 120 to the light emitting unit 150. At this time, the source electrode 124 and the drain electrode 123 may be made of a conductive metal, for example, a metal material such as copper (Cu), aluminum (Al), molybdenum (Mo), or an alloy thereof, but is limited thereto. That is not the case.

An interlayer insulating layer 133 may be disposed to insulate the gate electrode 121, the source electrode 123, and the drain electrode 124. At this time, a source electrode 123 and a drain electrode 124 in contact with the active layer 122, respectively, may be disposed on the interlayer insulating layer 133.

The passivation layer 134 may serve to prevent unnecessary electrical connections between components of the thin film transistor 120 and prevent contamination or damage from the outside. The passivation layer 134 may be formed of an inorganic insulating film such as silicon oxide (SiOx) or silicon nitride (SiNx).

The thin film transistor 120 can be classified into an inverted staggered structure and a coplanar structure depending on the positions of the components constituting the thin film transistor 120. In a thin film transistor with an inverted staggered structure, the gate electrode is located on the opposite side of the source electrode and the drain electrode with respect to the semiconductor layer 122. Additionally, in a thin film transistor with a coplanar structure, the gate electrode is located on the same side as the source electrode and the drain electrode based on the semiconductor layer.

In FIG. 1, the thin film transistor 120 is shown as a thin film transistor with a coplanar structure, but it may also be a thin film transistor with an inverted staggered structure.

Additionally, for convenience of explanation, only the driving thin film transistor is shown in FIG. 1 among the various thin film transistors that may be included in the organic light emitting display device 100. However, various driving elements such as switching thin film transistors, capacitors, etc. are used in the organic light emitting display device 100. ) can be included.

In order to protect the thin film transistor 120 and alleviate the step caused by the thin film transistor 120, a planarization layer 135 may be disposed on the thin film transistor 120. At this time, the planarization layer 135 may be composed of an organic material such as polyimide or photo acryl.

Anode 140 may be disposed on planarization layer 135. The anode 140 is an electrode that supplies holes to the light emitting unit 150. The anode 140 can be electrically connected to the thin film transistor 120 through a contact hole in the planarization layer 135.

The anode 140 may be made of transparent conductive materials such as indium tin oxide (ITO) or indium zinc oxide (IZO).

In addition, when the organic light emitting display device 100 is a top emission type that emits light upward, the anode 140 reflects the light emitted from the light emitting portion from the anode 140 to the cathode more smoothly. (135) may further include a reflective layer so that it can be emitted in the upper direction where it is disposed. At this time, the anode 140 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 made of silver (Ag) or an alloy containing silver.

A bank 136 is disposed on the anode 140 and the planarization layer 135. The bank 135 serves to partition the pixel area that actually emits light and define the corresponding pixel area. The bank 136 may be made of organic polyimide, acryl, or benzocyclobutene (BCB)-based resin.

The cathode 160 is disposed on the light emitting unit 150 and serves to supply electrons to the light emitting unit 150. Since the cathode 160 must supply electrons, it may be made of a metal material such as magnesium (Mg) or silver-magnesium (Ag:Mg), which is a conductive material with a low work function.

In addition, when the organic light emitting display device 100 is a top emission type, the cathode 160 is made of indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (Indium tin oxide). It may be made of transparent conductive oxide of the Tin Zinc Oxide (ITZO), Zinc Oxide (ZnO), and Tin Oxide (TiO) series.

A light emitting unit 150 is disposed between the anode 140 and the cathode 160. The light emitting unit 150 includes various organic layers including a light emitting layer as needed, and the detailed structure and function of the light emitting unit 150 will be described in detail with reference to FIGS. 2 to 4.

FIG. 2 is an enlarged cross-sectional view of area

Referring to FIG. 2, in the organic light emitting display device 100, the anode 140 may be disposed on top of the planarization layer 135, and the bank 136 may be disposed on the anode 140 and the planarization layer 135. there is.

The bank 136 serves to partition an area that emits light. At this time, the bank 136 is disposed between the anode 140 and the light emitting unit 150, and the area that does not emit light is defined as the bank area, and the area where the anode 140 and the light emitting unit 150 come into contact and emit light is the pixel area. It can be defined as:

When strong UV from external light is irradiated from the top of the organic light emitting display device 100 or the organic light emitting display device 100 is exposed to UV for a long time, the planarization layer 135 of the organic light emitting display device 100 is Outgassing may occur when polyimide or photoacrylic reacts with UV. When this outgassing phenomenon occurs, negatively charged gas compounds such as Nmethylpyrrolidone (NMP) or hexanitrile may be generated. As the negatively charged gas compound is discharged to the outside of the planarization layer, the negative charge can move along the bank 136 disposed on the top of the planarization layer 135.

In a conventional organic light emitting display device, as described above, negative charges moving through the bank directly react with the light emitting portion formed on the top of the bank, which may deteriorate the performance and lifespan of the organic light emitting display device. However, in the organic light emitting display device 100 according to an embodiment of the present invention, a charge blocking layer is further disposed at the bottom of the hole injection layer included in the light emitting portion 150 to prevent negative charges from directly reacting with the light emitting portion. .

The charge blocking layer included in the organic light emitting display device 100 is disposed in direct contact with the bank 136. At this time, by blocking the negative charges moving through the bank 136 before moving to the light emitting unit 150, the effect of outgassing that may occur due to UV irradiation can be minimized.

The detailed structure and function of the charge blocking layer included in the organic light emitting display device according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 4.

FIG. 3 is a cross-sectional view showing the pixel area shown in FIG. 2 in detail to explain the pixel area of the organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 3, first, pixel areas that emit light in the organic light emitting display device 100 may each emit light of one color.

For example, red light may be emitted from the first pixel area (R), green light may be emitted from the second pixel area (G), and blue light may be emitted from the third pixel area (B). In this way, a display unit capable of emitting white light can be formed by combining pixel areas that emit light of different colors.

The first pixel region (R), second pixel region (G), and third pixel region (B) of the organic light emitting display device 100 each include an anode 140, a charge blocking layer 220, and a light emitting unit 150. , it may include a cathode 160 and a capping layer 290, and the light emitting part 150 includes a hole injection layer 230, a hole transport layer (240, 242, 244), a light emitting layer (250, 252, 254), and an electron It may further include a transport layer 260.

The anode 140 is an electrode configured to supply holes to the light emitting unit 150. The anode 140 may be formed of transparent conductive materials such as indium tin oxide (ITO) or indium zinc oxide (IZO).

The organic light emitting display device 100 shown in FIG. 3 is a top emission type device that emits light toward the top where the cathode 160 is disposed. At this time, the anode 140 may further include a reflective layer so that the light emitted from the light emitting unit can be reflected by the anode 140 and more smoothly emitted toward the top where the cathode 160 is disposed. Additionally, the anode 140 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.

The charge blocking layer 220 may be disposed on the anode 140 in the first pixel region (R), the second pixel region (G), and the third pixel region (B). The charge blocking layer 220 serves to block negative charges generated from the planarization layer disposed below.

The charge blocking layer 220 has a high hole mobility so that the performance of the device does not deteriorate when holes are injected from the anode 140 into the hole injection layer 230, and has the characteristic of blocking negative charges that may flow from the bank. Eggplant can be selected from among materials. Accordingly, the charge blocking layer 220 may be made of the same material as the hole transport layers 240, 242, and 244. If the charge blocking layer is made of the same material as the hole transport layer, the process can be simplified.

Alternatively, depending on the structure or characteristics of the organic light emitting display device 100, the charge blocking layer 220 disposed on the top of the anode 140 excluding the area directly in contact with the bank may be removed.

The hole injection layer 230 is disposed on the anode 140 or the charge blocking layer 220. The hole injection layer 230 serves to facilitate the injection of holes from the anode 140. The hole injection layer 230 is, for example, HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine) ), and NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine).

The hole transport layers 240, 242, and 244 are disposed on the hole injection layer 230 and serve to smoothly transfer holes from the hole injection layer 230 to the light emitting layers 250, 252, and 254. The hole transport layers 240, 242, and 244 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,N-dimethylamino) -9,9-spirofluorene) and MTDATA (4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine).

Micro cavity means that light of a specific wavelength is amplified by constructive interference as light is repeatedly reflected between two layers spaced apart by the optical length.

As shown in FIG. 3, when the organic light emitting display device 100 emits different light for each pixel area, the wavelength of the emitted light is different. Therefore, in order to implement a microcavity, the wavelength of the light emitted from each pixel area is different. The resonance distance must be set separately. In the organic light emitting display device 100, the thickness of the hole transport layers 240, 242, and 244 can be adjusted differently in order to set the resonance distance differently for each pixel area.

The optimal thickness of the first hole transport layer 240, the second hole transport layer 242, and the third hole transport layer 244 can be independently determined within a thickness range that can form the optical distance of the microcavity.

The light emitting layer (250, 252, 254) is disposed on the hole transport layer (240, 242, 244). The light-emitting layers 250, 252, and 254 may include a material capable of emitting light of a specific color, and the light-emitting material may be formed using a phosphorescent material or a fluorescent material.

When the first light-emitting layer 250 emits red light, it includes a host material containing CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl), and PIQIr (acac) (bis (1 A dopant containing at least one selected from the group consisting of -phenylisoquinoline) acetylacetonate iridium), PQIr(acac)(bis(1-phenylquinoline) acetylacetonate iridium), PQIr(tris(1-phenylquinoline) iridium), and PtOEP(octaethylporphyrin platinum) It may be made of a phosphorescent material containing. Alternatively, the first light-emitting layer 250 may be made of a fluorescent material containing PBD:Eu(DBM)3(Phen) or Perylene.

When the second light emitting layer 252 emits green light, it contains a host material containing CBP or mCP and a dopant material such as an Ir complex containing Ir(ppy)3 (fac tris(2-phenylpyridine)iridium). It may be made of a phosphorescent material containing. Additionally, the second light-emitting layer 252 may be made of a fluorescent material containing tris(8-hydroxyquinolino)aluminum (Alq3).

When the third light emitting layer 254 emits blue light, it may be made of a phosphorescent material including a host material including CBP or mCP and a dopant material including (4,6-F2ppy)2Irpic. In addition, the third light-emitting layer 254 includes spiro-DPVBi(4,4'-Bis(2,2-diphenyl-ethen-1-yl)biphenyl), DSA(1-4-di-[4-(N,N -di-phenyl)amino]styryl-benzene), PFO-based polymer, and PPV-based polymer.

The electron transport layer 260 is disposed on the light-emitting layers 250, 252, and 254, and serves to transfer electrons from the electron injection layer to the light-emitting layers 250, 252, and 254. The thickness of the electron transport layer 260 can be adjusted considering electron transport characteristics. The electron transport layer 260 is, for example, Liq (8-hydroxyquinolinolato-lithium), PBD (2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4oxadiazole), TAZ (3 -(4-biphenyl)4-phenyl-5-tert-butylphenyl-1,2,4-triazole), spiro-PBD, BCP(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline) and It may be made of one or more selected from the group consisting of BAlq (bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium). The electron transport layer 260 may be omitted depending on the structure or characteristics of the organic light emitting display device 100.

Although not shown in FIG. 3, an electron injection layer may be disposed on the electron transport layer 260. The electron injection layer is an organic layer that facilitates the injection of electrons from the cathode 160 to the light emitting layers 250, 252, and 254. The electron injection layer may be a metal inorganic compound such as BaF2, LiF, NaCl, CsF, Li2O and BaO, and HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3, Consisting of 6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine), and NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine) It may be one or more organic compounds selected from the group.

The cathode 160 is disposed on the light emitting unit 150 and supplies electrons to the light emitting unit 150. Since the cathode 160 must supply electrons, it may be formed of a metal material such as magnesium (Mg) or silver-magnesium (Ag:Mg), which is a conductive material with a low work function.

The organic light emitting display device 100 shown in FIG. 3 is a top emission type device that emits light toward the top where the cathode 160 is disposed. That is, the light emitted from the light emitting unit 150 is emitted to the outside of the organic light emitting display device 100 through the cathode 160. At this time, the cathode 160 is made of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and zinc oxide (ZnO). And it may be a tin oxide (TiO)-based transparent conductive oxide.

A capping layer 290 may be further disposed on the cathode 160 to protect the organic light emitting display device 100 and to better extract light emitted from the light emitting unit 150. However, depending on the structure or characteristics of the organic light emitting display device 100, the capping layer 432 may be omitted.

In FIG. 3 , the organic light emitting display device 100 is shown as having a top emission structure, but it can also be configured as an organic light emitting display device having a bottom emission structure.

FIG. 4 is a cross-sectional view showing the bank area shown in FIG. 2 in detail to explain the bank area of the organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 4, the bank area of the organic light emitting display device 100 includes a planarization layer 135, a bank 136, a charge blocking layer 330, a hole injection layer 340, an electron transport layer 350, and a cathode ( 160) and a capping layer 370 may be disposed. At this time, a portion of the bank area may further include the hole transport layer and the light emitting layer described in FIG. 3.

A bank 136, which is made of polyimide, acrylic, or benzocyclobutene (BCB)-based resin and serves to partition the pixel area, is disposed on top of the planarization layer 135 made of an organic material such as polyimide or photoacrylic. It can be.

The charge blocking layer 330 may be disposed on the bank 136.

When strong UV from external light is irradiated from the top of the organic light emitting display device 100 or the organic light emitting display device 100 is exposed to UV for a long time, the planarization layer 135 of the organic light emitting display device 100 is Outgassing may occur when polyimide or photoacrylic reacts with UV. When this outgassing phenomenon occurs, negatively charged gas compounds such as Nmethylpyrrolidone (NMP) or hexanitrile may be generated. As the negatively charged gas compound is discharged to the outside of the planarization layer, it can move along the bank 136 disposed on the top of the planarization layer 135. At this time, the charge blocking layer 330 disposed in direct contact with the upper part of the bank 136 blocks negative charges moving through the bank 136 before they move to the light emitting unit, minimizing the effect of outgassing that may occur due to UV irradiation. You can do it.

The material used for the charge blocking layer 330 may be selected from materials that have high hole mobility and have the property of blocking negative charges that may flow from the bank 136. Therefore, the charge blocking layer 330 can be made of the same material as the hole transport layer in the pixel area.

The hole injection layer 340 is disposed on the charge blocking layer 330, for example, HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6, In the group consisting of 7,10.11-hexacarbonitrile), CuPc (phthalocyanine), and NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine) It may consist of one or more selected items.

The electron transport layer 350 may be disposed on the hole injection layer 340 in the bank region, for example, Liq (8-hydroxyquinolinolato-lithium), PBD (2-(4-biphenyl)-5-(4- tert-butylphenyl)-1,3,4oxadiazole), TAZ(3-(4-biphenyl)4-phenyl-5-tert-butylphenyl-1,2,4-triazole), spiro-PBD, BCP(2,9- It may be composed of one or more selected from the group consisting of dimethyl-4,7-diphenyl-1,10-phenanthroline) and BAlq (bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium). The electron transport layer 350 may be omitted depending on the structure or characteristics of the organic light emitting display device 100.

Although not shown in FIG. 4, the electron injection layer may be disposed on the electron transport layer 350, and may be a metal inorganic compound such as BaF2, LiF, NaCl, CsF, Li2O, and BaO, and may be a metal inorganic compound such as HAT-CN (dipyrazino[2 ,3-f:2',3'-h]quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc(phthalocyanine), and NPD(N,N'-bis(naphthalene-1-yl)- It may be any one or more organic compounds selected from the group consisting of N,N'-bis(phenyl)-2,2'-dimethylbenzidine).

The cathode 160 may be formed of a metal material such as magnesium (Mg) or silver-magnesium (Ag:Mg), which is a conductive material with a low work function. Alternatively, when the organic light emitting display device 100 is a top emission type that emits light upward, the cathode 160 is made of indium tin oxide (ITO), indium zinc oxide (IZO), It may be a transparent conductive oxide of the indium tin zinc oxide (ITZO), zinc oxide (ZnO), and tin oxide (TiO) series.

A capping layer 370 may be further formed on the cathode 160 to protect the organic light emitting display device 100. Depending on the structure or characteristics of the organic light emitting display device 100, the capping layer 370 may be omitted.

FIGS. 5A and 5B are diagrams illustrating the lifespan of a conventional organic light emitting display device and an organic light emitting display device according to an embodiment of the present invention measured before and after UV irradiation.

At this time, the lifespan of the organic light emitting display device was evaluated by measuring the luminance under the condition of applying a current at a current density of 20.5 mA/cm ² at 40°C. The horizontal axis represents time (Time, h), and the vertical axis represents the luminance reduction rate (L/L0), that is, the luminance (L) at the corresponding time compared to the initial luminance (L0).

Looking at FIG. 5A to illustrate the lifespan characteristics of an organic light emitting display device that does not include a conventional charge blocking layer, the time until the luminance reaches 95% of the initial luminance after UV irradiation compared to before UV irradiation, that is, It can be seen that the 95% life time (T95) of the organic light emitting display device is reached faster. That is, in a conventional organic light emitting display device, it can be seen that the luminance decreases more rapidly after UV irradiation compared to before UV irradiation. Accordingly, it can be seen that the performance of the hole injection layer of the conventional organic light emitting display device deteriorates due to UV irradiation, and as a result, the lifespan after UV irradiation is greatly reduced.

Looking at FIG. 5B to illustrate the lifespan characteristics of an organic light emitting display device including a charge blocking layer according to an embodiment of the present invention, it can be seen that the lifespan of the organic light emitting display device before and after UV irradiation hardly changes. That is, even if the organic light emitting display device according to an embodiment of the present invention is exposed to UV for a long time, its lifespan is not reduced and its performance can be continuously maintained.

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

An organic light emitting display device according to an embodiment of the present invention includes a substrate having a pixel area, an anode on the substrate, a light emitting portion including a hole injection layer, a light emitting layer, and an electron transport layer, and a cathode on the light emitting portion. , a bank in contact with the anode, and a charge blocking layer on the bank and in contact with the hole injection layer, the light emission performance and lifespan of the organic light emitting display device can be improved.

According to another feature of the present invention, the organic light emitting display device further includes a planarization layer on the substrate, and the anode and the bank may be disposed on top of the planarization layer.

According to another feature of the present invention, the planarization layer may be composed of one of polyimide and photoacrylic.

According to another feature of the present invention, the light emitting unit further includes a hole transport layer, and the charge blocking layer may be made of the same material as the hole transport layer.

According to another feature of the present invention, the pixel area may be configured to emit light having one of red, green, and blue colors.

According to another feature of the present invention, light can be emitted to the outside through the cathode.

The organic light emitting display device according to an embodiment of the present invention is on a bank, an anode, and a bank that contacts the anode and partitions the first pixel area, the second pixel area, and the third pixel area. and a hole injection layer disposed in the third pixel region, a first hole transport layer, a second hole transport layer, and a third hole disposed on the hole injection layer and disposed in the first pixel region, the second pixel region, and the third pixel region, respectively. A first light-emitting layer, a second light-emitting layer, and a third light-emitting layer, which are on a transport layer, a first hole transport layer, a second hole transport layer, and a third hole transport layer, and are respectively disposed in the first pixel area, the second pixel area, and the third pixel area, It is on the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer, and the electron transport layer is disposed in the first pixel area, the second pixel area, and the third pixel area, and the electron transport layer is on the first pixel area, the second pixel area. and a cathode disposed in the third pixel region, and a charge blocking layer located on the bank and in contact with the hole injection layer, thereby improving light emission performance and lifespan of the organic light emitting display device.

According to another feature of the present invention, the first pixel area, the second pixel area, and the third pixel area may be configured to emit light having red, green, and blue colors, respectively.

According to another feature of the present invention, the organic light emitting display device may further include a planarization layer disposed below the anode and the bank.

According to another feature of the present invention, the planarization layer may be composed of one of polyimide and photoacrylic.

According to another feature of the present invention, light emitted from the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer may be emitted to the outside through the cathode.

According to another feature of the present invention, the charge blocking layer may be composed of the same material as the first hole transport layer, the second hole transport layer, and the third hole transport layer.

According to another feature of the present invention, the first hole transport layer, the second hole transport layer, and the third hole transport layer may have different thicknesses.

An organic light emitting display device according to an embodiment of the present invention includes a substrate having a pixel area, a planarization layer on the substrate, an anode on the planarization layer, and a light emitting part on the anode and including a hole injection layer, a light emitting layer, and an electron transport layer. , a cathode on the light emitting part, a bank in contact with the anode on the planarization layer, and a charge blocking layer on the bank that is in contact with the hole injection layer to prevent light emission performance and lifespan from being reduced by outgassing occurring in the planarization layer. As a result, the charge blocking layer blocks the charges caused by outgassing, thereby improving the light emission performance and lifespan of the organic light emitting display device.

According to another feature of the present invention, the light emitting unit further includes a hole transport layer, and the charge blocking layer may be made of the same material as the hole transport layer.

According to another feature of the present invention, the pixel area may be configured to emit light having one of red, green, and blue colors.

According to another feature of the present invention, light emitted from the light emitting unit may be emitted to the outside through the cathode.

Organic light emitting display devices according to embodiments of the present invention can be applied to display devices, including TVs, mobiles, tablet PCs, monitors, laptop computers, and vehicle displays. there is. Alternatively, the organic light emitting display device according to an embodiment of the present invention may also be applied to a wearable display device, a foldable display device, and a rollable display device.

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.

100: Organic light emitting display device
110: Substrate 120: Thin film transistor
121: gate electrode 122: semiconductor layer
123: drain electrode 124: source electrode
131: buffer layer 132: gate insulating layer
133: interlayer insulation layer 134: passivation layer
135: Flattening layer 136: Bank
140: anode 150: light emitting unit
220, 330: charge blocking layer 230, 340: hole injection layer
240, 242, 244: Hole transport layer
250, 252, 254: light emitting layer
260, 350: electron transport layer 160: cathode
290, 370: capping layer

Claims (18)

A substrate having a pixel area that emits light;
an anode on the substrate;
a bank that partitions the pixel area and is in contact with the anode;
a light emitting portion located on the anode and the bank and including a hole injection layer, a light emitting layer, and an electron transport layer;
a cathode on the light emitting unit; and
An organic light emitting display device, comprising a charge blocking layer on the anode and the bank, in contact with the hole injection layer below the hole injection layer, and in contact with the entire upper surface of the anode in the pixel area. According to claim 1,
Further comprising a planarization layer on the substrate,
The anode and the bank are disposed on top of the planarization layer. According to clause 2,
An organic light emitting display device, wherein the planarization layer is made of one of polyimide and photoacrylic. According to claim 1,
The light emitting unit further includes a hole transport layer disposed on the hole injection layer,
An organic light emitting display device, wherein the charge blocking layer is made of the same material as the hole transport layer. According to claim 1,
An organic light emitting display device, wherein the pixel area is configured to emit light having one of red, green, and blue colors. According to clause 5,
An organic light emitting display device, wherein the light is emitted to the outside through the cathode. A bank that contacts the anode and partitions the first pixel area, the second pixel area, and the third pixel area;
a hole injection layer on the anode and the bank and disposed in the first pixel area, the second pixel area, and the third pixel area;
a first hole transport layer, a second hole transport layer, and a third hole transport layer on the hole injection layer and disposed in the first pixel area, the second pixel area, and the third pixel area, respectively;
A first light-emitting layer and a second light-emitting layer are on each of the first hole transport layer, the second hole transport layer, and the third hole transport layer, and are respectively disposed in the first pixel region, the second pixel region, and the third pixel region. and a third light emitting layer;
an electron transport layer on the first emitting layer, the second emitting layer, and the third emitting layer, and disposed in the first pixel region, the second pixel region, and the third pixel region;
a cathode on the electron transport layer and disposed in the first pixel area, the second pixel area, and the third pixel area; and
An organic light emitting display device, comprising: a charge blocking layer disposed between the bank and the hole injection layer and in contact with the hole injection layer throughout the first pixel area, the second pixel area, and the third pixel area. According to clause 7,
The organic light emitting display device wherein the first pixel area, the second pixel area, and the third pixel area are configured to emit light having red, green, and blue colors, respectively. According to clause 7,
An organic light emitting display device further comprising a planarization layer disposed below the anode and the bank. According to clause 9,
An organic light emitting display device, wherein the planarization layer is made of one of polyimide and photoacrylic. According to clause 7,
An organic light emitting display device, wherein light emitted from the first emission layer, the second emission layer, and the third emission layer is emitted to the outside through the cathode. According to clause 7,
The charge blocking layer is comprised of the same material as the first hole transport layer, the second hole transport layer, and the third hole transport layer. According to clause 7,
The first hole transport layer, the second hole transport layer, and the third hole transport layer have different thicknesses. A substrate having a pixel area that emits light;
a planarization layer on the substrate;
an anode on the planarization layer;
a bank partitioning the pixel area on the planarization layer and disposed in contact with the anode;
a light emitting portion located on the anode and the bank and including a hole injection layer, a light emitting layer, and an electron transport layer; and
Including a cathode on the light emitting part,
An organic light emitting display device comprising a charge blocking layer between the anode and the light emitting unit and in contact with the hole injection layer on the entire upper surface of the anode disposed in the pixel area. According to claim 14,
The light emitting unit further includes a hole transport layer disposed on the hole injection layer,
An organic light emitting display device, wherein the charge blocking layer is made of the same material as the hole transport layer. According to claim 14,
An organic light emitting display device, wherein the pixel area is configured to emit light having one of red, green, and blue colors. According to claim 16,
An organic light emitting display device, wherein light emitted from the light emitting unit is emitted to the outside through the cathode. According to claim 1,
The charge blocking layer is disposed between the anode and the hole injection layer in the entire area where the anode and the hole injection layer overlap.

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