KR102429886B1 - Organic light emitting display device - Google Patents

Abstract

The present invention relates to an organic light emitting display device, wherein the light emitting having an anode, an organic material layer in contact with the anode and containing a soluble polyimide, a hole injection layer sequentially stacked on the anode, a hole transport layer, an organic light emitting layer and an electron transport layer a cathode on the sub and the light emitting section. By forming the organic material layer of soluble polyimide, the outgassing phenomenon can be minimized and the lifespan of the organic light emitting diode display 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 particularly, to an organic light emitting display device having an improved lifespan.

The organic light emitting display device is a self-luminous display device, and unlike a liquid crystal display, it does not require a separate light source, so it can be manufactured in a lightweight and thin form. In addition, the organic light emitting display device is not only advantageous in terms of power consumption by low voltage driving, but also has excellent color realization, response speed, viewing angle, and contrast ratio (CR). have.

In general, an organic light emitting display device includes an anode, a hole injection layer (HIL), a hole transport layer (HTL), an organic light emitting layer (EML), an electron transport layer; ETL), an Electron Injection Layer (EIL) and a cathode. When holes are injected from the anode into the organic emission layer and electrons are injected from the cathode into the organic emission layer, the injected electrons and holes recombine to form excitons to generate light.

However, when the organic light emitting display device is used for a long time, the light emitting performance of the organic light emitting display device is deteriorated. The reasons for the deterioration of the light emitting performance of the organic light emitting display device are various. For example, when the organic light emitting diode display device is left at a high temperature, the lifespan of the organic light emitting diode display may decrease. In particular, the continuous exposure of the organic light emitting diode display to UV (Ultra Violet) and visible light by external light is a major cause of reducing the lifespan of the organic light emitting display apparatus. That is, even when continuously exposed to UV and visible light in natural light, there is a problem in that the lifespan characteristics of the organic light emitting display device are deteriorated.

1 is a schematic enlarged cross-sectional view for explaining a cause of a decrease in lifespan due to irradiation of a Xe lamp in a conventional organic light emitting display device. Referring to FIG. 1 , a conventional organic light emitting display device includes a planarization layer 34 for planarizing an upper portion of a substrate, an anode 40 for supplying holes, a light emitting unit 50 including an organic light emitting layer, and a cathode for supplying electrons ( 60 are sequentially stacked, and a bank 35 for dividing adjacent sub-pixel regions is included.

When the organic light emitting diode display is exposed to UV light for a long time, an out gasing phenomenon occurs in the planarization layer 34 or the bank 35 adjacent to the light emitting unit 50 or the anode 40 . The light emitting part 50 may be damaged by the gas compound 70 generated from the planarization layer 34 or the bank 35 . More specifically, the planarization layer 34 disposed under the anode 40 or the bank 35 adjacent to the light emitting unit 50 may be generally formed of photoacrylic such as acrylate. . At this time, the photoacrylic is easily decomposed because it is vulnerable to heat resistance and UV irradiation, and the gas compound 70 is formed. The gas compound 70 reacts with the light emitting part formed of an organic material adjacent to the planarization layer 34 or the bank 35 while being discharged to the outside.

In particular, when the gas compound 70 generated by the out-gassing phenomenon has a negative charge, it reacts with a material having a positive charge (+) constituting the hole injection layer disposed at the outermost part, and the characteristics of the hole injection layer This decreases, and thus the hole injection layer cannot smoothly inject holes into the light emitting layer.

As such, 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 is deteriorated, and pixel shrinkage occurs, resulting in the organic light emitting display. There is a problem in that the life of the device is reduced.

The inventors of the present invention have recognized that polyimide having high thermal stability and excellent mechanical properties can be used to improve heat resistance and light resistance of an organic material layer adjacent to an anode or a light emitting part such as a planarization layer or a bank.

Meanwhile, in order to form a planarization layer or a bank using polyimide, a patterning process is required. However, polyimide, which is generally insoluble in an organic solvent, has a disadvantage in that it is difficult to pattern by using it as a photosensitive material by itself. In order to solve this problem, a method using polyamic acid or polyamic ester, which is a precursor of polyimide, may be introduced. That is, since it is difficult to form a planarization layer or bank using polyimide itself as a photosensitive resin, polyamic acid as a precursor capable of forming polyimide is used together with a photoactive compound, patterning, polymerization and curing Through the process, it is possible to use a method of causing an imidation reaction of the polyamic acid to finally form a polyimide.

However, when the planarization layer or the bank layer is formed by generating the polyimide from the polyamic acid or polyamic ester, outgassing may occur during the imidization reaction of the polyamic acid or polyamic ester. As described above, the generated gas reacts with the light emitting unit to reduce the lifespan of the organic light emitting diode display.

In addition, in order to form and cure the polyimide from the polyamic acid at the same time, a certain amount of the photoactive compound must be included. In this case, the photoactive compound may be decomposed into by-products such as aldehydes, ketones, alcohols, and acid compounds by UV irradiation, thereby adversely affecting the organic light emitting device.

In addition, although polyimide is a material having excellent heat resistance and light resistance, when polyimide is also exposed to UV for a long time, a gas having a partially negative charge such as hexanenitrile may be formed by outgassing phenomenon. The generated gas may be combined with the light emitting unit to cause a direct problem, or may slowly permeate between the anode and the light emitting unit, thereby contaminating the upper part of the anode, thereby reducing the performance and lifespan of the organic light emitting diode display.

Accordingly, the present inventors did not form a polyimide using polyamic acid or polyamic ester as a precursor, but instead used a soluble polyimide imidized in advance without a separate imidization reaction to form an organic light emitting layer or bank formed thereon. The display device was invented. That is, by forming a planarization layer or bank containing soluble polyimide, an organic light emitting diode display capable of suppressing an outgassing phenomenon and minimizing deterioration of the lifespan of the organic light emitting display device was invented.

The problem to be solved by the present invention is to provide an organic light emitting display device capable of minimizing the outgassing phenomenon by using soluble polyimide without forming a planarization layer or bank composed of polyimide using imidization reaction of polyamic acid. will provide

Another problem to be solved by the present invention is to improve the lifespan of an organic light emitting display device.

The problems 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 following description.

In order to solve the above problems, an organic light emitting display device according to an embodiment of the present invention is in contact with an anode, an organic material layer containing soluble polyimide, a hole injection layer sequentially stacked on the anode, and a hole transport layer , a light emitting portion having an organic light emitting layer and an electron transporting layer, and a cathode on the light emitting portion. By forming the organic material layer of soluble polyimide, the outgassing phenomenon can be minimized and the lifespan of the organic light emitting diode display can be improved.

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

An object of the present invention is to improve performance and lifespan of an organic light emitting diode display by minimizing an outgassing phenomenon occurring from an organic material layer including polyimide.

In addition, the present invention minimizes the outgassing phenomenon occurring from the photoactive compound by minimizing the use of the photoactive compound when the planarization layer and the bank are formed using the photosensitive polyimide resin composition.

The effect according to the present invention is not limited by the contents exemplified above, and more various effects are included in the present invention.

1 is a schematic enlarged cross-sectional view for explaining a cause of a decrease in lifetime due to UV irradiation in a conventional organic light emitting display device.
2 is a schematic cross-sectional view illustrating an organic light emitting display device according to an embodiment of the present invention.
3 is a graph measuring the amounts of outgassing and polar compounds collected after UV irradiation in the planarization layers prepared by Example 1, Comparative Example 1, and Comparative Example 2;
FIG. 4a is a graph showing the rate of decrease in luminance according to UV irradiation time in the planarization layers prepared according to Example 1, Comparative Example 1, and Comparative Example 2. FIG.
4b to 4d are graphs showing FT-IR analysis results of Example 1, Comparative Example 1, and Comparative Example 2 measured before and after UV irradiation according to Experimental Example 2, respectively.
5 is a graph showing the change in mass when the planarization layers prepared in Example 1, Comparative Example 1, and Comparative Example 2 were exposed to a temperature of 230°C.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be embodied in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention pertains 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 the embodiments of the present invention are exemplary, and thus the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. When 'include', 'have', 'consist', etc. mentioned in the present invention are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless specifically stated otherwise.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between the two parts unless 'directly' is used.

Reference to a device or layer “on” another device or layer includes any intervening layer or other device directly on or in the middle of another device.

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

Like reference numerals refer to like elements throughout.

The size and thickness of each component shown in the drawings are shown for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component.

Each feature of the various embodiments of the present invention may be partially or wholly combined or combined with each other, technically various interlocking and driving are possible, and each of the embodiments may be implemented independently of each other or may be implemented together in a related relationship. may be

Hereinafter, the present invention will be described with reference to the drawings.

2 is a schematic cross-sectional view illustrating an organic light emitting display device according to an exemplary embodiment. Referring to FIG. 2 , the organic light emitting diode display 100 includes a substrate 110 , a thin film transistor 120 , an anode 140 , a light emitting unit 150 , and a cathode 160 .

The organic light emitting diode display 100 includes a plurality of sub pixels. A sub-pixel refers to an area of a minimum unit in which actual light is emitted. In addition, a plurality of sub-pixels may be gathered to form a minimum group capable of expressing white light. For example, three sub-pixels are one group, and a red sub-pixel, a green sub-pixel, and a blue pixel sub are one. can form a group of However, the present invention is not limited thereto, and various sub-pixel designs are possible. In FIG. 2 , only one sub-pixel among a plurality of sub-pixels of the organic light emitting display device 100 is illustrated for convenience of explanation.

The substrate 110 is formed of an insulating material to support various components of the organic light emitting diode display 100 during a manufacturing process. For example, the substrate 110 may be made of a material having flexibility, such as glass or plastic. A buffer layer 131 is formed on the substrate 110 to protect various components of the organic light emitting diode display 100 from penetration of moisture (H ₂ O) and hydrogen (H ₂ ) from outside the substrate 110 . do. However, the substrate 110 may be removed during the manufacturing process of the organic light emitting display device 100 , and the buffer layer 131 may be omitted depending on the structure or characteristics of the organic light emitting display device 100 .

A thin film transistor 120 including a gate electrode 121 , an active layer 122 , a source electrode 123 , and a drain electrode 124 is formed on the buffer layer 131 . For example, an active layer 122 is formed on the substrate 110 , and a gate insulating layer 132 for insulating the active layer 122 and the gate electrode 121 is formed on the active layer 122 . . An interlayer insulating layer 133 for insulating the gate electrode 121, the source electrode 123, and the drain electrode 124 is formed on the interlayer insulating layer 133, and the source electrode 122 is in contact with the active layer 122, respectively. 123 ) and a drain electrode 124 are formed. In this specification, for convenience of explanation, only a driving thin film transistor among various thin film transistors that may be included in the organic light emitting diode display 100 is illustrated, but a switching thin film transistor and a capacitor may also be included in the organic light emitting display apparatus 100 . In addition, although the thin film transistor 120 is described as having a coplanar structure in this specification, a thin film transistor having a staggered structure may also be used.

A planarization layer 134 is formed on the thin film transistor 120 . The planarization layer 134 functions to planarize the upper portion of the substrate 110 . The planarization layer 134 may be formed of a single layer or a plurality of layers. The planarization layer 134 includes a contact hole for electrically connecting the thin film transistor 120 and the anode 140 . The planarization layer 134 may be made of an organic material. For example, the planarization layer 134 may be made of polyimide or acryl. The planarization layer 134 of the organic light emitting diode display according to an exemplary embodiment may include soluble polyimide to suppress outgassing occurring in the planarization layer 134 . Details related to the material constituting the planarization layer 134 will be described later.

The anode 140 is disposed on the planarization layer 134 . The anode 140 is an electrode configured to supply holes to the organic light emitting layer of the light emitting unit 150 . The anode 140 may be electrically connected to the thin film transistor 120 through the contact hole of the planarization layer 134 , for example, may be electrically connected to the source electrode 123 of the thin film transistor 120 . The anode 140 is spaced apart for each pixel.

When the organic light emitting diode display 100 according to an embodiment of the present invention is a top emission type, the anode 400 includes a reflective layer 141 and a transparent conductive layer 142 . The reflective layer 141 is configured such that light emitted from the organic light emitting layer is reflected and more smoothly emitted upwardly. The reflective layer 141 may be made of a material having excellent reflectivity, for example, silver (Ag) or an alloy containing silver, for example, silver or APC (Ag/Pd/Cu). The transparent conductive layer 142 is formed of a transparent conductive material, and for example, a transparent conductive oxide (TCO) such as indium tin oxide (ITO), indium zinc oxide (IZO), or the like. ) can be formed. Meanwhile, as described above, the anode 400 may have a two-layer structure in which a transparent conductive layer 142 and a reflective layer 141 formed of a transparent conductive material are sequentially stacked, and also a transparent conductive layer, a reflective layer and a transparent conductive layer. It may be a three-layer structure stacked in this order.

A bank 135 is formed on the anode 140 and the planarization layer 134 . The bank 135 divides adjacent sub-pixel areas. Also, the bank 135 may divide a pixel region including a plurality of sub-pixel regions. In this case, the bank 135 is in contact with the light emitting unit 150 , and more specifically, directly contacts the hole injection layer. The bank 135 may be made of an organic material. For example, the bank 135 may be made of polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto. Organic light emitting display according to an embodiment of the present invention Bank 135 of the device may include a soluble polyimide to inhibit outgassing that occurs in bank 135 . Details related to the material constituting the bank 135 will be described later.

The cathode 160 is disposed on the anode 140 . The cathode 160 supplies electrons to the organic emission layer. Since the cathode 160 needs to supply electrons, it is formed of a conductive material having a low work function. More specifically, the cathode 160 may be a metal material such as magnesium (Mg), silver-magnesium (Ag:Mg), or the like. In addition, when the organic light emitting diode display 100 according to an embodiment of the present invention is a top emission method, the cathode 160 is formed of indium tin oxide (ITO), indium zinc oxide (IZO). ), Indium Tin Zinc Oxide (ITZO), Zinc Oxide (ZnO), and Tin Oxide (TiO) based transparent conductive oxides may be used.

The light emitting unit 150 is disposed between the anode 140 and the cathode 160 . The light emitting unit 150 includes various organic layers as needed, but an organic light emitting layer for emitting light must be included.

Although not shown in FIG. 2 , the light emitting unit 150 includes a hole injection layer (HIL) disposed on the anode 140 , a hole transport layer (HTL) disposed on the hole injection layer, and holes and an organic light emitting layer (EML) disposed on the transport layer and an electron transport layer (ETL) disposed on the organic light emitting layer.

The hole injection layer is disposed on the anode 140 . The hole injection layer is an organic layer that facilitates injection of holes from the anode 140 to the organic emission layer. The hole injection layer is, for example, HAT-CN (dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10.11-hexacarbonitrile), CuPc (phthalocyanine), and It may consist of at least one selected from the group consisting of NPD (N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-2,2'-dimethylbenzidine), but is not limited thereto. .

The hole transport layer is disposed on the hole injection layer. The hole transport layer is an organic layer that smoothly transfers holes from the hole injection layer to the organic light emitting layer. The hole transport layer is, 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), but may consist of any one or more selected from the group consisting of, but is not limited thereto.

The organic light emitting layer is disposed on the hole transport layer. The organic emission layer may include a material capable of emitting light of a specific color. For example, the organic light-emitting layer may include a light-emitting material capable of emitting red light, green light, blue light, or yellow-green light. However, the present invention is not limited thereto and may include a light emitting material capable of emitting light of another color. In this case, the light emitting material may be formed using a phosphorescent material or a fluorescent material.

The electron transport layer is disposed on the organic light emitting layer and is an organic layer that transfers electrons from the electron injection layer to the organic light emitting layer. The thickness of the electron transport layer may be adjusted in consideration of electron transport characteristics. The electron transport layer 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 BAlq (bis (2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminium) may be made of any one or more selected from the group consisting of, but is not limited thereto. The electron transport layer may be omitted depending on the structure or characteristics of the organic light emitting diode display 100 .

The electron injection layer is disposed on the electron transport layer. The electron injection layer is an organic layer that facilitates injection of electrons from the cathode 160 to the emission layer. The electron injection layer may be a metal inorganic compound such as BaF ₂ , LiF, NaCl, CsF, Li ₂ O, and BaO. In addition, the electron injection layer is 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) may be any one or more organic compounds selected from the group consisting of, but is not limited thereto. The electron injection layer may be omitted depending on the structure or characteristics of the organic light emitting diode display 100 .

The organic light emitting display device 100 according to an embodiment of the present invention has a planarization layer made of an organic material when strong UV is irradiated from the outside, exposed to UV or visible light for a long time, or when the organic material is decomposed over time. It aims to suppress the outgassing phenomenon occurring in 134 and the bank 135 . Specifically, the planarization layer or bank of the organic light emitting diode display 100 according to an exemplary embodiment includes soluble polyimide.

The soluble polyimide is a pre-imidized polyimide. The pre-imidized polyimide means a polyimide formed by terminating the imidization reaction in advance. More specifically, as a concept in contrast to the process of forming a polyimide through imidization reaction while patterning, polymerization and curing a resin composition containing polyamic acid or polyamic ester, the pre-imidized polyimide is first It is synthesized through an imidization reaction, and may be included in the resin composition as it is and used for patterning and curing processes.

The soluble polyimide is a polyimide that can be dissolved in an organic solvent, and may include a functional group capable of imparting a soluble function. For example, the soluble polyimide may contain a fluorine group or a chloro group.

For example, the soluble polyimide may be represented by Formula 1 below.

[Formula 1]

X ₁ is a tetravalent aromatic or aliphatic organic group, Y ₁ is a divalent aromatic or aliphatic organic group; At least one of X ₁ and Y ₁ is substituted with at least one of a fluorine group and a chloro group, and m is an integer from 10 to 1000.

For example, in Formula 1, the substituent X may be at least one selected from tetravalent organic groups represented by the following Formulas.

The planarization layer 134 or the bank 135 may further include a photoactive compound and a crosslinking agent as well as soluble polyimide. Specific details regarding the photoactive compound and the crosslinking agent will be described in more detail in the photosensitive resin composition.

Hereinafter, the photosensitive resin composition for forming the planarization layer 134 or the bank layer 135 will be described.

The photosensitive resin composition includes a soluble polyimide, a photoactive compound, a crosslinking agent and a solvent.

A photoactive compound (PAC) is a compound that can generate acid when exposed to light. It generates acid by photoreaction and is then added to the developer so that the light-irradiated portion through exposure can be dissolved in the developer. It functions to increase solubility. The photoactive compound may be a compound including a functional group represented by Formula 2 or Formula 3 below.

[Formula 2]

[Formula 3]

For example, the photoactive compound may be Diazonaphthoquinone (DNQ).

The photoactive compound is preferably 5 to 15 parts by weight based on 100 parts by weight of the soluble polyimide. If the content of the photoactive compound is less than 5 parts by weight, it is difficult to easily perform a photo pattern through the photosensitive resin composition, and if the content of the photoactive compound is more than 15 parts by weight, the amount of gas formed from the formed planarization layer or bank is large, so that organic light emission The lifespan of the display device may be reduced.

The crosslinking agent functions as a link between the soluble polyimides. The crosslinking agent has an epoxy group, and it is preferable to have two or more epoxy groups in the bonsai. The crosslinking agent is preferably an aromatic or aliphatic compound containing two or more epoxy groups in the molecule. The epoxy group of the crosslinking agent may be linked to the phenol group of the soluble polyimide.

The crosslinking agent is preferably 5 to 20 parts by weight based on 100 parts by weight of the soluble polyimide. If the content of the crosslinking agent is less than 5 parts by weight, curing of the photosensitive resin composition may not proceed smoothly. The life of the device may be reduced.

The solvent is not particularly limited as long as it can dissolve the polyimide-based polymer compound, and for example, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N-vinylpyrrolidone. Don, N-methylcaprolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, m-cresol, γ-butyrolactone, ethyl cellosolve, butyl cellosolve, ethyl carbitol, It may be at least one selected from the group consisting of butylcarbitol, ethylcarbitol acetate, butylcarbitol acetate, ethylene glycol, ethyl lactate, butyl lactate, cyclohexanone, and cyclopentanone, but is not limited thereto.

In addition, the photosensitive resin composition may further include other additives such as a dissolution rate control agent, a sensitizer, an adhesion enhancer, and a surfactant, in addition to the above-described components.

For example, the surfactant may be used without any particular limitation as long as it can be used in the photosensitive resin composition, and among them, it may be preferable to use a fluorine-based surfactant or a silicone-based surfactant.

The planarization layer 134 or the bank 135 may be formed from the above-described photosensitive resin composition. The photosensitive resin composition may be applied on a substrate using a conventional method such as spin coating, slit spin coating, roll coating, die coating, curtain coating, and the like, and an exposure process may be performed. The exposure and development process also uses a method used for forming a photosensitive layer using a conventional polyimide photosensitive resin composition, and is not particularly limited.

In the exposure step, examples of light sources irradiated with light irradiation means include electromagnetic waves, ultraviolet to visible light, electron beams, X-rays, laser beams, and the like. In addition, as a method of irradiating the light source, known means such as a high-pressure mercury lamp, a xenon lamp, a carbon arc lamp, a halogen lamp, a cold cathode tube for a copier, an LED, and a semiconductor laser can be used.

The planarization layer 134 or the bank 135 formed from the above-described photosensitive resin composition may be formed of a block copolymer including a soluble polyimide. In a photosensitive resin composition including a soluble polyimide, a photoactive compound, and a crosslinking agent, a crosslinking reaction between a crosslinking agent having an epoxy group and a soluble polyimide is performed in a curing process that is performed after exposure and development. Adjacent soluble polyimides are linked together by a crosslinking agent. Accordingly, the planarization layer 134 or the bank 135 may be composed of a block copolymer in which soluble polyimide forms repeating units. Specifically, a block copolymer may be formed while the hydroxyl functional group of the soluble polyimide and the epoxy group of the crosslinking agent react.

For example, the block copolymer constituting the planarization layer 134 or the bank 135 may include a repeating unit represented by Chemical Formula 4 below.

[Formula 4]

In Formula 4, X ₂ is a tetravalent aromatic or aliphatic organic group, Y ₂ is a divalent aromatic or aliphatic organic group, and Z ₂ is a divalent aliphatic organic group; At least one of X ₂ and Y ₂ is substituted with at least one of a fluorine group and a chloro group.

The organic light emitting diode display 100 according to an embodiment of the present invention includes a planarization layer 134 under the anode 140 or a sub-pixel area disposed on and adjacent to the anode 140 and the planarization layer 134 . It includes a bank 135 that separates them. In this case, at least one of the planarization layer 134 and the bank 135 includes soluble polyimide. The planarization layer 134 or the bank 135 formed of soluble polyimide has excellent heat resistance and light resistance, so that it is possible to minimize the occurrence of outgassing in an environment irradiated with high temperature and UV. Accordingly, the lifespan of the organic light emitting display device 100 may be improved.

As described above, polyimide is generally insoluble, so it is difficult to immediately form an organic layer by dissolving the polyimide in a solution through patterning, developing, and curing processes. Therefore, in order to form an organic material layer including polyimide, that is, a planarization layer or bank, it was dissolved in a polyamic acid solution, which is a precursor of polyimide and has soluble properties, and had to go through coating, polymerization, exposure, development, and curing processes. Forming the polyimide layer using the imidization reaction of polyamic acid requires a separate polymerization process, and other components of the organic light emitting display device may be damaged due to the outgassing phenomenon occurring during the imidization reaction, The generated gas may cause problems later.

However, in the organic light emitting display device according to an embodiment of the present invention, a planarization layer and a bank are formed using a photosensitive resin composition including a pre-imidized polyimide, thereby polymerizing compared to the case of using a polyamic acid. can be excluded, so that the process can be simplified. In addition, it is possible to solve the problem of outgassing that occurred during the imidization reaction of the polyamic acid, and the problem of outgassing that occurs as the polyamic acid remaining after the imidization reaction is decomposed can also be solved.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for illustration of the present invention, and the scope of the present invention is not limited by the following examples.

In Example 1, Comparative Example 1 and Comparative Example 2, different binder resins were used, and a photosensitive resin composition composed of the contents of each component described in Table 1 below was prepared. A planarization layer was formed using the prepared photosensitive resin composition.

binder resin photoactive compounds crosslinking agent Etc Example 1 Soluble polyimide
100 parts by weight DNQ
10 parts by weight epoxy compound
10 parts by weight speed regulator
2 parts by weight Comparative Example 1 polyacrylate
100 parts by weight DNQ
20 parts by weight epoxy compound
10 parts by weight speed regulator
2 parts by weight Comparative Example 2 polyamic acid
100 parts by weight DNQ
20 parts by weight epoxy compound
10 parts by weight speed regulator
2 parts by weight

Experimental example One

After irradiating the planarization layer prepared by Example 1, Comparative Example 1 and Comparative Example 2 with a Xe lamp having an intensity of 2.4W/m ² at 420 nm wavelength for 2 hours, using H&S-MS equipment The amount of outgassed gas was collected and measured. In addition, the amount of polar compound contained in the solution was measured by collecting the solution using P&T-MS equipment. The results are shown in FIG. 3 .

3 is a graph measuring the amounts of outgassing and polar compounds collected after UV irradiation in the planarization layers prepared by Example 1, Comparative Example 1, and Comparative Example 2;

Referring to FIG. 3 , it can be seen that the outgassing phenomenon hardly occurred in the planarization layer of Example 1 formed using the soluble polyimide even after UV irradiation.

Experimental example 2

While continuously irradiating the planarization layer prepared by Example 1, Comparative Example 1 and Comparative Example 2 with a Xe lamp having an intensity of 2.4 W/m ² at a wavelength of 420 nm, the rate of change in luminance that is lowered compared to the initial luminance measured. The results are shown in Fig. 4a.

FIG. 4a is a graph showing the rate of decrease in luminance according to UV irradiation time in the planarization layers prepared according to Example 1, Comparative Example 1, and Comparative Example 2. FIG.

Referring to FIG. 4A , in Comparative Example 1 using acrylate as the binder resin and Comparative Example 2 using polyamic acid as the binder resin, the luminance decreased by 20% or more before 100 hours. However, in Example 1 using the soluble polyimide, the luminance decreased by 20% or more after 200 hours. Therefore, in Example 1 using polyimide, the outgassing phenomenon caused by UV irradiation was suppressed, and it could be confirmed that the light resistance was excellent.

Meanwhile, FIGS. 4b to 4d are graphs showing the FT-IR analysis results of Example 1, Comparative Example 1, and Comparative Example 2 measured before and after UV irradiation according to Experimental Example 2, respectively.

Referring to FIGS. 4c and 4d , it can be seen that the shape of the FT-IR graph is significantly changed before and after UV irradiation. This shows that the planarization layer formed by UV irradiation was deformed. 4c and 4d, it can be confirmed that the shape of the FT-IR graph is almost identical to FIG. 4b showing Example 1 even after UV irradiation. This shows that Example 1 hardly causes decomposition or deformation of the planarization layer even after UV irradiation.

Experimental example 3

The planarization layer prepared by Example 1, Comparative Example 1, and Comparative Example 2 was exposed to a temperature of 230°C, and then the mass change of the planarization layer according to time change was measured. The results are shown in FIG. 5 .

5 is a graph showing the change in mass when the planarization layers prepared in Example 1, Comparative Example 1, and Comparative Example 2 were exposed to a temperature of 230°C.

Referring to FIG. 5 , it was confirmed that Comparative Example 1 using acrylate as the binder resin had remarkably insufficient heat resistance. On the contrary, it was confirmed that Example 1 using soluble polyimide had the best heat resistance compared to Comparative Examples.

Although the 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 within the scope without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

An embodiment of the present invention can be described as follows.

In order to solve the above problems, an organic light emitting display device according to an embodiment of the present invention includes an anode, an organic material layer in contact with the anode, including a soluble polyimide, a hole injection layer sequentially stacked on the anode, and a light emitting part having a hole transport layer, an organic light emitting layer and an electron transport layer, and a cathode on the light emitting part.

According to an embodiment of the present invention, the soluble polyimide may be a pre-imidized polyimide.

According to an embodiment of the present invention, the organic material layer may further include a photoactive compound and a crosslinking agent.

According to an embodiment of the present invention, the organic material layer may be formed of a block copolymer including a soluble polyimide.

According to an embodiment of the present invention, the block copolymer may include a repeating unit represented by the following formula (4).

[Formula 4]

(In Formula 4, X ₂ is a tetravalent aromatic or aliphatic organic group, Y ₂ is a divalent aromatic or aliphatic organic group, Z ₂ is a divalent aliphatic organic group; X ₂ and Y ₂ At least one of X 2 and Y 2 is fluorine It is substituted with at least one of a group and a chloro group.)

According to an embodiment of the present invention, the organic layer is made of a photosensitive composition including a soluble polyimide, a photoactive compound, and a crosslinking agent, and may be formed by curing the photosensitive composition.

According to an embodiment of the present invention, the photosensitive composition may include 5 to 15 parts by weight of the photoactive compound and 5 to 20 parts by weight of the crosslinking agent based on 100 parts by weight of the soluble polyimide.

According to an embodiment of the present invention, the soluble polyimide may be represented by the following formula (1).

[Formula 1]

(In Formula 1, X ₁ is a tetravalent aromatic or aliphatic organic group, Y ₁ is a divalent aromatic or aliphatic organic group; at least one of X ₁ and Y ₁ is substituted with at least one of a fluorine group and a chloro group , and m is an integer from 10 to 1000.)

According to an embodiment of the present invention, the organic material layer is a bank disposed on one end of the anode to partition the light emitting area, and the bank may be in contact with the hole injection layer.

According to an embodiment of the present invention, the organic material layer may be a planarization layer disposed under the anode and spaced apart from the light emitting part by the anode.

Although the 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 within the scope 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 spirit of the present invention, but to illustrate, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: organic light emitting display device
110: substrate
120: thin film transistor
121: gate electrode
122: active layer
123: source electrode
124: drain electrode
131: buffer layer
132: gate insulating layer
133: interlayer insulating layer
134: planarization layer
135: bank
140: anode
150: light emitting part

Claims (10)

thin film transistor;
a planarization layer disposed on the thin film transistor;
an anode disposed on the planarization layer;
a bank disposed on the anode and the planarization layer to cover both ends of the anode to partition a light emitting area;
a light emitting unit having a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron transport layer sequentially stacked on the anode; and
and a cathode on the light emitting part,
At least one of the planarization layer and the bank is made of a block copolymer including a soluble polyimide,
The block copolymer includes a repeating unit represented by the following Chemical Formula 4, an organic light emitting display device.
[Formula 4]

(In Formula 4, X ₂ is a tetravalent aromatic or aliphatic organic group, Y ₂ is a divalent aromatic or aliphatic organic group, Z ₂ is a divalent aliphatic organic group; X ₂ and Y ₂ At least one of It is substituted with at least one of a fluorine group and a chloro group.) The method of claim 1,
and the soluble polyimide is a pre-imidized polyimide. 3. The method of claim 2,
and at least one of the planarization layer and the bank further comprises a photoactive compound and a crosslinking agent. delete delete 4. The method of claim 3,
and at least one of the planarization layer and the bank is formed of a photosensitive composition comprising the soluble polyimide, the photoactive compound, and the crosslinking agent, and is formed by curing the photosensitive composition. 7. The method of claim 6,
The photosensitive composition comprises, based on 100 parts by weight of the soluble polyimide, 5 parts by weight to 15 parts by weight of the photoactive compound and 5 parts by weight to 20 parts by weight of the crosslinking agent. 8. The method of claim 7,
The soluble polyimide is represented by the following Chemical Formula 1, an organic light emitting display device.
[Formula 1]

(In Formula 1, X ₁ is a tetravalent aromatic or aliphatic organic group, Y ₁ is a divalent aromatic or aliphatic organic group; at least one of X ₁ and Y ₁ is substituted with at least one of a fluorine group and a chloro group , and m is an integer from 10 to 1000.) delete delete

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