KR101335422B1 - Fabricating method of electroluminescent device - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic light emitting device, the method of manufacturing an organic light emitting device according to the present invention comprises the steps of preparing a substrate having a plurality of pixel areas defined; Forming a first electrode on the pixel region of the substrate; Forming barrier ribs on the substrate on which the first electrode is formed to separate pixel regions by using roll printing; Forming a light emitting layer on the first electrode between the barrier ribs; And forming a second electrode on the substrate on which the light emitting layer and the partition wall are formed.

Bulkhead, roll printing, multilayer

Description

Manufacturing method of organic electroluminescent device {FABRICATING METHOD OF ELECTROLUMINESCENT DEVICE}

1 is a conceptual view showing a conventional general organic light emitting device.

2 is a band diagram of the organic light emitting device.

3A to 3D are views illustrating a process of forming a barrier rib and forming an organic light emitting material in the barrier rib in the method of manufacturing an organic light emitting diode according to the related art.

4 is a cross-sectional view showing an organic light emitting device manufactured by the manufacturing method according to the present invention.

5A through 5B are cross-sectional views sequentially illustrating a method of manufacturing an organic light emitting diode according to the present invention.

6a to 6c are sequential views showing a process of forming a partition wall using roll printing.

<Description of the symbols for the main parts of the drawings>

110 substrate 120 first electrode

131: electron injection layer 133: electron transport layer

135 light emitting layer 137 hole transport layer

139: hole injection layer 140: second electrode

150: bulkhead 151: printing roll

The present invention relates to a method of manufacturing an organic light emitting device, and more particularly, by forming a barrier rib separating the light emitting layer by roll printing, thereby reducing defects that may occur when forming the barrier rib using photolithography.

As the 21st century is an information society, it is important to develop high-performance flat panel display devices for multimedia because it is necessary to easily obtain information from anywhere. In particular, technology development related to device development of semiconductors and display devices is becoming important in relation to communication and computers. Among them, an organic electroluminescent device is an element attracting attention as a color display device.

1 is a conceptual diagram illustrating a conventional organic EL device, and FIG. 2 is a band diagram of the organic EL device.

As shown in FIG. 1, the organic light emitting diode has a structure in which a light emitting material is inserted between a metal electrode having a high work function and a low metal electrode. The metal electrode having a high work function is used as an anode 7 for injecting holes into the light emitting material and the low metal electrode is used as a cathode 3 for injecting electrons into the light emitting material.

In order to emit the emitted light to the outside of the light emitting device, one electrode uses a transparent material having almost no light absorption in the light emitting wavelength region. Indium Tin Oxide (ITO) is most commonly used as the transparent electrode, and this metal is usually used as the anode 7 into which holes are injected. As the cathode 3, a metal having a low work function is generally used to facilitate the injection of electrons.

The principle of light emission of the organic light emitting device is as follows. When holes and electrons are injected into the organic light emitting layer 5 at the anode 7 and the cathode 3 having a high work function, excitons are generated in the organic light emitting layer 5, and the excitons emit and disappear. As a result, light corresponding to the energy difference between the low unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of the organic light emitting layer 5 shown in FIG. 2 is generated.

In the organic light emitting device operating on the above principle, the light emitting layer may be formed as a mono-layer, but may be formed as a multi-layer by laminating the organic conductive film, and holes are generally injected from the anode. A hole injection layer, a hole transport layer through which injected holes are transported to a light emitting layer, an electron injection layer through which electrons are injected from a cathode, an electron transport layer through which injected electrons are transported to a light emitting layer, and the transported electrons and holes meet excitons It consists of a light emitting layer.

In this case, an organic light emitting material emitting red, green, and blue light is formed for each pixel to form an image.

In order to form different organic light emitting materials in the light emitting layer, barrier ribs are formed between the pixels, and an organic light emitting material is formed in the pixel region formed of the barrier ribs.

3A to 3C illustrate a process of forming a barrier rib and forming an organic light emitting material in the barrier rib in the method of manufacturing an organic light emitting diode according to the related art.

Referring to the drawings, the first electrode 20 is formed as a cathode for each pixel on the insulating substrate 10, and the electron injection layer 31 and the electron transport layer 33 are formed on the first electrode 20. This is formed sequentially.

A partition is formed between the pixel and the pixel on the electron transport layer 33. To form the partition, first, a photoresist 50A is applied to the electron transport layer 33 as shown in FIG. 3A. Next, as shown in FIG. 3B, light is irradiated and exposed through a mask 80 having a transmissive region and a blocking region therebetween corresponding to the partition wall on which the photoresist 50A is to be formed. Thereafter, when the developing solution is added to the exposed photoresist 50A, the barrier rib 50 made of photoresist is formed between the pixel and the pixel as shown in FIG. 3C. Next, as shown in FIG. 3d, the organic light emitting layer 35 emitting red, green, and blue light is formed on the substrate 10 on which the barrier rib 50 is formed.

At this time, if the photoresist 50A is the positive type, the photoresist of the portion exposed to light is removed. If the photoresist 50A is the positive type, the photoresist of the portion not exposed to the light is removed. In the figure, a negative photoresist is shown, and a positive photoresist may be used.

However, in the method of forming a barrier rib by removing the photoresist using the light exposure method as described above, when the development is performed after the exposure process, the photoresist of the portion not exposed to light is removed, and the photoresist is removed. The upper surface exposed to the portion—for example, the electron transport layer—is damaged by the reaction with the developing solution.

As a result, the light emitting layer may not effectively function as an electron transport layer in the light emitting composition process with the light emitting layer, thereby greatly affecting the efficiency and lifetime of the organic light emitting device.

An object of the present invention for solving the above problems is to provide a high-quality organic electroluminescent device manufacturing method that forms and provides a partition without exposure and development using a photoresist.

According to an aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, including: preparing a substrate in which a plurality of pixel regions are defined; Forming a first electrode on the pixel region of the substrate; Forming barrier ribs on the substrate on which the first electrode is formed to separate pixel regions by using roll printing; Forming a light emitting layer on the first electrode between the barrier ribs; And forming a second electrode on the substrate on which the light emitting layer and the partition wall are formed.

Here, the forming of the partition wall using the roll printing may include preparing a printing roll coated with an organic insulating material on an outer circumferential surface thereof; Patterning the organic insulating material applied to the printing roll by applying the printing roll to the cliché; Transferring the patterned organic insulating material onto a substrate on which a first electrode is formed; And hardening the transferred organic insulating material to form a partition wall.

At this time, the step of forming the partition by curing the organic insulating material is characterized in that the curing by irradiating the organic insulating material with light such as ultraviolet rays, the organic insulating material is benzocyclobutene (BCB), polyacrylic series, poly It is characterized in that any one of the mid-based organic material, the partition wall may be formed higher than the height of the light emitting layer.

On the other hand, the step of forming the light emitting layer may be formed by printing or inkjet.

And forming an electron injection layer on the entire surface of the substrate on which the first electrode is formed between the forming of the first electrode and the forming the partition wall, and forming an electron transport layer on the electron injection layer. And forming a hole transport layer on the entire surface of the substrate on which the light emitting layer and the partition wall are formed between forming the light emitting layer and forming the second electrode, and forming a hole injection layer on the hole transport layer, respectively. It may further include.

In this case, the hole injection layer, the hole transport layer, the electron transport layer, the electron injection layer can be formed by a vacuum deposition method.

In addition, the first electrode may be formed of a metal having a work function smaller than that of the second electrode, and the second electrode may be formed of a transparent conductive material having a work function greater than that of the first electrode, and vice versa. .

Meanwhile, preparing a substrate in which a plurality of pixel regions are defined may include forming a gate line and a gate electrode on an insulating substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer and an ohmic contact layer on the gate insulating film; And forming a source electrode and a drain electrode on the ohmic contact layer, and forming a data line substantially crossing the gate electrode to define a pixel area, wherein the source electrode and the drain electrode are formed on the substrate. Forming a protective layer thereon and forming a contact hole exposing a portion of the drain electrode, and electrically connecting the first electrode to the drain electrode through the contact hole.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the formation of a film or layer on another film or layer includes not only when two films or layers are in contact with each other but also when another film or layer is present between the two films or layers.

In the present invention, the first electrode and the second electrode are the pixel electrode and the common electrode, respectively, and the cathode and the anode may be changed according to the material for forming the electrode. In particular, when the electrode is formed of a material having a relatively high work function, the electrode becomes an anode providing holes, and when the electrode is formed of a material having a relatively low work function, the electrode becomes a cathode providing electrons. In the present invention, a case in which the first electrode (ie, the pixel electrode) is formed of a metal having a low work function will be described. However, the present invention is not limited thereto, and the second electrode may be formed of a metal having a low work function.

4 is a cross-sectional view showing an organic light emitting device manufactured by the manufacturing method according to the present invention.

Referring to the drawings, a gate electrode 102 is formed on a substrate 110 made of an insulating material such as glass or quartz. The gate insulating film 105 is formed of an insulating material such as silicon nitride (SiN _x ) or silicon oxide (SiO ₂ ) on the gate electrode 102. The semiconductor layer 106 made of amorphous silicon and the n + amorphous silicon layer doped with n-type impurities are sequentially formed on the gate electrode 102. The n + amorphous silicon layer is separated on both sides of the gate electrode 102 to form an ohmic contact layer 107.

The source electrode 103 and the drain electrode 104 are formed on the ohmic contact layer 107 so as to be spaced apart from the gate electrode 102.

At this time, although not shown, gate lines and data lines are formed on the substrate 110 to cross the sides and define pixel regions. The gate electrode 102 is branched off the gate line and is formed, and the source electrode 103 is branched off the data line.

A passivation layer 108 is formed on an entire surface of the substrate 110 on which the source electrode 103 and the drain electrode 104 are formed, and a contact hole for exposing a part of the drain electrode 104 is formed in the passivation layer 108. have.

The first electrode 120 is formed on the passivation layer 108. The first electrode 120 is also referred to as a pixel electrode and is formed of a conductive material. The first electrode 120 is formed of a metal such as aluminum (Al) or chromium (Cr), which has a lower work function than the second electrode 140, which will be described later. In this case, the first electrode 120 serves as a cathode to supply electrons to the organic light emitting layer 135 to be formed later.

An electron injection layer (EIL) 131 is formed on the entire surface of the substrate 110 on which the first electrode 120 is formed, and an electron transport layer (ETL) 133 is formed on the electron injection layer 131. Laminated sequentially. The electron injection layer 131 and the electron transport layer 133 may be formed of a conductive organic material.

A partition wall 150 is formed on the electron transport layer 133 to surround a portion corresponding to the region of the first electrode 120. The partition wall 150 is formed around the pixel area by separating the first electrode 120. The partition wall 150 is formed of an organic material having heat resistance and solvent resistance, such as benzocyclobutene (BCB), polyacrylic series, and polyimide series.

An emission layer 135 is formed on the electron transport layer 133 not covered by the barrier wall 150. The light emitting layer 135 includes a red light emitting layer R emitting red, a green light emitting layer G emitting green, and a blue light emitting layer B emitting blue.

Various organic materials may be used for the emission layer 135, but a perylene-based polyfluorene derivative, a polyparaphenylene vinylene derivative, a polyphenylene derivative, a polyvinylcarbazole, a polythiophene derivative, or a polymer material thereof It can be used by doping with a pigment | dye, a laumine pigment | dye, rubrene, a perylene, 9, 10- diphenyl anthracene, tetraphenyl butadiene, nile, coumarin 6, quinacridone, etc.

A hole transport layer (HTL) 137 is formed on the substrate 110 including the light emitting layer 135 and the partition wall 150, and a hole injection layer (HIL) 139 is formed on the hole transport layer 137. Is laminated. The hole transport layer 137 and the hole injection layer 139 may be formed of a conductive organic material.

The second electrode 140 for injecting holes into the hole injection layer 139 is formed on the hole injection layer. The second electrode 140 is also called a common electrode and is formed of a conductive material. The second electrode 140 is formed of indium tin oxide (ITO) or indium zinc oxide (IZO), which are transparent conductive materials having a higher work function than the first electrode 120. In this case, the second electrode 140 serves as an anode to provide holes to the emission layer 135.

The organic electroluminescent device described above is a top emission in which the first electrode 120 is an opaque metal electrode, and the second electrode 140 is transparent, such as ITO, in which an image is formed in the upper direction of the second electrode 140. top emission). However, the present invention is not limited thereto, and may be applied to a bottom emission method.

Hereinafter, a method of manufacturing an organic light emitting device according to the present invention will be described with reference to the drawings.

5A through 5B are cross-sectional views sequentially illustrating a method of manufacturing an organic light emitting diode according to the present invention. In this drawing, a thin film transistor is formed under the first electrode 120 to apply a voltage to the first electrode 120 to show the lamination process of the first electrode 120, the organic layer, and the second electrode 140. Are omitted.

First, as shown in FIG. 5A, a substrate 110 having a plurality of pixel regions defined therein is prepared to form a first electrode 120.

In order to prepare the substrate 110 in which a plurality of pixel regions are defined, a process of forming a thin film transistor for applying a voltage to the first electrode 120 on the insulating substrate 110 may be included. Referring to FIG. 4, to form a thin film transistor, a gate line and a gate electrode 102 are formed on the insulating substrate 110, and a gate insulating layer 105 is formed on the gate electrode 102. The semiconductor layer 106 and the ohmic contact layer 107 are formed on the gate insulating layer 105, and the source electrode 103 and the drain electrode are formed on the ohmic contact layer 107 with the gate electrode 102 spaced apart from each other. Form 104. In this case, a data line defining a plurality of pixel regions may be formed to cross the gate line.

Next, a passivation layer 108 is formed on the substrate 110 including the source electrode 103, the drain electrode 104, and the like, and a contact hole exposing a portion of the drain electrode 104 is formed. In addition, a first electrode 120 is formed in the pixel region of the substrate 110 on which the thin film transistor is formed by a metal having a low work function such as aluminum or chromium and electrically connected to the thin film transistor through the contact hole.

Next, as shown in FIG. 5B, the electron injection layer 131 and the electron transport layer 133 are sequentially formed on the entire surface of the substrate 110 on which the first electrode 120 is formed. The electron injection layer 131 and the electron transport layer 133 may be formed of a conductive organic material and may be formed by a vacuum deposition method.

Vacuum deposition is a method of forming a thin film on a substrate by heating and evaporating the raw material of the film to be formed in a vacuum chamber. More specifically, the chamber containing the metal or quartz substrate is evacuated to high vacuum, and then a target and a substrate to be evaporated are inserted into the chamber. The raw material is then heated using a resistive heating or electron beam device to distill the deposited material. At this time, the thin film is formed by condensation of the distilled deposition material on the surface of the cold substrate.

Next, as shown in FIG. 5C, a partition wall 150 for dividing the pixel area is formed on the substrate 110 on which the first electrode 120 is formed. The partition wall 150 is formed at an edge portion of the pixel area and serves to distinguish the light emitting layer 135 to be formed later.

According to an embodiment of the present invention, the partition wall 150 is formed using roll printing, and FIGS. 6A to 6C are sequential views showing a process of forming the partition wall 150 using roll printing. When the barrier rib 150 is formed by using roll printing, defects occurring during the process of exposing and developing the photoresist using conventional photolithography may be prevented. In particular, the electron transport layer 133 may be prevented from being damaged by reacting with the developer.

Referring to the drawings, the organic insulating material 150A to form the partition wall 150 is coated on the outer circumferential surface of the printing roll 151. In the process of applying the organic insulating material 150A, the supply container 154 is filled with the organic insulating material 150A to be printed on the outer circumferential surface of the printing roll 151, and then the supply container 154 filled with the organic insulating material 150A. ) To the printing roll 151, it may be made by the process of applying the organic insulating material (150A) to the outer peripheral surface by rotating the printing roll 151.

Next, as shown in FIG. 6B, first, a cliché 155 having a groove corresponding to a pattern to be formed is prepared, and the printing roll 151 is contacted and rotated on the cliché 155 for printing. The organic insulating material 150A pattern of the roll 151, that is, the pattern of the partition wall 150 is formed.

Thereafter, as shown in FIG. 6C, the printing roll 151 coated with the organic insulating material 150A having the pattern is contacted and rotated on the substrate 110 to form the partition 150 to thereby form the organic insulating material 150A pattern. It is transferred to the substrate 110.

Next, the barrier rib 150 is formed by irradiating the organic insulating material 150 transferred to the substrate 110 with light such as ultraviolet rays and photocuring the light. At this time, the partition wall 150 is preferably formed higher than the height of the light emitting layer 135 to be formed later.

After the partition wall 150 is formed, a light emitting layer 135 is formed on the first electrode 120 between the partition wall 150 and the partition wall 150 as shown in FIG. 5D. The emission layer 135 may be formed by various methods using various organic materials. For example, it can be formed by the printing method, it may be formed by dropping the organic light emitting material droplets by the inkjet method. In the drawing, the light emitting layer 135 is formed by the inkjet method using the dispenser 170, but this is only an example and is not limited to the method of forming the light emitting layer 135. In this case, the light emitting layer 135 is formed of a red light emitting layer R emitting red, a green light emitting layer G emitting green, and a blue light emitting layer B emitting blue.

After forming the light emitting layer 135, as shown in FIG. 5E, the hole transport layer 137 and the hole injection layer 139 are sequentially formed on the substrate 110 on which the light emitting layer 135 and the partition wall 150 are formed. . The hole injection layer 139 and the hole transport layer 137 are formed of a conductive organic material and may be formed by a vacuum deposition method.

Next, as shown in FIG. 5F, the second electrode 140 is formed of a transparent conductive material having a high work function such as ITO. The second electrode 140 serves as an anode and serves to supply holes to the hole injection layer 139. In this case, the second electrode 140 may be formed only in the pixel area as needed, and may be patterned in various shapes.

As described above, the organic light emitting diode as shown in FIG. 4 may be manufactured.

The detailed description of the invention should be construed as illustrative of preferred embodiments rather than as limiting the scope of the invention. For example, the present invention has been described with respect to an organic light emitting device having a top emission method, but is not limited thereto and may be applied to an organic light emitting device having a bottom emission method.

In addition, the present invention has been described with respect to the organic light emitting device in which a plurality of organic layers are formed between the first electrode and the second electrode, but various applications such as a single layer or a form in which any organic layer is omitted are applicable. That is, a barrier rib is formed on the first electrode and a light emitting layer formed of a single layer is formed, an electron transport layer is formed on the first electrode, a barrier rib is formed, and then a light emitting layer is formed, or only a hole injection layer is formed after the light emitting layer. It is possible to apply by varying the organic layer in various ways.

Accordingly, the invention is not to be determined by the embodiments described, but should be determined by equivalents to the claims and the appended claims.

As described above, according to the present invention, by forming a partition wall by using roll printing, a defect that may occur when the partition wall is formed can be reduced, thereby providing a high quality organic light emitting device.

Claims (19)

Preparing a substrate in which a plurality of pixel regions are defined; Forming a first electrode on the pixel region of the substrate; Sequentially forming an electron injection layer and an electron transport layer on the entire surface of the substrate on which the first electrode is formed; Forming barrier ribs on the substrate on which the electron transport layer is formed to separate pixel regions by using roll printing; Forming a light emitting layer by an inkjet method using a dispenser on the electron transport layer corresponding to the first electrode between the partition walls; Sequentially forming a hole transport layer and a hole injection layer on the entire surface of the substrate including the light emitting layer and the partition wall; And And forming a second electrode on the hole injection layer. The barrier rib is formed higher than the height of the light emitting layer, characterized in that the organic light emitting device manufacturing method. The method of claim 1, Forming a partition wall using the roll printing, Preparing a printing roll coated with an organic insulating material on an outer circumferential surface thereof; Patterning the organic insulating material applied to the printing roll by applying the printing roll to the cliché; Transferring the patterned organic insulating material onto a substrate on which a first electrode is formed; And And hardening the transferred organic insulating material to form a partition on the substrate on which the electron transport layer is formed. 3. The method of claim 2, Hardening the organic insulating material to form a partition on the substrate on which the electron transport layer is formed, wherein the organic insulating material is irradiated with light to cure the organic insulating material. The method of claim 3, The light is a manufacturing method, characterized in that the ultraviolet. 3. The method of claim 2, The organic insulating material is a benzocyclobutene (benzocyclobutene), polyacryl-based, polyimide-based manufacturing method characterized in that any one of the organic material. delete delete delete delete The method of claim 1, The electron injection layer, the electron transport layer, the hole injection layer, the hole transport layer is a manufacturing method, characterized in that formed by vacuum deposition method. delete delete delete delete delete delete delete The method of claim 1, Preparing a substrate in which a plurality of pixel regions are defined, Forming a gate line and a gate electrode on the insulating substrate; Forming a gate insulating film on the gate electrode; Forming a semiconductor layer and an ohmic contact layer on the gate insulating film; And And forming a source electrode and a drain electrode on the ohmic contact layer and forming a data line substantially crossing the gate electrode to define a pixel region. 19. The method of claim 18, Between preparing a substrate in which the plurality of pixel regions are defined and forming a first electrode on the pixel region of the substrate, a protective film is formed on a substrate on which the source electrode and the drain electrode are formed, and a part of the drain electrode is formed. Forming a contact hole exposing the contact hole; The forming of the first electrode on the pixel area of the substrate may include forming the first electrode to electrically connect with the drain electrode through the contact hole.

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