KR20020083717A - Organic electroluminescence device and method for fabricating thereof - Google Patents

Abstract

PURPOSE: An organic electroluminescence device and method for manufacturing the same is provided to prevent damage of a pixel by suppressing abnormal electric field generated from an edge of an anode electrode, while preventing performance deterioration of a display. CONSTITUTION: An organic electroluminescence device comprises an anode electrode(510) formed into a matrix shape at a transparent substrate(600); a power supply unit for selectively applying power having a predetermined size corresponding to the image data to be applied to the anode electrode; an insulation film wrapping around an end of the anode electrode; organic luminescence layers(530,540) formed at the top surface of the anode electrode and the insulation film; and a cathode electrode(570) formed at the top surfaces of organic luminescence layers, and which permits power having a predetermined size to be selectively applied.

Description

Organic electroluminescent device and its manufacturing method {ORGANIC ELECTROLUMINESCENCE DEVICE AND METHOD FOR FABRICATING THEREOF}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an organic electroluminescent device and a method of manufacturing the same, and more particularly to the formation of an abnormal electric field intensively formed at an edge of an anode electrode injecting holes into an organic light emitting material. The organic electroluminescent device and its manufacture, which are suppressed to prevent the pixel defects and increase the lifespan, and to prevent the degradation of the display performance due to the separation of the organic light emitting material and the mixing with other organic light emitting material generated in the process of realizing the same. It is about a method.

In recent years, the development and dissemination of the display device, which is a kind of "interface device" that converts the data in the form of an electrical signal generated by the information processing device, which is being rapidly developed, has been rapidly developed with the technology development of the information processing device. It's going on.

Such display apparatuses are implemented in various forms according to the purpose of use, and are currently being installed in almost all information processing apparatuses.

In recent years, organic electroluminescent devices have been dramatically reduced in volume and weight by using organic electroluminescence materials that emit light by an electric field vehicle, resulting in the need for a full color, light supply means such as “backlight”. Has been developed.

In this organic electroluminescent device, light is generated from the organic electroluminescent material by applying a forward current to the two conductive electrodes while one of the organic electroluminescent materials is formed between two transparent conductive electrodes. It uses the principle of emitting to the outside through the transparent conductive electrode.

To implement this, specifically, a transparent conductive electrode (hereinafter referred to as an anode electrode) is formed in a matrix on a transparent substrate. Subsequently, an organic light emitting material generating a red wavelength, a green wavelength, and a blue wavelength is patterned on an upper surface of each transparent conductive electrode to form an organic emission layer. Subsequently, a metal material is deposited to a predetermined thickness over the entire surface of the transparent substrate so that the organic light emitting layer is included, thereby forming another conductive electrode (hereinafter referred to as a cathode electrode).

At this time, one anode electrode-one organic light emitting layer-one cathode electrode forms one pixel, and the plurality of pixels are arranged in a matrix to constitute an organic electroluminescent device.

As such, the pixels constituting the organic electroluminescent device generate light having a predetermined luminance from the organic light emitting layer formed between the anode electrode and the cathode electrode of each pixel by the line driving method, and the light passes through the anode electrode and the transparent substrate. The predetermined image is displayed while being released to the outside.

However, in the organic electroluminescent device composed of a plurality of pixels arranged in a matrix form, an abnormal electric field is frequently formed at the edge portion of the anode electrode, causing problems such as pixel breakage, display performance deterioration, and shortened lifetime. Is generated.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to prevent abnormal formation of an electric field at an anode electrode of an organic electroluminescent device, thereby preventing pixel breakage, display performance degradation, and lifespan shortening. It is to avoid.

Another object of the present invention is to overcome the poor formation of the organic light emitting layer generated in the process of preventing the abnormal electric field is formed in the anode of the organic electroluminescent device.

1 is a block diagram illustrating an equivalent circuit of an organic electroluminescent device.

2 is a flowchart for explaining <First Embodiment> according to the present invention.

3 is an enlarged view of a portion B of FIG. 2.

4 is a process diagram illustrating a thin film transistor and an anode electrode formed on a transparent substrate according to an embodiment of the present invention.

FIG. 5 is a process diagram illustrating that an organic insulating film is coated on an upper surface of a transparent substrate according to one embodiment of the present invention.

6 is a process diagram illustrating that an organic insulating layer is exposed by a pattern mask according to an embodiment of the present invention.

7 is a flowchart illustrating a double step formed in an organic insulating layer according to an exemplary embodiment of the present invention.

FIG. 8 is an enlarged view of portion C of FIG. 7.

9 is a flowchart illustrating a red organic light emitting layer formed on an upper surface of an anode according to an embodiment of the present invention.

FIG. 10 is a process diagram illustrating a green organic light emitting layer formed on an upper surface of an anode according to an embodiment of the present invention.

FIG. 11 is a flowchart illustrating a blue organic light emitting layer formed on an upper surface of an anode according to an embodiment of the present invention.

FIG. 12 is an enlarged view of a portion D of FIG. 11.

13 to 17 are process diagrams for implementing the <second embodiment> of the present invention.

The organic electroluminescent device manufacturing method for achieving the object of the present invention is formed in a matrix form on a transparent substrate, the anode electrode to which a predetermined size of power corresponding to the image data is selectively applied by the power supply means; Forming an insulating film surrounding an edge of the anode electrode, forming an organic light emitting layer on an upper surface of the anode except for the edge of the anode electrode, and a cathode to which a power having a predetermined size is selectively applied to the upper surface of the organic light emitting layers Forming an electrode.

In addition, the organic electroluminescent device for realizing the object of the present invention is an anode electrode formed in a matrix form on a transparent substrate, power supply means for selectively applying a power of a predetermined size corresponding to the image data to be applied to the anode electrode And an insulating film formed to surround the edge of the anode electrode, an organic light emitting layer formed on an upper surface of the anode electrode and a part of the insulating film, and a cathode electrode formed to selectively apply a power having a predetermined size to the upper surface of the organic light emitting layers.

Hereinafter, an organic electroluminescent device and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in the equivalent circuit of FIG. 1, the organic electroluminescent device 900 is composed of a plurality of organic electroluminescent elements. In one embodiment, three organic electroluminescent devices 901, 902, 903; 904 constitute one organic electroluminescent device 900.

The organic electroluminescent device 904 is composed of two thin film transistors 100 and 200, one image holding capacitance 300, driving signal applying lines 410, 420, 430 and a pixel 500 for driving the thin film transistors 100 and 200. do.

Specifically, the two thin film transistors 100 and 200 are the switching TFT 100 and the driving TFT 200.

They have gate electrodes 110 and 210, source electrodes 120 and 220, and drain electrodes 130 and 230 in common.

Meanwhile, the driving signal applying lines 410, 420, and 430 are again parallel to each other and are insulated so as not to be shorted with the conductive gate lines 410 and the gate lines 410 spaced apart from each other, and the conductive data lines 420 are perpendicular to the gate lines 410. And a bias line 430 formed between an arbitrary data line 420 and an adjacent data line 420.

The switching TFT 100 described above is formed in the vicinity of the gate line 410 and the data line 420 having such a configuration.

At this time, power is supplied from the gate line 410 to the gate electrode 110 of the switching TFT 100, and power is supplied from the adjacent data line 420 to the source electrode 120.

When power is supplied to the gate electrode 110 while the power is supplied to the source electrode 120 as described above, the power applied to the source electrode 120 is amplified by the drain electrode 130 of the switching TFT 100. It is output through the channel layer (not shown) in the state.

At this time, the power output from the drain electrode 130 of the switching TFT 100 is supplied differently through two paths.

Power supplied through any one path is supplied to one electrode 310 of the image retention capacitance 300 as shown in FIG. 1.

At this time, since the other electrode 320 of the image retention capacitance is always supplied from the bias line 430, the image retention capacitance 300 is charged as soon as the power is output from the drain electrode 130 of the switching TFT 100. It begins to be.

The electric charge charged in the image holding capacitance 300 is realized for a predetermined time, for example, one frame from the moment when the power applied from the gate line 410 of the switching TFT 100 is turned off. During this time, it is supplied to the gate electrode 210 of the driver TFT 200.

On the other hand, the power supplied through the other path is supplied to the gate electrode 210 of the driving TFT 200.

At this time, since the source electrode 220 of the driving TFT 200 is always supplied with power from the bias line 430, the bias line 430 at the moment when power is supplied to the gate electrode 210 of the driving TFT 200. ) Is output to the drain electrode 230 of the driving TFT 200.

Power output to the drain electrode 230 of the driving TFT 200 is applied to the pixel 500.

Each pixel 500 formed in each organic electroluminescent device 904 is formed on an anode electrode made of a transparent and conductive indium tin oxide material, an organic light emitting layer formed on the anode electrode, and an upper surface of the organic light emitting layer. Consisting of a cathode electrode.

At this time, since a power having a predetermined size is always supplied to the cathode, the electric power output from the drain electrode 230 of the driving TFT 200 is applied to the anode at any moment, so that an electric field is formed between the anode and the cathode. The change occurs, whereby light having a predetermined wavelength is generated in the organic light emitting layer, and light is emitted to the outside through the anode electrode, thereby performing display.

An abnormal electric field is easily generated in each of the anode electrodes constituting the pixel 500 of the organic electroluminescent element 904 operated by the driving method, thereby reducing pixel defects and lifespan.

In order to prevent this, in the present invention, as shown in FIG. 2, the edge portion of the anode electrode 510 is covered with the insulating layer 590 to suppress abnormal electric field generation occurring at the edge portion of the anode electrode 510. do. In this case, a photoresist thin film may be used as the insulating film 590.

After covering the edge portion of the anode electrode 510 with the insulating film 590, one of the red organic light emitting layer 520, the green organic light emitting layer 530, and the blue organic light emitting layer 540 is deposited on the top surface of the anode electrode 510. Process is performed.

In this case, the red organic light emitting layer 520, the green organic light emitting layer 530, and the blue organic light emitting layer 540 have shadows in which fine openings 555 are formed, as shown in FIG. 2, in order to deposit organic light emitting materials only at desired positions. A mask (550) is used.

The size of the opening 555 of the shadow mask 550 is slightly larger than the area of the organic light emitting layer actually required in consideration of misalignment with the anode electrode 510.

As such, when the size of the opening 555 of the shadow mask 550 is slightly larger than that of the anode electrode 510, the organic electroluminescent layers 520, 530, and 540 inevitably have a sidewall of the insulating film 590 as shown in FIG. 2. It is raised to a part of the upper surface of the (590).

As such, when the organic EL layer 520, 530, 540 is raised to a part of the upper surface of the insulating layer 590, the shadow mask 550 and the organic EL layer 520, 530, 540 are in contact with each other as shown in FIG. 3. As shown in FIG. 2, the organic light emitting layers 520, 530, and 540 may be buried under the shadow mask 550.

As such, when the organic electroluminescent layers 520, 530, and 540 are buried on the bottom surface of the shadow mask 550, for example, the green organic organic light emitting material is deposited on the shadow mask 550 while the shadow mask 550 is shifted, and thus the green organic light emitting layer is positioned adjacent to the organic mask. A mixture of the light emitting material and the red organic light emitting material on the shadow mask may result in the green organic light emitting material not generating the color of the designated green wavelength.

As such, the problem caused by the mutual interference between the shadow mask 550 and the organic electroluminescent layers 520, 530, and 540 is overcome by two embodiments of the present invention.

<First Embodiment>

4 is a cross-sectional view of the transparent substrate 600 formed with the switching TFT 100, the driving TFT 200, and the anode electrode 510 of the pixel 500 shown in FIG. to be.

Subsequently, as shown in FIG. 5, a photoresist thin film 700 is formed on a top surface of the transparent substrate 600 to a predetermined thickness by a spin coater or the like over the entire surface.

Thereafter, the photoresist thin film 700 is subjected to a pre-baking process, and is patterned so that the upper surface has a double step while surrounding the edge of the anode electrode 510.

As such, in order to pattern the photoresist thin film 700 to have a double step while covering the edge of the anode electrode 510, a pattern mask having a partially different light transmittance should be used when patterning the photoresist thin film 700.

More specifically, referring to FIG. 6, the portion 810 of the pattern mask 800 to which the anode electrode 510 is exposed to the outside reaches a 100% photoresist thin film 700 having a predetermined wavelength length. Be sure to

On the other hand, the portion of the pattern mask 700 in which the photoresist thin film 700 should not be removed at all, for example, the portion 820 covering the edge of the anode electrode 510 does not reach 100% of light having a predetermined wavelength length. Do not

On the other hand, the portion 830 of the photoresist thin film 700 to form the double step has a special light so as to be transmissive to allow partial exposure to proceed.

Thereafter, when the development process is performed, the organic insulating layer 710 is formed to surround the edge of the anode electrode 510 as shown in FIG. 7.

Of course, as shown in detail in FIG. 8, the organic insulating layer 710 is provided with double steps 715, 718; 720 having a height difference H.

Subsequently, after the baking process is performed once again with the double step 720 formed on the organic insulating layer 710, the red organic layer is disposed in the state where the shadow mask 550 is positioned on the designated anode electrode 510 as shown in FIG. 9. A light emitting material is deposited on the top surface of the anode 510 through the opening 555 of the shadow mask 550 to form a red organic light emitting layer 520.

In this case, the deposited red organic light emitting layer 520 may have an upper surface of the anode electrode 510, a side surface of the organic insulating layer 710, and a double stepped portion formed by the size of the opening 555 of the shadow mask 550. Leads to the top of).

Thereafter, as shown in FIG. 10, the opening 555 of the shadow mask 550 is shifted to be transferred to the anode electrode 510 adjacent to the red organic light emitting layer 520, so that the alignment is accurately performed, and the green organic light emitting material is shadowed. The green organic emission layer 530 is formed by depositing on the upper surface of the anode 510 through the opening 555 of the mask 550.

Thereafter, as shown in FIG. 11, the opening 555 of the shadow mask 550 is shifted again to be accurately aligned in a state where the opening 555 is transferred to the anode electrode 510 adjacent to the green organic light emitting layer 540. As the opening 555 of the shadow mask 550, a blue organic light emitting material is deposited on the top surface of the anode 510 to form a blue organic light emitting layer 540.

In this case, the red, green, and blue organic light emitting layers 520, 530, and 540 formed on the organic insulating layer 710 having the double step 720 are formed on the lower step 718 of the double step 720 as shown in FIG. 12. The bottom surface of the mask 550 has a distance of h. As a result, the bottom surface of the shadow mask 550 is not contaminated by the organic light emitting material, so that the organic light emitting layers 520, 530, 540 are damaged, and different organic light emitting materials are not mixed by the shadow mask 550.

Second Embodiment

13 is shown below another embodiment of the present invention.

In the above-described <first embodiment>, since the photoresist thin film is used as the organic insulating film 710, in order to maintain the shape of the photoresist thin film, the organic insulating film 710 should not be exposed to light and oxygen.

At this time, the organic light emitting material is also deteriorated by oxygen, the metal can (not shown) is covered in order to prevent degradation of the organic light emitting material, and the change of the shape of the photoresist thin film is prevented because the compound that blocks the absorbent and oxygen is injected. The shape change of the photoresist thin film may occur due to various causes which have not yet been identified.

On the other hand, in <Second Embodiment> described below with reference to FIG. 13, an organic insulating film has an organic material having a more stable structure by forming an insulating film and forming a double step in the insulating film with an insulating material having stable properties by light, oxygen, or other materials. An insulating film is disclosed.

In order to achieve this, as shown in FIG. 13, any insulating material except photoresist is formed on the upper surface of the transparent substrate 600 to a predetermined thickness, and the chemical vapor deposition of the insulating film 740 is performed. The photoresist thin film 750 is formed on the upper surface of the insulating film 740 with a predetermined thickness in a state formed by a semiconductor manufacturing process such as the like.

Thereafter, the photoresist thin film is exposed to surround the edge portion of the anode electrode 510 through a pattern mask (not shown) to allow the photoresist thin film to pattern the shape of FIG. 13. The patterned photoresist thin film is denoted by reference numeral 750.

Subsequently, as shown in FIG. 14, the insulating film 740 is patterned by an etchant or plasma etching facility using the patterned photoresist thin film 750 as a mask. Hereinafter, reference numeral 745 will be given to the patterned insulating layer 740.

Thus, as shown in FIG. 14, the edge of the anode electrode 510 is covered by the patterned insulating layer 745, and the center portion except for the edge of the anode electrode 510 is exposed to the outside.

Thereafter, a thin photoresist thin film is formed on the upper surface of the transparent substrate 600 again.

Subsequently, the photoresist thin film is patterned by exposure. In this case, as shown in FIG. 15, a portion where the patterning is performed by exposure is a portion where the double step is to be formed in the insulating layer 745.

Thereafter, the patterned photoresist thin film 765 is developed such that only a portion of the insulating layer 745 on which the double step is to be formed is exposed to the outside, as shown in FIG. 15.

Hereinafter, reference numeral 745a will be given to the portion of the insulating film exposed to the outside.

Subsequently, partial etching is performed on the exposed portion of the insulating layer 745a by an etchant or plasma to form a double stepped 720 in the insulating layer 745 as shown in FIG. 16.

Subsequently, a red organic light emitting layer 520, a green organic light emitting layer 530, and a blue organic light emitting layer 540 are formed on the top surface of the anode electrode 510 by performing the same process as illustrated in FIGS. 9 to 11. ) Are all formed.

In this case, the red organic light emitting layer 520, the green organic light emitting layer 530, and the blue organic light emitting layer 540 may be formed without contacting the shadow mask 550 by the double step 720 at all.

Thereafter, as illustrated in FIG. 17, a metal cathode electrode 570 is formed over the entire surface of the transparent substrate 600.

When the display is performed by the organic electroluminescent device manufactured by such a method as follows.

First, when a predetermined power is applied to all the data lines 420, when a voltage higher than the threshold voltage of the switching TFT 100 is applied to the gate line 410, the power applied to the data line 420 is switched. It is applied to the drain electrode 130 through the channel layer of the TFT 100.

Thereafter, the power applied to the drain electrode 130 charges the image holding capacitance 300 in a parallel manner and simultaneously applies a voltage higher than the threshold voltage to the gate electrode 210 of the driving TFT 200.

At this time, when the power supply is interrupted to the drain electrode 230 of the switching TFT 200 because the power supply higher than the threshold voltage is applied to the gate line 210 only for a very short time, the charge stored in the image holding capacitance 300 is reduced. Is discharged.

As a result, the turn-on voltage is continuously applied to the gate electrode 210 of the driving TFT 200 by the time required for the image holding capacitance 300 to be discharged, so that the anode of the pixel 500 is moved from the bias line 430. A predetermined current is continuously supplied to the electrode 510.

As a result, as the forward current is supplied between the anode electrode 510 and the cathode electrode 570, light having red, green, and blue wavelengths is generated in the organic electroluminescent layers 520, 530, and 540, respectively, and the generated light is the anode electrode 510. ) And enters the user's eye after passing through the transparent substrate 600.

As described in detail above, the edge of the anode electrode is covered by an insulating film having a double step, and the center part except the edge of the anode is opened so that the bottom of the open part and the double step of the anode electrode are opened. By allowing the organic insulating film to be formed up to the portion, abnormal electric field formation occurring at the edge of the anode electrode is suppressed, thereby preventing pixel breakage and shortening of life.

In addition, it is possible to prevent some damage of the organic light emitting layer generated in the process of covering the edge of the anode electrode and to prevent display performance degradation caused by mixing of the organic light emitting layer that is not desired.

Claims (11)

An anode formed in a matrix on a transparent substrate; Power supply means for selectively applying power of a predetermined size corresponding to the image data to be applied to the anode electrode; An insulating film formed to surround an edge of the anode electrode; An organic light emitting layer formed on an upper surface of the anode electrode and a part of the insulating film; And And a cathode electrode formed to selectively apply a power having a predetermined size to the top surfaces of the organic light emitting layers. The organic electroluminescent device of claim 1, wherein the insulating film is an organic insulating film and is a photoresist material. The organic electroluminescent device according to claim 1, wherein an upper end of the insulating film has a height difference, and an organic light emitting layer is formed to a portion of the insulating film having a lower height. Forming an anode electrode formed on the transparent substrate in the form of a matrix, to which power of a predetermined size corresponding to the image data is selectively applied by the power supply means; Forming an insulating film surrounding an edge of the anode electrode; Forming organic light emitting layers on an upper surface of the anode except for the edge of the anode; And Forming a cathode electrode to which a power having a predetermined size is selectively applied on the upper surfaces of the organic light emitting layers. The method of claim 4, wherein forming the insulating film Forming an insulating material over the entire surface of the transparent substrate in a predetermined thickness; And patterning the insulating material such that an edge of the anode electrode is wrapped and a central portion except the edge of the anode electrode is opened. 6. The method of claim 5, wherein the insulating material is an organic insulating material that reacts with light and is a photoresist material. The method of claim 4, wherein forming the insulating film Forming an insulating material over the entire surface of the transparent substrate in a predetermined thickness; And Patterning the insulating material such that an edge of the anode electrode is wrapped, a central portion except the edge of the anode electrode is opened, and a portion of the edge electrode surrounding the edge of the anode has a height difference. . The method of manufacturing an organic electroluminescent device according to claim 7, wherein the organic light emitting layer is formed up to a portion of the upper surface of the insulating film having a lower height. 8. The method of claim 7, wherein the insulating material is a photoresist material that reacts with light. The organic electroluminescence device of claim 9, wherein a height difference at a portion surrounding the edge of the anode electrode is formed by a double step, and the double step is formed by controlling an exposure amount in a pattern mask required for patterning the organic insulating material. Method of manufacturing the device. The method of claim 4, wherein forming the insulating film Forming an insulating material over the entire surface of the transparent substrate in a predetermined thickness; Forming a photoresist thin film on an upper surface of the insulating material; Patterning the photoresist thin film so that the portion of the photoresist thin film corresponding to the edge of the anode electrode is not exposed, and the remaining portion of the photoresist thin film except for the edge of the anode electrode is exposed and removed; Patterning the insulating material exposed to the outside via the patterned photoresist thin film; Forming a photoresist thin film on the transparent substrate; Patterning the photoresist thin film to expose edges of the insulating material remaining after the patterning; And Patterning the insulating material exposed to the outside to generate a height difference.