KR20070102063A - Organic electro-luminescence display device and fabricating method thereof - Google Patents

Abstract

An organic electro luminescence display device and a method for manufacturing the same are provided to prevent an oxidation of a cathode electrode by forming a conductive buffer layer on the cathode electrode and by exposing the cathode electrode to air in a process. An organic electro luminescence display device includes a substrate(122), a cathode electrode(112), an organic light emitting layer(110), a conductive buffer layer(115), an anode electrode(104), and an insulation layer(106). The cathode electrode(112) is formed on an electro luminescence cell region, which is defined by a cross of a data line and a gate line, on the substrate(122). The organic light emitting layer(110) is formed on the cathode electrode(112). The conductive buffer layer(115) is formed between the cathode electrode(112) and the organic light emitting layer(110). The anode electrode(104) is formed on the organic light emitting layer(110).

Description

Organic electroluminescent display device and manufacturing method therefor {ORGANIC ELECTRO-LUMINESCENCE DISPLAY DEVICE AND FABRICATING METHOD THEREOF}

1 is an equivalent circuit diagram of a conventional organic light emitting display device.

FIG. 2 is a cross-sectional view illustrating a partial region of the organic light emitting display device illustrated in FIG. 1.

3 is a view for explaining a light emission principle of an organic light emitting display device.

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

5A through 5E are cross-sectional views illustrating a method of manufacturing an organic light emitting display device according to a first embodiment of the present invention.

6 is a cross-sectional view of an organic light emitting display device according to a second exemplary embodiment of the present invention.

7A to 7D are cross-sectional views illustrating a method of manufacturing an organic light emitting display device according to a second exemplary embodiment of the present invention.

 <Brief description of symbols for the main parts of the drawings>

4, 104, 204: anode electrode 6, 106, 206: insulating film

10, 110, 210: organic light emitting layer 12, 112, 212: cathode electrode

22, 122, 222: substrate 24, 124: gate electrode

26, 126: source electrode 28, 128: drain electrode

30, 130: protective film 34, 134: drain contact hole

36, 136: gate insulating film 38, 138: active layer

40, 140: ohmic contact layer 115, 215: conductive buffer film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, to an organic light emitting display device and a method of manufacturing the same, which can prevent the oxidation of a cathode electrode to improve performance and extend its life.

Recently, there is a growing interest in flat panel display devices capable of reducing the large weight and volume of cathode ray tubes. Such flat panel displays include liquid crystal displays, plasma display panels, field emission displays, and electro-luminescence (EL) displays. have.

Among them, the EL display device is classified into an inorganic EL display device and an organic EL display device according to the material of the light emitting layer. The EL display device is a self-luminous device that emits light by itself, and has a fast response speed and high light emission efficiency, luminance, and viewing angle. In comparison with the organic EL display device, the inorganic EL display device consumes more power and cannot obtain high luminance, and cannot emit various colors of R (Red), G (Green), and B (Blue). On the other hand, the organic EL display device is driven at a low voltage of several tens of volts, has a high response speed, can obtain high luminance, and can emit various colors of R, G, and B, which is suitable for next-generation flat panel display devices.

As shown in FIG. 1, the organic EL display device includes subpixels 60 arranged in regions defined by intersections of the gate line GL and the data line DL. When the gate pulse is supplied to the gate line GL, the sub pixel 60 receives a data signal from the data line DL and emits light with light corresponding to the data signal to display an image.

To this end, the sub-pixel 60 is connected to the EL cell OLED, the gate line GL, the data line DL, and the base voltage source GND, in which the anode electrode is connected to the driving voltage source VDD, and the EL cell OLED. And a cell driver 62 connected to the cathode electrode. The cell driver 62 includes a switching thin film transistor (“TFT”) T1, a driving TFT (T2), and a capacitor (C).

The switching TFT T1 is turned on when the gate pulse is supplied to the gate line GL, and supplies the data signal supplied to the data line DL to the node N. The data signal supplied to the node N is charged to the capacitor C and supplied to the gate electrode of the driving TFT T2. The driving TFT T2 adjusts the amount of light emission of the EL cell OLED by controlling the amount of current I supplied from the driving voltage source VDD to the EL cell OLED in response to the data signal supplied to the gate electrode. Since the data signal charged in the capacitor C is discharged even when the switching TFT T1 is turned off, the driving TFT T2 is driven until the data signal of the next frame is supplied. The light emission of the EL cell OLED is maintained by supplying the current I from VDD to the EL cell OLED.

FIG. 2 is a cross-sectional view illustrating a portion of the subpixel illustrated in FIG. 1 in detail.

Referring to Fig. 2, a conventional organic EL display element includes a switching TFT (T1, see Fig. 1), a driving TFT (T2) having a gate electrode 24 connected to a drain electrode of the switching TFT, and a driving TFT. An EL cell (OLED) to which the cathode electrode 12 is connected to the drain electrode 28 of the TFT (T2) is provided.

The switching TFT is connected to a gate electrode connected to the gate line GL (see FIG. 1), a source electrode connected to the data line DL (see FIG. 1), and connected to the gate electrode 24 of the driving TFT (T2). A drain electrode is provided.

The driving TFT T2 includes a gate electrode 24 connected to the drain electrode of the switching TFT, a source electrode 26 connected to the base voltage source GND, a cathode electrode 12 of the EL cell OLED, A drain electrode 28 to be connected and an active layer 38 forming a channel between the source electrode 26 and the drain electrode 28 are provided.

The driving TFT T2 will be described in detail. The gate electrode 24 formed together with the gate line, the source and drain electrodes 26 and 28 formed together with the data line, the gate electrode 24 and the gate insulating film are described. An active layer 38 overlapping with the gap 36 and forming a channel between the source electrode 26 and the drain electrode 28, and the active layer 38, the source electrode 26, and the drain electrode 28. Ohmic contact layer 40 for reducing the contact resistance of the. And a drain contact hole 34 which exposes the drain electrode 28 through the protective film 30 for contact between the cathode electrode 12 and the drain electrode 28 of the EL cell OLED.

The EL cell OLED includes an organic light emitting layer 10 and an anode electrode 4 and a cathode electrode 12 insulated by an insulating film 6 and having an organic light emitting layer 10 formed therebetween.

The anode electrode 4 is formed by depositing a transparent conductive material such as indium tin oxide (ITO) on the entire surface. The anode electrode 4 is supplied with a drive signal for releasing holes from the drive voltage source VDD (see Fig. 1).

The cathode electrode 12 is connected to the drain electrode 28 of the driving TFT (T2) through the drain contact hole 34, and is formed for each EL cell OLED area. The cathode electrode 12 is supplied with a driving signal for emitting electrons from the drain electrode 28 of the driving TFT (T2).

The organic light emitting layer 10 is formed by stacking an electron injection layer 10a, an electron transport layer 10b, a light emitting layer 10c, a hole transport layer 10d, and a hole injection layer 10e. The organic light emitting layer 10 is supplied with driving signals from the anode electrode 4 and the cathode electrode 12. Then, holes are emitted from the anode electrode 4 as shown in FIG. 3, and the emitted holes move to the emission layer 10c through the hole injection layer 10e and the hole transport layer 10d, and electrons are emitted from the cathode electrode 12. The emitted electrons are transferred to the light emitting layer 10c via the electron injection layer 10a and the electron transport layer 10b, and thus the organic light emitting layer 10 is visible light by recombination of holes and electrons in the light emitting layer 10c. Occurs. At this time, the generated visible light comes out through the anode electrode 4, which is a transparent electrode, so that the organic EL display element displays an image.

On the other hand, the cathode electrode 12 of the organic EL display device is made of an aluminum-based metal containing aluminum (Al), aluminum neodium (AlNd) and the like having excellent reflection characteristics in order to increase the housekeeping light emitted to the anode electrode (4). It is formed using. However, such aluminum-based metals have excellent reflection properties while being easily oxidized. Therefore, the surface of the cathode electrode 12 is oxidized when the cathode electrode 12 is exposed to air during the manufacturing process of the organic EL display element, thereby forming a surface oxide film. Accordingly, the organic EL display device has a problem that electrons injected into the electron injection layer 10a from the cathode electrode 12 are disturbed by the surface oxide film formed on the surface of the cathode electrode 12, thereby degrading its performance. Has In addition, the organic EL display device has a disadvantage in that the lifetime is reduced by the surface oxide film.

Accordingly, an object of the present invention relates to an organic light emitting display device and a method of manufacturing the same, which can prevent oxidation of a cathode electrode, thereby improving performance and extending its life.

In order to achieve the above object, the organic light emitting display device according to an embodiment of the present invention includes a cathode electrode formed in the electroluminescent cell region defined by the intersection of the data line and the gate line on the substrate; An organic emission layer formed on the cathode; A conductive buffer film formed between the cathode electrode and the organic light emitting layer; An anode electrode is formed on the organic light emitting layer.

The organic light emitting display device further includes an insulating film exposing a region where the organic light emitting layer is to be formed on the cathode, and the conductive buffer film is formed on the cathode electrode exposed by the insulating film.

The organic electroluminescent display further includes an insulating film exposing a region where the organic light emitting layer is to be formed on the conductive buffer layer, wherein the conductive buffer layer is formed on the entire surface of the cathode electrode.

The cathode electrode includes an aluminum-based metal including aluminum (Al) or aluminum neodium (AlNd).

The conductive buffer layer is a compound formed by heat treatment of the aluminum-based metal and amorphous silicon to which amorphous silicon or an impurity is added.

The organic light emitting display device includes a driving electrode including a drain electrode connected to the cathode electrode, a source electrode facing each other with the drain electrode and a channel interposed therebetween, and a gate electrode overlapping with the channel and the gate insulating layer interposed therebetween. A transistor is further provided.

The organic light emitting display device may further include a switching thin film transistor connected to a gate electrode of the driving thin film transistor.

A method of manufacturing an organic light emitting display device according to an embodiment of the present invention includes the steps of forming a cathode electrode in the area of the electroluminescent cell defined by the intersection of the data line and the gate line on the substrate; Forming an insulating film on the cathode to expose a region where the organic light emitting layer is to be formed; Forming a conductive buffer film on the cathode electrode exposed by the insulating film; Forming an organic light emitting layer on the conductive buffer layer; And forming an anode on the organic light emitting layer.

The forming of the conductive buffer layer may include forming an amorphous silicon or amorphous silicon to which an impurity is added on a substrate; Heat-treating the substrate.

The method of manufacturing the organic light emitting display device may further include etching the amorphous silicon or the amorphous silicon to which the impurities are added in a region excluding the conductive buffer layer.

A method of manufacturing an organic light emitting display device according to an embodiment of the present invention includes the steps of forming a cathode electrode and a conductive buffer layer covering the entire surface of the cathode electrode in the area of the electroluminescent cell defined by the intersection of the data line and the gate line on the substrate; ; Forming an insulating layer on the conductive buffer layer to expose a region where the organic light emitting layer is to be formed; Forming an organic light emitting layer on the conductive buffer film exposed by the insulating film; And forming an anode on the organic light emitting layer.

The forming of the cathode electrode and the conductive buffer layer may include: continuously depositing the aluminum-based metal and amorphous silicon or amorphous silicon to which the impurities are added on the substrate; Heat treating the substrate; Patterning the cathode electrode and the conductive buffer layer using a mask process.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 7D.

4 is a cross-sectional view illustrating an organic EL display device according to a first embodiment of the present invention.

Referring to Fig. 4, the organic EL display device according to the first embodiment of the present invention is a driving TFT in which a switching TFT (T1, see Fig. 1) and a gate electrode 124 are connected to a drain electrode of the switching TFT. (T2) and EL cell (OLED) to which cathode electrode 112 is connected to drain electrode 128 of driving TFT (T2).

The switching TFT is connected to a gate electrode connected to the gate line GL (see FIG. 1), a source electrode connected to the data line DL (see FIG. 1), and a gate electrode 124 of the driving TFT T2. A drain electrode is provided.

The driving TFT T2 includes a gate electrode 124 connected to the drain electrode of the switching TFT, a source electrode 126 connected to the base voltage source GND (see FIG. 1), and a cathode electrode of the EL cell OLED. A drain electrode 128 connected to 112 and an active layer 138 forming a channel between the source electrode 126 and the drain electrode 128 are provided.

The driving TFT T2 will be described in detail. The gate electrode 124 formed together with the gate line, the source and drain electrodes 126 and 128 formed together with the data line, the gate electrode 124 and the gate insulating film are described. An active layer 138 overlapping with the 136 interposed therebetween to form a channel between the source electrode 126 and the drain electrode 128, and between the active layer 138 and the source electrode 126 and the drain electrode 128. Ohmic contact layer 140 to reduce the contact resistance. And a drain contact hole 134 that exposes the drain electrode 128 through the passivation layer 130 for contact between the cathode electrode 112 and the drain electrode 128 of the EL cell OLED.

The EL cell OLED is insulated by the organic light emitting layer 110, the insulating film 106, and the anode electrode 104 and the cathode electrode 112 having the organic light emitting layer 110 formed therebetween, and the cathode electrode 112. And a conductive buffer film 115 formed between the organic light emitting layer 110.

The anode electrode 104 is formed by depositing a transparent conductive material on the entire surface. The anode electrode 104 is supplied with a driving signal for releasing holes from the driving voltage source VDD (see FIG. 1).

The cathode electrode 112 is connected to the drain electrode 128 of the driving TFT (T2) through the drain contact hole 134 and is formed for each EL cell (OLED) region. The cathode electrode 112 is supplied with a driving signal for emitting electrons from the drain electrode 128 of the driving TFT (T2).

The conductive buffer layer 115 is formed to cover the exposed region of the cathode electrode 112 on the cathode electrode 112 exposed by the insulating layer 106 to provide a region in which the organic emission layer 110 is formed. The conductive buffer film 115 is formed by depositing amorphous silicon (a-Si) or amorphous silicon (a-Si) to which an impurity is added on an aluminum-based metal forming the cathode electrode 112, and then heat-treating it. At this time, the conductive buffer film 115 is formed to a thickness of 100 Å or less.

The organic emission layer 110 is formed by stacking the electron injection layer 110a, the electron transport layer 110b, the emission layer 110c, the hole transport layer 110d, and the hole injection layer 110e. When the driving signals are supplied from the anode electrode 104 and the cathode electrode 112 to the organic light emitting layer 110, the electrons emitted from the anode electrode 112 and the electrons emitted from the anode electrode 104 are in the light emitting layer 110c. Recombination generates visible light. At this time, the generated visible light comes out through the anode electrode 104, which is a transparent electrode, so that the organic EL display element displays an image.

Hereinafter, a method of manufacturing the organic EL display device according to the first embodiment of the present invention will be described with reference to FIGS. 5A to 5E.

Referring to FIG. 5A, a method of manufacturing an organic EL display device according to a first exemplary embodiment of the present invention includes aluminum (Al) and aluminum neodium (AlNd) on a substrate 122 on which a switching TFT and a driving TFT (T2) are formed. And then patterning the aluminum-based metal including the ()) to form a cathode electrode 112 connected to the drain electrode 128 of the driving TFT (T2) through the drain contact hole 134. The insulating layer 106 exposing the cathode electrode 112 on which the organic light emitting layer 110 is to be formed is formed on the cathode electrode 112 by patterning the entire surface of the insulating material.

Next, amorphous silicon (a-Si) or amorphous silicon (a-Si) to which impurities are added is deposited on the substrate 122 on which the cathode electrode 112 is formed.

Subsequently, the substrate 122 on which the amorphous silicon (a-Si) or the amorphous silicon (a-Si) with the impurity is added is heat-treated to heat the aluminum 122 and the amorphous silicon (a-Si) or the amorphous silicon with the impurity. A conductive buffer film 115 is formed on the region where (a-Si) is in contact, that is, the exposed cathode electrode 112 as shown in FIG. 5C. At this time, the conductive buffer film 115 is formed to a thickness of 100 Å or less. In the dry etching process, amorphous silicon (a-Si) in the region excluding the conductive buffer layer 115 is removed as shown in FIG. 5D. The conductive buffer film 115 has a stronger etching property than amorphous silicon (a-Si) or amorphous silicon (a-Si) to which impurities are added. Therefore, in the dry etching process, amorphous silicon (a-Si) or amorphous silicon (a-Si) to which impurities are added is removed through the control of the etching rate, and the conductive buffer layer 115 is not removed.

Thereafter, an organic light emitting layer 110 is formed by depositing an organic light emitting material on the substrate 122 on which the conductive buffer film 115 is formed, as shown in FIG. 5E, and subsequently, the anode electrode 104 is formed of ITO (Induim Tin Oxide) or IZO. It is formed by depositing a transparent conductive material such as (Induim Zinc Oxide) on the entire surface.

As described above, the organic EL display device and the method of manufacturing the same according to the first exemplary embodiment of the present invention form the conductive buffer layer 115 on the cathode electrode 112 exposed to the region where the organic emission layer 110 is formed. During the process of forming the 110, the cathode electrode 112 may be prevented from being exposed to air and oxidized. Accordingly, the organic EL display device according to the first embodiment of the present invention can prevent the oxidation of the cathode electrode 112, thereby improving its performance and extending its lifespan.

6 is a cross-sectional view illustrating an organic EL display device according to a second embodiment of the present invention.

In the second embodiment of the present invention, detailed descriptions of components substantially the same as those of the first embodiment will be omitted.

Referring to FIG. 6, the organic EL display device according to the second embodiment of the present invention is disposed on the cathode electrode 112 where the organic EL display device of the first embodiment of the present invention is exposed to a region where the organic light emitting layer 110 is formed. Unlike the conductive buffer film 115 formed, the conductive buffer film 215 covering the entire surface of the cathode electrode 212 is provided on the cathode electrode 212.

Hereinafter, a method of manufacturing an organic EL display device according to a second exemplary embodiment of the present invention will be described with reference to FIGS. 7A to 7D.

Referring to FIG. 7A, a method of manufacturing an organic EL display device according to a second exemplary embodiment of the present invention may include aluminum (Al) and aluminum neodium (AlNd) on a substrate 222 on which a switching TFT and a driving TFT (T2) are formed. Aluminum-based metal and amorphous silicon (a-Si) or amorphous silicon (n + a-Si) doped with n + impurities, and the like, and the entire surface-deposited aluminum-based metal and amorphous silicon (a-Si) Or a cathode electrode 212 connected to the drain electrode 228 of the driving TFT T2 through the drain contact hole 234 by patterning amorphous silicon (n + a-Si) doped with n + impurity and a cathode electrode ( An amorphous silicon film 215a covering 212 is formed.

Then, the substrate 222 is heat-treated to form a conductive buffer layer 215 on the cathode electrode 212 as shown in FIG. 7B. The conductive buffer film 215 is formed to a thickness of 100 kPa or less.

Subsequently, an insulating material is deposited on the entire surface and then patterned to form an insulating film 206 exposing the region where the organic light emitting layer 210 is to be formed on the cathode electrode 212 and the conductive buffer film 215 as shown in FIG. 7C.

The organic light emitting layer 210 is formed by depositing an organic light emitting material on the substrate 222 on which the insulating film 206 is formed, as shown in FIG. 7D, and subsequently, the anode electrode 204 is formed of indium tin oxide (ITO) or induim zinc (IZO). It is formed by depositing a transparent conductive material such as oxide) on the entire surface.

As described above, the organic EL display device and the method of fabricating the same according to the second exemplary embodiment of the present invention form the conductive buffer layer 215 covering the entire surface of the cathode electrode 212 on the cathode electrode 212 to form the cathode electrode 212. This can be prevented from being exposed. Accordingly, the organic EL display device according to the second exemplary embodiment of the present invention can prevent the oxidation of the cathode electrode 212, thereby improving its performance and extending its lifespan.

As described above, the organic EL display device and the method of manufacturing the same according to the embodiment of the present invention can prevent the cathode electrode from being exposed to air during oxidation by forming a conductive buffer film on the cathode electrode. Accordingly, the organic EL display device according to the embodiment of the present invention can improve the performance and extend the life by preventing oxidation of the cathode.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (18)

A cathode electrode formed on the substrate in the electroluminescent cell region defined by the intersection of the data line and the gate line; An organic emission layer formed on the cathode; A conductive buffer film formed between the cathode electrode and the organic light emitting layer; And an anode electrode formed on the organic light emitting layer. The method of claim 1, An insulating film exposing an area on which the organic light emitting layer is to be formed, on the cathode electrode; And the conductive buffer layer is formed on the cathode electrode exposed by the insulating layer. The method of claim 1, And an insulating film exposing a region where the organic light emitting layer is to be formed on the conductive buffer film. And the conductive buffer layer is formed on the entire surface of the cathode electrode. The method of claim 1, The cathode is an organic electroluminescent display device comprising an aluminum-based metal containing aluminum (Al) or aluminum neodium (AlNd). The method of claim 4, wherein The conductive buffer layer is an organic light emitting display device, characterized in that the compound formed by the heat treatment of the aluminum-based metal and amorphous silicon or amorphous silicon added to the impurities. The method of claim 1, And a driving thin film transistor including a drain electrode connected to the cathode electrode, a source electrode facing each other with the drain electrode and a channel interposed therebetween, and a gate electrode overlapping with the channel and the gate insulating layer interposed therebetween. An organic electroluminescent display element. The method of claim 7, wherein And a switching thin film transistor connected to the gate electrode of the driving thin film transistor. Forming a cathode in an electroluminescent cell region defined by the intersection of a data line and a gate line on the substrate; Forming an insulating film on the cathode to expose a region where the organic light emitting layer is to be formed; Forming a conductive buffer film on the cathode electrode exposed by the insulating film; Forming an organic light emitting layer on the conductive buffer layer; A method of manufacturing an organic light emitting display device, comprising the step of forming an anode electrode on the organic light emitting layer. The method of claim 8, The cathode is a method of manufacturing an organic light emitting display device, characterized in that formed of an aluminum-based metal containing aluminum (Al) or aluminum neodium (AlNd). The method of claim 9, Forming the conductive buffer film, Forming an amorphous silicon or an amorphous silicon to which an impurity is added on the substrate; The method of manufacturing an organic electroluminescent display device comprising the step of heat-treating the substrate. The method of claim 10, And etching the amorphous silicon or the amorphous silicon to which the impurity is added in a region excluding the conductive buffer layer. The method of claim 8, And forming a driving thin film transistor having a drain electrode connected to the cathode electrode. The method of claim 12, And forming a switching thin film transistor connected to the gate electrode of the driving thin film transistor. Forming a cathode electrode and a conductive buffer layer covering the entire surface of the cathode electrode in an area of the EL cell defined by the intersection of the data line and the gate line on the substrate; Forming an insulating layer on the conductive buffer layer to expose a region where the organic light emitting layer is to be formed; Forming an organic light emitting layer on the conductive buffer film exposed by the insulating film; A method of manufacturing an organic light emitting display device, comprising the step of forming an anode electrode on the organic light emitting layer. The method of claim 14, The cathode is a method of manufacturing an organic light emitting display device, characterized in that formed of an aluminum-based metal containing aluminum (Al) or aluminum neodium (AlNd). The method of claim 15, Forming the cathode electrode and the conductive buffer film, Continuously depositing amorphous silicon to which the aluminum-based metal and amorphous silicon or impurities are added onto the substrate; Heat treating the substrate; And patterning the cathode electrode and the conductive buffer layer using a mask process. The method of claim 13, And forming a driving thin film transistor having a drain electrode connected to the cathode electrode. The method of claim 17, And forming a switching thin film transistor connected to the gate electrode of the driving thin film transistor.

Images