KR20110051783A - Organic electro-luminescence device - Google Patents

Abstract

PURPOSE: An organic electro-luminescence device is provided to connect an anode electrode with first and second cathode electrode lines, thereby preventing the voltage of a cathode electrode from dropping. CONSTITUTION: A driving thin film transistor is form on each pixel area of a first substrate(101). An organic electro-luminescent diode(E) comprises a first electrode(111), an organic light emitting layer(113), and a second electrode(115). The first electrode is an anode electrode. The second electrode is a cathode electrode. A circuit unit(140) includes a scan driver and a gate driving circuit in both edges of the first substrate. First and second cathode electrode wires are located in each outer side of the circuit unit. A second substrate(102) is located on the organic electro-luminescent diode and the driving thin film transistor.

Description

Organic electroluminescent device

The present invention relates to a top emission type organic light emitting display device, and particularly, to prevent voltage drop of a second electrode.

Until recently, cathode ray tubes (CRT) have been mainly used as display devices. However, in recent years, flat panel such as plasma display panel (PDP), liquid crystal display device (LCD), organic electro-luminescence device (OLED), which can replace CRT Display devices are widely researched and used.

Among the flat panel display devices as described above, the organic light emitting display device (hereinafter referred to as OLED) is a self-light emitting device, and since the backlight used in the liquid crystal display device which is a non-light emitting device is not necessary, a light weight can be achieved.

In addition, the viewing angle and contrast ratio are superior to the liquid crystal display device, and it is advantageous in terms of power consumption, it is possible to drive the DC low voltage, the response speed is fast, and the internal components are solid, so it is strong against external shock, and the operating temperature range is also high. It has a wide range of advantages.

In particular, since the manufacturing process is simple, there is an advantage that can reduce the production cost more than the conventional liquid crystal display device.

OLEDs having these characteristics are largely divided into a passive matrix type and an active matrix type. The passive matrix type constitutes a device in a matrix form while crossing signal lines, whereas an active matrix type is a pixel. The thin film transistor, which is a switching element that turns on / off, and the driving thin film transistor which transmits current and the capacitor which maintains voltage for one frame are positioned per pixel.

In recent years, the passive matrix type has many limited elements such as resolution, power consumption, and lifespan. Accordingly, active matrix type OLEDs capable of realizing high resolution and large screens have been actively studied.

1 is a view schematically showing a cross section of a general OLED.

As illustrated, the OLED 10 has a driving thin film transistor DTr formed for each pixel region P on the first substrate 1, and includes a first electrode constituting the organic light emitting diode E. 11), the organic light emitting layer 13, and the second electrode 15 are sequentially formed.

The driving thin film transistor DTr includes the active layer 21, the gate electrode 23, the drain and the source electrodes 27 and 29, and an insulating layer 25 between the driving thin film transistor DTr. The organic light emitting diode E is located.

In this case, the first electrode 11 of the organic light emitting diode E is connected to the drain electrode 27 of the driving thin film transistor DTr, and the first electrode 11 is formed for each pixel region P, A bank 26 is positioned between the first electrodes 11.

Here, in the OLED 10, the first electrode 11 is made of a conductive material having a relatively high work function, and serves as an anode, and the second electrode 15 has a lower work function than the first electrode 11. It is made of a conductive material and serves as a cathode electrode.

On the other hand, the second electrode 15 is formed by low temperature deposition in order to minimize the damage of the organic light emitting layer (13).

As a result, the second electrode 15 has a poor film quality and a high specific resistance.

Here, the high resistivity of the second electrode 15 does not apply the same cathode voltage for each pixel position, but causes a voltage difference in a region close to and far from the region where the voltage is input by the IR drop. do.

This, in turn, causes nonuniformity in brightness or image characteristics, and causes a problem of increasing power consumption of the OLED 10.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide an organic light emitting device capable of preventing a voltage drop.

Accordingly, the second object is to improve the luminance and image characteristics by providing a uniform signal.

In order to achieve the above object, the present invention is a light emitting region and a non-light emitting region is defined, the first substrate formed with a driving thin film transistor, the organic light emitting diode consisting of the first and second electrodes and the light emitting layer; First and second cathode electrode wirings formed in the non-light emitting area along both edges of the first substrate in the longitudinal direction and electrically connected to the second electrodes; The second substrate is spaced apart from the first substrate, and includes a second substrate made of a metal foil. The first and second cathode electrode wirings and the second substrate are electrically connected to each other through a conductive material. The second cathode electrode wiring provides an organic light emitting diode that receives a voltage through the second substrate.

The first cathode electrode wiring is connected to a driving circuit to receive a voltage directly from the driving circuit, and the second cathode electrode wiring is formed on the other edge facing the one edge of the first substrate on which the first cathode electrode wiring is formed. Located.

The conductive material may be provided at each corner of the second substrate to electrically connect the first and second cathode electrode wirings to the second substrate, and the conductive material may be a conductive adhesive tape or silver paste. One of (Ag paste) is selected.

The driving thin film transistor may include a semiconductor layer, a gate electrode, a drain, and a source electrode, and the first electrode may be electrically connected to the drain electrode.

The first and second cathode electrode wirings are made of the same layer and the same material as the gate electrode, and the first and second cathode electrode wirings are made of the same layer and the same material as the drain and source electrodes.

As described above, according to the present invention, the voltage drop of the cathode electrode is formed by forming the first and second cathode electrode wirings on one edge where the voltage of the first substrate is input and the other edge which is a region far from the portion where the voltage is input. There is an effect that can be prevented.

As a result, a uniform signal can be applied to the organic light emitting display device, whereby luminance and image characteristics can be made uniform.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

FIG. 2A is a plan view schematically illustrating a configuration of an auxiliary electrode wiring on an OLED substrate according to an exemplary embodiment of the present invention, and FIG. 2B is a cross-sectional view schematically illustrating a cross section taken along II-II ′ of FIG. 2A.

As shown in FIG. 2A, at one edge of the first substrate 101 of the OLED 100, a driver IC 110 in which a driving circuit is mounted is configured, and first and second cathodes connected to the driver IC 110. Electrode wirings 300a and 300b are formed along both edges of the first substrate 101.

Here, the first and second cathode electrode wirings 300a and 300b are electrically connected to the second electrode 115, which is a cathode of the organic light emitting diode, and the first and second cathode electrode wirings 300a and 300b are connected to each other. A first hundreds of micrometers to several millimeters along one edge of the first substrate 101 from which the voltage is input from the driver IC 110 and the other edge of the first substrate 101, which is a region far from the portion at which the voltage is input. It is disposed along the longitudinal direction of the substrate 101.

In particular, the OLED 100 of the present invention is for encapsulating the OLED 100 a second cathode electrode wiring 300b formed along the other edge of the first substrate 101, which is a region far from the voltage input region. It is characterized in that it is electrically connected to the first cathode electrode wiring (300a) through the metal foil (102).

In this case, the first and second cathode electrode wirings 300a and 300b and the metal foil 102 may be formed of conductive adhesive tape (not shown) or silver paste in each corner region of the metal foil 102 defined as an area A on the drawing. (Ag paste: not shown) to be electrically connected to each other.

Through this, the first cathode electrode wiring 300a is electrically connected to the driver IC 110 to receive a voltage from the driver IC 110, and the metal foil 102 receives the voltage applied from the driver IC 110. Through the second cathode electrode wiring 300b is applied.

That is, the second electrode 115 which is the cathode electrode of the OLED 100 according to the embodiment of the present invention receives the voltage in both the region near and the region from which the voltage is input.

As a result, the same voltage is applied to all the pixels arranged in the pixel unit without generating an IR drop.

2B, the driving thin film transistor DTr is formed in each pixel region P, and the anode constituting the organic light emitting diode E is formed on the first substrate 101. The first electrode 111 which is an electrode, the organic light emitting layer 113 and the second electrode 115 which is a cathode are sequentially formed.

The first electrode 111 is electrically connected to the driving thin film transistor DTr.

In addition, circuit portions 140 on which scan drivers and gate driving circuits are mounted are positioned at both edges of the first substrate 101, and the first and second cathode electrode wirings 300a and 300b are disposed on the outer sides of the circuit portion 140, respectively. This is located.

The first and second cathode electrode wirings 300a and 300b may be formed of the same layer and the same material as the gate electrode 23 of FIG. 1, or may include the drain and source electrodes of FIG. , 29) can be composed of the same layer and the same material.

Accordingly, the first and second cathode electrode wirings 300a and 300b are formed outside the circuit unit 140 by gate wirings (38 of FIG. 1) connected to the gate driving circuit of the circuit unit 140.

The second electrode 115 is deposited on the entire surface of the first substrate 101, and the second electrode 115 is electrically connected to the first and second cathode electrode wirings 300a and 300b.

The second substrate 102 is disposed on the driving thin film transistor DTr and the organic light emitting diode E, and the first and second substrates 101 and 102 are formed through the protective layer 130 having adhesiveness. Are spaced apart from each other.

Through this, the OLED 100 is encapsulated.

In this case, the protective layer 130 may include barium oxide (BaO) or calcium oxide (CaO) having a hydrophobic property or a hygroscopic property therein. As a result, the protective layer 130 itself may be hydrophobic to prevent moisture penetration or to prevent contact with the organic light emitting layer 113 due to the hygroscopic property even if moisture penetrates into the protective layer 130. .

As described above, in the OLED 100 of the present invention, the protective layer 130 is formed directly on the organic light emitting diode E, thereby eliminating the existing failure turn.

Accordingly, the conventional polymer material may be prevented from penetrating a pollutant such as moisture or gas from the outside into the OLED 100 through a failure turn as the temperature is heated or stored for a long time.

In addition, the OLED 100 of the present invention does not cause the OLED 100 to be pressed by the protective layer 130 even when a pressure such as pressing from the outside is applied, and thus the first and second of the organic light emitting diode E Cracks in the electrodes 111 and 115 or the driving thin film transistor DTr may be prevented.

As a result, problems such as dark spot defects may be prevented from occurring, thereby preventing the problem of uneven brightness or image characteristics.

Meanwhile, the first substrate 101 may be formed of a transparent material such as glass or plastic material, and the second substrate 102 may be formed of a metal foil or the like.

At this time, the OLED 100 of the present invention can form the second substrate 102 to a thin thickness than the case of forming the second substrate 102 by a metal foil to form a second substrate with glass, OLED ( 100) can reduce the overall thickness.

In addition, despite reducing the thickness of the OLED 100 can improve the durability of the OLED 100 itself, it is also possible to improve the heat dissipation characteristics of the OLED (100).

Accordingly, the OLED 100 of the present invention is a bottom emission type in which light emitted through the organic light emitting layer 113 emits toward the first electrode 111.

In particular, in the OLED 100 of the present invention, the first and second cathode electrode wirings 300a and 300b are electrically connected to each other through a second substrate 102 made of a metal foil, so that the organic light emitting diode E The voltage drop (IR drop) of the second electrode 115, which is the cathode electrode, does not occur, and the same voltage is applied to all the pixels P. In this case, the first and second cathode electrode wirings 300a and 300b and Each of the second substrates 102 is electrically connected to each other through the conductive adhesive tape 310.

As a result, when the first cathode electrode wiring 300a receives a voltage from the driver IC (110 of FIG. 2A), the voltage applied to the first cathode electrode wiring 300a is transferred to the second substrate 102 through the second substrate 102. It is applied to the cathode electrode wiring (300b), the second electrode 115 of the organic light emitting diode (E) is one edge and the voltage is input through the first and second cathode electrode wiring (300a, 300b) The same voltage is applied at the other edge, which is a region far from the site.

Accordingly, the voltage drop IR drop does not occur to all the pixels P arranged in the pixel portion, and the same voltage is applied.

That is, the second electrode 115, which is the cathode electrode of the OLED 100, is formed by low temperature deposition in order to minimize damage of the organic light emitting layer 113 by heat or plasma, resulting in poor film quality and high resistivity.

Therefore, the same cathode voltage is not applied to each position of the pixel P, but a voltage difference occurs in a region close to and far from the region where the voltage is input due to an IR drop. Non-uniformity is generated and causes a problem of increasing power consumption of the OLED 100.

However, according to the present invention, first and second cathode electrode wirings 300a and 300b are formed on both edges of the OLED 100, that is, one edge where a voltage is input and the other edge that is a region far from the portion where the voltage is input. This problem is prevented by allowing the second electrode 115 to be electrically connected to the first and second cathode electrode wirings 300a and 300b.

Here, the first and second cathode electrode wirings 300a and 300b and the second electrode 115 of the organic light emitting diode E will be described in more detail with reference to FIG. 3.

3 is a schematic cross-sectional view of an OLED according to an embodiment of the present invention.

As shown, the OLED 100 according to the present invention is divided into a light emitting area PA and a non-light emitting area NA, where a plurality of driving thin film transistors DTr and organic light emitting diodes are disposed in the light emitting area PA. The diode E is formed, and the first and second cathode electrode wirings 300a (300b of FIG. 2B) are formed in the non-light emitting area NA.

In more detail, the semiconductor layer 201 is formed on the first substrate 101 of the emission area PA of the OLED 100, and the semiconductor layer 201 is made of silicon and the center portion of the active layer forms a channel. The regions 201b and the drain and source regions 201a and 201c doped with a high concentration of impurities on both sides of the active region 201b.

The gate insulating film 203 is formed on the semiconductor layer 201.

A gate electrode 205 and a gate wiring extending in one direction are formed on the gate insulating film 203 so as to correspond to the active region 201b of the semiconductor layer 201.

A first interlayer insulating film 207a is formed over the gate electrode 205 and the upper surface of the gate wiring, wherein the first interlayer insulating film 207a and the lower gate insulating film 203 are formed on both sides of the active region 201b. And first and second semiconductor layer contact holes 208a and 208b exposing the drain and source regions 201a and 201c, respectively.

Next, upper portions of the first interlayer insulating layer 207a including the first and second semiconductor layer contact holes 208a and 208b are spaced apart from each other and exposed through the first and second semiconductor layer contact holes 208a and 208b. And drain and source electrodes 211 and 213 in contact with the source regions 201a and 201c, respectively.

At this time, the first and second cathode electrode wirings 300a and 300b of FIG. 2B are formed in the non-light emitting area NA of the substrate 101. The first and second cathode electrode wirings 300a and 300b of FIG. 2B are formed. The silver may be formed of the same layer and the same material as the gate electrode 205, and may be formed of the same layer and the same material as the drain and source electrodes 211 and 213.

In the present invention, the first and second cathode electrode wirings 300a (300b of FIG. 2B) will be described as an example of the same layer and the same material as the drain and source electrodes 211 and 213.

And a second interlayer having a drain contact hole 215 exposing the drain electrode 211 over the first interlayer insulating film 207a exposed between the drain and source electrodes 211 and 213 and the two electrodes 211 and 213. The insulating film 207b is formed.

At this time, the semiconductor layer 201 including the drain and source electrodes 211 and 213 and the drain and source regions 201b and 201c in contact with the electrodes 211 and 213 and the gate insulating layer formed on the semiconductor layer 201 The 203 and the gate electrode 205 form a driving thin film transistor DTr.

Although not shown in the drawing, a data line (not shown) defining the pixel area P is formed to cross the gate line (not shown). The switching thin film transistor (not shown) has the same structure as the driving thin film transistor DTr and is connected to the driving thin film transistor DTr.

In addition, the switching and driving thin film transistor (DTr) shows, as an example, a top gate type in which the semiconductor layer 201 is made of a polysilicon semiconductor layer, as an example of pure and impurity amorphous. It may be formed of a bottom gate type made of silicon.

In addition, the first electrode 111 constituting the organic light emitting diode E, the organic light emitting layer 113, and the second electrode 115 are sequentially disposed in an area that substantially displays an image on the second interlayer insulating film 207b. It is formed.

The first and second electrodes 111 and 115 and the organic light emitting layer 113 formed therebetween form an organic light emitting diode (E).

The first electrode 111 is connected to the drain electrode 211 of the driving thin film transistor DTr through the drain contact hole 215 of the second interlayer insulating film 207b. The first electrode 111 is formed in each pixel region. The banks 221 are formed between the first electrodes 111 formed for each pixel area P, respectively.

That is, the bank 221 is formed in a matrix type having a lattice structure as a whole of the substrate 101, and the first electrode 111 is separated into pixel regions P with the bank 221 as a boundary portion for each pixel region. Formed.

The second electrode 115 is connected to the first and second cathode electrode wirings 300a (300b of FIG. 2B) formed in the non-light emitting area NA.

In this case, the first electrode 111 is formed of indium tin oxide (ITO), which is a material having a relatively high work function value to serve as an anode electrode, and the second electrode 115 is formed of a cathode ( It is made of a metal material with a relatively low work function to act as a cathode.

In addition, the light emitted from the organic light emitting layer 113 is driven by the bottom emission method emitted toward the first electrode 115.

The organic light emitting layer 113 may be composed of a single layer made of a light emitting material, and in order to increase the light emitting efficiency, a hole injection layer, a hole transporting layer, an emitting material layer, an electron transporting layer ( It may be composed of multiple layers of an electron transporting layer and an electron injection layer.

Here, the second electrode 115 connected to the first and second cathode electrode wirings 300a (300b of FIG. 2B) receives a voltage through the first and second cathode electrode wirings 300a (300b of FIG. 2B). In this case, the first cathode electrode wiring 300a is directly applied with a voltage from the driver IC (110 of FIG. 2A), and the second cathode electrode wiring (300b of FIG. 2B) is applied to the first cathode electrode wiring 300a. The voltage is applied through the second substrate 102.

Accordingly, the first and second cathode electrode wirings 300a (300b of FIG. 2B) formed on the first substrate 101 are electrically connected to each other through the second substrate 102 and the conductive adhesive tape 310.

 In this way, the second electrode 115 is connected to the first and second cathode electrode wirings 300a (300b of FIG. 2B), whereby the second electrode 115 has a poor film quality and a high specific resistance, thereby positioning the pixel P. The same cathode voltage is not applied to each other, but a voltage difference occurs in a region near and far from a voltage input region due to an IR drop, which causes an unevenness in luminance or image characteristics. It is possible to prevent the problem that increases the power consumption of 100).

When a predetermined voltage is applied to the first electrode 111 and the second electrode 115 according to the selected color signal, the OLED 100 may be formed from holes and second electrodes 115 injected from the first electrode 111. The applied electrons are transported to the organic light emitting layer 113 to form excitons, and when these excitons transition from the excited state to the ground state, light is generated and emitted in the form of visible light.

At this time, since the emitted light passes through the transparent first electrode 111 to the outside, the OLED 100 implements an arbitrary image.

As described above, in the OLED 100 of the present invention, the first and second cathode electrodes are disposed at both edges of the first substrate 101, that is, one edge where a voltage is input and the other edge that is a region far from a portion where a voltage is input. The wiring 300a (300b of FIG. 2B) is formed, and the second electrode 115 is electrically connected to the first and second cathode electrode wirings 300a (300b of FIG. 2B), thereby forming the second electrode 115. It is possible to prevent the IR drop from occurring.

Through this, it is possible to prevent a problem in which unevenness in brightness and image characteristics occurs or power consumption of the OLED 100 is improved.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

1 schematically illustrates a cross section of a typical OLED.

Figure 2a is a plan view schematically showing a state in which the auxiliary electrode wiring is configured on the OLED substrate in accordance with an embodiment of the present invention.

FIG. 2B is a schematic cross-sectional view taken along the line II-II ′ of FIG. 2A;

3 shows schematically a cross section of an OLED according to an embodiment of the invention;

Claims (9)

A first substrate having a light emitting region and a non-light emitting region, the organic light emitting diode comprising a driving thin film transistor, first and second electrodes, and a light emitting layer; First and second cathode electrode wirings formed in the non-light emitting area along both edges of the first substrate in the longitudinal direction and electrically connected to the second electrodes; A second substrate which is spaced apart from the first substrate at a predetermined interval and is formed of a metal foil Wherein the first and second cathode electrode wirings and the second substrate are electrically connected to each other through a conductive material, and the second cathode electrode wiring is applied with a voltage through the second substrate. . The method of claim 1, The first cathode electrode wiring is connected to a driving circuit, the organic light emitting diode is applied directly from the driving circuit. The method of claim 2, The second cathode electrode wiring is positioned on the other edge facing the one edge of the first substrate on which the first cathode electrode wiring is formed. The method of claim 1, The conductive material is provided in each corner region of the second substrate, the organic light emitting device to electrically connect the first and second cathode electrode wiring and the second substrate to each other. The method of claim 1, The conductive material is an organic light emitting display device selected from a conductive adhesive tape or silver paste (Ag paste). The method of claim 1, The driving thin film transistor is an organic light emitting device comprising a semiconductor layer, a gate electrode and a drain and a source electrode. The method of claim 6, The first electrode is an organic light emitting device that is electrically connected to the drain electrode. The method of claim 6, The first and second cathode electrode wirings are formed of the same layer and the same material as the gate electrode. The method of claim 6, The first and second cathode electrode wirings are formed of the same layer and the same material as the drain and source electrodes.

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