KR102462498B1 - Organic light emitting diode display and manufacturing method of the same - Google Patents

Abstract

An organic light emitting diode display having a uniform luminance according to an embodiment of the present invention is provided. A flat layer having a contact hole is disposed on the substrate on which the auxiliary electrode is disposed. The contact hole of the planarization layer has an undercut structure at the contact point with the auxiliary electrode, the organic light emitting layer has a discontinuous section in the undercut structure of the contact hole, and the common electrode is connected to the auxiliary electrode inside the undercut structure. By connecting the auxiliary electrode and the common electrode through a contact hole having an undercut structure of a planarization layer, a uniform luminance of the organic light emitting diode display may be maintained.

Description

Organic light emitting display device and manufacturing method thereof

The present invention relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, in connecting a common electrode to an auxiliary electrode in order to maintain uniform luminance of the organic light emitting display device, a separate additional process is performed by using an undercut structure. To provide a new connection structure capable of connecting an auxiliary electrode and a common electrode without an organic light emitting diode display capable of increasing in size and high resolution, and a method for manufacturing the same.

An organic light emitting display (OLED) is a self-emission type display device, and unlike a liquid crystal display (LCD), it does not require a separate light source, so it can be manufactured in a lightweight and thin form. In addition, the organic light emitting diode display is being studied as a next-generation display device because it is advantageous in terms of power consumption due to low voltage driving, and has excellent color realization, response speed, viewing angle, and contrast ratio (CR).

The organic light emitting diode display (OLED) may be divided into a top emission type and a bottom emission type according to a transmission direction of light emitted through the organic light emitting device. In the bottom light emitting method, as a thin film transistor (driving device) and wiring electrodes for driving the organic light emitting device are disposed for each pixel, the light emitting area is inevitably limited, so the top light emission method is mainly used in recent years.

A typical top emission type organic light emitting display device includes a driving device (thin film transistor) disposed on a substrate, a driving device passivation layer disposed to cover the driving device, and an overcoat protecting the driving device. and a pixel electrode (anode) and a common electrode (cathode) for driving the organic light emitting layer.

As the pixel electrode, a conductive material having a relatively high work function value, for example, indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) may be used. In particular, the pixel electrode may be formed of at least two layers including a metal material having excellent reflection efficiency, for example, silver (Ag) or APC (Ag; Pb; Cu). Recently, a pixel electrode having a triple stacked structure of ITO/Ag alloy/ITO is mainly used.

In the organic light emitting display device, a plurality of pixels are disposed and light is emitted by electrons and holes injected into the organic light emitting layer disposed in each pixel, so it is important to uniformly supply a current applied to the organic light emitting display device.

In such a general top emission type organic light emitting display device, a conducting electrode connected to a plurality of pixels is mainly used for the upper common electrode, and since it is a top emission type organic light emitting diode display, a transparent conductive material having a property of transmitting light is used.

Since the transparent conductive material has a higher electrical resistance than metal, it is difficult to maintain the uniform luminance of the organic light emitting display device because the electrical resistance of the common electrode cannot be uniformly maintained when realizing the top emission type organic light emitting display device in a larger size. There may be difficulties.

Accordingly, in increasing the size of the organic light emitting diode display, many research tasks are being conducted on a structure capable of supplying a uniform current to the organic light emitting diode.

In an organic light emitting display device, a plurality of pixels including an organic light emitting device are disposed to display an image desired by a user by emitting light to the organic light emitting device.

The organic light emitting device includes two electrodes and an organic layer. In this case, the organic layer includes an organic light emitting layer, and for smooth exciton formation, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and the like may be further included.

One of the two electrodes may be a pixel electrode connected to the driving device, and the other may be a common electrode (cathode).

In the case of a top emission type organic light emitting display device, a common electrode is generally used as a transparent electrode, but since the transparent electrode has a high resistance value, the organic light emitting diode is more sensitive to the organic light emitting diode from the periphery to the center of the organic light emitting display device. The luminance of the supplied current is lowered due to an increase in the electrical resistance of the electrode.

In order to overcome the lowered luminance in the central portion, an auxiliary electrode may be disposed in the organic light emitting display device and connected to the common electrode to lower the electrical resistance of the common electrode and maintain it constant.

In order to connect the auxiliary electrode disposed on the upper portion of the organic light emitting layer and the common electrode disposed under the organic light emitting layer, a structure having an inverted taper structure including a barrier rib is disposed on the auxiliary electrode to induce a discontinuous section of the organic light emitting layer and form a discontinuous section. The open auxiliary electrode and the common electrode may be electrically connected.

The connection method of the reverse taper structure is a connection method using the step coverage difference between the organic light emitting layer and the common electrode. When the auxiliary electrode is formed at the lower end of the barrier rib structure and the organic light emitting layer and the common electrode are deposited, the common electrode is the organic light emitting layer. Compared to , since the step coverage is high, it can be disposed including the side of the barrier rib structure, so that it can be electrically connected to the auxiliary electrode at the lower end of the barrier rib structure.

For the barrier rib structure, a polyimide-based material may be used. However, such a barrier rib structure is prone to collapse during a manufacturing process and has disadvantages in that the aperture ratio of the organic light emitting diode display may be lowered. In addition, since an additional process for forming the barrier rib structure is required, there is a disadvantage in that the manufacturing cost of the organic light emitting display device may be increased. Accordingly, the inventors of the present invention have invented an auxiliary electrode connection structure of an organic light emitting display device capable of connecting an auxiliary electrode and a common electrode without using a barrier rib structure.

An object to be solved according to an embodiment of the present invention is to arrange a contact hole including an undercut structure on the auxiliary electrode to induce a discontinuous section of the organic light emitting layer to open the auxiliary electrode, and connect the open auxiliary electrode and the common electrode to achieve high resolution It is to provide an organic light emitting display device capable of providing a large area, and a method for manufacturing the same.

Another problem to be solved according to an embodiment of the present invention is to provide an organic light emitting display device having one side of a contact hole having an undercut shape and the other side having a slope shape in order to increase a connection success rate between a common electrode and an auxiliary electrode, and a method of manufacturing the same. will provide

The problems to be solved according to an embodiment of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, there is provided an organic light emitting display device capable of maintaining uniform luminance of the organic light emitting display device by arranging a contact hole having an undercut on the auxiliary electrode to connect the common electrode to the auxiliary electrode. A driving element and an auxiliary electrode are provided on a substrate, and a driving element protective layer and a planarization layer are provided on the driving element. A pixel electrode, an organic light emitting layer, and a common electrode are provided on the planarization layer, and the driving device protective layer and the planarization layer have contact holes for opening auxiliary electrodes, one surface of the contact hole has the shape of an undercut and the other side has the shape of an inclined surface. . The organic light emitting layer is discontinuous inside the undercut shape, and the common electrode is electrically connected to the auxiliary electrode inside the undercut shape to have a uniform electrical resistance. In this case, the inclined surface of the contact hole allows the common electrode to be more smoothly disposed inside the undercut. By disposing the contact hole having the undercut and the inclined surface on the auxiliary electrode as described above, it is possible to provide an organic light emitting diode display having uniform luminance by making the electrical resistance of the common electrode constant.

A method of manufacturing an organic light emitting display device according to an embodiment of the present invention is provided. A driving device and an auxiliary electrode are formed on the substrate. A driving device protection layer and a planarization layer are formed on the driving device, and a pixel electrode, an organic light emitting layer, and a common electrode are formed on the planarization layer. At this time, the driving device protective layer and the planarization layer are formed to form a contact hole to open the auxiliary electrode, one side having an undercut shape and the other side having an inclined surface. As described above, when the organic light emitting layer and the common electrode are formed thereafter, the common electrode and the auxiliary electrode can be electrically connected inside the undercut shape formed in the contact hole, thereby providing an organic light emitting display device having uniform luminance. .

According to an embodiment of the present invention, the luminance uniformity of the organic light emitting diode display can be improved by providing a connection structure through the contact hole of the flat layer in electrically connecting the auxiliary electrode and the common electrode to make the current of the common electrode uniform. there is an effect

In addition, by disposing the contact hole to have an undercut shape and an inclined surface shape, the connection rate between the common electrode and the auxiliary electrode can be improved.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

Since the content of the invention described in the problems to be solved above, the means for solving the problems, and the effects do not specify the essential characteristics of the claims, the scope of the claims is not limited by the matters described in the content of the invention.

1 is a schematic cross-sectional view of an organic light emitting diode display for explaining a connection between a common electrode and an auxiliary electrode according to an embodiment of the present invention.
2A to 2F are schematic cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to an exemplary embodiment.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative and the present invention is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless specifically stated otherwise.

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

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

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

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

Hereinafter, a connection structure of the auxiliary electrode and the common electrode including the contact hole according to an embodiment of the present invention will be described.

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

1 is a schematic cross-sectional view of an organic light emitting diode display for explaining a connection between a common electrode and an auxiliary electrode according to an embodiment of the present invention.

Referring to FIG. 1 , in the organic light emitting display device 100 , a driving device 120 , an auxiliary electrode 130 , and a pad electrode 140 are disposed on a substrate 110 .

The substrate 110 may be a glass substrate or a polyimide-based flexible substrate. A barrier layer 112 for minimizing penetration of moisture and oxygen may be disposed on the substrate 110 . Also, the substrate 110 may include an alignment mark 111 for process alignment.

The driving device 120 may be a thin film transistor using amorphous silicon, polycrystalline silicon, or an oxide semiconductor. In addition, the driving device 120 includes a gate electrode 121 , a gate insulating layer 122 , an active layer 123 , a source electrode and a drain electrode 124 , and a gate electrode 121 and a gate electrode 121 on the gate electrode 121 . An interlayer layer 113 which is an inorganic layer for preventing conduction between the source electrode and the drain electrode 124 and preventing contamination and damage under the gate electrode 121 may be further included. In FIG. 1 , the driving device 120 is illustrated as a top gate in which the gate electrode 121 is disposed on the active layer 123 , but the gate electrode 121 is in the active layer 123 and in the bottom gate in the active layer 123 . gate) may be a driving device.

The gate electrode 121 may include any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or these may be made of an alloy of, but is not limited thereto, and may be formed of various materials.

In addition, the gate electrode 121 may include, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). ) may be a multilayer made of any one selected from the group consisting of or an alloy thereof.

The source electrode and drain electrode 124, the pad electrode 140, and the auxiliary electrode 130 constituting the driving device 120 are disposed on the same plane using the same material to simplify the arrangement process, and It may be made of a low-resistance metal material such as copper (Cu) for smooth signal transmission.

The source and drain electrodes 124, the pad electrode 140, and the auxiliary electrode 130 may be disposed using a material such as copper (Cu) or silver (Ag), but may be disposed on an inorganic layer or an organic layer. When there may be a problem of adhesion, it may further include a motitanium (MoTi) layer, and may further include an ITO or IZO layer because it may be damaged in a process such as etching that accompanies after disposing the electrode. have. More specifically, for example, the source electrode and drain electrode 124 , the pad electrode 140 , and the auxiliary electrode 130 may be electrodes having a multilayer structure of MoTi, Cu, and ITO. In some embodiments, the auxiliary electrode 130 may be made of the same material as the gate electrode 121 instead of the source electrode and the drain electrode 124 .

A driving device protective layer 114 is disposed on the driving device 120 to protect the driving device 120 from being damaged in subsequent processes, etc., and a planarization layer 115 and An organic light emitting device 150 is disposed.

The organic light emitting device 150 includes a pixel electrode 151 disposed on a planarization layer 115 , an organic light emitting layer 152 , and a common electrode 153 , and the pixel electrode 151 is electrically connected to the driving device 120 . is connected to More specifically, the pixel electrode 151 is electrically connected to the source electrode and the drain electrode 124 of the driving device 120 through the pixel electrode connection part 116 .

The organic light emitting layer 152 emits light by electrons and holes injected from the pixel electrode 151 and the common electrode 153, and a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer for smooth exciton formation. and may be an organic light emitting layer having a multilayer structure including at least two light emitting layers.

The pixel electrode 151 and the common electrode 153 may be an anode electrode or a cathode electrode, and may be a transparent electrode capable of transmitting light emitted from the organic light emitting layer 152 , and emit light in one direction. One of the two electrodes may be a reflective electrode to induce .

Also, a bank layer 190 is disposed around the pixel electrode 151 to separate the pixels.

In the driving device protective layer 114 on the pad electrode 140 , a pad open part 141 for opening the pad electrode 140 is disposed, and a contact hole 160 for opening the auxiliary electrode 130 is disposed.

The contact hole 160 is disposed to have an undercut shape 161 on one side and an inclined surface shape 162 on the other side according to a difference in the degree of opening between the layers including the driving device protective layer 114 and the planarization layer 115 . Here, the inclined surface shape 162 may be a step shape including the protective layer 114 and the flat layer 115 as shown in FIG. 1 .

At least a portion of the inclined surface shape 162 of the contact hole 160 may have a structure covered by the bank layer 170 , or the inclined surface shape 162 made of only the driving element protective layer 114 and the flattening layer 115 . can be

The auxiliary electrode 130 and the common electrode 153 are electrically connected inside the undercut shape 161 of the contact hole 160 . The contact hole 160 having the undercut shape 151 is the auxiliary electrode 130 . ) is opened and the organic light emitting layer 152 is discontinuous rather than disposed inside the undercut shape 161 . The discontinuous and open auxiliary electrode 130 is electrically connected in the process of disposing the common electrode 153 . do.

Since the common electrode 153 has a higher step coverage than the organic light emitting layer 152 , the organic light emitting layer 152 is discontinuous inside the undercut shape 161 , and the common electrode 153 has a high step coverage. It is disposed to the inside of the undercut shape 161 and is electrically connected to the auxiliary electrode 130 .

2A to 2F are schematic cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to an exemplary embodiment.

Referring to FIG. 2A , the driving device 220 , the pad electrode 240 and the auxiliary electrode 230 are formed on the substrate 210 . The substrate 210 may include a buffer layer 212 and may include forming an alignment mark 211 on the substrate 210 for process alignment.

In the driving device 220 , an active layer 223 is formed, a gate insulating layer 222 and a gate electrode 221 are formed in this order, and an interlayer layer 213 for insulating the gate electrode 221 is formed. Then, a source electrode and a drain electrode 224 are formed, and the source electrode and the drain electrode 224 are formed to be electrically connected to the active layer 223 , respectively.

The pad electrode 240 , the source electrode and drain electrode 224 , and the auxiliary electrode 230 may be simultaneously formed using the same material.

The pad electrode 240, the source and drain electrodes 224, and the auxiliary electrode 230 are formed using a material having a low electrical resistance such as copper (Cu) or silver (Ag), copper (Cu) or silver ( Ag) has low deposition stability, so motitanium (MoTi) is first formed, and then copper (Cu) or silver (Ag) is formed to increase deposition stability. In addition, copper (Cu) or silver (Ag) is highly likely to be corroded in a subsequent process, so ITO or IZO is formed on top of copper (Cu) or silver (Ag).

As described above, when the pad electrode 240 , the source electrode and the drain electrode 224 , and the auxiliary electrode 230 are formed in a multi-layered electrode structure, process stability can be further improved.

Referring to FIG. 2B , a driving device protection layer 214 for protecting the driving device 220 is formed on the driving device 220 , but a pixel electrode connection part that opens one of the source electrode and the drain electrode 224 . (216).

Next, a planarization layer 215 is formed on the driving device protective layer 214 using a material such as resin, and the pad electrode 240 , the pixel electrode connection part 216 , and the auxiliary electrode 230 are not covered. formed so as not to

The forming of the pixel electrode connection part 216 on the passivation layer 241 may be performed using a dry or wet etch process or a plasma etch process.

Referring to FIG. 2C , the pixel electrode 251 is formed on the planarization layer 215 . The pixel electrode 251 is formed to be electrically connected to the source electrode and the drain electrode 224 through the pixel electrode connection part 216 to receive an electrical signal and current from the driving device 220 .

Next, as shown in FIG. 2D , a pad open part 241 is formed on the driving device protective layer 214 to open the pad electrode 240 , and the driving device protective layer 214 on the auxiliary electrode 230 is formed. It is opened to form a contact hole 260 .

In forming the contact hole 260 , one side is formed to have an undercut shape 261 and the other side is formed to have an inclined surface shape 262 . The method of forming the contact hole 260 to have the undercut shape 261 and the inclined surface shape 262 can be formed by using a process margin and using a process such as etching the driving device protective layer 214 .

Next, referring to FIG. 2E , a bank layer 270 is formed around the pixel electrode 251 . The bank layer 270 may be disposed to cover at least a portion of the contact hole 260 , and when disposed to cover at least a portion of the contact hole 260 , one side of the contact hole 260 may have an inclined surface 262 . can be formed more efficiently.

Then, as shown in FIG. 2F , the organic light emitting device 250 is formed by forming the organic light emitting layer 252 and the common electrode 253 . In this case, since the step coverage of the organic light emitting layer 252 is not high enough to be formed to the inside of the undercut shape 261 of the contact hole 260 , a discontinuous section is formed. However, the common electrode 253 has a higher step coverage than the organic light emitting layer 252 , and is formed to the inside of the undercut shape 261 of the contact hole 260 , and is connected to the auxiliary electrode 230 opened by the contact hole 260 . do.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and various modifications may be made within the scope without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The protection scope of the present invention should be construed by the claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: organic light emitting display device
110, 210: substrate
111, 220: alignment mark
112, 212: buffer layer
113, 213: interlayer layer
114, 214: driving element protective layer
115, 215: flat layer
116, 216: pixel electrode connection part
120, 220: driving element
130, 230: auxiliary electrode
140, 240: pad electrode
150, 250: organic light emitting device
160, 260: contact hole
170, 270: bank layer

Claims (13)

a driving element and an auxiliary electrode on the substrate;
a protective layer and a planarization layer on the driving element; and
a pixel electrode, an organic light emitting layer and a common electrode on the flattening layer; includes
The protective layer and the planarization layer include a contact hole for opening the auxiliary electrode,
One side of the contact hole has an undercut shape and the other side has an inclined surface shape,
The shape of the inclined surface is a step shape including the protective layer and the flattening layer, in which the protective layer protrudes inwardly of the contact hole rather than the flattened layer,
The undercut shape is an eaves shape in which an upper end of the passivation layer disposed under the planarization layer is retreated to the outside of the contact hole than a lower end of the planarization layer. The method of claim 1,
The driving device includes a gate electrode, a source electrode, a drain electrode and an active layer,
The auxiliary electrode is made of the same material as the gate electrode or the drain electrode. 3. The method of claim 2,
and a pad electrode on the substrate and made of the same material as the auxiliary electrode. 4. The method of claim 3,
The source electrode, the drain electrode, the auxiliary electrode, and the pad electrode have a multilayer structure including MoTi, Cu, and ITO. 4. The method of claim 3,
The pad electrode, the source electrode, the drain electrode, and the auxiliary electrode are on the same plane. delete The method of claim 1,
Further comprising a bank layer disposed on the pixel electrode,
At least a portion of the inclined surface of the contact hole is formed of the bank layer. The method of claim 1,
The organic light emitting layer is discontinuous in the undercut of the contact hole. 9. The method of claim 8,
The common electrode is electrically connected to the auxiliary electrode inside the undercut shape of the contact hole. forming a driving device and an auxiliary electrode on a substrate;
forming a protective layer and a planarization layer on the driving device; and
forming a pixel electrode, an organic light emitting layer, and a common electrode on the planarization layer; includes
The step of forming the protective layer and the planarization layer,
opening the auxiliary electrode and forming a contact hole having an undercut shape on one side and an inclined surface shape on the other side;
The step of forming the contact hole,
forming the inclined surface shape such that the passivation layer protrudes inwardly of the contact hole rather than the planarization layer to form a step shape formed of the passivation layer and the planarization layer; and
and forming the undercut shape such that an upper end of the passivation layer disposed under the planarization layer is retracted outwardly of the contact hole from a lower end of the planarization layer to form an eaves shape. 11. The method of claim 10,
The step of forming the driving device and the auxiliary electrode,
forming a gate electrode of the driving device; and
and simultaneously forming the source electrode, the drain electrode, the auxiliary electrode, and the pad electrode of the driving device using the same material. 12. The method of claim 11,
The step of forming the source electrode, the drain electrode, the auxiliary electrode and the pad electrode,
applying MoTi, Cu and ITO; and
and patterning the MoTi, the Cu, and the ITO by etching. 11. The method of claim 10,
The forming of the pixel electrode, the organic light emitting layer, and the common electrode includes forming a bank layer on the pixel electrode.

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