KR20170005252A - Organic light emitting display device with light-scattering layer in electrode - Google Patents

Abstract

The present invention relates to an organic light emitting display device including a scattering layer in an electrode and a manufacturing method thereof. According to an aspect of the present invention, provided is the organic light emitting display device which includes an overcoat layer on which a plurality of micro lenses are arranged, an anode electrode which is arranged in contact with the micro lenses of the overcoat layer, an organic light emitting layer, and a cathode electrode. The anode electrode and the organic light emitting layer have curvatures according to the shape of the micro lens. Accordingly, the present invention can improve luminous efficiency by arranging the scattering layer on the organic light emitting display device or a display panel.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting diode (OLED) display device and a method of manufacturing the OLED display device,

The present invention relates to an organic light emitting display device including a scattering layer on an electrode and a method of manufacturing the same.

2. Description of the Related Art [0002] As an information-oriented society develops, there have been various demands for a display device for displaying images. Recently, a liquid crystal display (LCD), a plasma display panel (PDP) Various display devices such as an organic light emitting display (OLED) and the like are being utilized. Such various display apparatuses include display panels corresponding thereto.

Thin film transistors are formed in each pixel region of the display panel, and a specific pixel region in the display panel is controlled through the current flow of the thin film transistor. The thin film transistor is composed of a gate and a source / drain electrode.

In the organic light emitting diode display, a light emitting layer is formed between two different electrodes. When electrons generated in one electrode and holes generated in another electrode are injected into the light emitting layer, the injected electrons and holes are combined to form an exciton ) Is generated, and the generated exciton emits light while falling from an excited state to a ground state, thereby displaying an image.

On the other hand, a scattering layer may be included in the panel to transmit the light of the light emitting layer to the outside. It is necessary that the inclination angle of the scattering layer has a slope to induce total reflection of light.

In view of the foregoing, it is an object of the present invention to increase the light efficiency by disposing a scattering layer on an organic light emitting display or a display panel.

It is also an object of the present invention to arrange a scattering layer on an overcoat so that the anode disposed on the overcoat layer is used as an anode and as a reflector for scattering light to increase light efficiency.

In particular, in order to increase the reflection of the anode, the present invention places a scattering layer maintaining a high angle of the slope.

It is another object of the present invention to provide a display panel in which a scattering layer is disposed on a display panel to eliminate the phenomenon that light emitted from the organic light emitting layer is totally reflected in the ITO and the organic light emitting layer and is confined in the display panel, We want to increase the light efficiency through the progress of light and multiple reflections.

In order to achieve the above object, in one aspect, the present invention provides a liquid crystal display comprising an overcoat layer in which a plurality of microlenses are arranged, an anode electrode arranged in contact with the microlens of the overcoat layer, an organic light emitting layer and a cathode electrode, And the organic light emitting layer has a curvature according to the shape of the microlens.

The present invention also provides a method of manufacturing an organic light emitting display device in which a microlens array is formed on the overcoat layer corresponding to a light emitting region of a subpixel on a substrate, and an anode electrode, an organic light emitting layer, and a cathode electrode are formed on the overcoat layer to provide.

As described above, according to the present invention, a scattering layer is disposed on a display panel to eliminate the phenomenon that the light emitted from the organic light emitting layer is trapped while being totally reflected within the ITO and the organic light emitting layer.

According to the present invention, the light extraction efficiency can be improved by the array pattern by the microlens array pattern disposed in the overcoat layer below the anode electrode.

Further, according to the present invention, since the optical path changes by the microlens array disposed on the overcoat layer and is reflected to the outside of the organic light emitting layer, the lifetime of the organic light emitting layer can be improved.

1 is a view schematically showing a display device according to embodiments.
Figure 2 is a top emission configuration in which an embodiment of the present invention is applied.
3 is a cross-sectional view of a substrate on which a microlens array according to an embodiment of the present invention is disposed on an overcoat layer.
FIG. 4 is a view showing in more detail the area where the microlens array is arranged according to an embodiment of the present invention.
5 is a view showing a configuration in which microlenses having hexagonal depressions are arranged according to an embodiment of the present invention.
FIG. 6 is a three-dimensional view illustrating an overcoat layer on which the microlenses of FIG. 4 are arranged according to an embodiment of the present invention.
FIG. 7 is a three-dimensional view showing an overcoat layer on which the microlenses of FIG. 5 are arranged according to another embodiment of the present invention.
FIG. 8 is a three-dimensional view showing an overcoat layer in which microlenses having a rectangular depression are arranged according to another embodiment of the present invention.
FIGS. 9 to 11 are views showing masks for forming the recessed microlenses.
FIG. 12 is a view showing a non-emission region when the microlens array is not disposed under the anode electrode.
13 is a view illustrating a process of manufacturing an OLED display according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In the drawings, like reference numerals are used to denote like elements throughout the drawings, even if they are shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the components from other components, and the terms do not limit the nature, order, order, or number of the components. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; intervening "or that each component may be" connected, "" coupled, "or " connected" through other components.

1 is a view schematically showing a display device according to embodiments.

Referring to FIG. 1, a display device 100 according to an embodiment includes a plurality of first lines VL1 to VLm formed in a first direction (e.g., a vertical direction) A display panel 110 on which a plurality of second lines HL1 to HLn are formed, a first driver 120 for supplying a first signal to a plurality of first lines VL1 to VLm, A second driver 130 for supplying a second signal to the first and second lines HL1 to HLn and a timing controller 140 for controlling the first and second drivers 120 and 130.

The display panel 110 is provided with a plurality of first lines VL1 to VLm formed in a first direction (e.g., a vertical direction) and a plurality of second lines HL1 to HLn formed in a second direction (e.g., A plurality of pixels (P) are defined according to the intersection of the pixels.

Each of the first driving unit 120 and the second driving unit 130 may include at least one driver IC for outputting a signal for displaying an image.

A plurality of first lines VL1 to VLm formed in the first direction on the display panel 110 are formed in a vertical direction (first direction) to transmit a data voltage (first signal) And the first driver 120 may be a data driver for supplying the data voltage to the data line.

A plurality of second lines HL1 to HLn formed in the second direction on the display panel 110 are formed in a horizontal direction (second direction) to form a gate signal (first signal) And the second driver 130 may be a gate driver for supplying a scan signal to the gate line.

In addition, a pad portion is formed on the display panel 110 to connect the first driver 120 and the second driver 130. When the first driver 120 supplies a first signal to the plurality of first lines VL1 through VLm, the pad unit transmits the first signal to the display panel 110 and the second driver 130 similarly applies a plurality of second lines HL1 to HLn), and transmits the second signal to the display panel (110).

Each pixel includes one or more subpixels. The sub-pixel means a unit in which a specific kind of color filter is formed, or a color filter is not formed and the organic light emitting element can emit a specific color. (R), green (G), blue (B), and optionally white (W) as the color defined by the sub-pixel, but the present invention is not limited thereto. Since each sub-pixel includes a separate thin-film transistor and an electrode connected thereto, the sub-pixels constituting the pixel are also referred to as one pixel region. A first line may be arranged for each sub-pixel, and a plurality of sub-pixels constituting the pixel may share a specific first line. The configuration of the pixel / sub-pixel and the first line / second line may be variously modified and the present invention is not limited thereto.

An electrode connected to a thin film transistor for controlling light emission of each pixel region of a display panel is referred to as a first electrode and an electrode disposed on the entire surface of the display panel or arranged to include two or more pixel regions is referred to as a second electrode. When the first electrode is an anode electrode, the second electrode is a cathode electrode, and vice versa. Hereinafter, the anode electrode will be described as an embodiment of the first electrode, and the cathode electrode will be described as an example of the second electrode, but the present invention is not limited thereto.

In the above-described sub-pixel region, a color filter of a single color is disposed or not disposed. The color filter converts the color of a single organic light emitting layer into a color of a specific wavelength. In addition, a light-scattering layer may be disposed in each sub-pixel region to enhance light extraction efficiency of the organic light emitting layer. The above-described scattering layer can be indicated by a microlens array, a nano pattern, a diffuse pattern, or a silica bead.

Figure 2 is a top emission configuration in which an embodiment of the present invention is applied. A buffer 202 is disposed on the substrate 201 and an active layer 205, a gate insulator 207, a gate 210, an interlayer insulating layer 215, a source and a drain 220 A passivation layer 225, a first planarization layer 227 and a connection electrode 230 connected to the source or drain 220, a second planarization layer 235, A source or a drain 220 and an active 205 are connected through an anode 240 and a contact hole 218 formed in an interlayer insulating film 215. [ A bank 250, an organic emission layer 270, and a second electrode or a cathode 280 are disposed. The connection electrode 230 is selectively disposed and when the connection electrode 230 is not provided, the anode 240 may be directly connected to the source or drain 220.

2, an organic light emitting layer 270 (or an organic layer) is deposited on a first electrode 240 formed as a reflective electrode in a top emission structure that emits light in an upper (top) ). The optical waveguide mode composed of the surface plasmon component generated at the boundary between the metal and the organic layer and the organic layer inserted into the both reflection layers accounts for 60 to 70% of the emitted light. Light is not emitted and trapped in the organic light emitting layer. To solve this problem, it is necessary to totally reflect light to emit light to the outside. However, when the organic light emitting layer 270 is arranged in a plane as shown in FIG. 2, total reflection of light can not be induced.

In this specification, a scattering layer is disposed in the first electrode 240, the organic light emitting layer 270, and the second electrode 280 in order to induce total reflection of the light confined in the organic light emitting layer 270 to enhance the light emitting efficiency. In particular, the irregularities are disposed on the planarization layer, for example, the overcoat layer, disposed under the first electrode 240 for this purpose. In order to increase the light efficiency, the slope (slope) of the concave and convex can be increased, and a negative mask can be used for this purpose. Hereinafter, the microlens array will be described as an embodiment of the scattering layer, but the present invention is not limited thereto, and various structures for scattering light may be combined.

3 is a cross-sectional view of a substrate on which a microlens array according to an embodiment of the present invention is disposed on an overcoat layer. As indicated above, a microlens is disposed on the planarization layer, for example, the overcoat layer 235, as indicated at 310, and the anode 240, the organic emission layer 270, and the cathode (Not shown). The anode 240, the organic emission layer 270, and the cathode 280 are disposed in contact with a portion of the microlens recessed with the wall. The anode electrode is electrically connected to the source or the drain of the thin film transistor as shown in FIG. 2, and the present invention is not limited to the structure of the specific thin film transistor.

3, the anode electrode 240 and the organic light emitting layer 270 are disposed on the front surface, and there is no portion where the organic light emitting layer 270 is discontinuously disconnected. Therefore, light extraction An improvement in efficiency can be obtained. Since the microlens array pattern according to an embodiment of the present invention is a pattern disposed in the layer of the overcoat 235 below the anode electrode (lower electrode), the anode electrode is interposed between the organic light emitting layers 270 so as not to outgas the material of the overcoat layer. The device reliability of the organic light emitting layer 270 is improved.

In the OLED display device of the top emission type, the light trapped in the organic emission layer is more than 60% due to the structure in which the organic emission layer is formed between the lower reflection electrode and the upper semi-transparent electrode. However, The light path is changed by the microlens array disposed on the overcoat layer and is reflected to the outside of the organic light emitting layer, thereby improving the light emitting efficiency. Since there is no disconnection between the organic light emitting layer and the anode electrode due to the microlenses disposed in the overcoat layer, the light emitting efficiency can be increased without reducing the light emitting area.

FIG. 4 is a view showing in more detail the area where the microlens array is arranged according to an embodiment of the present invention. 401 is an enlarged view of the portion 310 of FIG. 402 is a plan view of the microlens corresponding to the cross section. And 402 is a plan view of the microlens arranged in the overcoat layer. The anode electrode 240, the organic light emitting layer 270, and the cathode 280 are also disposed on the wall 410b between the depressions 420a and 420b of the microlens. Accordingly, even if the light of the depressions 420a and 420b is totally reflected as in 411, the light can be emitted upward from the walls 410a and 410b of the microlens to increase the light efficiency.

As shown in FIG. 4, when the embodiment of the present invention is applied, light emitted into the organic emission layer 270 formed between the lower reflective electrode 240 and the upper semi-transparent electrode 280 in the top emission OLED (top emission OLED) It can be extracted to the outside of the device. For this, the angle between the walls 410a, 410b, and 410c of the microlenses and the depressions 420a and 420b can be increased. As shown in FIG. 4, the pattern of the microlens array having a large slope By forming under the reflective electrode 240 (anode electrode), a significant amount of light confined in the device due to total internal reflection, such as 411, is significantly improved in light emission efficiency due to a change in the optical path through the slope portion 415 of the microlens through reflection.

When the present invention is applied, a microlens formed by a depression and a wall may be disposed so as to increase the slope to increase light emission efficiency. The shape of the depressed portion may be variously configured, for example, a circle, a hexagon, a square, or a triangle. In FIG. 4, the case where the depression is circular is described.

5 is a view showing a configuration in which microlenses having hexagonal depressions are arranged according to an embodiment of the present invention. The shape of the depressed portion is hexagonal like 502, and the entire microlenses are arranged in a hexagonal shape. And the area where the distance between the microlenses is large is configured to have a wide width of the wall of the microlens.

As described above, the angle between the depression and the wall, that is, the angle formed by the wall with the horizontal plane of the depressed portion of the overcoat layer is 60 degrees or more, so that the light totally reflected inside the device can be extracted to the outside, .

FIG. 6 is a three-dimensional view illustrating an overcoat layer on which the microlenses of FIG. 4 are arranged according to an embodiment of the present invention. And a wall is disposed between the depressions to form a path through which light can be guided.

FIG. 7 is a three-dimensional view showing an overcoat layer on which the microlenses of FIG. 5 are arranged according to another embodiment of the present invention. And a wall is disposed between the depressions to form a path through which light can be guided. As shown in FIG. 7, in the case of a hexagonal structure, the microlenses can be densely arranged.

FIG. 8 is a three-dimensional view showing an overcoat layer in which microlenses having a rectangular depression are arranged according to another embodiment of the present invention. And a wall is disposed between the depressions to form a path through which light can be guided. In the case of a quadrilateral structure as shown in FIG. 8, the microlenses can be densely arranged. Further, even in the case of a triangular or rhombic depression, the thickness of the wall of the microlens can be kept constant.

Therefore, a polygonal or circular shape can be applied to arrange the recessed microlenses, and the shape of the microlenses can be configured by controlling the exposure amount and the exposure time.

As shown in FIGS. 4 to 8, the present invention is applied to microlenses having irregular depressions other than triangular, rhombic, or specific shapes in addition to hexagonal, circular, and rectangular microlenses. Also, the depression need not necessarily be a closed curve, but may have a depression of an open curve.

Circles, polygons, squares and the like can be selected in consideration of the distance between the microlenses, the height of the microlens, and the like. Further, in order to deposit the anode electrode and the organic light emitting layer, the shape of the microlens may be variously selected according to the exposure amount and the exposure time, and the present invention is not limited thereto.

In the microlens having a polygonal or circular depression in the patterning process of the overcoat layer, since the wall for guiding the inside light to the outside is densely arranged, the light confined in the inside of the device is extracted to the outside of the device through multiple reflections and refractions, The light extraction efficiency can be improved.

As shown in FIGS. 4 to 8, since the microlenses are arranged on the overcoat layer, and the electrode layer and the organic light emitting layer are disposed on the microlenses, the light trapped in the device by the light wave mode represented by the reflective layer formed above and below the organic light emitting layer It can be extracted to the outside without reducing the area. Particularly, the microlens array pattern having a high angle of inclination can not only bend the surface but also reflect the light refracted through the reflection film deposited on the pattern to the outside, thereby improving the light extraction efficiency.

In order to largely constitute the slope of the wall of the microlens described above, an embodiment of the present invention can use a negative photoresist.

When a negative photoresist is used, the portion receiving the light is left, and the portion not receiving the light disappears. A reverse-phase mask for using a negative photoresist can be used, and the shape of a reverse-phase mask will be described with reference to FIG. 9 to FIG.

FIG. 9 is a view showing a mask for forming a circular recessed microlens as shown in FIG. 6. FIG. A material blocking light is disposed, such as 910, to create a recessed circular micro lens of FIG.

10 is a view showing a mask for forming a hexagonal recessed microlens as shown in FIG. A light blocking material is disposed 1010 to create a recessed hexagonal microlens of FIG.

11 is a view showing a mask for making a quadrangular recessed microlens as shown in FIG. In order to make the microlenses of the recessed hexagons of FIG. 8, a material blocking light is disposed, such as 1110.

9 to 11, a microlens having a large slope can be manufactured. 9 to 11, the microlens array can have a slope of 32 degrees or more so as to be larger than a total reflection critical angle of light extracted from the organic light emitting layer to the outside. Particularly, according to the present invention, a microlens having a slope of 60 degrees can be manufactured. After forming a microlens pattern on the overcoat layer, a reflective layer for providing the function of an anode electrode is deposited using a reflective electrode material, and an organic light emitting layer and a transflective electrode functioning as a cathode electrode are sequentially formed thereon, The external light extraction efficiency can be improved.

It is possible to obtain a shape having a curvature in the element surface itself without a region which does not emit light by the microlens array pattern formed under the lower electrode, that is, the anode electrode. Further, a scattering layer is formed on the ITO lower overcoat layer, and a microlens array is patterned on the overcoat layer to improve light extraction. Particularly, a scattering layer is formed by using a reverse phase mask and a negative photoresist to increase the taper angle of the wall according to the optimal conditions of the scattering layer, thereby preventing outcoupling and improving the reliability of the light emitting device. .

FIG. 12 is a view showing a non-emission region when the microlens array is not disposed under the anode electrode. A bank 250 is disposed to place the shape of the microlens on the anode 240. And the organic light emitting layer 270 is disposed on the bank. The region 1201 where the organic light emitting layer 270 and the anode 240 are in contact is a light emitting region and the region 1202 in which the organic light emitting layer 270 and the anode 240 are separated due to the bank 250 emits light I never do that. Accordingly, there is a problem that light emitted from the region 1201 is guided and diffused from the region 1202 to the outside, but there is a problem that the non-emission area is included in the whole area. This is caused by the region where the non-conductive microlens array pattern is disposed on the anode electrode and the anode electrode and the organic light emitting layer are not in contact with each other.

Since the emitted light is reflected at an angle that can be extracted to the outside of the device after being guided by the organic light emitting layer inside the device in addition to the problem caused by the decrease in the light emitting area, the power can be greatly reduced. In addition, outgassing problems arise because the banks are disposed between the organic light emitting layer and the metal electrode.

However, the microlens array pattern shown in FIGS. 3 to 5 of the present invention is disposed under the anode electrode. That is, after the microlens array pattern is disposed on the overcoat layer, since the anode electrode and the organic light emitting layer are deposited, the organic light emitting layer emits light in each region of the wall and depressed portion of the microlens.

As described above, when the present invention is applied, the total light efficiency can be increased by removing the non-light emitting region.

In the present invention, the refractive index and the taper angle of the wall of the microlens can be increased by using the reversed phase mask and the negative photoresist shown in Figs. 9 to 11. Particularly, in the present invention, since no separate material is disposed between the organic light emitting layer and the anode electrode, the outgassing problem is solved and the device reliability is improved.

In the embodiment of the present invention, the optical efficiency can be increased without complicated processes in the process of generating the OLED display panel through patterning for forming the microlenses in the overcoat layer. In one embodiment, the lifetime of the organic light emitting layer can be improved by increasing the light efficiency of the display panel when the microlenses are formed by patterning the overcoat layer in the top emission type.

13 is a view illustrating a process of manufacturing an OLED display according to an embodiment of the present invention. A thin film transistor for controlling a plurality of subpixels is formed on a substrate (S1310). Examples of a thin film transistor formed on a back plane to which the present invention can be applied include amorphous silicon, metal oxide and polysilicon, and polysilicon Low temperature polysilicon (LTPS) and high temperature polysilicon (HTPS), but the present invention is not limited thereto.

After the above-described thin film transistor is formed, an overcoat layer is formed on the thin film transistor (S1320). Then, a microlens array is formed on the overcoat layer corresponding to the emission region of the subpixel (S1330). At this time, as an embodiment of forming the microlens array, the overcoat layer can be formed using a negative photoresist and a reverse phase mask.

Then, an anode electrode electrically connected to a source or a drain of the thin film transistor is formed on the overcoat layer corresponding to the light emitting region of the subpixel (S1340). Since the microlens array is formed in the overcoat layer, the anode is arranged along the shape of such microlens array. Thereafter, an organic light emitting layer and a cathode electrode are formed (S1350). Since the organic light emitting layer and the cathode electrode are also arranged in accordance with the bending of the anode electrode in the light emitting region, the anode electrode, the organic light emitting layer, and the cathode electrode all have the shape of a microlens array of the overcoat layer, The light confined inside the device of the display panel can be extracted to the outside, thereby increasing the light efficiency of the display panel.

In an embodiment of the present invention, when patterning a microlens array on an overcoat layer, a taper angle of a shape of a wall in a microlens is increased by using a reverse phase mask and a negative photoresist, so that light generated in the organic light emitting layer is totally reflected by the electrode, It is possible to increase the light efficiency by allowing the inside of the device to be extracted outside the device.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the appended claims. , Separation, substitution, and alteration of the invention will be apparent to those skilled in the art. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: display device 110: display panel
120: first driving part 130: second driving part
140: timing controller 235: overcoat layer
240: anode electrode 270: organic light emitting layer
280: cathode electrode

Claims (8)

Board;
A plurality of thin film transistors arranged on the substrate;
An overcoat layer disposed on the thin film transistor and having a plurality of microlenses arranged therein;
An anode electrode disposed on the overcoat layer and disposed in contact with the microlens and electrically connected to a source or a drain of the thin film transistor;
An organic emission layer disposed on the anode electrode and having a curvature according to the shape of the microlens; And
And a cathode electrode disposed on the organic light emitting layer.
The method according to claim 1,
The microlens having a depression and a wall surrounding the depression,
And the angle between the wall and the horizontal plane of the overcoat layer is 60 degrees or more.
The method according to claim 1,
Wherein the depression of the microlens has a circular or polygonal shape.
The method according to claim 1,
Wherein the anode electrode is a reflective electrode, and the cathode electrode is a semi-transparent electrode.
The method according to claim 1,
And the organic light emitting layer disposed on the wall of the microlens emits light.
The method according to claim 1,
Wherein light of the organic light emitting layer totally reflected between the first microlens and the second microlens is emitted from the top of the first microlens or the wall of the second microlens.
Forming a thin film transistor for controlling a plurality of subpixels on a substrate;
Forming an overcoat layer on the thin film transistor;
Forming a microlens array in the overcoat layer corresponding to a light emitting region of the subpixel;
Forming an anode electrode electrically connected to a source or a drain of the thin film transistor on the overcoat layer corresponding to a light emitting region of the subpixel; And
And forming an organic light emitting layer and a cathode electrode.
8. The method of claim 7,
Wherein the step of forming the microlens array is formed by using a negative photoresist and a reverse phase mask in the overcoat layer.

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