KR20140087914A - Organic Light Emitting Diode Display Device and Method for Manufacturing The Same - Google Patents

Abstract

An organic electro luminescent light emitting display device according to an embodiment of the present invention includes a first substrate defined by a plurality of pixels; thin film transistors formed in pixels of the substrate, respectively; anode electrodes formed in pixels of the substrate, respectively, and including reflective layers connected to the thin film transistors; a bank layer formed on the anode electrodes and overlapping the peripheries of the anode electrodes to define light emitting areas of the pixels; an organic light emitting layer formed in the light emitting areas of the anode electrodes; cathode electrodes formed on the organic light emitting layer; and a second substrate covering an entire surface of the first substrate including the cathode electrodes. Each of the pixels includes a transparent area and an opaque area, the thin film transistor is formed in the opaque area, and the anode electrode is formed in the transparent area and the opaque area.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display and a method of manufacturing the same, and more particularly, to an active organic light emitting display and a method of manufacturing the same.

As the information society becomes more sophisticated, the technology of display devices for displaying information has been developed. Particularly, in recent years, a lightweight, thin flat panel display has been spotlighted in place of a heavy and bulky cathode ray tube (CRT). Flat panel displays are becoming more thin and more portable. In particular, organic electroluminescent display devices, which are attracting attention as liquid crystal display devices, are self-luminous devices, which do not require a backlight, and are thinner and lighter than flat liquid crystal display devices. Further, the organic light emitting display device is an eco-friendly flat panel display device having a wide viewing angle, excellent contrast ratio, quick response time and low power consumption.

In addition, the organic light emitting display device is suitable for realizing a transparent or flexible flat panel display device because it does not need a backlight and emits light by an organic material. When the substrate is formed of a flexible material through which light is transmitted and each electrode is formed of a metal thin film, it is possible to realize a transparent and flexible flat panel display device which is easy to bend and allows light to transmit through the entire surface of the substrate .

In particular, the transparent organic electroluminescent display device forms a transparent region through which light is transmitted and can be seen to the background of the back side when not emitting light, and can be used for a window capable of displaying various information and a show window for displaying advertisement images.

1 is a cross-sectional view illustrating a portion of a general organic light emitting display device.

1, a general organic light emitting display includes a first substrate 101, a second substrate 102, a thin film transistor TR, an insulating layer 110, an anode electrode 120, a bank layer B, an organic light emitting layer 130, a cathode electrode 140, and an intermediate layer 150.

In particular, the organic light emitting display shown in FIG. 1 may be a transparent organic light emitting display.

First, a thin film transistor TR and an insulating layer 110 are sequentially formed on a transparent first substrate 101. The drawing shows one pixel, and the pixel is divided into a transparent region T / A and an opaque region O / A. The thin film transistor TR is formed in the opaque region O / A and the driving wiring including the thin film transistor TR is also formed in the opaque region O / A. In the transparent region T / A, nothing is formed except the transparent insulating layer 110 and the intermediate layer 150.

Next, the anode electrode 120 is formed on the insulating layer 110, and is connected to the thin film transistor TR. The bank layer B is formed at the edge of the anode electrode 120 to define the light emitting region E / A. An organic light emitting layer 130 and a cathode electrode 140 are formed on the anode electrode 120 of the light emitting region E / A. The organic light emitting layer 130 and the cathode electrode 140 are not formed in the transparent region, so that the transmittance of light in the transparent region can be increased.

FIG. 2 is a plan view when a general organic light emitting display device is in a non-light emitting mode. In the opaque region O / A excluding the transparent region T / A, external light is not transmitted.

Fig. 3 is a plan view in the light emitting mode. In the transparent region T / A except for the light emitting region E / A, external light is still transmitted. Even when the organic electroluminescence display device is driven in the light emission mode, since the transparent region T / A is present on the side surface of the light emitting region E / A, the contrast ratio is lowered and the visibility may be lowered.

In such a transparent organic electroluminescent display device, a pixel is divided into a transparent region T / A and a light emitting region E / A. In particular, the area of the light emitting region E / A is reduced to form the transparent region T / A, and the brightness can be reduced. In addition, when the transparent region T / A is increased to increase the transparency, the emission ratio E / A is relatively decreased, so that the contrast ratio is further reduced, which may cause visibility problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic electroluminescent display device capable of improving visibility.

According to an aspect of the present invention, there is provided an organic light emitting display including a first substrate defined by a plurality of pixels; A thin film transistor formed for each pixel on the substrate; An anode electrode formed for each pixel on the substrate and including a reflective layer connected to the thin film transistor; A bank layer formed on the anode electrode and overlapping an edge of the anode electrode to define a light emitting region of the pixel; An organic light emitting layer formed in the light emitting region on the anode electrode; A cathode electrode formed on the organic light emitting layer; And a second substrate covering the entire surface of the first substrate including the cathode electrode, wherein the pixel includes a transparent region and an opaque region, the thin film transistor is formed in an opaque region, Region and the non-transparent region.

According to another aspect of the present invention, there is provided a method of fabricating an organic light emitting display, including: forming a thin film transistor for each pixel on a first substrate defined by a plurality of pixels; Forming an anode electrode connected to the thin film transistor for each pixel; Forming a bank layer so as to overlap with the anode electrode at an edge; Forming an organic light emitting layer on the anode electrode; Forming a cathode electrode on the organic light emitting layer; And forming a second substrate over the entire surface of the first substrate including the cathode electrode, wherein the pixel includes a transparent region and an opaque region, the thin film transistor is formed in the opaque region, And the anode electrode is formed in the transparent region and the opaque region.

According to the present invention, there is an effect that luminance can be improved by extending the light emitting region to the transparent region.

Further, according to the present invention, there is an effect that the visibility can be improved by increasing the area of the light emitting region.

Further, according to the present invention, it is possible to increase the area of the light emitting region while maintaining the transparent region constant, and to improve the contrast ratio.

1 is a cross-sectional view illustrating a conventional organic light emitting display device;
FIG. 2 is a plan view illustrating a conventional organic light emitting display device in a non-light emitting mode; FIG.
3 is a plan view of a conventional organic light emitting display device in a light emitting mode;
4 is a cross-sectional view illustrating an organic light emitting display according to an exemplary embodiment of the present invention;
FIG. 5 is a plan view illustrating an organic light emitting display according to an exemplary embodiment of the present invention in a non-light emitting mode; FIG.
FIG. 6 is a plan view illustrating an organic light emitting display according to an exemplary embodiment of the present invention in a light emitting mode; FIG.
7 is a cross-sectional view illustrating an organic light emitting display device according to another embodiment of the present invention;
FIG. 8 is a plan view illustrating an organic light emitting display according to another embodiment of the present invention in a non-light emitting mode; FIG. And
9 is a plan view showing an organic light emitting display according to another embodiment of the present invention in a light emitting mode.

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

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

4, an organic light emitting display according to an exemplary embodiment of the present invention includes a first substrate 201, a second substrate 202, a thin film transistor TR, an insulating layer 210, And includes an electrode 220, a bank layer B, an organic light emitting layer 230, a cathode electrode 240 and an intermediate layer 250. The organic light emitting display may be a transparent organic light emitting display.

First, the first substrate 201 and the second substrate 202 may be made of glass or a metal including any one of aluminum (Al) and copper (Cu). In addition, the first substrate 201 and the second substrate 202 may be a flexible material or a transparent material that can be bent. For example, the first substrate 201 and the second substrate 202 may be formed of a material selected from the group consisting of polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate , polyethylenenaphthalate, polyethylene terephthalate (PET), and the like.

Next, a thin film transistor TR is formed on the first substrate 201. [ The thin film transistor TR may include a switching thin film transistor (not shown) and a driving thin film transistor (not shown). Since the organic light emitting display device is a current driving device, two or more thin film transistors are required as described above.

The switching thin film transistor inputs a data signal to the driving thin film transistor according to the gate signal, and the driving thin film transistor transmits the power supply voltage to the anode electrode 220 according to the inputted data signal.

As described above, the two or more thin film transistors TR must be connected to each other by a metal wiring in order to transmit and receive signals. In addition to the thin film transistor TR, the thin film transistors TR are also connected to circuit elements such as a storage electrode, Must be connected. And is connected to the anode electrode 220 in the case of the driving thin film transistor. In addition, in order to receive a gate signal, a data signal, and the like, various metal wirings must be formed and connected to the driving circuit substrate.

As described above, the driving circuit unit for driving the organic light emitting display device is formed of metal and may be formed as a multilayer. Therefore, the driving circuit portion may be an opaque region in which light is not transmitted.

On the other hand, if the driver circuit portion of the opaque region is formed on one side of the pixel, the remaining portion can be formed as a transparent region. A transparent organic electroluminescent display device can be realized by the above-described method.

Next, an insulating layer 210 is formed on the thin film transistor TR. The insulating layer 210 may be formed of a material having high insulation and transparency such as silicon oxide (SiOx) or silicon nitride (SiNx). Alternatively, the insulating layer 210 may be formed of a material having the same or similar refractive index as that of the first substrate 201 and the second substrate 202, thereby reducing optical loss due to total internal reflection.

The insulating layer 210 may serve as a protective layer for protecting the driving circuit portion while insulating the driving circuit portion including the thin film transistor TR from other elements.

Next, an anode electrode 220 is formed on the insulating layer 210. The anode electrode 220 may be formed in most regions of the pixel over the transparent region T / A and the opaque region O / A.

The anode electrode 220 may preferably include a reflective layer 221 and a transparent layer 222. The reflective layer 221 may be formed earlier or the transparent layer 222 may be formed earlier, but preferably the reflective layer 221 may be formed earlier. The reflective layer 221 may form a microcavity structure with the cathode electrode 240 to improve light extraction efficiency. Also, the reflective layer 221 may be formed of a metal having a thickness that does not transmit light, and may be formed in the opaque area O / A. On the other hand, the transparent layer 222 may be formed over the transparent region T / A and the opaque region O / A. When the transparent region T / A is in the light emission mode, it can also emit light in the transparent region T / A to increase the light emitting area.

The reflective layer 221 may be formed on the insulating layer 210 and connected to the thin film transistor TR. The reflective layer 221 may include any one of silver (Ag), aluminum (Al), neodymium (Nd), molybdenum (Mo), and titanium (Ti) having high reflectance. Further, the reflective layer 221 may be formed to have a thickness of micrometer unit or less in transparency in order to more reflect the emitted light emitted from the organic light emitting layer 230, but is not limited to the above description.

The transparent layer 222 may be formed on the reflective layer 221 to be in contact with the organic light emitting layer 230 and may be formed of a material having a large work function to supply holes to the organic light emitting layer 230. The transparent layer 222 may include any one of indium tin oxide (ITO), indium zinc oxide (ITO), and indium tin zinc oxide (ITO).

Next, the bank layer B is formed so as to overlap the edge region of the anode electrode 220. The bank layer B is formed on the anode electrode 220 to define a light emitting region E / A. Since the light emitting region E / A occupies almost all of the pixels, the bank layer B can be formed only in the region corresponding to the boundary line of the pixel.

Next, an organic light emitting layer 230 is formed on the anode electrode 220. [ The organic light emitting layer 230 may be formed throughout the transparent region T / A and the opaque region O / A, and may be the same as the region where the anode electrode 220 is formed. The region where the anode 220 and the organic light emitting layer 230 are in contact with each other may be the light emitting region E / A.

The organic light emitting layer 230 may be formed separately for each pixel or may be connected to the entire surface of the first substrate 201 while covering the bank layer B. [

The organic light emitting layer 230 is a place where holes transmitted from the anode electrode 220 meet electrons transmitted from the cathode electrode 240. The holes and the electrons combine with each other to form an exciton, And emits light having a wavelength equal to the band gap energy of the material for forming the organic light emitting layer 230.

Next, a cathode electrode 240 is formed on the organic light emitting layer 230. The cathode electrode 240 may be formed of a material having a small work function so as to supply electrons to the organic light emitting layer. For example, the cathode electrode may be formed of a metal or an alloy containing any one of silver (Ag), copper (Cu), aluminum (Al), and lithium (Li). In the case of the top surface emission type, since the light emitted from the organic light emitting layer is emitted in the direction of the cathode electrode, the cathode electrode may be a semi-transparent thin film in which the metal or alloy is formed as a very thin film.

The cathode electrode 240 may be formed over the transparent region T / A and the opaque region O / A in the same manner as the anode electrode 220 and the organic light emitting layer 230 and may be formed to cover the bank layer B . Since the cathode electrode 240 can be formed also in the transparent region T / A, the transparency of the cathode electrode 240 can affect the transparency of the transparent region T / A. Therefore, the cathode electrode 240 can be formed as a very thin film as described above so that the transmittance of the external light and the internally emitted light can be increased.

Next, an intermediate layer 250 may be interposed between the cathode electrode 240 and the second substrate 202 to adhere the second substrate 202 to the first substrate 201. The intermediate layer 250 may be an inorganic or organic material having the same refractive index as that of the first substrate 201 and the second substrate 202. The loss of the external light transmitted through the first substrate 201 and the second substrate 202 or the emission light emitted from the organic light emitting layer 230 can be reduced and the transparency of the transparent region T / And the brightness of the emitted light emitted from the light emitting region E / A can be improved.

A method of manufacturing an organic light emitting display according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 and 2. A thin film transistor TR is formed for each pixel on a first substrate 201, which is defined as a plurality of pixels. A driving circuit portion including the thin film transistor TR may be formed. The region where the thin film transistor TR and the driving circuit are formed may be preferably an opaque region O / A.

Next, an insulating layer 210 is formed on the thin film transistor TR to protect the thin film transistor TR and the driving circuit portion and isolate the thin film transistor TR and the anode electrode 220 from each other. The insulating layer 210 is patterned to expose a part of the thin film transistor TR and then the reflective layer 221 and the transparent layer 222 are sequentially formed on the insulating layer 210 to form the anode electrode 220. The order of forming the reflective layer 221 and the transparent layer 222 may be changed. When the reflective layer 221 is formed first, the thin film transistor TR may be connected to the reflective layer 221. When the transparent layer 222 is formed first, the transparent layer 222 may be connected to the thin film transistor TR. The reflective layer 221 is preferably formed in the opaque region O / A and the transparent layer 222 may be formed over the pixel preferably including the opaque region O / A and the transparent region T / A .

Next, the organic light emitting layer 230 and the cathode electrode 240 are sequentially formed in the light emitting region E / A on the anode electrode 220. [ The organic light emitting layer 230 and the cathode electrode 240 may be formed only in the light emitting region E / A or may cover the light emitting region E / A as well as the bank layer B.

Next, an intermediate layer 250 may be formed, and the second substrate 202 may be formed to cover the entire surface of the first substrate 201 via the intermediate layer 250. The intermediate layer 250 may be formed of a material that is preferably transparent so that external light can be transmitted through the transparent region T / A. And may include an adhesive material for adhesion of the second substrate 202. The intermediate layer 250 may be formed of at least one of the first substrate 201 and the second substrate 202 and a refractive index of at least one of the first substrate 201 and the second substrate 202 to reduce light loss of the external light transmitted through the intermediate layer 250 and the light emitted from the organic light- Is formed of the same material.

5 is a plan view illustrating an organic light emitting display according to an exemplary embodiment of the present invention in a light emitting mode.

As shown in FIG. 5, in the non-light emitting mode, a transparent region T / A having an area similar to that of a general organic light emitting display may be formed, so that external light can be transmitted through the transparent region T / A. The area of the transparent region T / A can be slightly increased as compared with the area of the existing transparent region T / A since the bank layer B is not formed in the central portion of the pixel.

FIG. 6 is a plan view illustrating an organic light emitting display according to an exemplary embodiment of the present invention in a light emitting mode. Referring to FIG.

As shown in FIG. 6, in the light emitting mode, the light emitting region E / A may occupy most of the pixel region. In the light emitting mode, the light emitting region E / A is formed in a region where the anode electrode 220 and the organic light emitting layer 230 are formed, since the region where the anode electrode 220 and the organic light emitting layer 230 are in contact is the light emitting region E / . ≪ / RTI > Or the light emitting region E / A may be the same as the formation region of the cathode electrode 240. In addition, the region excluding the light emitting region (E / A) may coincide with the region where the bank layer (B) is formed.

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

As shown in FIG. 7, the organic light emitting display device according to another embodiment of the present invention further includes a sub-bank layer SB at the center of the light emitting region E / A.

Since the anode electrode 220 includes the reflection layer 221 formed in the opaque region O / A, the transparent electrode layer 220 is formed on the reflective layer 221 corresponding to the boundary between the transparent region T / A and the opaque region O / The transparent layer 222, the organic light emitting layer 230, and the cathode electrode 240 may be formed in a stepped manner. At this time, the anode electrode 220 and the cathode electrode 240 may have regions similar to the peaks or tangents. When the anode electrode 220 and the cathode electrode 240 are formed with an apex, the charge has a characteristic of being attracted to a peak, so that more emitted light can be emitted from the organic light emitting layer 230 in the vicinity of the peak region. Since this may cause a luminance unbalance in the pixel, it is possible to further form the auxiliary bank layer SB near the peak.

The auxiliary bank layer SB is formed at a position corresponding to the boundary between the transparent region T / A on the anode electrode 220 and the opaque region O / A, and preferably overlaps the edge region of the reflective layer 221 And may be formed on the transparent layer 222 to cover the stepped region of the anode electrode 220. [ Further, the auxiliary bank layer SB may be formed of the same material at the same time when the bank layer B is formed.

8 is a plan view illustrating an organic light emitting display according to another embodiment of the present invention in the non-light emitting mode of the present invention.

As shown in FIG. 8, in the non-light emitting mode, external light can pass through the transparent region T / A and external light can not pass through the opaque region O / A. The auxiliary bank layer SB is formed at the center of the pixel, and the transparent region T / A and the light emitting region E / A are not formed.

9 is a plan view showing an organic light emitting display according to another embodiment of the present invention in a light emitting mode.

The entire region of the pixel except for the edge region of the pixel where the bank layer B is formed and the center of the pixel where the auxiliary bank layer SB is formed may be formed as the light emitting region E / A, as shown in Fig. 9 . If the auxiliary bank layer SB is formed with a minimum area, the luminescent region E / A can be increased by that much, and the luminance can be improved.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

201: first substrate 202: second substrate
210: insulating layer 220: anode electrode
221: reflective layer 222: transparent layer
230: organic light emitting layer 240: cathode electrode
250: intermediate layer TR: thin film transistor
B: bank layer

Claims (9)

A first substrate defined by a plurality of pixels;
A thin film transistor formed for each pixel on the substrate;
An anode electrode formed for each pixel on the substrate and including a reflective layer connected to the thin film transistor;
A bank layer formed on the anode electrode and overlapping an edge of the anode electrode to define a light emitting region of the pixel;
An organic light emitting layer formed in the light emitting region on the anode electrode;
A cathode electrode formed on the organic light emitting layer; And
And a second substrate covering the entire surface of the first substrate including the cathode electrode,
Wherein the pixel includes a transparent region and an opaque region, the thin film transistor is formed in an opaque region, and the anode electrode is formed in the transparent region and the opaque region. The method according to claim 1,
Wherein the reflective layer is formed in an opaque region. The method according to claim 1,
Wherein the anode electrode further comprises a transparent layer formed on the reflective layer, and the transparent layer is formed in the transparent region and the opaque region. The method according to claim 1,
The organic light emitting display device includes:
And an auxiliary bank layer is further formed on the anode electrode corresponding to a boundary between the transparent region and the opaque region. 5. The method of claim 4,
And the auxiliary bank layer overlaps the edge of the reflective layer. Forming a thin film transistor for each pixel on a first substrate defined by a plurality of pixels;
Forming an anode electrode connected to the thin film transistor for each pixel;
Forming a bank layer so as to overlap with the anode electrode at an edge;
Forming an organic light emitting layer on the anode electrode;
Forming a cathode electrode on the organic light emitting layer; And
And forming a second substrate to cover the entire surface of the first substrate including the cathode electrode,
Wherein the pixel includes a transparent region and an opaque region, the thin film transistor is formed in the opaque region, and the anode electrode is formed in the transparent region and the opaque region. The method according to claim 6,
Wherein the step of forming the anode electrode comprises:
Forming a reflective layer connected to the thin film transistor in the opaque region; And
And forming a transparent layer on the transparent region and the opaque region on the reflective layer. 8. The method of claim 7,
In the step of forming the bank layer,
And forming an auxiliary bank layer so as to overlap the edge region of the reflective layer on the anode electrode corresponding to a boundary between the transparent region and the opaque region. 9. The method of claim 8,
Wherein the bank layer and the auxiliary bank layer are formed at the same time.

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