KR20060074322A - Organic electro luminescence display and method for fabricating the same - Google Patents

Abstract

An organic light emitting display device in which a transparent moisture absorbent is deposited or coated on an upper substrate is provided. The organic light emitting display device includes a lower substrate on which an organic electroluminescent structure including a thin film transistor, a cathode electrode, an organic electroluminescent layer, and an anode electrode is formed, and an upper substrate on which at least a portion of a transparent absorbent layer is coated or deposited and encapsulated with a lower substrate. It includes. Also, a method of manufacturing an organic light emitting display device in which a transparent moisture absorbent is deposited or coated on an upper substrate is provided.

Organic electroluminescent display, moisture absorbent, coating, deposition, encapsulation

Description

Organic electroluminescent display and manufacturing method thereof {Organic electro luminescence display and method for fabricating the same}

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

2 is a flowchart illustrating a manufacturing process of an organic light emitting display device according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating a process of forming the organic electroluminescent structure of FIG. 2.

4 is a cross-sectional view illustrating a process of forming and attaching the upper substrate of FIG. 2.

(Explanation of symbols for the main parts of the drawing)

10: lower substrate 40: organic electroluminescent structure

50: upper substrate 60: moisture absorbent layer

70: adhesive

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display and a method of manufacturing the same, and more particularly, to an organic electroluminescent display and a method of manufacturing the same, in which a transparent absorbent is deposited or coated on an upper substrate.

In general, the organic electroluminescent display (OELD) among flat pannel displays has a wider operating temperature range than other flat panel displays, is more resistant to shock and vibration, has a wider viewing angle, and a higher response speed. It is rapidly attracting attention as a next-generation flat panel display because it can provide a clean moving image quickly.

Such an organic light emitting display device is a process in which electrons and holes form an electron-hole pair in a layer made of an organic material, or carriers are excited to a higher energy state and then fall back to a stabilized ground state. It utilizes the phenomenon of emitting light through.

Such an organic light emitting display device may be classified into a bottom emission type in which light generated by the above phenomenon is directed downward and a top emission type in which the light generated upward is directed upward. have.

On the other hand, the organic light emitting display device can be roughly divided into a thin film transistor forming process, an organic electroluminescent layer forming process, an encapsulation process and a module assembly process.

In particular, in the encapsulation process of the top emission type organic light emitting display, a technique of etching transparent glass and adding a transparent getter used as a hygroscopic agent to the etched portion is widely used.

By the way, the encapsulation technique using the transparent getter needs to etch the glass attached to the light emitting surface, and since the transparent getter is attached to the light emitting surface, there is a problem in that it is limited in its attachment position and area.

Therefore, in the organic light emitting display device having a top emission structure, an encapsulation process that does not require etching the glass attached to the light emitting surface and does not require the mounting of a transparent getter is required.

SUMMARY OF THE INVENTION An aspect of the present invention is to provide an organic electroluminescent display device that can protect an organic electroluminescent structure from moisture by coating or depositing a moisture absorbent on an upper substrate.

Another object of the present invention is to provide a method of manufacturing an organic light emitting display device which can protect an organic electroluminescent structure from moisture by coating or depositing a moisture absorbent on an upper substrate.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical 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, an organic light emitting display device includes a thin film transistor, a cathode electrode, an organic electroluminescent layer, and an anode electrode formed on a lower substrate and at least part of one surface thereof. The transparent moisture absorbent layer comprises an upper substrate coated or deposited and encapsulated with a lower substrate.                     

According to another aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, by forming an organic light emitting structure including a thin film transistor, a cathode, an organic light emitting layer, and an anode on a lower substrate. Providing a lower substrate, coating or depositing a transparent moisture absorbent layer on at least a portion of the one surface to provide an upper substrate, and encapsulating the upper substrate and the lower substrate.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a top emission type organic light emitting display device according to an embodiment of the present invention will be described with reference to FIG. 1.

As shown in FIG. 1, the organic light emitting display device 1 includes a lower substrate 10, an organic electroluminescent structure 40, an upper substrate 50, a moisture absorbent layer 60, an adhesive 70, and the like. .                     

The lower substrate 10 is a portion where a predetermined structure for emitting light is formed in the organic light emitting display device 1. As the lower substrate 10, a transparent insulating substrate such as a glass substrate or a film made of a polymer material is generally used.

Meanwhile, since the organic light emitting display device 1 according to the exemplary embodiment of the present invention is a top emission type, the lower substrate 10 does not necessarily need to be a transparent substrate, and if it is insulating, a substrate of another material may be used.

The organic electroluminescent structure 40 is formed on the lower substrate 10 and is a portion that emits light by applying a voltage from the outside. For emitting light, the organic electroluminescent structure 40 includes a thin film transistor, a lower electrode as a cathode electrode, an organic electroluminescent layer and an upper electrode as an anode.

The thin film transistor serves as a switching element formed in pixel units for implementing various colors. In particular, in the organic EL device having a full color structure of the RGB sub-pixels, they are formed in sub-pixel units.

The lower electrode as the cathode is where electrons are present from a power source applied from the outside, and serves to provide electrons to the organic EL layer to be formed on the lower electrode. The lower electrode is preferably formed of a metal material, and Mg, Ag, MgAg-Li, LiAl, LiF-Al, and the like are mainly used as the material.

The organic electroluminescent layer is a layer in which energy generated when excitons, which combine holes and electrons supplied from the outside, falls from an excited state to a ground state, is emitted as light energy. In general, the organic electroluminescent layer is formed by sequentially depositing a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and the like.

The upper electrode as an anode is a place where holes supplied from a power source applied from the outside exist, and serve to provide holes to the organic EL layer. The upper electrode preferably serves as an anode electrode, which is an anode electrode, and is formed of a transparent material through which light emitted from the organic electroluminescent layer can pass. As such a material, indium tin oxide (ITO) or indium zinc oxide (IZO) is mainly used.

The upper substrate 50 is used to protect the organic electroluminescent structure formed inside the lower substrate 10. In this case, since the upper substrate 50 emits light emitted from the organic EL layer, a transparent insulating substrate such as a glass substrate or a film made of a polymer material should be used.

The moisture absorbent layer 60 is formed inside the upper substrate 50 and the lower substrate 10 when the encapsulation is encapsulated, and serves to remove moisture to protect the organic EL structure from moisture. The moisture absorbent layer 60 is formed by coating or depositing on some or all of both surfaces, and is preferably formed to a thickness of about 100 nm to 1,000 nm. In addition, the moisture absorbent layer 60 is formed on one surface of the upper substrate facing the lower substrate 10 when the upper substrate 50 is encapsulated with the lower substrate 10, and is formed of a transparent material similar to the upper substrate 50. It must be deposited or coated. Accordingly, the moisture absorbent layer 60 is a transparent layer such as a layer made of a material such as SiO ₂ , BaO, MgO, TiO ₂ , polyethylene, or the like, which ensures transparency and functions as a moisture absorbent. Can be used.

The adhesive 70 is used to bond and seal the upper substrate 50 and the lower substrate 10 that face each other. Generally, a UV curing agent is used, and after the two substrates 10 and 50 are bonded, only the adhesive part is cured by irradiating UV light.

Hereinafter, a process of manufacturing the organic light emitting display device on the lower substrate will be described with reference to FIGS. 2 to 4.

2 is a flowchart illustrating a manufacturing process of an organic light emitting display device according to an embodiment of the present invention, FIG. 3 is a cross-sectional view illustrating a process of forming an organic electroluminescent structure of FIG. 2, and FIG. 4 is an upper substrate of FIG. 2. Cross-sectional views according to the step of forming and attaching.

First, an organic EL structure (see 40 of FIG. 3H) is formed on the lower substrate 10 (S100).

To this end, as shown in FIG. 3A, a buffer layer 12 is formed on the lower substrate 10. The semiconductor layer 14 is formed by depositing and patterning a polysilicon layer on the entire lower substrate 10 on which the buffer layer 12 is formed.

Here, the lower substrate 10 is preferably a glass substrate or an insulating substrate such as a synthetic resin, and the buffer layer 12 uses a material such as an oxide film.

Next, as shown in FIG. 3B, the gate insulating layer 16 is formed on the buffer layer 12 including the semiconductor layer 14. Thereafter, a gate metal material is deposited on the gate insulating layer 16 and patterned so that the gate 18 is formed on the gate insulating layer 16 on the semiconductor layer 14. Subsequently, one of the n-type and p-type impurities is ion-implanted into a portion of the semiconductor layer 14 overlapping with the gate 18 to form the high concentration source region / drain regions 15a and 15b.

Next, as shown in FIG. 3C, a material such as an oxide for forming the lower interlayer insulating film 20 is deposited on the lower substrate 10 on which the source regions / drain regions 15a and 15b are formed. Then, a lower interlayer insulating film having contact holes 19a and 19b for connecting the source electrode / drain regions 15a and 15b to be formed in a subsequent process to the source electrode / drain electrodes (see 21a and 21b in FIG. 3D). 20).

In this case, the contact holes 19a and 19b may be formed using a photolithography process that performs a photolithography process and an etching process, and the lower interlayer insulating layer 20 until the source / drain regions 15a and 15b are exposed. It is formed by etching.

Next, as shown in FIG. 3D, a metal material is deposited on the lower interlayer insulating film 20 including the contact holes 19a and 19b, and then patterned to form a source region / drain region 15a through the contact holes 19a and 19b. , Source electrode / drain electrodes 21a and 21b respectively contacting 15b are formed.

Next, as shown in FIG. 3E, an upper interlayer insulating film 22 made of an oxide film is formed on the lower substrate 10 on which the source and drain electrodes 21a and 21b are formed. Subsequently, one of the source electrode 21a or the drain electrode 21b, for example, a portion of the source electrode 21a is opened to connect the lower electrode to be formed in a subsequent process (see 24 in FIG. 3F). The contact hole 23 is formed in the interlayer insulating film 22.

Next, as shown in FIG. 3F, a conductive film is deposited on the upper interlayer insulating film 22 including the contact hole 23 with an opaque conductive material. Subsequently, the lower electrode 24, which is connected to the source electrode 21a through the contact hole 23, is patterned by photolithography, which performs a photo process and an etching process.

Here, the lower electrode 24 serves as a cathode electrode and is formed of a conductive material having high reflectance so as to serve as a reflective film of a top emission structure. In addition, the lower electrode 24 is formed to extend to the flat region of the upper interlayer insulating layer 22.

Next, as shown in FIG. 3G, the lower passivation layer 26 is formed on the lower substrate 10 on which the lower electrode 24 is formed as the planarization layer, and then the opening 27 is exposed to expose the flat portion of the lower electrode 24. To form.

The reason why the opening 27 is formed in the flat portion of the lower electrode 24 is that when the bend is formed on the surface of the lower electrode 24 serving as the reflective film, the lower electrode 24 is subjected to the lower electrode 24 by a subsequent process. This is because the reflection of light generated in the organic electroluminescent layer to be formed on the surface cannot be effectively performed. In addition, it is because an organic substance which functions as an organic electroluminescent layer cannot be easily deposited on the lower electrode 24 by a subsequent process.

Next, as shown in FIG. 3H, a mask is placed on the lower substrate 10 having the openings 27 formed thereon, and organic materials such as Alq3, BeBq2, and coumarin are deposited on the openings 27 through the deposition process. An organic electroluminescent layer 28 connected to the lower electrode 24 is formed.                     

Accordingly, the organic electroluminescent layer 28 emits red, green, and blue light by itself through the flow of current, and the emitted light emits light upward. On the other hand, the light directed downward is reflected by the predetermined region of the lower electrode 24 opened by the opening 27 and reflected upward.

After the organic electroluminescent layer 28 is formed, a conductive material is deposited and patterned on the lower substrate 10 on which the organic electroluminescent layer 28 is formed to form an upper electrode 30 functioning as an anode electrode. . Meanwhile, an upper passivation layer other than the lower passivation layer may be further formed on the upper electrode 30.

This completes the organic electroluminescent structure 40 including the thin film transistor, the lower electrode as the cathode, the organic electroluminescent layer, the upper electrode as the anode, and the like.

As described above, after the organic electroluminescent structure 40 is formed on the lower substrate 10, as illustrated in FIG. 4A, the transparent absorbent layer 60 is coated or deposited on the separately provided upper substrate 50 to form the transparent absorbent layer 60. ) Is formed (S102).

Since the upper substrate 50 is used as the light emitting surface, it is preferable that the upper substrate 50 is a transparent glass substrate or a transparent polymer film. In addition, the transparent moisture absorbent layer 60 is preferably a layer made of SiO ₂ , BaO, MgO, TiO ₂ , polyethylene, or a combination thereof, and has a thickness of 100 nm to 1,000 nm.

Next, as shown in FIG. 4B, the adhesive 70 is drawn on the upper substrate 50 on which the transparent moisture absorbent layer 50 is formed by using a screen printing technique (S104).                     

It is preferable to use the UV hardening | curing agent which is excellent in adhesive strength between glass and glass here.

As described above, after the adhesive 70 is drawn, the lower substrate 10 having the organic electroluminescent structure 40 is formed on the lower substrate 10 as shown in FIG. 4C, and the upper substrate 50 on which the adhesive is drawn. Cover and seal with (S106).

At this time, the portion of the adhesive 70 is irradiated with UV light and cured using a mask to finish the sealing process. Through the above process, as shown in FIG. 1, an organic light emitting display device in which a moisture absorbent is coated or deposited on an upper substrate is completed.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments and can be variously modified and implemented by those skilled in the art without departing from the technical scope of the present invention.

For example, in the description of the organic light emitting display device according to an exemplary embodiment of the present invention, the organic light emitting display device has been described with reference to a top emission organic light emitting display device, but is not limited thereto. It can be usefully used for the display device.

As described above, according to the present invention, since the organic electroluminescent structure is encapsulated by coating or depositing a moisture absorbent on the upper substrate, the upper substrate does not need to be etched in order to attach a moisture absorber getter, and the deposition or Since the absorbent to be coated is made of a transparent material, it is useful not only for a bottom emission type organic light emitting display but also for a top emission type organic light emitting display.

Claims (8)

A lower substrate having an organic electroluminescent structure including a thin film transistor, a cathode electrode, an organic electroluminescent layer, and an anode electrode; And An organic light emitting display device comprising: an upper substrate on which at least a portion of a transparent moisture absorbent layer is coated or deposited and is encapsulated with the lower substrate. According to claim 1, And the upper substrate is encapsulated with the lower substrate by an adhesive. According to claim 1, And the upper substrate and / or the lower substrate is a transparent film made of transparent glass or an inorganic material. According to claim 1, The transparent moisture absorbent layer is an SiO ₂ , BaO, MgO, TiO ₂ , polyethylene layer or a stacked structure thereof. Preparing an lower substrate by forming an organic EL structure including a thin film transistor, a cathode electrode, an organic EL layer, and an anode on the lower substrate; Coating or depositing a transparent moisture absorbent layer on at least a portion of one surface to prepare an upper substrate; And And encapsulating the upper substrate and the lower substrate. The method of claim 5, wherein the encapsulation step, Drawing an adhesive to the upper substrate; Attaching an upper substrate on which the adhesive is drawn to a lower substrate on which the organic electroluminescent structure is formed; And And irradiating and curing the portion on which the adhesive is drawn with UV light to cure the organic light emitting display device. The method of claim 5, And the upper substrate and / or the transparent lower substrate are films made of transparent glass or transparent inorganic material. The method of claim 5, The transparent moisture absorbent layer is a SiO ₂ , BaO, MgO, TiO ₂ , polyethylene layer or a stacked structure thereof organic light emitting display device manufacturing method.

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