KR20080095521A - Organic electroluminescent device and method for fabricating thereof - Google Patents

Abstract

An organic electroluminescent device and a method for fabricating the same are provided to perform double-sided emission by forming a positive electrode and a negative electrode made of transparent conductive material. An organic electroluminescent device includes a first electrode(101), a second electrode(110), an organic light emitting layer(105), an electron injection layer(103), an electron transport layer(104), a hole injection layer(107), and a hole transport layer(106). The organic light emitting layer is disposed between the first electrode and the second electrode. The electron injection layer and the electron transport layer are disposed between the first electrode and the organic light emitting layer. The hole injection layer and the hole transport layer are disposed between the second electrode and the organic light emitting layer. The first electrode includes a first electrode layer(101a) and a second electrode layer(101b) made of transparent conductive material.

Description

Organic electroluminescent device and method for fabrication thereof

1 is a cross-sectional view of an organic light emitting display device according to the prior art.

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

3A to 3D are cross-sectional views illustrating a manufacturing process of an organic light emitting display device according to the present invention.

4A and 4B are views for explaining a process of forming a transparent cathode of an organic light emitting display device according to the present invention.

5 is a cross-sectional view of an organic light emitting display device having upper and lower emission directions according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100: insulating substrate 101: first electrode

101a: first electrode layer 101b: second electrode layer

103: electron injection layer 104: electron transport layer

105: organic light emitting layer 110: second electrode

120: first metal pattern 130: second metal pattern

The present invention relates to an organic electroluminescent device, and more particularly to an organic electroluminescent device capable of emitting light in the vertical direction and a manufacturing method thereof.

Recently, display apparatuses for displaying data in the form of electrical signals processed by the information processing apparatus and the information processing apparatus as images have been developed.

Examples of the representative display device include a liquid crystal display device, an organic light emitting display device, a plasma display panel, and the like. A liquid crystal display displays an image using liquid crystal, an organic light emitting display displays an image using an organic light emitting material, and a plasma display panel displays an image using plasma. The display devices described above are mainly employed in information processing devices such as computers, laptops, watches, mobile phones, MP3 players, television receiver sets and the like.

The organic electroluminescent device displaying an image using the organic light emitting material has an advantage of greatly reducing volume and weight since it does not require a light supply means such as a backlight.

The organic light emitting device includes a pair of conductive electrodes and an organic light emitting layer interposed between the conductive electrodes. The organic light emitting layer includes an organic light emitting material. When forward current is applied to the conductive electrodes of the organic light emitting device, light is generated from the organic light emitting layer.

1 is a cross-sectional view of a conventional organic light emitting display device.

Referring to FIG. 1, an organic light emitting device 10 includes a first electrode 1, a second electrode 2, an electron injection layer 3, An electron transport layer 4, an organic light emitting layer 5, a hole injection layer 6, and a hole transport layer 7.

The electron injection layer 3 is disposed on the first electrode 1, and the electron transport layer 4 is disposed on the electron injection layer 3.

The hole injection layer 6 is disposed on the second electrode 2, and the hole transport layer 7 is disposed on the hole injection layer 6.

The organic light emitting layer 5 is interposed between the electron transport layer 4 and the hole transport layer 7.

The holes are provided to the organic light emitting layer 5 through the second electrode 2, the hole injection layer 6 and the hole transport layer 7, and the electrons are the first electrode 1, the electron injection layer 3 and the electron transport layer. It is provided to the organic light emitting layer 5 via (4), and light is generated in the organic light emitting layer 5.

However, the electrode adjacent to the hole injection layer 6 of the first electrode 1 and the second electrode 2 of the conventional organic light emitting device 10 is an anode, formed of a transparent conductive material, The electrode adjacent to the electron injection layer 3 is a cathode, and is formed of an opaque conductive material having a low work function. Therefore, in the organic light emitting device 10 of the prior art, light can only be emitted in the direction of the anode due to the material of the selected electrode. That is, the light emission direction is limited only to the anode direction using the transparent conductive material.

Therefore, in the prior art, there is a limit of application to various display devices because it cannot emit in the positive and negative directions.

If the cathode is a transparent conductive material, it does not meet the low work function conditions, causing a problem of low luminous efficiency.

It is an object of the present invention to provide an organic electroluminescent device capable of emitting both sides by forming both a positive electrode and a negative electrode of an organic electroluminescent device with a transparent conductive material, and a method of manufacturing the same.

In addition, the present invention uses the negative electrode of the organic electroluminescent device as a transparent conductive material, and by forming a transparent metal film of uniform thickness on the surface of the negative electrode in order to lower the work function, the organic electroluminescent device having improved device characteristics And other methods for providing the same.

In order to achieve the above object, the organic light emitting device according to the present invention,

A first electrode;

Second electrode;

An organic emission layer disposed between the first electrode and the second electrode; And

An electron injection layer and an electron transport layer disposed between the first electrode and the organic light emitting layer;

A hole injection layer and a hole transport layer disposed between the second electrode and the organic light emitting layer,

The first electrode includes a first electrode layer and a second electrode layer made of a transparent conductive material.

Organic electroluminescent device manufacturing method according to another embodiment of the present invention,

Forming a first electrode layer on the substrate, and subsequently forming first and second metal films sequentially;

Forming a second electrode layer on the first electrode layer by performing a heat treatment process on the substrate on which the second metal film is formed;

Removing the first and second metal layers existing on the second electrode layer, and subsequently forming an electron injection layer, an electron transport layer, an organic emission layer, a hole transport layer, and a hole injection layer; And

Forming a second electrode on the hole injection layer.

Organic electroluminescent device according to another embodiment of the present invention,

A first substrate;

A second substrate;

A thin film transistor formed on each of the sub-pixels on the first substrate; And

A light emitting diode comprising a first electrode, an organic light emitting layer, and a second electrode respectively connected to the thin film transistor on the first substrate,

The first electrode is composed of first and second electrode layers made of a transparent conductive material, and the second electrode is formed of a transparent conductive material and is capable of emitting both upper and lower surfaces.

According to the present invention, both the positive electrode and the negative electrode of the organic light emitting device can be formed of a transparent conductive material, thereby emitting both sides of light.

In addition, the present invention improves device characteristics by using a negative electrode of the organic light emitting device as a transparent conductive material and forming a transparent metal film having a uniform thickness on the negative electrode surface in order to lower the work function.

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

Hereinafter, with reference to the drawings of the organic light emitting display device according to the present invention will be described in detail. The following embodiments are provided as examples to ensure that the spirit of the present invention can be fully conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like numbers refer to like elements throughout.

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

As shown in FIG. 2, the organic light emitting display device according to the present invention may include a first cathode 101 disposed on the transparent insulating substrate 100 including a transparent and conductive material. For example, the first electrode 101 is composed of a first electrode layer 101a and a second electrode layer 101b, and examples of materials that can be used for the first electrode layer 101a include indium tin oxide (Indium Tin Oxide). ITO), Indium Zinc Oxide (IZO), and amorphous conducting oxide (TCO: Transparent Conducting Oxide) including amorphous Indium Tin Oxide (a-ITO).

The second electrode layer 101b is formed of a conductive material having a low work function value in order to lower the high work function characteristic of the first electrode layer 101a. For example, a metal may be used in combination with the oxygen component of the first electrode layer 101a to form a transparent thin film layer having high conductivity. As an example, in the present invention, a TiO-based metal film may be formed on the first electrode layer 101a by using a Ti-based and a heat treatment process, but the present invention is not limited to the Ti-based metal. That is, it is possible as long as it is an electroconductive material which can combine with an oxygen component and can form a metal film.

The electron injection layer 103 and the electron transporting layer 104 are formed on the second electrode layer 101b of the first electrode 101, and the organic light emitting layer 105 is formed on the electron transporting layer 104. The organic light emitting layer 105 may use various polymer materials suitable for generating red, green, and blue light.

In addition, first and second metal patterns 120 and 130 serving as power terminals are formed at both edges of the first electrode 101. The first metal pattern 120 uses a Ti-based metal capable of oxygen bonding with the second electrode layer 101b of the first electrode 101. The second metal pattern 120 uses aluminum, copper, silver, platinum, tungsten, molybdenum, or the like having excellent conductivity.

The hole transport layer 106 is formed on the organic light emitting layer 105. The hole transport layer 106 serves to transport a plurality of holes to the organic light emitting layer 105. The hole injection layer 107 is disposed on the hole transport layer 106, and the hole injection layer 107 may include, for example, CuPc (Cu-Phthalocyanine). The second electrode 110 is formed on the hole injection layer 107. The material of the second electrode 110 is a transparent conductive material, indium tin oxide (ITO), indium zinc oxide (IZO), amorphous indium tin oxide (a-ITO), or the like. ) Can be used.

In addition, although CuPc is cited as an example of a material forming the hole injection layer 107, various hole transport compounds having a function of transferring holes injected from the second electrode 110 to the organic light emitting layer 105 may be used. For example, examples of the material forming the hole injection layer 107 include a hole-injectable polypyrine compound, a phthalocyanine compound, a hole-transporting aromatic tertiary amine, a trisphenothiazinyltriphenylamine derivative, or a trisphenoxadinytriphenyl Amine derivatives, polythiophene, the compound containing a carbazole group, etc. are mentioned.

Alternatively, examples of the material forming the hole injection layer 107 include a triazole compound, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative, a pyrazorone derivative, a phenylenediamine derivative, an arylamine derivative, an oxa Sol derivatives, styrylanthracene derivatives, fluorene derivatives, hydrazone derivatives, stilbene derivatives, porphyrin compounds, aromatic tertiary amine compounds, styrylamine compounds, butadiene compounds, polystyrene derivatives, hydrazone derivatives, triphenylmethane derivatives, tetra Phenylbenzidine derivatives, polyaniline polymer materials, polythiophene polymer materials, polypyrrole polymer materials and the like can be used.

Accordingly, the organic electroluminescent device of the present invention forms the first electrode 101 by forming both the first electrode 101, which is a negative electrode, and the second electrode 110, which is a positive electrode, made of a transparent metal. There is an effect that can emit light in the direction and the second electrode (110) direction.

In addition, in order to solve the problem of increasing the work function of the electrode by forming the negative electrode as a transparent conductive material, the metal film having a low work function and high transparency is uniformly formed to improve the light efficiency characteristics of the organic light emitting device. It has an improved effect.

3A to 3D are cross-sectional views illustrating a manufacturing process of an organic light emitting display device according to the present invention.

As shown in FIG. 3A, a transparent conductive material is formed on the transparent insulating substrate 100. The transparent conductive material may include a transparent conductive oxide (TCO) including indium tin oxide (ITO), indium zinc oxide (IZO), and amorphous indium tin oxide (a-ITO). Transparent Conducting Oxide.

When the transparent conductive material is formed on the insulating substrate 100 as described above, the first electrode layer 101a is formed on the insulating substrate 100 by etching by a photolithography method including a mask.

Then, as shown in FIG. 3B, when the first electrode layer 101a is formed on the insulating substrate 100, the first metal film 120a and the second metal film 130a having a low work function and high conductivity are formed. ) Are sequentially formed on the entire area of the insulating substrate 100.

The material of the first metal film 120a is a conductive material capable of forming a thin film by combining with an oxygen component included in the material of the first electrode layer 101a. In the present invention, a Ti-based metal or an alloy thereof is used. In addition, the second metal layer 130a may use aluminum, copper, silver, gold, tungsten, molybdenum, or an alloy thereof having high conductivity.

As described above, when the first metal film 120a and the second metal film 130a are formed on the insulating substrate 100 on which the first electrode layer 101a is formed, the first metal film 120a and the first metal film 120a are formed. A process of forming a metal thin film by oxygen bonding on the interface of the first electrode layer 101a is performed.

As such, when the heat treatment process is completed, as shown in FIG. 3C, the second electrode layer 101b formed by oxygen bonding is formed on the first electrode layer 101a formed on the insulating substrate 100 to form an organic light emitting display device. The first electrode 101 of is completed. That is, the cathode of the organic electroluminescent device of the present invention is formed in a double layer structure.

Subsequently, a process of removing the first metal film and the second metal film formed on the first electrode 101 by a photolithography method including a mask is performed to supply power terminals to both edge regions of the first electrode 101. The first metal pattern 120 and the second metal pattern 130, which may play a role, are formed.

At this time, a commercially available etching gas is an HF-based etching gas, but the first metal film and the second metal film are etched, but the second electrode layer 101b formed on the first electrode layer 101a is a TiO-based metal and is not etched. It exists uniformly on 1 electrode layer 101a.

In addition, since the second electrode layer 101b is formed by an oxygen bonding process by metal contact, its thickness is very thin and thus high transparency. In addition, since the material of the second electrode layer 101b includes Ti having high conductivity and low work function, the material of the second electrode layer 101b serves to compensate for the disadvantage of the first electrode layer 101a formed of a transparent conductive material.

Accordingly, the first electrode 101 is formed of a transparent conductive material and thus has a high light transmittance, and generally has a low work function characteristic unlike the transparent conductive material. Therefore, it can serve as a negative electrode of the organic light emitting device.

In addition, when the electrode is formed by the above process, there is an advantage of forming a uniform transparent negative electrode on the large panel.

When the first metal pattern 120 and the second metal pattern 130 are formed, as shown in FIG. 3D, the electron injection layer 103 and the electron transport layer 104 are sequentially formed on the first electrode 101. To form.

Then, an organic emission layer 105 is formed on the electron transport layer 104 to generate blue, green, red or white light. When the organic light emitting layer 105 is formed, the hole transport layer 106 and the hole injection layer 107 are sequentially formed, and then the second electrode 110 made of a transparent conductive material is formed. The material of the second electrode 110 may be indium tin oxide (ITO), indium zinc oxide (IZO), or amorphous indium tin oxide (a-ITO).

As described above, in the present invention, since both the positive electrode and the negative electrode of the organic light emitting device are formed of a transparent conductive material, there is an advantage in that double-sided light emission characteristics can be realized.

Specifically, the process of forming the transparent negative electrode of the organic light emitting device is as follows.

4A and 4B are views for explaining a process of forming a transparent cathode of an organic light emitting display device according to the present invention.

4A and 4B, when the first electrode layer 101a made of a transparent conductive material containing an oxygen component is formed on the insulating substrate 100, the first metal film 130a made of Ti or an alloy thereof. ) Is formed by a deposition process. Thereafter, the heat treatment process is performed to activate the oxygen component of the first electrode layer 101a and to excite the metal atoms of the first metal layer 130a so that the metal atoms (ions) and oxygen can be combined.

When the heat treatment process proceeds as described above, the second electrode layer 101b made of the TiO series metal film is completed on the interface where the first electrode layer 101a and the first metal film 130a come into contact with each other.

Accordingly, the second electrode layer 101b and the first metal layer 130a are formed on the first electrode layer 101a, and an etching process for removing the first metal layer 130a is performed. In this case, when the etching gas HF is used, only the first metal layer 130a may be selectively removed without reacting with the second electrode layer 101b.

As such, the first electrode 101 including the first electrode layer 101a and the second electrode layer 101b can realize high transparency and low work function, and thus can be used as a cathode of the organic light emitting device.

5 is a cross-sectional view of an organic light emitting display device having upper and lower emission directions according to another embodiment of the present invention.

Referring to FIG. 5, an organic light emitting display device capable of emitting and displaying light in both upper and lower sides in accordance with the present invention is provided.

For convenience of description, the pixel area is illustrated based on one pixel area including red, green, and blue B subpixels.

As illustrated, a thin film transistor T and a first electrode 212 are formed on the transparent substrate 201 of the first substrate 210 for each subpixel, and the thin film transistor T and the first electrode are formed. An organic light emitting layer 214 having red, green, and blue colors is formed on an electrode 212, and a second electrode 216 is formed on the organic light emitting layer 214. The anode is formed. The first and second electrodes 212 and 216 serve to supply electrons and holes to the organic light emitting layer 214.

As such, the first substrate 210 on which the organic light emitting layer 214 is formed is bonded by the second substrate 230 and the seal 240.

In the present invention, the first electrode 212 is a cathode and the second electrode 216 is an anode because the display is driven by an organic light emitting display device capable of emitting both surfaces. The second electrode 216 generally uses a metal such as ITO, IZO, or ITZO made of a transparent conductive material. In the present invention, the first electrode 212 is also formed of an electrode with a transparent conductive material. The detailed structure is formed of a first electrode layer 212a made of a transparent conductive material and a TiO material having high conductivity and low work function on the first electrode layer 212a by applying the processes described with reference to FIGS. 4A and 4B. 2 electrode layers 212b were laminated. For a specific process, refer to the cathode forming process of the organic light emitting device.

The organic light emitting layer 214 may be formed from a layer in contact with the first electrode 212 to an electron injection layer 214a, an electron transporting layer 214b, an emission layer 214c, an emission layer, and a hole transporting layer. 214d (hole transporting layer), a hole injection layer (214e (hole injection layer)) in a stacked structure in order.

In this case, the light emitting layer 214c has a structure in which light emitting materials that implement red, green, and blue colors are sequentially disposed for each subpixel.

As described above, in the organic light emitting display device of the present invention, since both the first electrode 212 and the second electrode 216 serving as the cathode and the anode are formed of a transparent conductive material, an upper surface of the second substrate 230 is formed. Direction and a bottom direction, which is a rear surface of the first substrate 210. Therefore, there is an advantage that can display the image in both directions.

As described in detail above, the present invention has the effect of forming both the positive electrode and the negative electrode of the organic electroluminescent device with a transparent conductive material, thereby emitting both sides.

In addition, the present invention has the effect of improving the device characteristics by using a negative electrode of the organic light emitting device as a transparent conductive material, and forming a transparent metal film of uniform thickness on the negative electrode surface in order to lower the work function.

Claims (20)

A first electrode; Second electrode; An organic emission layer disposed between the first electrode and the second electrode; And An electron injection layer and an electron transport layer disposed between the first electrode and the organic light emitting layer; A hole injection layer and a hole transport layer disposed between the second electrode and the organic light emitting layer, And the first electrode comprises a first electrode layer and a second electrode layer made of a transparent conductive material. The organic electroluminescent device according to claim 1, wherein the first electrode layer is formed of any one metal of IZO, ITO or a-ITO. The organic electroluminescent device according to claim 1, wherein the second electrode layer is an oxygen bonded metal. The organic electroluminescent device according to claim 1, wherein the second electrode layer is a TiO series transparent metal film. The organic electroluminescent device according to claim 1, wherein the second electrode is formed of any one metal of IZO, ITO or a-ITO. The organic light emitting device of claim 1, wherein the organic light emitting layer is formed of a polymer material capable of generating red, green, or blue light. The organic light emitting device of claim 1, wherein the first electrode further comprises a power supply terminal. 8. The organic light emitting device of claim 7, wherein the power supply terminal is formed by stacking first and second metal patterns. The organic light emitting device of claim 8, wherein the first metal pattern is Ti or an alloy thereof. The organic light emitting device of claim 8, wherein the second metal pattern is any one of aluminum, copper, silver, platinum, tungsten, and molybdenum. Forming a first electrode layer on the substrate, and subsequently forming first and second metal films sequentially; Forming a second electrode layer on the first electrode layer by performing a heat treatment process on the substrate on which the second metal film is formed; Removing the first and second metal layers existing on the second electrode layer, and subsequently forming an electron injection layer, an electron transport layer, an organic emission layer, a hole transport layer, and a hole injection layer; And And forming a second electrode on the hole injection layer. The method of claim 11, wherein the etching gas used to remove the first and second metal layers formed on the second electrode layer is HF. The method of claim 11, wherein the first electrode layer is formed of any one metal of IZO, ITO, or a-ITO. 12. The method of claim 11, wherein the second electrode layer is an oxygen-bonded metal. 12. The method of claim 11, wherein the second electrode layer is a TiO-based transparent metal film. The method of claim 11, wherein the second electrode is formed of any one metal of IZO, ITO, or a-ITO. The method of claim 11, wherein the organic light emitting layer is formed of a polymer material capable of generating red, green, or blue light. 12. The method of claim 11, wherein the first metal film is Ti or an alloy thereof. 12. The method of claim 11, wherein the second metal film is any one of aluminum, copper, silver, platinum, tungsten, and molybdenum. A first substrate; A second substrate; A thin film transistor formed on each of the sub-pixels on the first substrate; And A light emitting diode comprising a first electrode, an organic light emitting layer, and a second electrode respectively connected to the thin film transistor on the first substrate, The first electrode is composed of first and second electrode layers made of a transparent conductive material, the second electrode is formed of a transparent conductive material, characterized in that the upper and lower sides can emit light.

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