KR20060058610A - Organic electro luminescence display and methode for manufacturing the same - Google Patents

Abstract

The diamond-like carbon thin film is formed on the organic light emitting display as a light absorption and antireflection film to replace the commonly used expensive polarizing plate and reflects unreflected light and incident external light from the reflection film. The present invention provides an organic light emitting display device and a method of manufacturing the same, which improve the problem of contrast and visibility by using interference-enhanced absorption characteristics.

Organic electroluminescent display, diamond like carbon (DLC), chemical vapor deposition (CVD), black cathode

Description

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

1 is a view for explaining the transmittance characteristics of a conventional organic light emitting display device with a polarizing plate.

FIG. 2A is a schematic cross-sectional structure diagram of an organic light emitting display device using a diamond like carbon thin film (DLC). FIG.

2B is a cross-sectional structure diagram of an organic light emitting display device using a diamond-like carbon thin film (DLC) and a light absorption layer.

3 is a schematic cross-sectional structure diagram of an organic light emitting display device in which a diamond like carbon thin film (DLC) is formed according to the present invention.

<Description of Symbols for Main Parts of Drawing>

100 transparent substrate 220 first electrode

230: hole injection layer 240: hole transport layer

250: light emitting layer 260: electron transport layer

270: electron injection layer 280: organic layer

290: second electrode 300: diamond-like carbon thin film (DLC)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, to form a diamond-like carbon thin film (DLC) layer having a low black color and chemically stable on a second electrode. The present invention relates to an organic light emitting display device and a method of manufacturing the same, which can improve a problem of contrast and visibility caused by reflecting reflected light and incident external light.

In general, organic electroluminescent displays (OLEDs) in flat panel displays have a wider operating temperature range than other flat panel displays, are more resistant to shock and vibration, have a wider viewing angle, and a higher response speed. As it has the advantage of providing fast moving images, it is attracting attention as the next generation flat panel display device.

Such an organic light emitting display device can be classified into a passive matrix type requiring a separate driving source according to a driving method and an active matrix type having an integrated thin film transistor functioning as a switching element. have.

Since the active matrix type organic light emitting display device is indirectly driven by a thin film transistor, which is a switching element, the voltages supplied to the pixels can be completely independent of each other and be continuous, and thus have many advantages such as high resolution, high image quality, and large area. Have

In addition, the organic light emitting display device may further include a bottom emission structure that emits light emitted from the light emitting layer in a downward direction of the substrate and a top emission structure that emits upward of the substrate. It can be divided into branches.

In such an organic light emitting display device, a problem of reflecting unreflected light and incident external light in a metal reflective film causes a large amount of light loss and a decrease in contrast and visibility. The phosphorus method is a method using a polarizing plate and a method using a black matrix, and an anode electrode deposited on a transparent substrate in the Republic of Korea Patent Publication No. 2003-0016577 and connected to an external positive potential, a thin film deposited and formed by an organic material Injecting holes and electrons from the anode electrode and the cathode electrode to form a diamond-like carbon thin film by controlling the deposition energy of carbon ions on the emitting layer (EML), the light emitting layer (EML) emitted by the injected electrons and holes, Diamond with Cathode Electrode Formed on Diamond Carbon Thin Film In an organic light emitting display device including a d-phase carbon thin film or an organic light emitting display device including a diamond-like carbon thin film, a light absorption layer using carbon particles between a transparent substrate and an anode electrode or between an anode electrode and a light emitting layer. And a method including the same.

1 is a view for explaining the transmittance characteristics of a conventional organic light emitting display device with a polarizing plate.

FIG. 2A illustrates a schematic cross-sectional view of an organic light emitting display device using a diamond like carbon thin film (DLC).

FIG. 2B illustrates a cross-sectional view of an organic light emitting display device using a diamond like carbon (DLC) and a light absorption layer.

In each of the above-mentioned methods, a method using a black matrix forms a black matrix in a thin film transistor and a capacitor region except for an indium tin oxide (ITO), thereby absorbing external light incident thereto. It is to prevent the reflection of light. And the method using the polarizing plate 12 shown in FIG. 1 is to attach the expensive polarizing plate 12 to the front of the glass substrate 10 to absorb the external light 16 to prevent reflection by the external light. In addition, the diamond-like carbon thin film forming the transparent anode electrode 120, the organic light emitting layer 180, the diamond-like carbon thin film 190 and the cathode electrode 200 on the transparent substrate 100 shown in Figure 2a The organic light emitting display device or the method including the light absorbing layer 110 between the transparent substrate and the anode electrode is grown in a cesium (Cs) atmosphere to form a diamond-like carbon film has a low electron affinity (Electron affinity) It improves the light emission by activating electron injection into the light emitting layer by the low work function of cesium, and including the light absorption layer using carbon particles to improve the luminous efficiency of the organic light emitting layer and the light incident from the outside It is a method to improve contrast and visibility problems caused by reflection and interference.

However, the use of the polarizing plate 12 in the above method has a constant light transmittance of about 45%, resulting in high light loss, and only partially transmitting the display light 14 emitted from the light emitting layer of the display device, resulting in lowered contrast. Rather, the use of expensive polarizers and the addition of an attachment process leads to an increase in manufacturing costs. In the case of the organic light emitting display device including only the diamond-like carbon thin film 190 or the diamond-like carbon thin film 190 and the light absorption layer 110 shown in FIG. 2B, the diamond-like carbon thin film ( 190 alone does not effectively prevent contrast and visibility deterioration due to light incident from the outside, and thus additionally needs to form a light absorption layer 110 using carbon particles between the transparent substrate 100 and the anode electrode 120. Only a part of the display light emitted from the light emitting layer is transmitted, and the increase in the process results in an increase in the process and cost.

Accordingly, the present invention is to solve the problems of the prior art as described above, by forming a diamond-like carbon thin film layer on the second electrode to reduce the reflectance of the metal electrode and to enhance the interference-enhanced absorption characteristics of the incident external light It is an object of the present invention to provide an organic light emitting display device which can prevent a decrease in contrast and visibility and reduce manufacturing costs.

The present invention to achieve the above object,

A first electrode formed on the transparent substrate;

An organic film layer having at least a light emitting layer formed on the first electrode;

A second electrode formed on the organic layer;

An organic light emitting display device including a diamond carbon thin film having a very low black color and being chemically stable on the second electrode is provided.

In addition, the manufacturing method for achieving the above object,

Forming a first electrode on the transparent substrate;

Forming an organic layer including at least an emission layer on the first electrode;

Forming a second electrode on the organic layer;

Provided is a method of manufacturing an organic light emitting display device, including forming a diamond carbon thin film having a very low black color on the second electrode and being chemically stable.

In this case, the first electrode is formed of one type of transparent electrode selected from the group consisting of ITO, IZO and In ₂ O ₃ ,

The second electrode provides a method of manufacturing an organic light emitting display device, wherein the second electrode is formed of one selected from the group consisting of Ca, Mg, MgAg, Ag, Ag alloy, Al, and Al alloy.

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

3 is a view for explaining a schematic cross-sectional structure of an organic light emitting display device including a diamond-like carbon thin film according to the present invention.

Referring to FIG. 3, the first electrode 220 is formed on the entire surface of the substrate 100 formed of any one of glass, quartz, and plastic. In this case, the first electrode may be an anode electrode and is formed of one type of transparent electrode selected from the group consisting of ITO, IZO, and In ₂ O ₃ .

Subsequently, an organic layer 280 having at least a light emitting layer on the first electrode is formed. In this case, the organic layer may further include various layers depending on its function and an emitting layer (EL) 250 that emits light using excitons generated through the combination of injected holes and electrons. Hole injection layer (HIL) 230 to facilitate the release of holes to the hole (Hole injection layer; HTL) 240 for transporting holes injected from the hole injection layer to the light emitting layer (HTL) 240 An electron transport layer (ETL) 260 which transports electrons injected from the electron injection layer to the light emitting layer, and an electron injection layer (EIL) 270 for easily emitting electrons; It may comprise or be formed of a multilayer film of at least one layer or more. In this case, the organic film layer may generally use both a low molecular weight and a high molecular material, and a light emitting layer forming method commonly used such as spin coating, vacuum deposition, and laser thermal transfer may be used according to a generally used material.

 The second electrode 290 is formed on the organic layer 280. In this case, the second electrode may be a cathode electrode for supplying electrons, and the second electrode as described above may be generally used as both a transparent and translucent cathode electrode, but it is preferable to have a light transmitting property. In this case, when the second electrode is a cathode, the material used is selected from the group consisting of Ca, Mg, MgAg, Ag, Ag alloys, Al, and Al alloys having a low work function of 4.5 eV or less, which facilitates electron emission. It is desirable to form one material.

After the formation of the second electrode 290 as described above, the diamond-like carbon thin film 300 which is very low black and chemically stable in order to prevent a decrease in visibility and contrast caused by reflecting incident external light according to the present invention ).

In addition to the above-described structure, in some cases, a transparent metallic oxide film such as IZO may be formed between the second electrode 290 and the diamond-like carbon thin film 300.

The method of forming a diamond-like carbon thin film as described above is a gas mixed with methane (CH ₄ ) and hydrogen (H ₂ ) or a gas mixed with ethane (C ₂ H ₆ ) and hydrogen (H ₂ ) and power density, etc. Plasma is used to form a diamond-like carbon thin film by chemical reaction of reactive gases generated from the plasma. At this time, it can be deposited by selecting from three chemical vapor deposition methods such as Electron Cyclotron Resonance (ECR), Microwave, and Radio Frequency (RF) Plasma. Has low reflectivity, very low black color, and is amorphous, with a refractive index between 1.8 and 2.2. In the case of the diamond-like carbon thin film, the characteristics of the film may be variously changed depending on the composition of the plasma during deposition, that is, the mixing ratio or power density of the gas used.

In this case, the deposited diamond-like carbon thin film has a band gap between 1.2 eV and 3.6 eV, and has a large surface roughness, thereby increasing the refractive index while reducing the reflectance, thereby further improving the interference-enhanced absorption characteristics. In addition, as mentioned above, the refractive index and reflectance characteristics can be changed according to the mixing ratio and power density of the mixed gas during deposition using the chemical vapor deposition method, so that the diamond phase having the respective refractive index and reflectance according to the deposition conditions is different. The carbon thin film can be formed.

Therefore, when the diamond-like carbon thin film having the above characteristics is applied to the light absorption and anti-reflection thin film of the organic light emitting display device, the total transmittance of the light generated by lowering the total internal reflection during driving is improved, and the incident external light It can be seen that by preventing the reflection by increasing the utilization ratio of the internal light to 50% to improve the external light efficiency, and greatly improve the contrast and visibility.

According to the present invention as described above, the diamond-like carbon thin film is very chemically stable, has a very low black color, and has an excellent light absorption characteristic and has a low reflectance. When the diamond-like carbon thin film is applied as a light absorbing and anti-reflection thin film of an organic light emitting display device, a separate polarizing plate is not required, and the manufacturing cost can be reduced by simplifying the process compared to the conventional anti-reflective structure. The interference-enhanced absorption characteristics can absorb unreflected light and incident external light from the metal reflective film, bring about the use of internal light and increase the external light efficiency, thereby improving contrast and visibility.

It is to be understood that the techniques of the present invention described above may be variously modified and changed by those skilled in the art without departing from the spirit and scope of the invention as set forth in the claims below. There will be.

Claims (19)

With a transparent substrate, A first electrode formed on the substrate; An organic film layer having at least a light emitting layer formed on the first electrode;        A second electrode formed on the organic layer; And a diamond-like carbon thin film formed on the second electrode.        The method of claim 1, The first electrode is an organic light emitting display, which is an anode made of one type of transparent electrode selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and In ₂ O ₃ . Device.        The method of claim 1, And the second electrode is a cathode electrode made of one material selected from the group consisting of Ca, Mg, MgAg, Ag, Ag alloys, Al and Al alloys.        The method of claim 1, The method of depositing the diamond-like carbon thin film is an organic light emitting display device using a chemical vapor deposition (CVD) method.        The method of claim 1, An organic light emitting display device in which the band gap of the diamond-like carbon thin film is 1.2 eV to 3.6 eV.        The method of claim 1, An organic electroluminescent device, wherein the diamond-like carbon thin film is amorphous.        The method of claim 1, The refractive index of the diamond carbon thin film is an organic light emitting display device of 1.8 to 2.2.        The method of claim 1, The diamond-like carbon thin film is an organic light emitting display device using a gas in which methane (CH ₄ ) and hydrogen (H ₂ ) are mixed or a gas in which ethane (C ₂ H ₆ ) and hydrogen (H ₂ ) are mixed.        The method of claim 4, wherein The chemical vapor deposition method is an organic electroluminescent display using one method selected from the group consisting of Electron Cyclotron Resonance (ECR), Microwave and Radio Frequency (RF) Plasma Device. With a transparent substrate, A first electrode formed on the substrate; An organic film layer having at least a light emitting layer formed on the first electrode;        A second electrode formed on the organic layer; A transparent conductive metal oxide film formed on the second electrode, and And a diamond-like carbon thin film formed on the transparent conductive metal oxide film. The method of claim 10, The first electrode is an organic light emitting display, which is an anode made of one type of transparent electrode selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), and In ₂ O ₃ . Device.        The method of claim 10, And the second electrode is a cathode electrode made of one material selected from the group consisting of Ca, Mg, MgAg, Ag, Ag alloys, Al and Al alloys. The method of claim 10, The transparent conductive metal oxide film is indium zinc oxide (IZO) organic light emitting display device.        The method of claim 10, The method of depositing the diamond-like carbon thin film is an organic light emitting display device using a chemical vapor deposition (CVD) method.        The method of claim 10, An organic light emitting display device in which the band gap of the diamond-like carbon thin film is 1.2 eV to 3.6 eV.        The method of claim 10, An organic electroluminescent device, wherein the diamond-like carbon thin film is amorphous.        The method of claim 10, The refractive index of the diamond carbon thin film is an organic light emitting display device of 1.8 to 2.2.        The method of claim 10, The diamond-like carbon thin film is an organic light emitting display device using a gas in which methane (CH ₄ ) and hydrogen (H ₂ ) are mixed or a gas in which ethane (C ₂ H ₆ ) and hydrogen (H ₂ ) are mixed.        The method of claim 13, The chemical vapor deposition method is an organic electroluminescent display using one method selected from the group consisting of Electron Cyclotron Resonance (ECR), Microwave and Radio Frequency (RF) Plasma Device.

Images