KR20050064863A - Organic electro luminescence device and fabrication method thereof - Google Patents

Abstract

In the method of manufacturing an organic light emitting display device according to the present invention, in the method of manufacturing an organic light emitting display device in which a first electrode, an organic light emitting layer, and a second electrode are sequentially stacked on a substrate,

Applying a photoresist comprising fine particles dispersed on a substrate on a surface in contact with the first electrode; Exposing the photoresist including the fine particles to cure photoresists other than the fine particles; Removing the uncured fine particles and etching to form a recess pattern on the substrate; Removing the photoresist and exposing the substrate having a predetermined recess pattern by etching; And sequentially forming the first electrode, the organic light emitting layer, and the second electrode on the substrate to which the recess pattern is exposed.

According to the present invention, by increasing the incident angle of the light incident from the organic light emitting layer to the substrate by the concave portion pattern, the amount of light emitted to the outside is greatly increased to improve the external light emitting efficiency, low current due to high light efficiency As a result, driving is possible, and thus deterioration of the device is delayed, resulting in minimization of color coordinate variation.

Description

Organic electroluminescent device and its manufacturing method {Organic Electro luminescence Device and fabrication method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device in which a plurality of concave portions patterns are formed on a glass substrate in contact with an anode, and a method of manufacturing the same.

Recently, as the size of the display device increases, the demand for a flat display device having less space is increasing. As one of the flat display devices, the technology of the organic light emitting display device is rapidly developing, and several prototypes have been announced. .

The organic EL device has a structure in which an organic thin film layer is provided between a cathode, which is a transparent electrode such as ITO, and a cathode using a metal having low work function (Ca, Li, Al: Li, Mg: Ag, etc.). When a forward voltage is applied to the device, holes and electrons are injected from the anode and the cathode, respectively, and the injected holes and electrons combine to form excitons, and the excitons undergo radiative recombination. This is called.

The material of the organic thin film layer may be classified into a low molecular weight or a high molecular material. The low molecular material uses a vacuum deposition method, and the high molecular material forms a thin film on a substrate by a spin coating method. In addition, in order to operate the device at low voltage, the organic thin film layer is manufactured to be very thin, about 1000 kW. The thin film must be uniform and free from defects such as pin holes.

The organic thin film layer may be made of a single material, but generally uses a multilayer structure of several organic materials. In addition, the fluorescent dye or the phosphorescent dye is doped so that the light emitting transition effectively occurs in the light emitting layer. In this case, it is important to ensure that the excitons produced by the host are effectively transferred to the doped pigment.

The reason why the organic EL device is manufactured in a multilayer thin film structure is that the mobility of holes and electrons varies greatly in the case of an organic material. Therefore, when the hole transport layer (HTL) and the electron transport layer (ETL) are used, holes and electrons are formed in the organic light emitting layer ( EML) can be effectively delivered. In this way, when the density of holes and electrons is balanced in the organic light emitting layer, the light emission efficiency is increased.

In some cases, a hole injection layer (HIL), such as a conductive polymer or Cu-PC, is additionally inserted on the anode and the hole transport layer to lower the energy barrier of hole injection, and furthermore, between the LiF and the cathode transport layer. A thin buffer layer (electron injection layer (EIL)) of about 5-10 kHz, etc. is added to reduce the energy barrier of electron injection, thereby increasing luminous efficiency and lowering the driving voltage.

The organic EL device has an advantage of being able to drive at a lower voltage (ex 10V or less) than a plasma display (PDP) or an inorganic electroluminescent device, and has excellent features such as a wide viewing angle, high speed response, and high contrast. It can be used as a pixel of a graphic display, a pixel of a television image display or a surface light source.

In addition, since the device can be formed on a flexible transparent substrate such as plastic, it can be made very thin and light, and the color is good, it is suitable for the next-generation flat panel display device, and it is also a backlight compared to LCD. (No back light), low power consumption.

1 is a cross-sectional view showing the structure of a conventional organic EL device.

Referring to FIG. 1, a conventional organic EL device includes a substrate 1, a first electrode 2, a hole injection layer 3, a hole transport layer 4, an organic light emitting layer 6, an electron transport layer 7, and an electron. An injection layer 8 and a second electrode 9 are included.

Here, the substrate 1 generally uses glass, but may be bent plastic or PET film. Since the production of the organic EL device does not require a high temperature process, a substrate capable of withstanding a process temperature of 100 ° C. is useful, which includes most thermal plastics.

A first electrode (anode) 2 material is deposited on the substrate 1. As the material of the first electrode 2, various metals having a high work function may be selected. Indium tin oxide (ITO) is generally used because it has a relatively high work function and is transparent in itself.

The hole injection layer 3 is formed on the first electrode 2. The material used as the hole injection layer 3 is made of metal, that is, an electron band (valance band) of the material so that the entrance of holes from the first electrode 2 into the organic film is not disturbed. There should be no significant difference from the fermi level, and at the same time the material should have good adhesion to the metal.

Next, a hole transport layer 4 is formed on the hole injection layer 3. As the material used for the hole transport layer 4, a material having no significant difference between the work function of ITO, which is commonly used as the first electrode, and the electron band of the material is used.

The hole injection layer 3 and the hole transport layer 4 as described above may form a hole injection / transport layer as one layer.

The organic emission layer 6 is formed on the hole transport layer 4. Axons formed by combining holes and electrons injected from the first and second electrodes 1 and 9, respectively, fall into a ground state and emit light, and conduction bands of the hole transport layer 4 and the electron transport layer 7, respectively, The emission color is determined by the band gap of the electron band.

The electron transport layer 7 and the electron injection layer 8 are continuously formed on the organic light emitting layer 6, or the electron injection / transport layer is formed. In the case of green light emission, Alq3, which is used as the organic light emitting layer, has an excellent electron transport ability, so that an electron injection / transport layer is often not used.

Next, a second electrode 9 is formed on the electron injection layer 8. As the metal used as the second electrode, a material having a low work function is used. Generally, the smaller the work function of the electrode, the easier the electron injection but the higher the reactivity. There is difficulty. MgAg, CaAl, and the like are often used as the second electrode.

However, in the conventional organic EL device structure as described above, the refractive index of the organic EL layers 3, 4, 6, 7, and 8 including the organic light emitting layer is generally about 1.7, whereas the first electrode as the anode ( The refractive index of 2) is 1.8 to 2.1, the refractive index of the glass substrate 1 is about 1.46, and since the refractive indexes of the substrate 1 and the first electrode 2 are large, even if light is generated in the organic light emitting layer 6 Due to the optical coupling phenomenon in the substrate 1 and the first electrode 2, there is a problem that the external light emitting efficiency is only about 20% of the internal light emitting efficiency.

That is, about 80% of the light emitted from the organic light emitting layer 6 is not emitted to the outside, which causes disadvantages such as an increase in driving voltage and short light emitting lifetime in driving the actual device.

According to the present invention, a plurality of recess patterns are formed on a substrate on a surface in contact with an anode, thereby expanding an area of an interface between the anode and the substrate, and increasing the size of an incident angle of light from the organic light emitting layer to the substrate by the recess patterns. The present invention relates to an organic light emitting display device and a method for manufacturing the same, which greatly increase the amount of light emitted to the outside to improve external light emission efficiency.

In order to achieve the above object, an organic light emitting display device according to the present invention is an organic light emitting display device having a structure in which a first electrode, an organic light emitting layer, and a second electrode are sequentially stacked on a substrate, wherein the first electrode and A plurality of recessed pattern is formed on the board | substrate of the surface which abuts.

The substrate may be an organic substrate or a polymer substrate, and the first electrode may be a transparent indium-tin-oxide (ITO) electrode as an anode, and the second electrode may be a metal electrode having a low work function as a cathode. Is used.

In addition, the organic light emitting layer is composed of one or more multilayers.

In addition, the method of manufacturing an organic light emitting display device according to the present invention is a method of manufacturing an organic light emitting display device, in which a first electrode, an organic light emitting layer, and a second electrode are sequentially stacked on a substrate.

Applying a photoresist comprising fine particles dispersed on a substrate on a surface in contact with the first electrode; Exposing the photoresist including the fine particles to cure photoresists other than the fine particles; Removing the uncured fine particles and etching to form a recess pattern on the substrate; Removing the photoresist and exposing the substrate having a predetermined recess pattern by etching; And sequentially forming the first electrode, the organic light emitting layer, and the second electrode on the substrate to which the recess pattern is exposed.

At this time, the etching is a dry or wet etching method, the fine particles are nano-sized (nano-size) material that is not cured by exposure, removing the fine particles, a predetermined solvent (solvent) Characterized by melting the fine particles through.

In addition, the first electrode is formed on the substrate to which the recess pattern is exposed by a sputtering method, and further comprising a planarization step of minimizing the thickness variation of the first electrode film.

According to the present invention as described above, according to the present invention, by increasing the incident angle of the light incident on the substrate by the recess pattern, the amount of light emitted to the outside is greatly increased to improve the external light emission efficiency, high light efficiency As a result, low current driving is possible, and thus deterioration of the device is delayed, resulting in minimization of color coordinate variation.

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

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

Referring to FIG. 2, the organic EL device according to the present invention includes a substrate 200, a first electrode 220, a hole injection layer 241, a hole transport layer 243, an organic emission layer 245, and an electron transport layer 247. And an electron injection layer 249 and a second electrode 260, and a plurality of recess patterns 210 are formed on the substrate 200 on the surface in contact with the first electrode 220. It is characterized by the presence.

In this case, the substrate 200 generally uses glass, but a polymer or a bendable plastic or PET film may be used. Since the production of the organic EL device does not require a high temperature process, a substrate capable of withstanding a process temperature of 100 ° C. is useful, which includes most thermal plastics.

In addition, a transparent indium tin oxide (ITO) electrode is used as an anode, and a second electrode 260 is a metal electrode having a low work function as a cathode, and the organic light emitting layer 240 may be comprised of one or more multilayers as shown.

In addition, as described above, the substrate 200 has a plurality of recess patterns 210 formed on a surface of the substrate 200 in contact with the first electrode 220, through which the substrate 200 and the first electrode 220 are formed. The area of the interface between) is greatly expanded.

As described above, in the substrate 200 having the concave portion pattern 210 formed therein, the light output efficiency decreases due to the difference in refractive index between the interface of the first electrode 220 and the substrate 200. By increasing the amount of light to be emitted, it is possible to greatly increase the amount of light emitted to the outside.

In addition, since the recess pattern 210 is generally spherical in shape, the incident angle of the external incident light at the interface is kept close to 0 degrees, so that the reduction of the light output efficiency due to the critical angle can be greatly reduced.

In the related art, the bending patterns formed on the organic substrate are formed on the opposite side of the surface contacting the first electrode, which is effective only for light emitted from the glass substrate and does not affect the internal optical coupling phenomenon. There was a disadvantage.

On the contrary, according to the present invention, since the light efficiency can be increased by 51% by the first electrode 220, the light output efficiency is greatly increased by overcoming the internal optical coupling phenomenon.

Hereinafter, a manufacturing process of an organic light emitting display device according to the present invention will be described with reference to FIG. 3.

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

As shown in FIG. 3A, a photoresist 300 including fine particles 310 dispersed on a substrate 190 such as glass, a polymer, a transparent plastic, or the like is coated.

Herein, the fine particles 310 are nano-sized materials that are not cured by exposure, and may be plastic or rubber.

That is, the resin (resin) used as a general PR material, the nano-sized plastic, rubber particles are included to form a photoresist 300 according to the present invention, the photoresist 300 is a first electrode after It is applied to the substrate 190 of the surface to be formed.

Next, as shown in FIG. 3B, the photoresist 300 including the fine particles 310 is exposed to cure the photoresist 300 other than the fine particles 310.

That is, the photoresist 300 is a photoresist having a property of being cured by exposure, except that the fine particles 310 included in the photoresist are not cured by such exposure.

Next, as shown in FIG. 3C, the uncured fine particles 310 are removed and the photoresist portion 300 from which the fine particles 310 have been removed is etched.

In this case, the etching may be performed by a dry or wet etching method, the fine particles are removed by dissolving the fine particles through a predetermined solvent (solvent).

After such an etching process, the photoresist 300 is removed, and when the photoresist is removed, the substrate 200 on which the predetermined recess pattern 210 is formed is exposed by etching. That is, the first substrate 190 is changed to the substrate 200 on which the predetermined recess pattern is formed. This is shown in Figure 3d.

As described above, the first electrode 220, the organic light emitting layer 240, and the second electrode 260 are sequentially formed on the substrate 200 on which the plurality of recess patterns 210 are formed. An electroluminescent device is formed, which is shown in FIG. 3e.

In this case, the first electrode 220 is formed on the substrate 200 on which the recess pattern 210 is exposed by sputtering, and the planarization step of minimizing the thickness variation of the film of the first electrode 220 is performed (not shown). May be further included.

The first electrode 220, the organic light emitting layer 240, and the second electrode 260 are described in more detail as follows.

As the material of the first electrode 220, various metals having a high work function may be selected. In general, ITO has a relatively high work function, and because it is transparent in itself, it is commonly used as the first metal.

The hole injection layer 241 is formed on the first electrode 220. The material used as the hole injection layer is made of a metal, that is, the band of the material has a greater than the Fermi level (fermi level) of the first electrode so as not to prevent the hole from entering the organic film from the first electrode There should be no difference and at the same time the material should have good adhesion with the metal.

Next, a hole transport layer 243 is formed on the hole injection layer 241. As the material used for the hole transport layer, a material having no significant difference between the work function of ITO, which is commonly used as the first electrode, and the electron band of the material is used.

The hole injection layer 241 and the hole transport layer 243 as described above may form a hole injection / transport layer as one layer.

The organic emission layer 245 is formed on the hole transport layer 243. Axons formed by combining holes and electrons injected from the first and second electrodes 220 and 260, respectively, fall into a ground state to emit light, and each conduction band of each of the hole transport layer 243 and the electron transport layer 247 is formed. The emission color is determined by the band gap of the electron band.

The electron transport layer 247 and the electron injection layer 249 are continuously formed on the organic emission layer 245, or the electron injection / transport layer is formed. In the case of green light emission, Alq3, which is used as the organic light emitting layer, has an excellent electron transport ability, so that an electron injection / transport layer is often not used.

The hole injection layer 241, the hole transport layer 243, the organic emission layer 245, the electron transport layer 247, and the electron injection layer 249 described above form the organic light emitting layer 240.

Next, a second electrode 260 is formed on the electron injection layer 2498. As the metal used as the second electrode, a material having a low work function is used. Generally, the smaller the work function of the electrode, the easier the electron injection but the higher the reactivity. There is difficulty. MgAg, CaAl, and the like are often used as the second electrode.

The organic light emitting display device and the method of manufacturing the same according to the present invention form a plurality of concave portion patterns on a substrate on a surface in contact with an anode to expand the area of the interface between the anode and the substrate, and the organic light emitting layer by the concave portion pattern. By increasing the size of the incident angle of the light incident on the substrate, the amount of light emitted to the outside is greatly increased to improve the external light emitting efficiency, and the low light driving is possible due to the high light efficiency, thereby deteriorating the device As a result, the variation of color coordinates is minimized as a result.

1 is a cross-sectional view showing the structure of a conventional organic EL device.

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

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

<Explanation of symbols for the main parts of the drawings>

200: substrate 210: recess pattern

220: first electrode 240: organic light emitting layer

260: second electrode 300: photoresist

310: fine particles

Claims (9)

In an organic light emitting display device having a structure in which a first electrode, an organic light emitting layer, and a second electrode are sequentially stacked on a substrate, The organic light emitting device, characterized in that a plurality of recess pattern is formed on the substrate of the surface in contact with the first electrode. The method of claim 1, The substrate is an organic light emitting device, characterized in that the organic substrate or a polymer (polymer) substrate. The method of claim 1, The first electrode is a transparent indium tin oxide (ITO) electrode is used as the anode, the second electrode is an organic electroluminescent device, characterized in that the electrode of a metal material having a low work function is used as the cathode. The method of claim 1, The organic light emitting device is characterized in that the organic light emitting device is composed of one or more multilayers. In the method of manufacturing an organic light emitting device in which the first electrode, the organic electroluminescent layer, and the second electrode are sequentially stacked on the substrate, Applying a photoresist containing fine particles dispersed on a substrate on a surface in contact with the first electrode; Exposing the photoresist including the fine particles to cure photoresists other than the fine particles; Removing the uncured fine particles and etching to form a recess pattern on the substrate; Removing the photoresist and exposing the substrate having a predetermined recess pattern by etching; And sequentially forming the first electrode, the organic light emitting layer, and the second electrode on the exposed substrate pattern. The method of claim 5, The fine particle is a method of manufacturing an organic light emitting device, characterized in that the nano-sized (nano-size) material that is not cured by exposure. The method of claim 5, Removing the fine particles, the organic electroluminescent device manufacturing method, characterized in that made by melting the fine particles through a predetermined solvent (solvent). The method of claim 5, The first electrode is formed by sputtering on a substrate on which the recess pattern is exposed, and further comprising a planarization step of minimizing the variation of the thickness of the first electrode film. The method of claim 5, The etching is a method of manufacturing an organic light emitting device, characterized in that performed by a dry etching method or a wet etching method.