KR20000045277A - Organic electroluminescence device and method for fabricating the same - Google Patents

Abstract

PURPOSE: An organic electroluminescence device is provided to improve a luminescence efficiency and to prevent a device deterioration of a surface between an anode electrode and an organic film. CONSTITUTION: An organic electroluminescence device an insulation substrate(21), an anode electrode(22), an organic film(23), a cathode electrode(24), and a buffer layer(27). The organic film(23) consists of a hole transfer layer(231), a luminescence layer(232) and an electron transfer layer(233). The buffer layer(27) is formed between the anode electrode(22) and the organic layer(23) in order to increase an adhesion force, and consists of a photosensitive high polymer film whose surface is processed by ultraviolet rays. The cathode electrode is formed on the organic film(23). A positive terminal of a DC voltage is connected to the anode electrode(22), and a negative terminal thereof is connected to the cathode electrode(24).

Description

Organic electroluminescent device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to a surface treatment technology capable of improving bonding adhesion between an anode electrode and an organic film or a cathode electrode and an organic film having a high work function.

Electroluminescent devices are faster in response to light-receiving devices such as liquid crystal display devices (LCDs). It is attracting attention as the next generation flat panel display device. EL devices are used for LCD backlights, portable terminals, car navigation systems (CNS), notebook computers and wall-mounted TVs.

The organic EL device is a carrier injection type, and is a structure in which organic materials having different carrier transport properties between electrodes having different work functions, for example, anodes and cathodes, are stacked to a thickness of several hundred micrometers by vacuum deposition or spin coating, respectively. Has

1 is a cross-sectional view of a conventional organic EL device. In the organic EL device of FIG. 1, the anode electrode 12, the hole transport layer 131, the light emitting layer 132, the organic layer 13 of the electron transport layer 133, and the metal cathode electrode 14 are formed on a transparent insulating substrate 11. ) Has a stacked structure.

In the conventional organic EL device, an electrode material having a high work function, for example, an ITO material, which is a transparent conductive film, is used to smoothly supply holes to the hole transport layer 131 of the organic layer 13 from the anode electrode 12.

In the conventional organic EL device as described above, a material having a high work function is used as the anode electrode 12 to smoothly inject holes from the anode electrode 12 into the hole transport layer 131 of the organic layer 13. (12) forming a material having a high work function into a stable thin film, and sequentially forming an organic layer 13 and an anode electrode 14 of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133 thereon. In order for the lower layer to have good thin film manufacturing characteristics of the anode electrode.

However, since ITO, which is used as a conventional anode electrode, is an inorganic material having a high work function, and the organic layer having a three-layer structure stacked thereon is an organic material, the surface interface of the inorganic material and the organic material is poor in adhesion and the bonding energy between atoms is significantly different. Therefore, there is a problem in that the luminous efficiency and luminance of the device is lowered and the quality of the device is lowered.

The present invention provides an organic EL device capable of improving the adhesion between two layers by forming a photosensitive polymer film between an ITO film and an organic film used as an anode electrode, and a method for manufacturing the same. There is a purpose.

Another object of the present invention is to provide an organic EL device and a method of manufacturing the same, which can improve luminance by improving luminous efficiency and prevent deterioration of the device at the interface between the anode electrode and the organic film to obtain long life.

It is still another object of the present invention to provide an organic EL device and a method of manufacturing the same, which form a photosensitive polymer film between a cathode electrode and an organic film to improve adhesion between two layers, thereby increasing luminous efficiency.

It is still another object of the present invention to provide an organic EL device which can improve luminous efficiency, improve luminance, and prevent device deterioration at the interface between the anode electrode and the organic film to obtain long life.

1 is a cross-sectional structure diagram of a conventional organic electroluminescent device;

2 is a cross-sectional structure diagram of an organic light emitting diode according to an embodiment of the present invention;

3 is a view for explaining a surface treatment method of the organic light emitting device of FIG.

4 is a view for explaining another surface treatment method in the organic light emitting device of FIG.

5 is a cross-sectional structure diagram of an organic light emitting device according to another embodiment of the present invention;

6 is a view showing an example of a photosensitive polymer film as a buffer layer according to an embodiment of the present invention;

7 is a view showing an example of a buffer layer doped with a photosensitive low molecular weight in an organic film according to an embodiment of the present invention,

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

21 substrate 22 anode electrode (ITO)

23: organic film 231: hole transport layer

232: light emitting layer 233: electron transport layer

24: cathode electrode 25: DC power

27, 28: buffer layer

In order to achieve the above object of the present invention, the present invention is an organic EL device comprising a cathode electrode, a hole transport layer, a light emitting layer and an electron transport layer and an organic electrode formed sequentially on the substrate, between the anode electrode and the organic film It is characterized in that to provide an organic light emitting device comprising a buffer layer formed in order to improve their interfacial properties.

In addition, the present invention provides an organic EL device in which an organic film and a cathode electrode, each of which comprises an anode electrode, a hole transport layer, a light emitting layer and an electron transport layer, are sequentially formed on a substrate. An organic electroluminescent device comprising a buffer layer formed is provided.

According to an embodiment of the present invention, a photosensitive polymer membrane having SiO _n as a main chain and a photosensitive derivative as a side chain is used as the buffer layer, and one of chalcone derivatives, PVC derivatives or azobenzene derivatives is used as the photosensitive derivative.

According to an embodiment of the present invention, the buffer layer is made of a material having molecular arrangement in which molecules are arranged in a predetermined direction. When the photosensitive derivative is hydrophobic, an organic film having hydrophobicity is used as the electron transporting layer of the organic film, and when the photosensitive derivative is hydrophilic, an organic film having hydrophilicity is used as the electron transporting layer of the organic film. When the photosensitive derivative is hydrophobic, the organic layer having hydrophobicity is used as the hole transport layer of the organic film, and when the photosensitive derivative is hydrophilic, the buffer layer having the hydrophilic organic film as the hole transporting layer of the organic film has a thickness of 2 to 20 nm. .

In addition, the present invention comprises the steps of forming an anode electrode on the substrate; Forming a buffer layer on the anode electrode to improve interface characteristics with the anode electrode; Irradiating UV to the buffer layer; Forming an organic layer of a hole transport layer, a light emitting layer, and an electron transport layer on the buffer layer; It provides a method of manufacturing an organic light emitting device comprising the step of forming a cathode electrode on the organic film.

The present invention comprises the steps of forming an anode electrode on the substrate; Forming an organic film including a hole transport layer, a light emitting layer, and an electron transport layer on the anode electrode; Forming a buffer layer on the organic film to improve interfacial properties with the organic film; Irradiating UV to the buffer layer; It provides a method for manufacturing an organic electroluminescent device comprising the step of forming a cathode electrode.

According to the method of manufacturing an organic light emitting device according to an embodiment of the present invention, a photosensitive polymer film having SiO _n as a main chain and a photosensitive derivative as a side chain is formed by spin coating or vacuum deposition as the buffer layer. As the photosensitive derivative, one of a chalcone derivative, a PVC derivative or an azobenzene derivative is used.

According to the method of manufacturing an organic field device according to an embodiment of the present invention, a material having a molecular arrangement in which molecules are arranged in a predetermined direction is used as the buffer layer. When the photosensitive derivative is hydrophobic, an organic film having hydrophobicity is formed as the hole transport layer of the organic film. When the photosensitive derivative is hydrophilic, an organic film having hydrophilicity is formed as the hole transport layer of the organic film. The buffer layer is formed to a thickness of 2 to 20nm.

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

2 illustrates a cross-sectional structure of an organic EL device according to an embodiment of the present invention. An EL device according to an embodiment of the present invention is an organic film 23 and a cathode electrode formed of an anode electrode 22, a hole transport layer 231, a light emitting layer 232, and an electron transport layer 233 on an insulating substrate 21. (24) has a structure stacked sequentially.

As the substrate 21, a transparent substrate that can transmit and see light emitted from the light emitting layer 232 of the organic layer 23 is used. The anode electrode 22 serves to supply holes, and a transparent electrode such as ITO capable of transmitting light emitted from the light emitting layer 232 of the organic layer 23 is used.

The hole injection layer 231 constituting the organic layer 23 transports holes from the anode electrode 22 to the light emitting layer 232 and prevents the disappearance of electrons moved to the light emitting layer 232. The light emitting layer 232 is an organic layer that emits light by combining electrons supplied from the cathode electrode 24 and holes supplied from the anode electrode 22. Various kinds of materials are used according to the color of light emitted, Determines the quantum efficiency. The electron transport layer 233 supplies electrons supplied from the cathode electrode 22 to the light emitting layer 232 and prevents the disappearance of holes moving from the light emitting layer 232. The cathode electrode 24 serves to supply electrons.

Further, in the organic EL device according to the embodiment of the present invention, a buffer layer 27 is formed between the anode electrode 22 and the organic layer 23 to increase the adhesion between them. At this time, as the buffer layer 27 for increasing the adhesion between the anode electrode 22 and the organic film 23, vacuum deposition or spin coating of a photosensitive polymer film containing SiO _n based, for example, SiO ₂ as a main chain is performed. coating). After spin-coating the photosensitive polymer film 27, the surface is treated by UV irradiation.

As the photosensitive polymer film including SiO ₂ as a main chain, a material having a structural formula as shown in FIG. 5 is used.

As described above, as the buffer layer 27 for improving the interfacial properties between the anode electrode 22 and the organic film 23, a material doped with a photosensitive low molecule in the organic film is formed by spin coating or vacuum deposition. At this time, there are two methods for forming the buffer layer 27, in place of the photosensitive polymer having SiO ₂ as a main chain, the photosensitive derivative of FIG. 5, for example chalcone, in the general polymer material having the chemical formula shown in FIG. A derivative, PVC (Poly Vinyl Cinnamate) derivative, or azobenzene (azobenzene) is added, mixed and dissolved in a solvent (solvent) spin coating method, another method is spin coating a polymer as shown in Figure 6 on the anode electrode (23) Then, there is a method of vacuum depositing the photosensitive low molecular weight (photosensitive derivative) as described above.

In the same manner as described above, the organic film is doped with a photosensitive low molecular weight to form a buffer layer 27 and then subjected to surface treatment by UV irradiation.

Since the photosensitive polymer film 27 is irradiated with UV, dark spots exist because side chains connected to the main chain are irregularly arranged as shown in FIG. 3B. When the surface treatment by UV irradiation, the photosensitive polymer film 27 not only improves adhesion at the interface between the anode electrode 22 and the organic film 23 because the side chains connected to the main chain are irregularly arranged as shown in FIG. 3B. By rearranging the molecules regularly, the hole injection efficiency is improved and thus the luminous efficiency is increased.

Such an organic EL device applies a direct current voltage 25 having a negative voltage to the cathode electrode 24 and a positive voltage to the anode electrode 22 to provide an electric field of several MV / cm between the organic films 23. When this is induced, electrons are transported from the cathode electrode 24 to the organic film 23, and holes are transported from the anode 22 to the organic film 23, and the light emitting layer 232 is formed through the electron transport layer 233 and the hole transport layer 231. ), And the electrons and holes injected from the emission layer 232 recombine to emit light.

Accordingly, in one embodiment of the present invention, the photosensitive polymer film is spin-coated or vacuum-deposited to a thickness of 2 to 20 nm with a buffer layer 27 for improving interfacial properties on the anode electrode 22, and then molecularly grown by irradiating UV. Improve hole injection efficiency by heat. In addition, in the present invention, when the photosensitive polymer is grown by using the spin coating method, the thin film is easily formed, thereby preventing the damage of the thin film at a low temperature, and in the case of vacuum deposition, the rearrangement of the molecules is improved. It is effective in increasing the luminous efficiency.

According to an embodiment of the present invention, when the photosensitive low molecular weight used to form the buffer layer is hydrophobic, the hole transport layer 231 of the organic layer 23 also uses a hydrophobic organic film, and when the photosensitive low molecular weight is hydrophilic, When the hole transport layer 231 of the film 23 is formed using a hydrophilic organic film, the injection of electrons and holes is made smoother.

As described above, when the photosensitive polymer film is formed in a directional manner, when the photosensitive low molecule, that is, the photosensitive derivative, is hydrophobic, the hole transport layer 231 formed thereon is hydrophobic, as shown in FIG. 4. By aligning the side chains, the molecular rearrangement can be further improved.

5 shows a cross-sectional structure of an organic EL device according to another embodiment of the present invention. In the organic EL device according to the other embodiment shown in FIG. 5, the buffer layer 28 is formed between the cathode electrode 24 and the organic film 23 in order to improve the interfacial characteristics therebetween.

As described in detail above, according to the organic EL device of the present invention, in order to improve the interfacial properties between the anode electrode and the organic film or the cathode electrode and the organic film, a photosensitive polymer film or a material doped with a photosensitive low molecule in organic By forming by spin coating or vacuum deposition, the luminous efficiency can be increased to improve the luminance, and the deterioration of the device at the interface can be prevented, thereby increasing the life of the device.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (19)

In an organic EL device in which an organic film consisting of an anode electrode, a hole transport layer, a light emitting layer, and an electron transport layer and a cathode electrode are sequentially formed on a substrate, And a buffer layer formed between the anode electrode and the organic film to improve their interfacial properties. The organic electroluminescent device according to claim 1, wherein a photosensitive polymer film having SiO _n as a main chain and a photosensitive derivative as a side chain is used as the buffer layer. The organic electroluminescent device according to claim 2, wherein one of a chalcone derivative, a PVC derivative and an azobenzene derivative is used as the photosensitive derivative. The organic light emitting device of claim 3, wherein the buffer layer is formed of a material having molecular arrangement in which molecules are arranged in a predetermined direction. The method of claim 4, wherein when the photosensitive derivative is hydrophobic, an organic film having hydrophobicity is used as the hole transport layer of the organic film, and when the photosensitive derivative is hydrophilic, an organic film having hydrophilicity is used as the hole transport layer of the organic film. Organic electroluminescent device. The organic light emitting device of claim 1, wherein the buffer layer has a thickness of about 2 nm to about 20 nm. In an organic EL device in which an organic film consisting of an anode electrode, a hole transport layer, a light emitting layer, and an electron transport layer and a cathode electrode are sequentially formed on a substrate, And a buffer layer formed between the cathode electrode and the organic film to improve their interfacial properties. The organic electroluminescent device according to claim 7, wherein a photosensitive polymer film having SiO _n as a main chain and a photosensitive derivative as a side chain is used as the buffer layer. The organic electroluminescent device according to claim 8, wherein the photosensitive derivative is one of a chalcone derivative, a PVC derivative or an azobenzene derivative. The organic light emitting device of claim 9, wherein the buffer layer is formed of a material having molecular arrangement in which molecules are arranged in a predetermined direction. The method of claim 10, wherein when the photosensitive derivative is hydrophobic, an organic film having hydrophobicity is used as the electron transporting layer of the organic film, and when the photosensitive derivative is hydrophilic, an organic film having hydrophilicity is used as the electron transporting layer of the organic film. Organic electroluminescent device. The organic light emitting device of claim 7, wherein the buffer layer has a thickness of 2 to 20 nm. Forming an anode electrode on the substrate; Forming a buffer layer on the anode electrode to improve interface characteristics with the anode electrode; Irradiating UV to the buffer layer; Forming an organic layer of a hole transport layer, a light emitting layer, and an electron transport layer on the buffer layer; A method of manufacturing an organic light emitting display device, comprising the step of forming a cathode electrode on the organic film. The organic electroluminescent device according to claim 13, wherein a photosensitive polymer film having SiO _n as a main chain and a photosensitive derivative as a side chain is formed by spin coating or vacuum deposition. The organic electroluminescent device according to claim 14, wherein one of a chalcone derivative, a PVC derivative and an azobenzene derivative is used as the photosensitive derivative. The organic light emitting device of claim 15, wherein the buffer layer is formed of a material having molecular arrangement in which molecules are arranged in a predetermined direction. 17. The method of claim 16, wherein when the photosensitive derivative is hydrophobic, an organic film having hydrophobicity is formed as the hole transport layer of the organic film, and when the photosensitive derivative is hydrophilic, an organic film having hydrophilicity is formed as the hole transport layer of the organic film. An organic electroluminescent device. The organic light emitting device of claim 13, wherein the buffer layer is formed to a thickness of 2 to 20 nm. Forming an anode electrode on the substrate; Forming an organic film including a hole transport layer, a light emitting layer, and an electron transport layer on the anode electrode; Forming a buffer layer on the organic film to improve interfacial properties with the organic film; Irradiating UV to the buffer layer; A method of manufacturing an organic light emitting display device, comprising the step of forming a cathode electrode.