KR20060093205A - Method for manufacturing organic light emitting device using dry etching - Google Patents

Abstract

The present invention provides a method of manufacturing an organic light emitting device including an organic film between a pair of electrodes, the method comprising forming a cathode layer on the organic film and patterning the organic film by dry etching using the cathode layer as a mask. The present invention relates to a method for manufacturing an organic light emitting device using dry etching. According to the method of the present invention, by accurately patterning an organic film by a simple process, the manufacturing cost can be reduced and manufacturing processability can be improved. It can be applied to a wide range of organic light emitting devices as well as organic light emitting devices.

Organic light emitting device, organic film, patterning, dry etching, electron injection layer, electron transport layer, hole suppression layer, polymer, low molecular weight

Description

Manufacturing method of organic light emitting device using dry etching {MANUFACTURING METHOD OF ORGANIC LIGHT EMITTING DISPLAY UTILIZING DRY ETCHING}

1A to 1F are schematic views illustrating a laminated structure of an organic light emitting diode according to exemplary embodiments of the present invention.

2 is a flowchart illustrating a method of manufacturing an organic light emitting diode according to an embodiment of the present invention.

Figure 3 is a current transfer curve showing the current transfer characteristics of the organic light emitting device manufactured according to the present invention.

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

10: anode 11: hole injection layer

12 light emitting layer 13 hole suppression layer

14 cathode + 15 electron transport layer

16: hole transport layer

The present invention relates to a method of manufacturing an organic light emitting device, and more particularly, in manufacturing an organic light emitting device including an organic film between a pair of electrodes, after forming a cathode layer on the organic film, the cathode layer is used as a mask The present invention relates to a method of manufacturing an organic light-emitting device using dry etching, which can improve manufacturing processability by patterning an organic film precisely by a simple process characterized by patterning the organic film by dry etching.

The organic light emitting device is an active light emitting display device using a phenomenon in which light is generated while electrons and holes are combined in an organic film when a current flows through a thin film of fluorescent or phosphorescent organic compound (hereinafter referred to as an organic film). It is possible, and the parts are simple, so that the manufacturing process is simple and has a wide viewing angle at high quality. In addition, video can be fully realized, high color purity can be realized, and low power consumption and low voltage can be driven to have electrical characteristics suitable for portable electronic devices.

The organic light emitting device may be classified into a device using a polymer material and a device using a low molecular material in terms of the characteristics of a material for forming an organic film and a manufacturing process. Low-molecular devices undergo dry processes using vacuum equipment such as thermal evaporation or vapor phase deposition, while polymer devices dissolve in an appropriate solvent and then wet process to form thin films by spin coating or printing. Will go through. Therefore, the polymer device has a simple and inexpensive manufacturing process compared to the low-molecular device, and the polymer material has a high glass transition temperature, thereby providing a thin film of excellent mechanical properties. In addition, in terms of driving voltage and power consumption, polymer devices have superior characteristics to low-molecular devices, and thus, they are recognized to be advantageous over low-molecules in terms of large area, high definition, and process management. Therefore, the development of a technology related to the manufacture of a polymer organic light emitting device is required in the future.

In the manufacture of an organic light emitting device, a patterning method for forming an organic film including a light emitting layer in a desired pattern is one of particularly important techniques. As a conventional method of patterning an organic film, a vacuum deposition method, a laser induced thermal image (LITI), an inkjet printing method, and the like are known. Among them, the vacuum deposition method has a limit that can be applied only to low molecular materials, and the laser transfer method also has excellent processability and film characteristics, but has a limit that can be applied only to low molecular materials. On the other hand, the inkjet printing method can be used for the polymer material, but before the inkjet process, the surface treatment or the formation of the partition wall must be performed so that it can be deposited only where desired. Therefore, the process becomes complicated and the manufacturing cost increases.

The present invention is to overcome the above-mentioned problems of the prior art, one object of the present invention is to provide a method of manufacturing an organic light emitting device that can simplify the manufacturing process and lower the manufacturing cost.

Another object of the present invention is to provide a method of manufacturing an organic light emitting device that can be applied to the production of a low molecular weight organic light emitting device as well as a polymer organic light emitting device.

One aspect of the present invention for achieving the above object is

In manufacturing an organic light emitting device including an organic film between a pair of electrodes, after forming a cathode layer on the organic film, patterning the organic film by dry etching using the cathode layer as a mask The manufacturing method of the organic light emitting element using dry etching characterized by the above-mentioned.

In the present invention, the organic layer includes one or more layers of an electron transport layer, an electron injection layer, and a hole suppression layer in addition to the light emitting layer, and the dry etching step may be a step of dry etching one or more of these layers together with the light emitting layer.

The organic layer may optionally include a hole injection layer and / or a hole transport layer below the light emitting layer.

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

The present invention relates to a method for manufacturing an organic light emitting device including a step of patterning an organic film that can be applied to a polymer organic light emitting device. The organic film is formed by a printing method including a spin coating method, and a cathode layer is formed thereon. After that, the organic layer is patterned by dry etching using the cathode layer as a mask. In the method of manufacturing an organic light emitting device according to the present invention, the organic film patterning step may be subdivided into an organic film forming process, a cathode layer forming process, and a process of patterning the organic film by dry etching using the cathode layer as a mask.

The most important feature of the method of the present invention is the patterning of the organic film by dry etching using the cathode layer as a mask. The dry etching process is used, so that the cathode formation and patterning operations are less affected by the moisture and chemical composition of the organic film. do. Wet etching has the disadvantage that the lower part of the mask is also etched because the isotropic etching proceeds due to chemical action by strong acid. However, dry etching is performed by plasma with chemical active gas. As a reactive ion etching method which etches by the action of ions in the inside, anisotropic etching is performed in which the etching proceeds only in the vertical direction of the substrate surface, so that high precision and fine processing can be performed.

In the present invention, the organic film may be manufactured as a single organic light emitting layer, but may be generally manufactured in a multilayer structure of various organic materials. The organic film of the multilayer structure has a structure of a hole related layer, an electron related layer and a light emitting layer. The hole related layer may be classified into a hole injection layer and a hole transport layer, and the electron related layer may include an electron injection layer and an electron transport layer. The reason why the organic layer is formed in the multilayer structure is that the mobility of holes and electrons varies greatly in the case of organic materials. Thus, holes and electrons are effectively transferred to the light emitting layer by using the hole transport layer and the electron transport layer at the anode and cathode interfaces, respectively. This is to improve the luminous efficiency.

In the present invention, the organic layer may be formed of a low molecular material or a high molecular material. In the present invention, the low molecular weight material or the polymer material that can be used as the material of the organic film may use all materials known in the manufacture of the organic light emitting device.

1A to 1F are schematic views illustrating a laminated structure of an organic light emitting device according to various exemplary embodiments of the present invention. As shown in FIGS. 1A to 1F, the structure of the organic film may be variously modified when the organic light emitting device is manufactured by the method of the present invention.

Basically, as shown in FIG. 1A, the organic light emitting diode has a structure in which the organic light emitting layer 12 is stacked between a pair of electrodes of the anode 10 and the cathode 14. Referring to FIG. 1B, an organic light emitting diode according to another embodiment of the present invention has a structure in which a light emitting layer 12, a hole suppression layer (HBL) 13, and a cathode 14 are sequentially stacked on an anode 10. Have The organic light emitting device of FIG. 1C further includes a hole injection layer (HIL) 11 between the anode 10 and the light emitting layer 12. The organic light emitting device of FIG. 1D has the same stacked structure as that of FIG. 1C except that an electron transport layer (ETL) 15 is formed instead of the hole suppression layer (HBL) 13 formed on the light emitting layer 12. . The organic light emitting device of FIG. 1E has a two-layer film structure in which a hole suppression layer (HBL) 13 and an electron transport layer 15 are sequentially stacked instead of the hole suppression layer (HBL) 13 formed on the light emitting layer 12. Except that, it has the same laminated structure as in the case of Fig. 1C. The organic light emitting device of FIG. 1F has the same structure as the organic light emitting device of FIG. 1E except that the organic light emitting device further includes a hole transport layer 16 between the hole injection layer 11 and the light emitting layer 12. In the organic light emitting device having such a structure, the hole transport layer 16 serves to suppress impurity penetration from the hole injection layer 11 into the light emitting layer 12.

The structure of the organic light emitting device to which the method of the present invention can be applied is not limited to the above-described structure, but can be applied to other organic light emitting devices having various laminated structures. For example, the method of the present invention may be applied to a case in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially stacked on a substrate. Due to the various layer configurations of the organic light emitting device, the layer to be dry etched during the organic film patterning is changed.

With reference to FIG. 1F, the manufacturing method of the organic light emitting element by this invention is demonstrated in more detail.

When fabricating an organic light emitting device by the method of the present invention, first, a patterned anode 10 is formed on a substrate (not shown). Here, the substrate is a substrate used in a conventional organic light emitting device, preferably a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling and waterproof. And the thickness of the substrate is preferably 0.3 to 1.1 mm.

The material for forming the anode 10 is not particularly limited. If the anode is a cathode, the anode is made of a conductive metal or an oxide thereof, which is easy to inject holes, and specific examples thereof include indium tin oxide (ITO), indium zinc oxide (IZO), nickel (Ni), and platinum. (Pt), gold (Au), iridium (Ir) and the like are used.

After cleaning the substrate on which the anode 10 is formed, UV / ozone treatment is performed. At this time, an organic solvent such as isopropanol (IPA) or acetone is used as the washing method.

The hole injection layer 11 is selectively formed on the anode 10 of the cleaned substrate. When the hole injection layer 11 is formed in this manner, the contact resistance between the anode 10 and the light emitting layer 12 is reduced, and the hole transport capacity of the anode 10 with respect to the light emitting layer 12 is improved, thereby driving the device's driving voltage. It is possible to obtain the effect of improving overall and lifespan characteristics. The hole injection layer 11 may be formed of any material that is commonly used. Specific examples thereof include PEDOT {poly (3,4-ethylenedioxythiophene)} / PSS (polystyrene parasulfonate), a starburst material, and copper. Phthalocyanine, polythiophene, polyaniline, polyacetylene, polypyrrole, polyphenylene vinylene, derivatives thereof, and the like. Spin coating is performed on the anode 10 using this material, and then dried to form a hole injection layer 11. The thickness of the hole injection layer 11 is 300-2000 kPa here, More preferably, it is 500-1100 kPa.

Subsequently, an organic light emitting layer 12 is formed by coating a light emitting layer forming composition including red, green, and blue light emitting materials on the hole injection layer 11 by spin coating or inkjet. When the light emitting layer 12 is formed by a spin coating method, the light emitting layer 12 may be formed quickly and simply and at a constant thickness. In addition to spin coating, dip coating, inkjet printing, spray coating, or roll coating may be used. Any solvent that can be used in the wet process can be used as long as it can dissolve the light emitting compound, and specific examples include toluene, chlorobenzene, xylene and the like.

A hole transport layer 16 may be selectively formed between the hole injection layer 11 and the light emitting layer 12. Herein, the hole transport layer forming material may be used as long as the material satisfies the hole transportability, and specific examples thereof may include polytriphenylamine.

The hole suppression layer 13 and / or the electron transport layer 15 are formed on the emission layer 12 by using a deposition or spin coating method. Here, the hole suppression layer 13 prevents excitons formed from the light emitting material from moving to the electron transport layer 15 or prevents holes from moving to the electron transport layer 15.

The hole suppression layer 13 may be formed of a phenanthroline compound, an imidazole compound, a triazole compound, an oxadiazole compound, an aluminum complex, BAlq etc. are used.

Subsequently, a conductive metal layer is laminated on the light emitting layer 12 to form a cathode layer 14, and then the light emitting layer 12 is patterned by dry etching. When the cathode is formed in a multilayer, a second cathode layer may be formed on the cathode layer.

The negative electrode material usable for forming the negative electrode layer in the present invention is not particularly limited, and a metal having a small work function, that is, Li, Cs, Ba, Ca, Ca / Al, LiF / Ca, LiF / Al, BaF ₂ / Ca , Mg, Ag, Al, alloys thereof, or multiple layers thereof.

As described above, the layer that is dry etched in the process of patterning the organic layer by dry etching may vary according to the stacked structure of the organic light emitting device. For example, when the organic light emitting device has a structure including a single organic light emitting layer between a pair of electrodes, only the organic light emitting layer is dry etched. Alternatively, when at least one of the electron transport layer, the electron injection layer, and the hole suppression layer is inserted between the organic light emitting layer and the cathode layer, the light emitting layer and these layers may be dry etched together.

In the present invention, the active gas usable for the dry etching includes, but is not necessarily limited to, oxygen, CF ₄ , SF ₆ , argon, nitrogen, and the like.

The present invention will be described in more detail with reference to the following examples. These examples are merely to explain preferred embodiments of the present invention, but the present invention is not limited to these embodiments.

Example

According to the process as shown in FIG. 2, an organic thin film transistor capable of driving an organic light emitting diode was formed on a substrate, and an organic light emitting diode was manufactured according to the method of the present invention thereon, and its performance was evaluated.

First, a gate electrode 2 having a thickness of 1,500 Å was formed on the cleaned glass substrate 1 using aluminum by vacuum deposition (S1). Tetrabutoxy titanate as an organic metal compound and a polymer of a mixture of a polyamide-based material and a polyacrylic-based material (hereinafter referred to as "MAPTMS") as an organic gate insulating film 3 thereon (Ti (OC ₄ H ₉ ) ₄ ) was mixed in a 70:30 weight ratio, dissolved in butanol, and a solution having a concentration of 10% by weight) was coated with a spin coating method at a thickness of 7,000 Pa at 2,000 rpm, and then Baking at 100 ° C for 10 minutes and 150 ° C for 2 hours (S2). Next, gold was deposited to a thickness of 70 nm using a wet etching method with a channel length of 50 μm and a channel width of 0.3 mm as a source / drain electrode. Subsequently, pentacene (purchased by Aldrich) was deposited to a thickness of 700 kPa under conditions of vacuum degree of 2 × 10 ^-7 Torr, substrate temperature of 80 ° C, and deposition rate of 0.5 ° C / sec by OMBD (Organic molecular beam deposition). ) Was formed (S3). As the semiconductor protective layer, polyvinyl alcohol was deposited to a thickness of 300Å by a spin coating method as a primary protective layer, dried for 10 minutes in a 100 ° C convection oven, and spin PR (PC-403, JSR) was used as a secondary protective layer. After deposition of 2 μm by coating, soft baking in a 100 ° C. convection oven was followed by full exposure for 20 seconds, and then hard baking for 1 hour on a 100 ° C. hot plate to prepare an organic thin film transistor (S4).

Subsequently, PEDOT (Bayer) and polypyrofluorene-based blue light emitting materials (TS-9) were completely coated with a thickness of 50 nm and 80 nm, respectively, by spin coating, and dried by baking for 10 minutes on a 120 ° C. hot plate. (S5). For patterning the organic light emitting layer, aluminum was thermally deposited to a thickness of 70 nm using a shadow mask to form a first cathode layer 7. Thereafter, the organic light emitting layer was patterned by dry etching at 50 Torr for 10 minutes using an oxygen plasma (S6). Subsequently, aluminum was thermally deposited to a thickness of 70 nm using a shadow mask to form a second cathode layer 8 and thermally deposited to 70 nm thickness using aluminum for connection to a transistor (S7).

Comparative example

An organic light emitting device was manufactured in the same manner as in Example, except that a conventional method was used instead of dry etching when the organic light emitting layer was patterned, and then evaluated.

Using the devices fabricated in Examples and Comparative Examples of the present invention, the current transfer curve of the organic light emitting device was measured using a KEITHLEY Semiconductor characterization system (4200-SCS), and the results are shown in FIG. 3. As shown in FIG. 3, it can be seen that the present invention exhibits almost the same current transfer characteristics as the organic light emitting device of the method used in the conventional organic light emitting device (comparative example). Therefore, the present invention enables the manufacture of a display having the same characteristics by using a general coating method including a spin coating and a dry etching process in the existing process that was limited to the inkjet method.

 According to the method of manufacturing the organic light emitting device of the present invention, by accurately patterning the organic film by a simple process, the manufacturing cost can be reduced and the manufacturing processability can be improved. In addition, the polymer organic light emitting device (PLED) has an advantage that can be applied widely.

Claims (8)

In manufacturing an organic light emitting device including an organic film between a pair of electrodes, after forming a cathode layer on the organic film, and patterning the organic film by dry etching using the cathode layer as a mask. Method for producing an organic light emitting device using dry etching. The method of claim 1, wherein the organic layer comprises at least one layer of an electron transport layer, an electron injection layer, and a hole suppression layer in addition to the light emitting layer, wherein the dry etching step is a step of dry etching at least one of these layers together with the light emitting layer. The manufacturing method of the organic light emitting element. The method of claim 2, wherein the organic layer selectively includes at least one of a hole injection layer and a hole transport layer under the light emitting layer. The method of claim 1, wherein the organic layer is formed of a low molecular weight material. The method of claim 1, wherein the organic film is formed of a polymer material. The method of claim 1, wherein the organic layer is formed by dip coating, spin coating, printing, spray coating, inkjet printing, or roll coating. The method of claim 1, wherein the dry etching is performed using a gas selected from the group consisting of oxygen, CF ₄ , SF ₆ , argon, and nitrogen. The method of claim 1, wherein the cathode layer is formed of two or more multilayers.

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