KR100318853B1 - Method of preparing a full-color organic electroluminescent display using a multi-metal mask - Google Patents

Abstract

The present invention relates to a method for manufacturing a full-color organic electroluminescent display using a multi-metal mask, wherein after forming a hole transport layer on an ITO (anode transparent electrode) -glass substrate, a substrate having a hole transport layer is formed. While moving using a micro-actuator, the red, green, and blue light emitting materials, and the negative electrode, are vacuumed over the red, green, and blue metal masks placed in any order on the same mask system. By depositing, a full color organic electroluminescent display can be easily produced on the same mask system, and the manufactured full color organic electroluminescent display has excellent luminous efficiency and a high fill factor value of about 0.7 or more.

Description

METHODS OF PREPARING A FULL-COLOR ORGANIC ELECTROLUMINESCENT DISPLAY USING A MULTI-METAL MASK}

The present invention relates to a method for manufacturing a full-color organic electroluminescent display using a multi-metal mask, specifically, a full-color organic electroluminescent display having excellent luminous efficiency by using a multi-metal mask and a micro-actuator on the same mask system. It relates to a method of manufacturing.

In order for the organic electroluminescent device to be applied to various products, a full color medium-to-large display should be developed, and a method using various organic light emitting layers (FIG. 1A) and a color filter (FIG. 1B) as various development methods of the conventional full color display. , A method using a cavity mode (FIG. 1c), a color converting layer (CCL) (FIG. 1d), a method using a structure in which color changes according to an applied voltage (FIG. 1e), and each layer There is a method (stacking) (stacking) the device (red) to implement the red, green and blue colors. Among these, if there is no problem in the manufacturing process, the method using the individual organic light emitting layer (FIG. 1a) can take advantage of the organic electroluminescent device which emits light directly, and is most effective in terms of luminous efficiency and product cost.

The most representative method performed to realize full color display using such individual organic light emitting layer is a lift-off method. FIG. 2 is a diagram illustrating a process of forming a micro-separator, in which a negative photoresister is coated on an ITO-glass substrate (FIG. 2A), and UV exposure using a photomask. And a process of forming a micro-separator by a lift-off method (FIG. 2C).

Scanning electron microscopy (SEM) photographs of the photoresist for development as a mask and the developed photoresist are shown as (3-1) and (3-2) in FIG. 3, respectively.

The formed micro-separator may be used to micro-patterning the organic light emitting layer and the negative electrode, which is shown in FIG. FIG. 4 includes a separator forming process (FIG. 4A) according to FIG. 2, a process of depositing an organic light emitting layer (FIG. 4B), and a process of depositing a negative electrode (FIG. 4C), and the organic light emitting layer and the negative electrode by these processes. Can be refined.

The method described above was recently developed by Idemitsu kosan, Japan, to develop a 5.2 inch full color display, and FIG. 5 is a photograph of a 5.2 inch size full color organic electroluminescent display in off and on states (5a each). And 5b).

However, the above lift-off method has no problem in realizing the refinement of a single color organic electroluminescent display, but at least one mask system is required to manufacture a full color organic electroluminescent display. In addition, in the case of the inorganic electroluminescent device, the photoresist remaining on the substrate is removed after the refinement, whereas the organic electroluminescent device has a problem in that the durability is inferior by completing the display production without removing it.

Accordingly, an object of the present invention is to provide a method for manufacturing a full-color organic electroluminescent display having excellent luminous efficiency by using a multi-metal mask and a fine driver on the same mask system.

1 is a diagram illustrating various development methods of a full-color display, which is conventionally used,

2 is a view showing a process of forming a micro-separator,

3 is a Scanning Electron Microscope (SEM) photograph of a photoresister and a developed photoresistor for the role of a mask,

4 is a view showing a process of micro-patterning the organic light emitting layer and the negative electrode using a micro-separator,

5 is a photograph of a 5.2 inch size full color organic electroluminescent display manufactured in a lift-off manner,

6 is a schematic diagram of a full color organic electroluminescent display manufactured according to the method of the present invention,

7 is a measurement diagram of a QVGA-class (pixel number: 320 × RGB × 240 dots) display applied to the method of the present invention.

8 is a view showing a multi-metal mask applied to the method of the present invention,

9, 10 and 11 are diagrams showing electroluminescence spectra, luminescence properties and chromaticity of organic electroluminescent devices manufactured in the preparation examples of the present invention, respectively.

12 is a view showing a refinement process using a multi-metal mask in an embodiment of the present invention.

In order to achieve the above object, in the present invention, after forming the hole transport layer on the ITO (anode transparent electrode) -glass substrate, while moving the substrate on which the hole transport layer is formed using a micro-actuator, the same mask A method of making a full-color organic electroluminescent display comprising passing through a red, green and blue metal mask positioned in any order on a system and vacuum depositing red, green and blue light emitting materials, and a negative electrode thereon. to provide.

Hereinafter, the present invention will be described in detail.

As shown in FIG. 6, one example of the organic electroluminescent display according to the present invention includes a glass substrate 6-1, a refined ITO (anode transparent electrode) layer 6-2, and a hole transport layer 6-3. , The organic light emitting layer (6-4) and the fine metal electrode (cathode) layer (6-5) of the fine structure is laminated sequentially, the sealant (6-6) and the glass cap (6-7) By encapsulation.

According to the present invention, an ITO-glass substrate manufactured to a proper size according to a conventional method is finely refined in the longitudinal direction by photolithography, wherein the spacing of the patterns to be formed is a pixel pitch of a display to be manufactured. ) For example, when modeling a 4.7-inch QVGA class (pixel number: 320 x RGB x 240 dots) display, the glass substrate size 7-1 is 112 mm x 84 mm as a basic specification as shown in FIG. The active region 7-2 is 96 mm x 72 mm, and the pixel pitch can be refined at intervals of 300 m based on 300 m. (7-3) is a substrate holder for mounting a substrate during vacuum deposition, and R.G.B. The shape of the pixel was enlarged 30 times and shown in (7-4).

Subsequently, a hole transport layer may be formed on the refined ITO layer. As the hole transporting material, all conventionally known ones can be used, and specific examples thereof include N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl- of Formula 1 below. 4,4'-diamine (TPD), poly-N-vinylcarbazole (PVK) and triphenylamine (TPA) and the like:

In order to improve the stability of the device, the hole transport material may be prepared by dispersing the hole transport material in a polyimide thin film having excellent thermal stability, and the polyimide is polyetherimide (PEI), or a dianhydride compound and a diamine compound. The polymerized polyimide precursor (polyamic acid) is thermally imidized. A solution prepared by dispersing the hole transport material in the soluble polyetherimide at the molecular level is coated on the cathode transparent electrode and then dried, or a solution in which the hole transport material is dispersed in the soluble polyimide precursor is coated on the anode transparent electrode. After coating or vacuum depositing the dianhydride compound, the diamine compound and the hole transport material, the hole transport layer of the present invention may be prepared by thermal imidization at 150 to 300 ° C.

For example, the PMDA-ODA polyamic acid of Formula 2, which is a polyimide precursor, may be heat treated to obtain PMDA-ODA polyimide of Formula 3:

According to the present invention, the substrate can be mounted on the substrate holder before the deposition in the case of forming the hole transport layer by vacuum deposition and after the coating in the case of wet coating. Subsequently, in the vacuum chamber, the substrate holder on which the substrate is mounted may be mounted on the mask holder on which the metal mask is mounted to deposit the organic light emitting material and the negative electrode.

The metal masks used in the present invention can be placed on the same mask system in any order as three types of red, green, and blue, and the structure of the mask holder on which the substrate holder is mounted is shown in detail in FIG. . The material of the metal mask may be conventional. In Fig. 8, (8-1), (8-2) and (8-3) represent metal masks for forming red, green and blue organic light emitting materials, and a negative electrode, respectively, which are shown in (8-7). As shown, the mask open positions are shifted at specific intervals to continuously represent the red, green and blue organic light emitting materials in strip form. For example, in the case of 4.7-inch QVGA display, the mask open position is shifted at intervals of 100 μm, and (8-8) enlarges and shows this in detail. In addition, in FIG. 8, (8-4) represents a region in which an organic light emitting material is deposited, that is, an active region, and (8-5) is a region in which a metal electrode is deposited, in which a lead wire connected to the driving driver is patterned. (8-6) is an area where the substrate holder is mounted on the mask holder. The sliding device is mounted so that the substrate holder and the mask holder can be precisely linearly moved by the micro driver so that the substrate holder can be correctly mounted on each mask. . The holder is equipped with a vacuum stepping motor and a tachometer for precise position control. At this time, by using a mask having magnetization, the substrate and the mask surface can be brought into close contact with the plank stone on the upper surface of the substrate.

When the substrate holder is correctly mounted on the mask, vacuum thermal evaporation of the organic light emitting material and the negative electrode of the corresponding color on the hole transport layer while linearly moving the three kinds of masks in an arbitrary order according to a conventional organic light emitting layer and a negative electrode forming method. You can.

As the organic light emitting material used in the present invention, typically 5,10,15,20-tetraphenyl-21H, 23H-phosphine zinc (Zn-TPP) of the following formula 4 for red, the following formula for green Tris (8-hydroxyquinolinolato) aluminum (Alq ₃ ) of 5, and 2- (2-hydroxyphenyl) benzoxazolato lithium (LiPBO) of the following Chemical Formula 6 for blue; The light emitting material of can be used.

The negative electrode formed on the organic light emitting layer is vacuum-deposited metal having a low work function such as lithium, calcium, magnesium or strontium, or an alloy of this metal with indium, silver or aluminum, or a metal such as indium, silver or aluminum alone. It can be formed by.

According to the present invention, the basic device thus manufactured can be sealed using a sealant and a glass cap to extend the life of the device.

The full color organic electroluminescent display manufactured according to the method of the present invention has excellent luminous efficiency because it uses ternary light that emits light directly, and the fill factor value that determines the brightness of the display is significantly higher than 0.7.

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited only to the following examples.

Production Example

Prior to manufacturing a full-color organic electroluminescent display, in order to understand the luminous efficiency of the display, the balance of color purity and brightness of red, green, and blue (RGB) colors, a single individual colored light emitting device was manufactured to produce a hole transport layer and RGB. Basic data on the organic light emitting layer were obtained. A single individual colored light-emitting device was fabricated as follows: An ITO-glass substrate was mounted in a vacuum chamber, on top of which 5 × 10 PMDA, ODA, and TPD, a hole transport material, were formed in a composition of 1: 1: 3. After vacuum deposition polymerization at ^-6 Torr vacuum and thermal imidization at 250 ℃ to prepare a polyimide hole transport layer having a thickness of 300 kPa. Under the same vacuum condition, Zn-TPP for red, Alq _{3 for} green, and LiPBO for blue were deposited separately on the hole transport layer at 360, 285, and 315 ° C., respectively, to prepare an organic light emitting layer having a thickness of 200 μs. Subsequently, an Mg-Ag (10: 1) alloy was deposited on the organic light emitting layer as a metal electrode layer, thereby preparing three types of organic electroluminescent devices (red, green, and blue).

FIG. 9 shows the electroluminescence spectra of the devices fabricated above, showing peaks at 635 nm for red (9-1), 515 nm for green (9-2), and 456 nm for blue (9-3), respectively. It can be seen that it represents the correct RGB color. 10A, 10B, and 10C show light emission characteristics of red, green, and blue light emitting devices, respectively, and from FIG. 11, the color purity of the R.G.B color is almost similar to that of the NTSC standard.

Example

The 4.7-inch QVGA class full color display is manufactured as follows:

1) First, the ITO-glass substrate was cut to a size of 112 mm × 84 mm and then subjected to a first wash.

2) The ITO membrane, which is a positive electrode, was photolithographically cleaned in a longitudinal direction of 300 µm and then washed secondarily.

3) After the substrate was mounted on the substrate holder and the vacuum chamber, the hole transport layer was deposited in the same manner as in Preparation Example.

4) Subsequently, the substrate holder was mounted on the mask holder while driving with a fine driver to deposit the light emitting material and the negative electrode. First, a substrate holder was mounted on a red mask, and Zn-TPP and Mg-Ag alloys were deposited in the same manner as in Preparation Example. Subsequently, substrate holders were sequentially mounted on the masks for green and blue by linear motion, and Alq ₃ and Mg-Ag alloys, and LiPBO and Mg-Ag alloys were deposited in the same manner as in Preparation Example.

5) The organic electroluminescent display of the basic structure formed by the above process was sealed using a glass cap and a sealant to prepare a full color 4.7 inch QVGA organic electroluminescent display having a pixel pitch of 300 μm.

The manufacturing process is shown in detail in FIG. In FIG. 12, (12-1), (12-2), and (12-3) are red, green, and blue masks, respectively, (12-4) is a region where an organic light emitting material is deposited, and (12-5) ) Is equipped with a sliding device for precise linear movement of the mask holder and the substrate holder. In addition, (12-6) indicates the portion where the deposition apparatus is mounted under the mask holder as the center portion of the vacuum deposition chamber, and (12-7) indicates the direction in which the substrate holder is precisely linearly moved over the mask holder. 8) shows the direction in which the linear linear movement of the mask holder.

The display manufactured as described above has excellent luminous efficiency by using ternary light emitting directly, and it was confirmed that it has a high filling factor value of about 0.75.

According to the method of the present invention, a full color organic electroluminescent display can be easily manufactured on the same mask system, and the display made according to the present invention is applicable to an opto-electronic device, and in particular, a car navigator, a computer and It can be applied to TV monitors, IMT-2000 terminals and AV terminals. In addition, the method of the present invention is applicable to a medium-large display of 4.7 inches or more, it is possible to manufacture a display that changes color due to the characteristics of the organic light emitting material constituting the display is expected to create a variety of applications.

Claims (6)

After forming a hole transport layer on an ITO (anode transparent electrode) -glass substrate, the substrate for which the hole transport layer is formed is moved by using a micro-actuator, and the red dragon is positioned in any order on the same mask system. And vacuum depositing red, green, and blue light emitting materials, and a negative electrode thereon through green and blue metal masks. The method of claim 1, Wherein the open positions of the red, green, and blue metal masks are shifted at specific intervals. The method of claim 1, 5,10,15,20-tetraphenyl-21H, 23H-phosphine zinc (Zn-TPP), tris (8-hydroxyquinolinolato) aluminum (Alq ₃ ) 2- (2-hydroxyphenyl) benzoxazolato lithium (LiPBO). The method of claim 1, And wherein the micro driver comprises a sliding device, a vacuum stepping motor and a tachometer. The method of claim 1, A method in which the substrate and the mask surface are brought into close contact with planks on the upper surface of the substrate using a mask having magnetization. A full color organic electroluminescent display made according to the method of any one of claims 1 to 5.