JP2001093668A - Organic light-emitting material, display using the same, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive, high-quality, high-performance large screen by using an organic light-emitting material, which was conventionally considered to have poor shape reproduction accuracy and not be able to perform patterning with uniform film thickness. Realize a full-color display. SOLUTION: An organic light emitting layer of an organic EL full color display using an organic light emitting element is formed by using an organic light emitting material whose physical properties such as viscosity are adjusted so that the organic light emitting layer can be formed by an offset printing method. It is formed by an offset printing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic light-emitting material for an organic EL full-color display to which an offset printing method can be applied, an organic EL full-color display using the same, and a method for manufacturing the same.

[0002]

2. Description of the Related Art An organic light-emitting device (organic EL device) has a structure in which a thin film containing a fluorescent organic compound is sandwiched between a cathode and an anode, and electrons and holes are injected into the thin film. The recombination produces excitons (excitons), which emit light when the excitons are deactivated (fluorescence,
This is an element that emits light using phosphorescence.

[0003] The features of this organic EL device are that it can emit a high-luminance surface light of about 100 to 100,000 cd / m ² at a low voltage of 10 V or less, and can change the color from blue to red by selecting the type of fluorescent substance. Light emission is possible.

[0004] Organic EL elements have attracted attention as realizing inexpensive large-area full-color display elements (IEICE Technical Report, Vol. 89, Nos. 106, 49).
Page, 1989). According to reports, organic dyes that emit strong fluorescence are used in the light-emitting layer, and bright blue, green, and red light is emitted. It is thought that a high-luminance full-color display could be realized by using an organic dye which emits strong fluorescence in a thin film state and has few pinhole defects.

Further, Japanese Patent Application Laid-Open No. 5-78655 discloses a thin film layer in which the components of the organic light emitting layer are made of a mixture of an organic charge material and an organic light emitting material, thereby preventing concentration quenching and expanding the range of light emitting material selection. It has been proposed to use a high-luminance full-color element.

The actual manufacturing method, and particularly the structure and manufacturing method of a full-color display panel, are disclosed in
Japanese Patent No. 9995 discloses a manufacturing method by printing, but does not disclose a detailed method, and it is difficult to perform high-definition patterning required for a full-color display panel. Furthermore, Japanese Patent Application Laid-Open No. 10-12377 discloses a manufacturing method using an ink jet, but it is difficult to form a film having a uniform thickness with a high definition pattern using an ink jet, and it is difficult to control the pattern shape.

[0007]

The organic thin film EL device using the above-mentioned organic dye emits blue, green and red light. However, as is well known, in order to realize a full-color display, it is necessary to arrange an organic light-emitting layer for emitting three primary colors for each pixel.

Conventionally, the technique of patterning an organic light emitting layer has been extremely difficult. One of the causes is that the metal surface of the reflective electrode material is unstable, and the patterning accuracy of vapor deposition is not high. Second, polymers and precursors forming the hole injection layer and the organic light emitting layer are not resistant to a patterning step such as photolithography. Further, there is a problem that patterning accuracy by printing is difficult to obtain, and patterning by inkjet is difficult to obtain film thickness accuracy, shape control is difficult, and the adjacent pixels are mixed.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an organic light emitting material which can pattern an organic light emitting layer with high precision and uniformity for each dye by an offset printing method. It is another object of the present invention to provide an organic EL full-color display having higher performance and a method of manufacturing the same.

[0010]

The configuration of the present invention which has been achieved to achieve the above object is as follows.

That is, the organic light-emitting material of the present invention is a material for forming an organic light-emitting layer of an organic EL full-color display using an organic light-emitting element.
The organic light-emitting device is characterized in that it has physical properties capable of forming an organic light-emitting layer having a light-emitting color corresponding to one of green and blue pixels.

The organic light-emitting material of the present invention preferably has a viscosity of 100 cp to 60000 cp, is added with a solvent having a boiling point of 70 ° C. or more, and has thixotropic rheological properties.

Further, the organic EL full-color display of the present invention is characterized in that an organic luminescent layer having a luminescent color corresponding to each of red, green and blue pixels is formed using the above-mentioned organic luminescent material of the present invention. Is what you do.

In the method of manufacturing an organic EL full-color display according to the present invention, the blanket cylinder and the stage on which the substrate and the intaglio plate are mounted are synchronized, and after the organic light-emitting material is received from the intaglio plate onto the silicon blanket, the organic light-emitting material is coated. An organic light emitting layer having an emission color corresponding to each pixel of red, green, and blue is formed by an offset printing method of transferring to a leaf substrate, and the organic light emitting material according to the present invention is used as the organic light emitting material. It is characterized by using a light emitting material.

The present invention realizes a high-performance organic EL full-color display having a wiring structure of a so-called simple matrix type or active matrix type. For example, an active matrix type organic EL full-color display as shown in FIG. In the display body, red, green, and blue organic light-emitting materials 305, 306, and 307 are patterned on a signal line 301, a gate line 302, a pixel electrode 303, and a thin film transistor 304 formed on a substrate by offset printing. The application realizes a full color display.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

(Organic Light-Emitting Materials) The organic light-emitting materials of each color include quinolinol-based metal complexes, benzoquinolinol-based metal complexes, benzoxazole-based metal complexes, phthalocyanines, polyferrins, azomethine-based metal complexes, phenanthroline europium complexes, styryl and Condensed aromatic compounds such as distyryl compounds, pyrene, rubrene, coronene, chrysene and diphenylanthracene; heteroaromatic compounds such as oxadiazoles, thiadiazoles and triazoles; heterocondensed ring compounds such as quinacridones and coumarins; polyphenylene And π-conjugated compounds such as polypyridine, polythiophene, polyfluorenylene, and polyphenylenevinylene, but are not limited thereto.

The above-mentioned organic luminescent material is prepared and used so as to have a physical property capable of forming an organic luminescent layer having a luminescent color corresponding to any one of red, green and blue pixels by an offset printing method. .

The viscosity of the organic light emitting material of each color is 10
0 cp to 60000 cp is preferred. This is 100c
Below p, when filling the ink into the intaglio (inking and doctoring) in offset printing, the ink cannot be filled sufficiently and oozes out of the recesses, or bleeds after transferring to the blanket or after being received by the substrate. . Also 60
If it is more than 000 cp, the ink cannot be sufficiently filled at the time of filling (inking and doctoring) the ink into the intaglio in offset printing, and the ink will be scraped out from the concave portion, and when transferred to the blanket, the ink in the intaglio will cohesively break while pulling the yarn. . Therefore, these make it impossible to reproduce the shape of the intaglio pattern.

As the solvent to be added to the organic luminescent material, if the boiling point is less than 70 ° C., it is accepted after the ink is filled (inking and doctoring) into the intaglio in offset printing, and the intaglio is dried and blanket after printing. The dried ink is too fast and the pattern shape is deformed, does not transfer to the blanket, or the ink transferred to the blanket cannot be received by the substrate. Therefore, the boiling point is preferably 70 ° C. or more, and substituted benzenes such as toluene, xylene, ethylbenzene, cymene, chlorobenzene, phenol, cresol, and nitrobenzene;
Nitrogen-containing compounds such as DMF, DMAc, NMP, diethanolamine, pyridine and quinoline, MEK, MIBK,
Ketones such as cyclohexanone, esters such as butyl acetate, amyl acetate and ethyl benzoate, polyhydric alcohols such as ethylene glycol, propylene glycol, ethylene glycol monomethyl ether and diethylene glycol diethyl ether and derivatives thereof can be used, but are not limited thereto. It is not something that can be done.

The thickness of the organic light emitting layer is 0.05 to 0.5.
A thickness of about 5 μm is required, preferably 0.1 to
It is about 0.3 μm.

(Hole Injection Layer) Examples of the hole injection layer include polyvinyl carbazole and its derivatives, polythiophene and its derivatives, polyphenylene and its derivatives, polyphenylene vinylene and its derivatives, polyolefin having a triarylamine skeleton, polyacryl, and polyacryl. Arylate, polycarbonate, polyester, polyamide, polyurethane, polyimide and the like can be used, but are not limited thereto.

(Offset printing machine) An offset printing machine is basically a sheet-fed proof printing machine, but has a lower printing position accuracy and printing conditions than a general waterless lithographic printing machine or intaglio printing machine for printing on paper. It is better to improve the setting so that it can be done with high accuracy.

A method for forming an organic light emitting layer using an offset printing machine will be briefly described with reference to FIG. 4, reference numeral 401 denotes a printing stage, 402 denotes an intaglio, 403 denotes an ink (organic light emitting material) ejector, 404 denotes an ink reservoir, 405 denotes a doctor blade, 406 denotes a blank cylinder, 407 denotes a blanket, 408 denotes a reception ink, and 409 denotes a receiving ink. Bran cylinder rotation direction,
410 is a printing stage moving direction, 411 is a substrate to be printed,
412 is a transfer ink.

As shown in FIG. 4A, an ink of an organic luminescent material is dropped on the intaglio 402, and the doctor blade 405 is used.
Filling the recesses of the intaglio 402 with ink while scraping,
Blanket 407 attached to blanket cylinder 406 and intaglio 4
02 is contacted with a constant pressure, the ink filled in the intaglio 402 is received on the surface of the blanket 407. Then, as shown in FIG.
The printing is performed by bringing the substrate and the substrate 411 of the organic EL display, which is the substrate to be printed, into contact with each other at a constant printing pressure and transferring ink from the surface of the blanket to the surface of the substrate.

[0026]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Embodiment 1) In this embodiment, an active matrix type organic EL full-color display as shown in FIG. 3 is manufactured.

As shown in FIG. 1, a signal line 109, a gate line 110, and a thin film transistor 10 are formed on a glass substrate 101.
After forming No. 2, an ITO transparent pixel electrode 103 was formed.

Next, polyvinyl carbazole was coated as a hole injection material to form a hole injection layer 104 having a thickness of 0.1 μm.

Next, organic light-emitting materials that emit red, green, and blue light were pattern-printed by the offset printing apparatus shown in FIG. 4 to form color-forming layers 105, 106, and 107 having a thickness of 0.1 μm. For a red light emitting material, 4- (disiaminomethylene) -2-methyl-6- (4-dimethylaminostyryl) -4H-pyran (DCM), and for a green light emitting material, [3
-(2-benzothiazolyl) -7- (diethylamino)
Coumarin] and 4,4′-bis- (2,4
2'-diphenyl-ethynyl) -biphenyl (DSA)
Was molecularly dispersed in polyvinyl carbazole to prepare a dispersion having a viscosity of 120 cp.

Finally, a 0.1-0.3 μm thick MgA
The g reflective electrode 108 was formed by an evaporation method. Thus, a direct-view type full-color organic EL display was completed.

(Embodiment 2) This embodiment is an example in which an active matrix type organic EL full-color display as shown in FIG. 3 is manufactured.

As shown in FIG. 2, a signal line 209, a gate line 210, and a thin film transistor 20 are formed on a glass substrate 201.
After forming No. 2, the AlLi reflective pixel electrode 203 was formed.

Next, the offset printing apparatus shown in FIG. 4 performs pattern printing of a luminescent material that emits red, green, and blue light,
Coloring layers 205, 206, and 207 having a thickness of 0.12 μm were formed. Polyalkyl-substituted phenylene vinylene for red light-emitting material, polyphenylene vinylene for green light-emitting material,
For the blue light emitting material, a polycyano-substituted phenylene vinylene is molecularly dispersed in polyvinyl carbazole, and has a viscosity of 1
A 20 cp dispersion was prepared and used.

Further, an ITO transparent electrode 208 was formed by a vapor deposition method, and a device having a single organic layer was formed. Thus, a direct-view type full-color organic EL display was completed.

(Example 3) As an organic light emitting layer, coumarin 6 was used as an organic light emitting material, and polyphenylbutylsilane was used as a hole injecting material. Similarly, as a red organic light emitting material, D
It was mixed with a hole injection material using CM to form a red light emitting layer. Further, DAS was used as a blue organic light emitting material, and the mixture was mixed with a hole injection material to form a blue light emitting layer. At this time, by making the concentration for each solvent 20%,
The viscosity of the organic light emitting layer solution was set to 700 cps.

In the same steps as in Example 1 or Example 2,
Each of the light emitting layers was printed by an offset printing apparatus to prepare an active matrix type organic EL display element.
Thus, a direct-view type full-color organic EL display was completed.

Example 4 An active matrix type organic EL display element was prepared in the same manner as in Example 3.
Thus, a direct-view type full-color organic EL display was completed. However, xylene (boiling point: about 140 ° C.) was used as a solvent for the organic light emitting material. As a result, printing was performed continuously 500 times, and the same characteristics were obtained for all 500 sheets.

Example 5 An active matrix type organic EL display element was produced in the same manner as in Example 3.
Thus, a direct-view type full-color organic EL display was completed. However, instead of the hole injection material, a polycarbonate having a triphenylamine skeleton (weight average molecular weight: 50,000) was used as a charge injection material to give thixotropic characteristics. As a result, printing was possible in which the variation in the element film thickness was 0.1 μm ± 0.003 μm, and a full-color organic EL display having less uneven light emission between the elements was obtained.

(Embodiment 6) In this embodiment, an organic EL full-color display having a simple matrix wiring structure is manufactured.

As shown in FIG. 5, a plurality of transparent lower wirings 502 were formed on the surface of a glass substrate 501 by using ITO, and black stripes 503 were formed in the gaps between them. An alkyl-substituted polythiophene is coated thereon as a hole injection material, and a hole injection layer 5 having a thickness of 0.07 μm is formed.
08 was formed.

Next, an organic coloring material for emitting red, green, and blue is printed by patterning using the offset printing apparatus shown in FIG.
06 was formed. Polyalkyl-substituted phenylene vinylene is used for the red light-emitting material, polyalkoxy-substituted phenylenevinylene is used for the green light-emitting material, and polyalkyl-substituted phenylenevinylene is used for the blue light-emitting material. used.

Finally, MgA having a thickness of 0.1 to 0.3 μm
g A reflective electrode (upper wiring) 507 was formed by a mask vapor deposition method to prepare an element. Thus, a direct-view simple matrix organic EL display was completed.

[0044]

According to the present invention, the organic light-emitting material, which has conventionally been considered to be inferior in shape reproducibility and incapable of patterning with uniform film thickness, has been made to have such material properties that it can be formed by a high-precision offset printing method. Thus, an organic EL display of full color display was realized. As a result, an inexpensive, high-quality, high-performance large-screen full-color display can be manufactured.

Further, the viscosity of the organic light emitting material is 100 cp or less.
By being 60,000 cp, the reproducibility of the print shape is improved. Therefore, color mixing of each color can be prevented.

Further, since the organic light-emitting material is added with a solvent having a boiling point of 70 ° C. or higher, drying of the organic light-emitting material can be prevented, and continuous printing can be performed. Stability is improved.

In addition, since the rheological properties of the organic light-emitting material exhibit thixotropic properties, smoothness (uniformity in film thickness) of a printed pattern is obtained, and unevenness in light emission is reduced.

Further, an inexpensive display can be made by using an organic EL full-color display having a simple matrix structure.

Further, by using a high-precision sheet-fed offset printing press, the alignment accuracy of each color is improved, color mixing is prevented, and the yield is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cross section of an active matrix type organic EL display according to Example 1 of the present invention.

FIG. 2 is a schematic diagram showing a cross section of an active matrix type organic EL display according to a second embodiment of the present invention.

FIG. 3 is a top view showing an organic coloring layer formed on a thin film transistor by the offset printing method of the present invention.

FIG. 4 is a process sectional view of the offset printing method of the present invention.

FIG. 5 is a schematic diagram showing a cross section of a simple matrix type organic EL display according to Example 6 of the present invention.

[Explanation of symbols]

 101 glass substrate 102 thin film transistor 103 transparent pixel electrode 104 hole injection layer 105 organic light emitting layer (red) 106 organic light emitting layer (green) 107 organic light emitting layer (blue) 108 reflective electrode 109 signal line 110 gate line 201 glass substrate 202 thin film transistor 203 Reflective pixel electrode 204 hole injection layer 205 organic light emitting layer (red) 206 organic light emitting layer (green) 207 organic light emitting layer (blue) 208 transparent electrode 209 signal line 210 gate line 301 signal line 302 gate line 303 pixel electrode 304 thin film transistor 305 Organic light emitting layer (red) 306 Organic light emitting layer (green) 307 Organic light emitting layer (blue) 401 Printing stage 402 Intaglio 403 Ink ejector 404 Ink reservoir 405 Doctor blade 406 Blank cylinder 407 Blanket 408 Receiving ink 40 9 Blank rotation direction 410 Printing stage movement direction 411 Substrate to be printed 412 Transfer ink 501 Glass substrate 502 Transparent lower wiring 503 Black stripe 504 Organic light emitting layer (red) 505 Organic light emitting layer (green) 506 Organic light emitting layer (blue) 507 Wiring 508 Hole injection layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Ueno 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Seiji Mashita 3- 30-2 Shimomaruko, Ota-ku, Tokyo Non-corporation F term (reference) 3K007 AB00 AB01 AB04 AB18 BA06 CA01 CB01 DA00 DB03 EB00 FA01

Claims (8)

[Claims] 1. A material for forming an organic light-emitting layer of an organic EL full-color display using an organic light-emitting element, wherein the organic light-emitting layer has an emission color corresponding to one of red, green, and blue pixels by an offset printing method. An organic light-emitting material having physical properties capable of forming a light-emitting layer. 2. The organic light emitting material according to claim 1, wherein the viscosity is 100 cp to 60000 cp. 3. The organic light emitting material according to claim 1, wherein a solvent having a boiling point of 70 ° C. or higher is added. 4. The organic light emitting material according to claim 1, wherein the rheological property is thixotropic. 5. The organic light emitting device according to claim 1, wherein an organic light emitting layer having an emission color corresponding to each of red, green, and blue pixels is provided in an organic EL full color display using an organic light emitting element. An organic EL full-color display formed using a material. 6. A simple matrix wiring structure in which a lower wiring is formed on a substrate, a hole injection layer is formed thereon, the organic light emitting layer is formed thereon, and an upper wiring is formed thereon. The organic EL full-color display according to claim 5, characterized in that: 7. A method of manufacturing an organic EL full-color display using an organic light emitting device, wherein a blanket cylinder and a stage on which a substrate and an intaglio are mounted are synchronized, and an organic light emitting material is received from the intaglio onto a silicon blanket. A method for manufacturing an organic EL full-color display body, comprising forming an organic light-emitting layer having a light-emitting color corresponding to each of red, green, and blue pixels by an offset printing method in which a material is transferred to a single-wafer substrate. 8. The organic light emitting material according to claim 1, wherein
The method for producing an organic EL full-color display according to claim 7, wherein the organic light-emitting material according to any one of the above is used.