JP2004335204A - Manufacturing method of organic electroluminescent device, organic electroluminescent device, and organic electroluminescent layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to provide a device of high reliability and high performance, provide a manufacturing method of a new organic electroluminescent device accompanied by a micro processing technology, and provide the new organic electroluminescent device obtained by that method. <P>SOLUTION: A first electrode 12 is formed on a substrate 11 which is transparent in a visible light wavelength region. Next, on the first electrode 12, a light-emitting layer 13 composed of a mixture of a low-molecular weight organic hole transport material, a low-molecular weight organic electron transport material, and low-molecular weight organic light-emitting materials is formed. Subsequently, a second electrode 14 is formed on the light-emitting layer 13, and the organic electroluminescent device 10 is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an organic electroluminescent device, the organic electroluminescent device, and an organic electroluminescent layer used for the organic electroluminescent device.
[0002]
[Prior art]
Organic electroluminescent devices have been actively researched and developed since the report of Tang and VanSlyke, "J. Appl. Phys. Lett. Vol. 51, pp. 913 (1987)". It has been commercialized in panels and mobile terminals. The organic thin film constituting the organic electroluminescent element is obtained by forming a low molecular weight organic material using a vapor deposition method or forming a high molecular weight organic material using a solution coating method.
[0003]
The deposition method of low-molecular organic materials is a method that is currently in practical use, and it is possible to fabricate devices with higher reliability than the solution coating method of high-molecular organic materials, and to stack multiple layers. The structure can be easily formed, and a device with high luminance and high efficiency can be realized. However, at the time of patterning, it is necessary to use a deposition mask, which hinders high definition and large area.
[0004]
On the other hand, as described above, the application method of the high molecular organic material is inferior to the vapor deposition method of the low molecular organic material in terms of the reliability and characteristics of the obtained device, but is combined with, for example, the inkjet method. Accordingly, a sufficiently high-definition light emitting region can be formed, and the present invention can be applied to a display of several tens of inches.
[0005]
[Problems to be solved by the invention]
As described above, the vapor deposition method and the coating method have advantages and disadvantages. In particular, a high-reliability and high-performance device can be provided for the realization of a next-generation organic electroluminescent device, and further, a fine processing technology can be provided. It has been desired to establish a technique for producing a novel organic electroluminescent device accompanied by the above.
[0006]
The present invention can provide a highly reliable and high-performance device, and also provides a method for manufacturing a novel organic electroluminescent device with fine processing technology, and a novel organic electroluminescent device obtained by the method. The purpose is to provide.
[0007]
[Means for Solving the Problems]
To achieve the above object, the present invention provides:
Preparing a transparent substrate in the visible light wavelength region,
Forming a first electrode on the substrate;
Forming a light-emitting layer made of a mixture of a low-molecular-weight organic hole-transporting material, a low-molecular-weight organic electron-transporting material, and a low-molecular-weight organic light-emitting material on the first electrode;
Forming a second electrode on the light emitting layer.
[0008]
Also, the present invention
A transparent substrate in the visible light wavelength region,
A first electrode formed on the substrate;
A light-emitting layer formed on the first electrode, comprising a mixture of a low-molecular organic hole transport material, a low-molecular organic electron transport material, and a low-molecular organic light-emitting material;
And a second electrode formed on the light emitting layer.
[0009]
The low-molecular-weight organic hole transport material, low-molecular-weight organic electron-transport material, and low-molecular-weight organic light-emitting material each mean an organic material having a molecular weight of 10,000 or less.
[0010]
Conventionally, in an organic electroluminescence element, a hole transport layer and an electron transport layer are formed as separate layers so as to sandwich a light emitting layer. Therefore, the light emitting layer portion sandwiched between the pair of electrodes has a multilayer structure in which a plurality of layers are stacked. For example, when an organic electroluminescent element is manufactured by the above-described coating method, the light-emitting layer itself is formed by the coating method, but the hole transport layer and the electron transport layer are manufactured by using an evaporation method.
[0011]
In contrast, according to the present invention, a mixture of a low-molecular organic hole transport material, a low-molecular organic electron transport material, and a low-molecular organic light-emitting material is prepared, and a light-emitting layer is formed from the mixture. I have to. As a result, the light emitting layer portion of the organic electroluminescent device is constituted by only a single light emitting layer. Therefore, if the mixture is dissolved in a predetermined organic solvent or the like, the light emitting layer portion of the organic electroluminescent device can be formed using only a coating method. As a result, fine patterning can be performed, and a fine processing technique can be realized.
[0012]
Further, if the low-molecular organic hole transport material, the low-molecular organic electron transport material, and the low-molecular organic light-emitting material are composed of a low-molecular material that is used in a vapor deposition method, the organic electroluminescence can be obtained. The reliability and performance of the device and also of the device comprising this device can be improved.
[0013]
As a result, according to the present invention, a high-reliability and high-performance device can be provided for the realization of a next-generation organic electroluminescent device, and further, a novel organic electroluminescent device with fine processing technology An element manufacturing technique can be provided.
[0014]
Details of the present invention and other features and advantages will be described in the following embodiments of the present invention.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on an embodiment of the present invention.
FIG. 1 is a configuration diagram showing an example of the organic electroluminescent device of the present invention. In the organic electroluminescent device 10 shown in FIG. 1, a transparent electrode 12 in the visible light wavelength region, a light emitting layer 13, and a metal electrode 14 are sequentially laminated on a substrate 11 transparent in the visible light wavelength region.
[0016]
The light emitting layer 13 is formed from a mixture of a low molecular weight organic hole transport material, a low molecular weight organic electron transport material, and a low molecular weight organic light emitting material having a molecular weight of 10,000 or less. Specifically, the mixture may be dissolved in an organic solvent or the like to form a solution, and the mixture solution may be formed on the substrate 11 by a coating method so as to cover the transparent electrode 12. Examples of the coating method include a spin coating method, an inkjet method, a spray method, and a microgravure method. By using such a coating method, fine patterning can be performed, and a fine processing technique can be realized.
[0017]
The application method in the present invention is not limited to the above specific examples, and other methods can be used as appropriate. Further, in addition to the coating method, the light emitting layer 13 can be formed by an evaporation method by preparing a bulk mixture without preparing a mixture solution, for example, by preparing a mixture solution.
[0018]
The thickness of the light emitting layer 13 is not particularly limited, but is preferably formed to 50 nm to 150 nm.
[0019]
In addition, when the above-described low-molecular organic hole transport material, low-molecular organic electron transport material, and low-molecular organic light-emitting material are composed of low-molecular materials used in a conventional deposition method, the organic electric field can be reduced. It is also possible to improve the reliability and performance of the light emitting element and also of the device having this element.
[0020]
As the low molecular weight organic hole transporting material, it is preferable to use a material exhibiting an amorphous property after forming a film, and N, N′-diphenyl-N, N ′-(3-methylphenyl)-[1, It is preferable to use an amine-based derivative such as 1′-biphenyl] -4,4-diamine (TPD) or bis [N- (1, naphthyl) -phenyl-phenyl] bendithene (α-NPD). In particular, it is preferable to use TPD.
[0021]
Examples of the organic electron transporting material include 2- (4-biphenyl) -5- (ptbutylphenyl) -1,3,4-oxadiazole (tBu-PBD) and 2,9-dimethyl-4,7. -Diphenyl-1,10-phenanthroline (BCP), 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5-bis (6 ′-(2 ′, 2 "-Bipyridyl))-1,1-dimethyl-3,4-diphenicillol (PyPySPyPy), bathophenanthroline (Bphen), and 4,4'-bis (9-carbazole) -biphenyl (CBP). It is preferable to use at least one selected from tBu-PBD, BCP, and CBP.
[0022]
As the organic light emitting material, any light emitting material such as a dendrimer-based material can be used in addition to an organic dye and a phosphorescent material.
[0023]
The mixture may also contain a host material such as 4,4'-bis (9-carbazole) -biphenyl (CBP).
[0024]
The transparent electrode 12 and the metal electrode 14 can be formed by using a known method such as an evaporation method.
[0025]
The transparent electrode 12 can be composed of ITO, which is a mixture of indium oxide and tin oxide, and IZO, which is a mixture of indium oxide and zinc oxide.
[0026]
The metal electrode 14 is made of a metal such as Al, Cs, and Er, an alloy such as MgAg, AlLi, AlLi, AlMg, and CsTe, or Ca / Al, MgAl, Li / Al, Cs / Al, Cs ₂ O / Al, and LiF. / Al, ErF ₃ / Al or the like.
[0027]
In addition, any of the transparent electrode 12 and the metal electrode 14 can be set as an anode and a cathode.
[0028]
In the organic electroluminescent device 10 shown in FIG. 1, a transparent electrode 12 is provided on the substrate 11 side, and a metal electrode 14 is provided on the light emitting layer 13 on the side opposite to the substrate 11. Therefore, light generated and emitted from the light emitting layer 13 is emitted from the transparent substrate 11 through the transparent electrode 12.
[0029]
FIG. 2 is a configuration diagram showing another example of the organic electroluminescent device of the present invention. In the organic electroluminescent device shown in FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals.
[0030]
The organic electroluminescent device 20 shown in FIG. 2 is the same as the organic electroluminescent device 10 shown in FIG. 1 except that the positions of the transparent electrode 12 and the metal electrode 14 are reversed.
In this case, light generated and emitted from the light emitting layer 13 is reflected by the metal electrode 14 and is emitted from the side opposite to the transparent substrate 11 via the transparent electrode 12.
[0031]
In the organic electroluminescent device 20 shown in FIG. 2, the generated light is emitted from the side opposite to the substrate, so that the substrate itself does not need to be transparent. Therefore, by forming the substrate itself from a metal and imparting a function as a metal electrode, the formation of a separate and independent metal electrode can also be omitted.
[0032]
In addition, as a modification of FIGS. 1 and 2, all the electrodes provided above and below can be made transparent electrodes, and light generated from both the substrate side and the opposite side can be extracted. Further, in FIGS. 1 and 2, the transparent electrode 12 and the metal electrode 14 are formed in a flat plate shape, but may be formed in a comb shape.
[0033]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
A transparent substrate made of glass was prepared, and the surface of the substrate was subjected to an ultraviolet ozone cleaner treatment for about 25 minutes. Next, TPD as a hole transporting material, a predetermined electron transporting material, and coumarin 6 (C6) as a green light emitting agent were mixed at a TPD: organic electron transporting material: C6 = 40: 160: 1, -The mixture solution was prepared by dissolving in dichloroethane solvent.
The proportion of the mixture in the solution was adjusted from 1% to 2% by weight.
[0034]
Next, an ITO electrode was formed on the transparent substrate to a thickness of 100 nm, and then the mixture solution was formed to a thickness of 104 nm to 109 nm so as to cover the ITO electrode, and baked for a predetermined time to form a light emitting layer. . Next, a LiF / Al electrode was formed to a thickness of 1/70 nm on the light emitting layer to form an organic electroluminescent device as shown in FIG.
[0035]
FIG. 3 is a graph showing a current density-voltage characteristic for each organic electron transport material, and FIG. 4 is a graph showing a luminance-current density characteristic for each organic electron transport material. As is clear from FIGS. 3 and 4, when tBu-PBD, BCP and CBP are used as the organic electron transporting material, the case of tBu-PBD has the highest luminance and the highest luminance is 1640 cd / m ² ( The current density was found to be 180 mA / cm ² ). The maximum luminance of BCP and CBP was 334 cd / m ² (current density of 155 mA / cm ² ) and 346 cd / m ² (current density of 318 mA / cm ² ), respectively.
[0036]
The maximum brightness when using PyPySPyPy and Bphen as an electron transport material were respectively ^{83cd / m 2, 27cd / m} 2.
[0037]
As described above, the present invention has been described in detail based on the embodiments of the present invention while showing specific examples, but the present invention is not limited to the above contents, and any modifications and Changes are possible.
[0038]
【The invention's effect】
As described above, according to the present invention, a highly reliable and high-performance device can be provided, and a method for manufacturing a novel organic electroluminescent element with fine processing technology, and a method obtained by the method. , A novel organic electroluminescent device.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of the organic electroluminescent device of the present invention.
FIG. 2 is a configuration diagram showing another example of the organic electroluminescent device of the present invention.
FIG. 3 is a graph showing current density-voltage characteristics of the organic electroluminescent device of the present invention.
FIG. 4 is a graph showing luminance-current density characteristics of the organic electroluminescent device of the present invention.
[Explanation of symbols]
10, 20 Organic electroluminescent element 11 Transparent substrate 12 Transparent electrode 13 Light emitting layer 14 Metal electrode

Claims (26)

Preparing a transparent substrate in the visible light wavelength region,
Forming a first electrode on the substrate;
Forming a light-emitting layer made of a mixture of a low-molecular-weight organic hole-transporting material, a low-molecular-weight organic electron-transporting material, and a low-molecular-weight organic light-emitting material on the first electrode;
Forming a second electrode on the light emitting layer. The method for manufacturing an organic electroluminescent device according to claim 1, wherein an organic host material is contained in the mixture. 3. The film according to claim 1, wherein the mixture is dissolved in an organic solvent to form a solution, and the obtained mixture solution is applied on the first electrode to form the film. 4. A method for producing an organic electroluminescent device according to the above. The method according to any one of claims 1 to 3, wherein the application of the mixture solution is performed using at least one of a spin coating method, an inkjet method, a spray method, and a microgravure method. A method for manufacturing an electroluminescent element. The organic electroluminescent device according to claim 1, wherein the first electrode is a transparent electrode in a visible light wavelength region, and the second electrode is a metal electrode. Production method. The organic electroluminescent device according to claim 1, wherein the first electrode is a metal electrode, and the second electrode is a transparent electrode in a visible light wavelength region. Production method. The method for manufacturing an organic electroluminescent device according to claim 1, wherein the first electrode has a comb shape. The low-molecular-weight organic hole transport material is N, N'-diphenyl-N, N '-(3-methylphenyl)-[1,1'-biphenyl] -4,4-diamine. A method for producing an organic electroluminescent device according to claim 1. The low molecular weight organic electron transporting material is 2- (4-biphenyl) -5- (ptbutylphenyl) -1,3,4-oxadiazole, 2,9-dimethyl-4,7-diphenyl- The organic electric field according to claim 1, wherein the organic electric field is at least one selected from the group consisting of 1,10-phenanthroline and 4,4′-bis (9-carbazole) -biphenyl. A method for manufacturing a light-emitting element. The method according to any one of claims 1 to 9, wherein the low-molecular-weight organic light-emitting material is an organic dye or a phosphorescent material. The method according to any one of claims 1 to 10, wherein the organic host material is 4,4'-bis (9-carbazole) -biphenyl. A transparent substrate in the visible light wavelength region,
A first electrode formed on the substrate;
A light-emitting layer formed on the first electrode, comprising a mixture of a low-molecular organic hole transport material, a low-molecular organic electron transport material, and a low-molecular organic light-emitting material;
An organic electroluminescence device, comprising: a second electrode formed on the light emitting layer. The organic electroluminescent device according to claim 12, wherein an organic host material is contained in the mixture. 14. The organic electroluminescent device according to claim 12, wherein the first electrode is made of a transparent electrode in a visible light wavelength region, and the second electrode is made of a metal electrode. 14. The organic electroluminescent device according to claim 12, wherein the first electrode comprises a metal electrode, and the second electrode comprises a transparent electrode in a visible light wavelength region. The organic electroluminescent device according to any one of claims 12 to 15, wherein the first electrode has a comb shape. The low-molecular-weight organic hole transport material is N, N'-diphenyl-N, N '-(3-methylphenyl)-[1,1'-biphenyl] -4,4-diamine. The organic electroluminescent device according to any one of claims 12 to 16, wherein The low molecular weight organic electron transporting material is 2- (4-biphenyl) -5- (ptbutylphenyl) -1,3,4-oxadiazole, 2,9-dimethyl-4,7-diphenyl- The organic electric field according to any one of claims 12 to 17, wherein the organic electric field is at least one selected from the group consisting of 1,10-phenanthroline and 4,4'-bis (9-carbazole) -biphenyl. Light emitting element. The organic electroluminescent device according to any one of claims 12 to 18, wherein the low molecular weight organic light emitting material is an organic dye or a phosphorescent material. The organic electroluminescent device according to any one of claims 12 to 19, wherein the organic host material is 4,4'-bis (9-carbazole) -biphenyl. An organic electroluminescent layer comprising a mixture of a low molecular weight organic hole transport material, a low molecular weight organic electron transport material, and a low molecular weight organic light emitting material. The organic electroluminescent layer according to claim 21, wherein an organic host material is contained in the mixture. The low-molecular-weight organic hole transport material is N, N'-diphenyl-N, N '-(3-methylphenyl)-[1,1'-biphenyl] -4,4-diamine. The organic electroluminescent layer according to claim 21 or 22, wherein The low molecular weight organic electron transporting material is 2- (4-biphenyl) -5- (ptbutylphenyl) -1,3,4-oxadiazole, 2,9-dimethyl-4,7-diphenyl- The organic electric field according to any one of claims 21 to 23, wherein the organic electric field is at least one selected from the group consisting of 1,10-phenanthroline and 4,4'-bis (9-carbazole) -biphenyl. Light emitting layer. The organic electroluminescent layer according to any one of claims 21 to 24, wherein the low molecular weight organic light emitting material is an organic dye or a phosphorescent material. The organic electroluminescent layer according to any one of claims 21 to 25, wherein the organic host material is 4,4'-bis (9-carbazole) -biphenyl.

Images