JP2010024407A - Luminous composition and method for producing organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminous composition which has high coating suitability and from which a high-performance organic EL element can be formed and to provide a method for producing the organic EL element. <P>SOLUTION: The luminous composition contains a luminous component, a hole transporting component and an electron transporting component and contains a low molecular weight polymer having 3,000-5,000 weight-average molecular weight, a middle molecular weight polymer having 30,000-80,000 weight-average molecular weight and a high molecular weight polymer having ≥100,000 weight-average molecular weight. Each of these polymers is composed of at least one of a luminous monomer for forming the luminous component, a hole transporting monomer for forming the hole transporting component and an electron transporting monomer for forming the electron transporting component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a luminescent composition and a method for producing an organic electroluminescence device.

Conventionally, organic electroluminescence elements (hereinafter referred to as “organic EL elements”) are known as planar light-emitting elements that emit light (see, for example, Patent Documents 1 to 5).
The organic EL element can be thinned, is a self-luminous element, has a wide viewing angle and high visibility, can be driven with a DC voltage, and has a low applied voltage of about 10V. Even in such a case, it has excellent characteristics such as high luminous efficiency such as high luminance emission, fast response speed, and light emission with a simple element structure.

  By the way, as an organic EL element, a single layer structure in which a light emitting layer made of an organic material is formed between an anode (anode layer) and a cathode (cathode layer), and hole injection between the anode and the light emitting layer. Known are those having a multilayer structure such as a structure having a transport layer and a structure having an electron injection layer between the cathode and the light-emitting layer. All of these organic EL elements are injected from the cathode. The electrons and holes injected from the anode recombine in the light emitting layer to emit light.

  In such an organic EL element, a light emitting layer can be formed by a dry method in which an organic material (light emitting composition) is formed by vacuum deposition, or a solution in which the organic material (light emitting composition) is dissolved. There is known a wet method that is formed by applying and drying. Among these methods, the dry method has a complicated process and is difficult to cope with mass production, and there is a limit to forming a light emitting layer having a large area. On the other hand, the wet method has a simple process and can be applied to mass production, and can easily form a light emitting layer with a large area. It is advantageous.

When an organic EL device is prepared by a wet method, the properties of the luminescent composition include not only that a high-performance organic EL device can be formed, but also coating properties when a solution in which the luminescent composition is dissolved is applied. It is also desirable that this is high.
JP 2002-31561 A JP 2001-284052 A JP 2003-171659 A JP 2007-087642 A JP 2007-016226 A

  However, if the molecular weight of the polymer contained in the light-emitting composition is reduced to increase the coating property, a high-performance organic EL device cannot be formed, and the molecular weight of the polymer contained in the light-emitting composition can be reduced. If the size is increased to improve the shape-retaining property of the luminescent composition so that a high-performance organic EL device can be formed, there is a problem that the coating property is lowered.

  An object of the present invention is to provide a luminescent composition capable of forming a high-performance organic EL device having high coating properties and a method for producing an organic EL device using a luminescent ink containing the luminescent composition. It is to provide.

In order to solve the above-mentioned problem, the invention described in claim 1
In a luminescent composition comprising a luminescent component, a hole transport component, and an electron transport component,
A low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer having a weight average molecular weight of 100,000 or more,
The polymer comprises at least one of a light-emitting monomer that forms the light-emitting component, a hole-transport monomer that forms the hole-transport component, and an electron-transport monomer that forms the electron-transport component. To do.

The invention described in claim 2
The luminescent composition according to claim 1,
The polymer is a binary copolymer of a tertiary aromatic amine derivative that is the hole transporting monomer and an oxadiazole derivative that is the electron transporting monomer.

The invention according to claim 3
In a luminescent composition comprising a phosphorescent light emitting component, a hole transport component, and an electron transport component,
A low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer having a weight average molecular weight of 100,000 or more,
The polymer includes a tertiary aromatic amine derivative that is a hole transporting monomer that forms the hole transporting component and an oxadiazole derivative that is an electron transporting monomer that forms the electron transporting component. It is an original copolymer.

The invention according to claim 4
In the manufacturing method of an organic electroluminescent element provided with the light emitting layer formed with the luminescent composition as described in any one of Claims 1-3,
The light emitting layer is formed by a step of printing the light emitting layer by a flexographic printing method using a light emitting ink containing the light emitting composition.

The invention described in claim 5
In the manufacturing method of the organic electroluminescent element of Claim 4,
The process includes
A first printing step for printing along one direction;
A second printing step for printing along a direction substantially orthogonal to the one direction,
The first printing step is performed at least once and the second printing step is performed at least once.

According to the present invention, the luminescent composition comprises a low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight having a weight average molecular weight of 100,000 or more. And a molecular weight polymer.
Therefore, the luminescent composition of the present invention contains a low molecular weight polymer for improving the coatability and a high molecular weight polymer for improving the shape retention, so that the coatability is improved. And a high-performance organic EL element can be formed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The scope of the invention is not limited to the illustrated example.

(Organic electroluminescence device (organic EL device))
First, an example of the organic EL element 10 provided with the light emitting layer 4 formed of the luminescent composition of the present invention will be described.
FIG. 1 is a schematic cross-sectional view illustrating an example of an organic EL element 10 including a light emitting layer 4 formed of the light emitting composition of the present invention.
For example, as shown in FIG. 1, the organic EL element 10 includes a substrate 1, an anode layer 2 disposed on the substrate 1, a hole injection transport layer 3 disposed on the anode layer 2, and hole injection. The light emitting layer 4 disposed on the transport layer 3, the electron injection layer 5 disposed on the light emitting layer 4, the cathode layer 6 disposed on the electron injection layer 5, and the anode layer 2 and the cathode layer 6 are electrically connected. And a direct-current power supply 7 to be connected to each other.
In the organic EL element 10, for example, when a DC voltage is applied between the anode layer 2 and the cathode layer 6 by the DC power source 7, the light emitting layer 4 emits light, and the light is transmitted to the hole injecting and transporting layer. 3, the anode layer 2 and the substrate 1 are transmitted and radiated to the outside.

(substrate)
The substrate 1 is a transparent substrate.
The substrate 1 is not particularly limited, and for example, a glass substrate, a transparent resin substrate, a quartz glass substrate, or the like can be used.

(Anode layer)
The anode layer 2 is a transparent electrode layer that supplies holes.
The anode layer 2 is not particularly limited. For example, an ITO (Indium Tin Oxide) film, a tin oxide (SnO ₂ ) film, a copper oxide (CuO) film, a zinc oxide (ZnO) film, or the like is used. it can.
Although the thickness of the anode layer 2 changes with kinds of material, it is 10-1000 nm, for example, Preferably it is 50-200 nm.

(Hole injection transport layer)
The hole injecting and transporting layer 3 is provided to efficiently supply holes to the light emitting layer 4 and has a function of receiving holes from the anode layer 2 and transporting them to the light emitting layer 4. is there.
The hole injection transport layer 3 is not particularly limited, and for example, a polymer thin film made of a polymer material containing a polythiophene compound and polystyrene sulfonic acid can be used. The hole injection / transport layer 3 may have a single layer structure or a multilayer structure in which the same or different hole injection / transport materials are stacked in multiple layers.
The thickness of the hole injection transport layer 3 is, for example, 10 to 200 nm, but is not particularly limited.

(Light emitting layer)
The light emitting layer 4 is a layer having a function of combining electrons and holes and emitting the binding energy as light.
The thickness of the light emitting layer 4 is, for example, 2 to 5000 nm, but is not particularly limited.

  For example, the light emitting layer 4 opposes the electron injecting layer 5 of the hole injecting and transporting layer 3 with a light emitting ink containing a light emitting composition including a light emitting component, a hole transporting component, and an electron transporting component. It is formed by coating on the side surface (which may be the surface of the electron injection layer 5 facing the hole injection transport layer 3).

<Luminescent composition>
The luminescent composition is, for example, any one of the following (A) to (C), and (B) or (C) is preferable from the viewpoint of driving voltage, light emission efficiency, and the like. That is, the luminescent composition preferably contains a bipolar polymer (a polymer comprising at least a hole transporting monomer and an electron transporting monomer) as a polymer.
(A) A luminescent composition comprising a luminescent agent as a luminescent component, a polymer of a hole transporting monomer that forms a hole transporting component, and a polymer of an electron transporting monomer that forms an electron transporting component ( B) A luminescent composition (C) comprising a luminescent agent as a luminescent component, and a binary copolymer of a hole transporting monomer that forms a hole transporting component and an electron transporting monomer that forms an electron transporting component. ) A luminescent composition comprising a terpolymer of a luminescent monomer that forms a luminescent component, a hole transportable monomer that forms a hole transport component, and an electron transport monomer that forms an electron transport component

  Examples of the luminescent composition include a low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer having a weight average molecular weight of 100,000 or more. And. Among these, a luminescent composition containing 3% or more of a polymer having a molecular weight of 4300 or less is preferable.

  That is, in the case of (A), the luminescent composition is, for example, a low molecular weight polymer (a polymer of a hole transporting monomer or a polymer of an electron transporting monomer) having a weight average molecular weight of 3000 to 5000, and A medium molecular weight polymer (a polymer of a hole transporting monomer or a polymer of an electron transporting monomer) having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer (a hole transporting property) having a weight average molecular weight of 100,000 or more. Among them, in particular, a polymer (a polymer of a hole-transporting monomer or an electron-transporting monomer) contained in a luminescent composition is included. A luminescent composition in which a ratio of a polymer having a molecular weight of 4300 or less (a polymer of a hole transporting monomer or a polymer of an electron transporting monomer) to the whole polymer) is 3% or more; Masui.

  In the case of (B), the luminescent composition is, for example, a low molecular weight polymer having a weight average molecular weight of 3000 to 5000 (binary copolymer of a hole transporting monomer and an electron transporting monomer) and , A medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000 (binary copolymer of a hole transporting monomer and an electron transporting monomer) and a high molecular weight polymer having a weight average molecular weight of 100,000 or more (hole A binary copolymer of a transporting monomer and an electron transporting monomer), and among these, in particular, a polymer (a hole transporting monomer and an electron transporting monomer included in the luminescent composition) The ratio of the polymer having a molecular weight of 4300 or less (binary copolymer of a hole transporting monomer and an electron transporting monomer) to the entire binary copolymer is 3% or more. preferable.

  In the case of the above (C), the luminescent composition is, for example, a low molecular weight polymer having a weight average molecular weight of 3000 to 5000 (a ternary copolymer of a luminescent monomer, a hole transporting monomer, and an electron transporting monomer). Polymer), a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000 (a terpolymer of a light emitting monomer, a hole transporting monomer, and an electron transporting monomer), and a weight average molecular weight of 100,000 or more. A high molecular weight polymer (a ternary copolymer of a light-emitting monomer, a hole transporting monomer, and an electron transporting monomer). Among them, in particular, a polymer contained in a light-emitting composition A polymer (light emitting monomer, hole transporting monomer, and electron transport) having a molecular weight of 4300 or less relative to the whole (a terpolymer of the light emitting monomer, the hole transporting monomer, and the electron transporting monomer). Proportion of terpolymer) of monomer, luminescent composition is 3% or more is preferable.

  Examples of the luminescent agent include a fluorescent luminescent agent and a phosphorescent luminescent agent, and a phosphorescent luminescent agent is preferable from the viewpoint of luminous efficiency.

The fluorescent agent is not particularly limited, and for example, a dye material, a metal complex material, a polymer material, or the like can be used.
Examples of the dye material include tetraphenylbutadiene derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, thiophene ring compounds, perylene derivatives, oligothiophene derivatives, and pyrazoline dimers.
Examples of metal complex materials include quinolinol complex, aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazolyl zinc complex, benzothiazole zinc complex, azomethyl zinc complex, porphyrin zinc complex, europium complex, etc. , Zn, Be or the like or a metal complex having a rare earth metal such as Tb, Eu or Dy and having a ligand such as oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure, or the like can be used.
Examples of the polymer material include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, and polymers obtained by polymerizing the above dye materials and metal complex materials. Can be used.
In addition, the kind of fluorescent luminescent agent contained in a luminescent composition may be one type, and multiple types may be sufficient as it.

Although it does not specifically limit as a phosphorescent agent, The complex compound of the metal chosen from iridium, platinum, and osmium is preferable. In addition, the kind of phosphorescent agent contained in the light emitting composition may be one kind or plural kinds.
Here, preferable specific examples of the phosphorescent agent include, for example, bis (2-phenylpyridyl) iridium acetylacetonate (the following general formula (1)), tris (2-phenylpyridyl) iridium, tris (2- ( 4-methylphenyl) pyridyl) iridium, tris (2-phenyl-3-methylpyridyl) iridium, phenylbenzothiazyliridium, difluorophenylpyridyliridium complex, and the like.

  Examples of the light emitting monomer include a fluorescent light emitting monomer and a phosphorescent light emitting monomer, and a phosphorescent light emitting monomer is preferable from the viewpoint of light emission efficiency.

The fluorescent light-emitting monomer is not particularly limited, and for example, a monomer having a compound such as a pigment material, a metal complex material, or a polymer material can be used.
As the monomer having a dye-based compound, for example, a monomer having a tetraphenylbutadiene derivative, a distyrylbenzene derivative, a distyrylarylene derivative, a thiophene ring compound, a perylene derivative, an oligothiophene derivative, a pyrazoline dimer, or the like can be used. .
Examples of the monomer having a metal complex compound include quinolinol complex, aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazole zinc complex, benzothiazole zinc complex, azomethyl zinc complex, porphyrin zinc complex, europium complex, etc. A monomer having a rare earth metal such as Al, Zn, Be or the like or Tb, Eu, Dy or the like, and having a metal complex having a oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure or the like as a ligand. Can be used.
For example, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, and the above-mentioned dye materials and metal complex materials are polymerized. Monomers having the like can be used.
In addition, the kind of fluorescent luminescent monomer contained in a luminescent composition may be one type, and may be multiple types.

Although it does not specifically limit as a phosphorescent monomer, The monomer which has the complex compound of the metal chosen from iridium, platinum, and osmium is preferable. In addition, the kind of phosphorescence-emitting monomer contained in a luminescent composition may be one type, and may be multiple types.
Here, preferable specific examples of the phosphorescent monomer include, for example, a monomer having bis (2-phenylpyridyl) iridium acetylacetonate (the following general formula (2)) and tris (2-phenylpyridyl) iridium. Monomer, monomer having tris (2- (4-methylphenyl) pyridyl) iridium, monomer having tris (2-phenyl-3-methylpyridyl) iridium, monomer having phenylbenzothiazyliridium, difluorophenylpyridyliridium complex Etc.

The hole transporting monomer is not particularly limited, and for example, a dye material, a polymer material, or the like can be used.
As the dye material, for example, tertiary aromatic amine derivatives such as triphenylamine derivatives and carbazole derivatives, thiophene ring compounds, pyridine ring compounds, oligothiophine derivatives, and the like can be used.
As the polymer material, for example, a polyparaphenylene vinylene derivative, a polythiophene derivative, a polyparaphenylene derivative, a polyfluorene derivative, a polyvinyl carbazole derivative, a material obtained by polymerizing the dye material, and the like can be used.
Among these, tertiary aromatic amine derivatives, particularly carbazole derivatives are preferred. In addition, the kind of hole transportable monomer contained in the light emitting composition may be one kind or plural kinds.
Here, specific examples of the carbazole derivative include, for example, N-vinylcarbazole (the following general formula (3)), 3,6-dimethyl-9-vinylcarbazole, 3,6-diethyl-9-vinylcarbazole, 3 -Methyl-9-vinylcarbazole, 3-ethyl-9-vinylcarbazole and the like. Among these, N-vinylcarbazole and 3,6-dimethyl-9-vinylcarbazole are preferable.

The electron transporting monomer is not particularly limited, and for example, a dye material, a polymer material, or the like can be used.
Examples of the dye material include oxadiazol derivatives, bathophenanthroline derivatives, triazole derivatives, silole derivatives, oxadiazole dimers, and the like.
As the polymer material, for example, a polysilane derivative, a polyacetylene derivative, or the like can be used.
Of these, oxadiazol derivatives are particularly preferable. In addition, the kind of electron transport monomer contained in the light emitting composition may be one kind or plural kinds.
Here, specific examples of the oxadiazol derivative include, for example, 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1,3,4-oxadiazole (the following general formula). Formula (4)), 2-β-naphthyl-5- (4-vinylphenyl) -1,3,4-oxadiazole, 2-α-naphthyl-5- (4-vinylphenyl) -1,3, 4-oxadiazole, 2-phenyl-5- (4-vinylphenyl) -oxadiazole, 2-phenyl-5- (4-vinyl-p-biphenyl) -1,3,4-oxadiazole, 2 -(P-biphenyl) -5- (4-vinylphenyl) -oxadiazole, 2- (p-biphenyl) -5- (4-propenylphenyl) -1,3,4-oxadiazole, 2-t -Butoxyphenyl-5- (4- (4-vinyl Eniru)-p-biphenyl) -1,3,4-oxadiazole, or those like substituted acryloyl group or a methacryloyl group in these oxadiazole derivatives. Among these, 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1,3,4-oxadiazole, 2-β-naphthyl-5- (4-vinylphenyl) -1,3,4-oxadiazole, 2- (p-biphenyl) -5- (4-vinylphenyl) -1,3,4-oxadiazole, 2- (p-biphenyl) -5- (4 -Propenylphenyl) -1,3,4-oxadiazole is preferred.

  Polymer of hole transporting monomer, polymer of electron transporting monomer, binary copolymer of hole transporting monomer and electron transporting monomer, light emitting monomer, hole transporting monomer and electron transporting monomer This ternary copolymer can be prepared, for example, by a cationic polymerization method, a radical polymerization method or an anionic polymerization method in an appropriate polymerization solvent.

The luminescent ink is prepared, for example, by dissolving or dispersing a luminescent composition or the like in a predetermined solvent.
The predetermined solvent is not particularly limited as long as the light emitting component, the hole transport component, the electron transport component, and the like can be dissolved or dispersed and the light emitting ink can have a predetermined viscosity. . Specifically, as the predetermined solvent, for example, a ketone solvent, an aromatic solvent, a halogenated solvent, or the like can be used, and more specifically, for example, cyclopentanone, cyclohexanone, chlorobenzene, toluene, xylene. Etc. can be used alone or in combination.

Here, the luminescent ink may be one obtained by adding various additives to a predetermined solvent in addition to the luminescent composition.
For example, the luminescent ink may be added with doping materials such as various phosphorescent agents for the purpose of, for example, improving the light emission efficiency of the light emitting layer 4 and changing the light emission wavelength of the light emitting layer 4.
Further, the luminescent ink may be added with various surfactants or the like for the purpose of improving printing characteristics, for example.

(Electron injection layer)
The electron injection layer 5 is provided to efficiently supply electrons to the light emitting layer 4 and has a function of receiving electrons from the cathode layer 6 and transporting them to the light emitting layer 4.
The electron injection layer 5 is not particularly limited, and examples thereof include bathophenanthroline materials (BPCs), lithium fluoride, magnesium fluoride, strontium oxide, anthraquinodimethane derivatives, diphenylquinone derivatives, and oxadiazole derivatives. Perylene tetracarboxylic acid derivatives and the like can be used. Among these, a bathophenanthroline-based material is particularly preferable. Further, the electron injection layer 5 may have a single layer structure or a multilayer structure in which the same or different electron injection materials are stacked in multiple layers.
Although the thickness of the electron injection layer 5 is 0.1-100 nm, for example, it is not specifically limited.

(Cathode layer)
The cathode layer 6 is an electrode layer that supplies electrons.
The cathode layer 6 is not particularly limited. For example, a metal film made of aluminum, calcium, magnesium, indium, or an alloy film of these metals can be used.
Although the thickness of the cathode layer 6 changes with kinds of material, it is 10-1000 nm, for example, Preferably it is 50-200 nm.

<Method for producing organic EL element>
Next, an example of the manufacturing method of the organic EL element 10 of the present invention will be described.

First, the anode layer 2 is formed on the substrate 1.
As a method for forming the anode layer 2, for example, a vacuum deposition method, a sputtering method, or the like can be used.
Further, a commercially available material in which an ITO film or the like is formed on the surface of a transparent substrate such as a glass substrate can be used as the anode layer 2 formed on the substrate 1.

Next, the hole injection transport layer 3 is formed on the anode layer 2.
Specifically, for example, the hole injection / transport layer 3 is formed by applying a predetermined hole injection / transport layer forming liquid on the anode layer 2.
The predetermined hole injecting and transporting layer forming liquid is obtained by, for example, dissolving or dispersing a predetermined hole injecting and transporting material (for example, a polythiophene compound and polystyrene sulfonic acid) in an appropriate solvent (for example, water or alcohol). Created.
As a method for applying the hole injection transport layer forming liquid, for example, a wet method such as a spin coating method, a dip method, an ink jet method, a printing method, or the like can be used.

Next, the light emitting layer 4 is formed on the hole injecting and transporting layer 3.
Specifically, for example, the light emitting layer 4 is formed by applying a light emitting ink on the hole injecting and transporting layer 3.
As a method for applying the luminescent ink, for example, a wet method such as a spin coating method, a dip method, a roll coating method, an ink jet method, a printing method, or the like can be used. Among these, a printing method, particularly a flexographic printing method. Is preferred.

Here, a method of forming the light emitting layer 4 by printing the light emitting layer 4 by a flexographic printing method using a light emitting ink will be described.
For example, first, the flexographic printing original plate is set on the plate cylinder of the flexographic printing machine without performing any operations such as development and wiping.
Next, a predetermined amount of luminescent ink is attached to the flexographic printing plate attached to the plate cylinder using an anilox roll or the like, the luminescent ink is transferred to a rubber cylinder called a blanket cylinder, and the luminescent ink transferred to the rubber cylinder is transferred to the original plate. Transfer to the hole injecting and transporting layer 3 which is the printing medium.
Next, the luminescent layer 4 is formed by solidifying the transferred luminescent ink by oxidative polymerization, UV light curing, hot air drying, or the like.

In addition, when forming the light emitting layer 4, it is preferable to print twice or more, especially the 1st printing step printed along one direction, and the 2nd printing printed along the direction substantially orthogonal to the said one direction. It is preferable to form the light emitting layer 4 in a step of performing each of the steps at least once. That is, for example, when the light emitting layer 4 is formed by printing twice, it is particularly preferable that the first printing direction and the second printing direction are substantially orthogonal.
Moreover, when using a printing system as a system for applying the luminescent ink, from the viewpoint of forming the luminescent layer 4 with high accuracy, the luminescent component, hole transport component, and electron transport component included in the luminescent composition are as described above. It is preferable to use a luminescent ink using a polymer material.

  Further, when the organic EL element 10 is colored, it is necessary to form a plurality of types of light emitting layers 4 using a plurality of types of luminescent inks having different types of light emitting components.

The plate material of the flexographic printing original plate is not particularly limited, and known materials can be used. Specific examples of the plate material include, for example, a plastic film (plastic film such as polyester, nylon, polyethylene, polypropylene, polycarbonate, polyimide, polyketone, and ABS resin), elastomer film, paper, and plastic film laminated paper. . From the viewpoint of strength and the like, a laminate obtained by laminating these plate materials on a support can also be used.
The thickness of the plate material is, for example, about 100 to 4000 μm, but is not particularly limited.

The method for producing the flexographic printing original plate is not particularly limited, but it is preferably produced by laser engraving, laser ablation or MEMS.
When producing the flexographic printing original plate, it is preferable to scan the convergent light at high speed, and it is easy to use. Further, a high output light source is suitable as the light source, and from this point, as the light to be irradiated, laser light, particularly infrared laser light having an oscillation wavelength in the wavelength range of 700 to 1100 nm is preferable. Specifically, For example, a 830 nm high-power semiconductor laser, a 1064 nm YAG laser, or the like is preferably used. Exposure machines equipped with these lasers are already on the market as so-called thermal plate setters (exposure machines).

Next, the electron injection layer 5 is formed on the light emitting layer 4.
Specifically, for example, the electron injection layer 5 is formed by applying a predetermined electron injection layer forming liquid on the light emitting layer 4.
The predetermined electron injection layer forming liquid is prepared, for example, by dissolving or dispersing a predetermined electron injection material (for example, a bathophenanthroline-based material) in an appropriate solvent.
As a method for applying the electron injection layer forming liquid, for example, a wet method such as a spin coating method, a dip method, an ink jet method, or a printing method can be used.
Further, the electron injection layer 5 may be formed using a dry method such as a vacuum deposition method instead of a wet method.

Next, the cathode layer 6 is formed on the electron injection layer 5.
As a method for forming the cathode layer 6, for example, a vacuum deposition method, a sputtering method, or the like can be used.
The above is an example of the manufacturing method of the organic EL element 10 of the present invention.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[1] Polymer Blend An experiment was conducted to demonstrate the effect of a luminescent composition containing a low molecular weight polymer, a medium molecular weight polymer and a high molecular weight polymer.

[1-1] About Luminescent Ink First, a luminescent ink containing a luminescent composition containing a low molecular weight polymer, a medium molecular weight polymer, and a high molecular weight polymer was prepared and evaluated.

[1-1-1] Preparation of luminescent ink A luminescent composition containing the luminescent composition (B) as a luminescent composition containing a low molecular weight polymer, a medium molecular weight polymer and a high molecular weight polymer. An ink was created.
That is, a low molecular weight binary copolymer (polymer L) having a weight average molecular weight of 3000 to 5000, a medium molecular weight binary copolymer (polymer M) having a weight average molecular weight of 30000 to 80000, and a weight average molecular weight of Plural kinds of luminescent inks containing luminescent compositions having different mixing ratios with a high molecular weight binary copolymer (polymer H) of 100,000 or more were prepared.

First, 0.05 part by mass of a phosphorescent agent (bis (2-phenylpyridyl) iridium acetylacetonate represented by the above general formula (1)), a binary of a hole transporting monomer and an electron transporting monomer Copolymer (91 mol% of N-vinylcarbazole represented by the above general formula (3) and 2- (4-tert-butyl) phenyl-5- (4- And a luminescent composition A containing 0.95 parts by mass of a binary copolymer consisting of 9 mol% of (binylbiphenyl) -1,3,4-oxadiazole.
Next, a luminescent ink prepared by dissolving the luminescent composition A in 30 parts by mass of cyclohexanone (a luminescent ink having a luminescent composition concentration of 3.3 wt%) and the luminescent composition A with 15 parts by mass of cyclohexanone. Luminescent ink prepared by dissolving in part (luminescent ink having a concentration of 6.7 wt% of luminescent composition) and luminescent ink prepared by dissolving luminescent composition A in 10 parts by mass of cyclohexanone (Luminescent ink having a concentration of the luminescent composition of 10 wt%).
In the luminescent composition A, a binary copolymer having a weight average molecular weight of 4200, a binary copolymer having a weight average molecular weight of 32,000, and a binary copolymer having a weight average molecular weight of 105,000 are used as the binary copolymer. A polymer blend in which the original copolymer is mixed is included. Hereinafter, the respective binary copolymers in the polymer blend are referred to as polymer L, polymer M, and polymer H in order from the one having the lowest weight average molecular weight.

An example of a method for synthesizing the binary copolymer in the polymer blend contained in the luminescent composition A will be described using a method for synthesizing the polymer M.
First, 10 mL of N-vinylcarbazole and 1.0 mmol of 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1,3,4-oxadiazole were used in a 20 mL pressure bottle. The inside of the pressure bottle was repeatedly replaced with nitrogen gas.
Next, 3.0 mol% of azobisisobutyronitrile and 6.9 mL of dehydrated dimethylformamide were added in a pressure-resistant bottle, and the monomer was polymerized at 60 ° C. for 72 hours.
As a result, a block component in which N-vinylcarbazole and 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1,3,4-oxadiazole are alternately polymerized ( a block copolymer comprising ab) and a block component (a) obtained by polymerizing N-vinylcarbazole.
In the above polymerization, the change in the composition of the reaction system was examined at regular time intervals, and N-vinylcarbazole and 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1 , 3,4-oxadiazole was carried out while confirming that they were polymerized alternately.

Next, the prepared block copolymer was analyzed.
As a result, a structural unit derived from N-vinylcarbazole in the block component (ab) and 2- (4-tert-butyl) phenyl-5- (4-binylbiphenyl) -1,3,4-oxadiazole The ratio of the sum of the structural units derived from N and the structural unit derived from N-vinylcarbazole in the block component (a) was 10:90 in molar ratio.
Further, the weight average polymerization degree of the block component (ab) was 30, and the weight average polymerization degree of the block component (a) was 600.
Moreover, the weight average molecular weight of the block copolymer was 32000 in terms of polystyrene by GPC (Gel Permeation Chromatography) method (solvent: tetrahydrofuran).
The polymer M was synthesized as described above, and it was confirmed that the synthesized polymer M was a binary copolymer having a weight average molecular weight of 30,000 to 80,000 and a medium molecular weight.

According to the above synthesis example, Polymer L, Polymer M and Polymer H having different polymerization average molecular weight and molecular weight distribution were prepared.
FIG. 2 shows GPC data showing the molecular weight distribution of the prepared polymer L, polymer M and polymer H.
From the GPC data shown in FIG. 2, the ratio of the binary copolymer having a molecular weight of 4300 or less to the entire polymer L is 40%, and the ratio of the binary copolymer having a molecular weight of 4300 or less to the entire polymer M is 1% or less. It was found that the ratio of the binary copolymer having a molecular weight of 4300 or less relative to the whole polymer H was 0%.

In addition, FIG. 3 shows GPC data showing the molecular weight distribution of a polymer blend prepared by mixing the prepared polymer L, polymer M, and polymer H in various ratios. Specifically, FIG. 3 shows a polymer blend having a mixing ratio (mixing weight ratio) of polymer L: polymer M: polymer H = 1: 8: 1 and a mixing ratio (mixing weight ratio) of polymer L: polymer M. : Polymer H = 3: 6: 1 polymer blend, mixing ratio (mixing weight ratio) of polymer L: Polymer M: Polymer H = polymer H = 3: 4: 3, polymer mixing ratio (mixing weight ratio) of polymer GPC data showing molecular weight distribution of L: polymer M: polymer H = 1: 6: 3.
From the GPC data shown in FIG. 3, the ratio of the binary copolymer having a molecular weight of 4300 or less to the entire polymer blend having a mixing ratio of polymer L: polymer M: polymer H = 1: 8: 1 is 4%. The ratio of the binary copolymer having a molecular weight of 4300 or less to the entire polymer blend of polymer L: polymer M: polymer H = 3: 6: 1 is 12%, and the mixing ratio is polymer L: polymer M: polymer H = The ratio of the binary copolymer having a molecular weight of 4300 or less to the entire 3: 4: 3 polymer blend is 12%, and the mixing ratio of the polymer L: polymer M: polymer H = 1: 6: 3 The proportion of the binary copolymer having a molecular weight of 4300 or less was found to be 4%.

<Example 1-1>
As the luminescent ink of Example 1-1, the light emission in which the mixing ratio (mixing weight ratio) is polymer L: polymer M: polymer H = 1: 8: 1 and the concentration of the luminescent composition is 3.3 wt%. Ink was made.
Specifically, first, the produced polymer L30 mg, the produced polymer M240 mg, and the produced polymer H30 mg were placed in a 20 mL screw vial.
Next, 10 mL of dehydrated cyclohexanone was added into the screw vial and heated at 60 ° C. for 10 minutes to dissolve the polymer L, polymer M, and polymer H.
Subsequently, the luminescent ink of Example 1-1 was created by stirring for 12 hours.

<Example 1-2>
As the luminescent ink of Example 1-2, the luminescent ink having a mixing ratio (mixing weight ratio) of polymer L: polymer M: polymer H = 3: 6: 1 and a concentration of the luminescent composition of 3.3 wt% Ink was made.
In addition, since the luminescent ink of Example 1-2 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of the polymer L, the polymer M, and the polymer H is different, details of the production method The detailed explanation is omitted.

<Example 1-3>
As the luminescent ink of Example 1-3, the mixing ratio (mixing weight ratio) is polymer L: polymer M: polymer H = 3: 4: 3, and the concentration of the luminescent composition is 3.3 wt%. Ink was made.
The luminescent ink of Example 1-3 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of polymer L, polymer M, and polymer H is different. The detailed explanation is omitted.

<Example 1-4>
As the luminescent ink of Example 1-4, the mixing ratio (mixing weight ratio) is polymer L: polymer M: polymer H = 1: 6: 3 and the concentration of the luminescent composition is 3.3 wt%. Ink was made.
The luminescent ink of Example 1-4 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of polymer L, polymer M, and polymer H is different. The detailed explanation is omitted.

<Comparative Example 1-1>
As the luminescent ink of Comparative Example 1-1, the luminescent ink having a mixing ratio (mixing weight ratio) of polymer L: polymer M: polymer H = 10: 0: 0 and a concentration of the luminescent composition of 3.3 wt% Ink was made.
In addition, since the luminescent ink of Comparative Example 1-1 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of the polymer L, the polymer M, and the polymer H is different, the details of the production method are as follows. The detailed explanation is omitted.

<Comparative Example 1-2>
As the luminescent ink of Comparative Example 1-2, the luminescence in which the mixing ratio (mixing weight ratio) is polymer L: polymer M: polymer H = 0: 10: 0, and the concentration of the luminescent composition is 3.3 wt%. Ink was made.
The luminescent ink of Comparative Example 1-2 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of polymer L, polymer M, and polymer H is different. The detailed explanation is omitted.

<Comparative Example 1-3>
As the luminescent ink of Comparative Example 1-3, the light emission in which the mixing ratio (mixing weight ratio) is polymer L: polymer M: polymer H = 0: 0: 10 and the concentration of the luminescent composition is 3.3 wt%. Ink was made.
In addition, since the luminescent ink of Comparative Example 1-3 is the same as the luminescent ink of Example 1-1 except that the mixing ratio of the polymer L, the polymer M, and the polymer H is different, the details of the production method are as follows. The detailed explanation is omitted.

[1-1-2] Evaluation of Luminescent Ink Using the rotary viscometer (manufactured by FUNGILAB), the luminescent ink of Example 1-1 to Example 1-4 and Comparative Example 1-1 to Comparative Example The shear rate (shear rate) dependence of the viscosity of 1-3 luminescent inks was measured.

Specifically, first, 8.0 mL of the luminescent ink of Example 1-1 was introduced into a stainless steel measuring tube of a rotary viscometer under a nitrogen atmosphere and installed in the rotary viscometer.
Subsequently, after setting the target rotation speed and rotating for 5 minutes, the viscosity was read visually. This operation was repeated 5 times, and when the numerical value of 5 times was stable, the average was taken as the viscosity at the share rate. When the numerical value of 5 times was not stable, the same measurement was performed after further rotating for 5 minutes.
The viscosities of the luminescent inks of Example 1-2 to Example 1-4 and the luminescent inks of Comparative Examples 1-1 to 1-3 were also measured in the same manner.
The results are shown in Table 1.

  Table 1 shows the viscosity when the rotational speed is 100 rpm, 50 rpm, 10 rpm, 5 rpm, and 1 rpm, and the thixo index (ratio of the viscosity when the rotational speed is 5 rpm to the viscosity when the rotational speed is 50 rpm). Show.

  From the results in Table 1, in all of the luminescent inks of Example 1-1 to Example 1-4 and the luminescent inks of Comparative Example 1-1 to Comparative Example 1-3, the viscosity increases as the rotational speed decreases. It was found to have the property (thixotropic).

[1-2] Organic EL device Next, an organic EL device was prepared using a luminescent ink containing a luminescent composition containing a low molecular weight polymer, a medium molecular weight polymer and a high molecular weight polymer. The evaluation was performed.

[1-2-1] Preparation of Organic EL Element An organic EL element was prepared using the luminescent inks of Example 1-1 to Example 1-4 created above.

<Example 1-5>
Using the luminescent ink of Example 1-1, an organic EL device of Example 1-5 was prepared.
Specifically, first, a substrate 1 (glass substrate (25 mm long, 12.5 mm wide)) on which an anode layer 2 (ITO film (thickness 190 nm)) is formed is prepared, and a spin coater is formed on the surface of the ITO film. Apply the hole injection transport layer forming solution under the condition that the press pin (300 rpm) is performed for 3 seconds and the main spin (4500 rpm) is performed for 12 seconds, and then heat treatment is performed at 150 ° C. for 30 minutes. Thus, a hole injection transport layer 3 having a thickness of 35 nm was formed.
Subsequently, the light emitting ink of Example 1-1 was apply | coated to the surface of the obtained hole injection transport layer 3, Then, the light emitting layer 4 with a thickness of 60 nm was formed by heat-processing for 10 minutes at 150 degreeC. .
Next, an electron injection layer 5 composed of a bathocuproine layer (20 nm) and a lithium fluoride layer (0.5 nm) was formed on the surface of the obtained light emitting layer 4 by vacuum deposition.
Next, a cathode layer 6 made of an aluminum layer (100 nm) was formed on the surface of the obtained electron injection layer 5 by a vacuum vapor deposition method, thereby producing an organic EL element of Example 1-5.
As the hole injecting and transporting layer forming liquid, H.P. C. “Vitron P4083” manufactured by Starck Co., Ltd. was used. In this “Vitron P4083”, the ratio of poly-3,4-ethylenedioxythiophene to polystyrene sulfonic acid is 1: 6 in terms of monomer, and the ratio of poly-3,4-ethylenedioxythiophene to polystyrene sulfonic acid is The total concentration is 1.6% by mass.

<Example 1-6>
The organic EL element of Example 1-6 was created using the luminescent ink of Example 1-2 in the same manner as the organic EL element of Example 1-5.

<Example 1-7>
The organic EL element of Example 1-7 was created using the luminescent ink of Example 1-3 by the same method as that of the organic EL element of Example 1-5.

<Example 1-8>
In the same manner as the organic EL element of Example 1-5, the organic EL element of Example 1-8 was prepared using the luminescent ink of Example 1-4.

<Comparative Example 1-4>
In the same manner as the organic EL element of Example 1-5, the organic EL element of Comparative Example 1-4 was prepared using the luminescent ink of Comparative Example 1-2.

[1-2-2] Evaluation of Organic EL Element Luminous efficiency of the organic EL element of Example 1-5 is obtained by causing the light emitting layer 4 to emit light by applying a direct current voltage to the organic EL element of Example 1-5. (Visibility efficiency) was measured. The area of the light emitting portion was 0.25 cm ² .
Luminous efficiency (luminous efficiency) was measured in the same manner for the organic EL elements of Examples 1-6 to 1-8 and Comparative Example 1-4.
The results are shown in Table 2.

Table 2 shows the luminous efficiency (luminous efficiency) at a current density of 10 mA / cm ² .

From the results of Table 2, it was found that the organic EL elements of Examples 1-5 to 1-8 had higher luminous efficiency than the organic EL elements of Comparative Example 1-4.
Thus, it was found that when the polymer L and the polymer H are mixed with the polymer M, the light emission efficiency is improved.

Moreover, from the result of Table 2, it turned out that the organic EL element of Example 1-5 has the highest luminous efficiency among the organic EL elements of Example 1-5 to Example 1-8.
Thus, polymer L: polymer M: polymer H = 1: 8: 1, polymer L: polymer M: polymer H = 3: 6: 1, polymer L: polymer M: polymer H = 3: 4: 3 , Polymer L: polymer M: polymer H = 1: 6: 3, polymer L: polymer M: polymer H = 1: 8: 1 is found to be the optimum mixing ratio (weight mixing ratio) It was.

[2] Printing direction Printing is performed in one direction in the step of forming the light emitting layer 4 using a light emitting ink containing a light emitting composition containing a low molecular weight polymer, a medium molecular weight polymer and a high molecular weight polymer. After that, an experiment was conducted to verify the effect of printing in a direction substantially perpendicular to the one direction.

[2-1] Preparation of organic EL device The mixing ratio (weight mixing ratio) is polymer L: polymer M: polymer H = 1: 8: 1, and the concentration of the luminescent composition is 6.7 wt% and 10 wt%. An organic EL element was prepared using a certain luminescent ink and evaluated.
The luminescent ink is the same as the luminescent ink of Example 1-1 except that the mixing ratio of the polymer L, the polymer M, and the polymer H and the concentration of the luminescent composition are different. Detailed description is omitted.

<Example 2-1>
The organic EL element of Example 2-1 was created using a luminescent ink having a concentration of the luminescent composition of 10 wt% and using one printing.
Specifically, first, a substrate 1 (glass substrate (25 mm long, 12.5 mm wide)) on which an anode layer 2 (ITO film (thickness 190 nm)) is formed is prepared, and a spin coater is formed on the surface of the ITO film. Apply the hole injection transport layer forming solution under the condition that the press pin (300 rpm) is performed for 3 seconds and the main spin (4500 rpm) is performed for 12 seconds, and then heat treatment is performed at 150 ° C. for 30 minutes. Thus, a hole injection transport layer 3 having a thickness of 35 nm was formed.
Next, using a flexographic printing machine (Matsuo Sangyo Co., Ltd.) on the surface of the obtained hole injecting and transporting layer 3, luminescent ink having a luminescent composition concentration of 10 wt% was applied and allowed to stand for 1 minute. After that, the light emitting layer 4 was formed by heat treatment at 150 ° C. for 14 minutes.
Next, an electron injection layer 5 composed of a bathocuproine layer (20 nm) and a lithium fluoride layer (0.5 nm) was formed on the surface of the obtained light emitting layer 4 by vacuum deposition.
Next, a cathode layer 6 made of an aluminum layer (100 nm) was formed on the surface of the obtained electron injection layer 5 by a vacuum vapor deposition method, thereby producing an organic EL element of Example 2-1.

<Example 2-2>
The organic EL device of Example 2-2 was prepared by using a luminescent ink having a concentration of 6.7 wt% of the luminescent composition, setting the number of times of printing twice, and the first printing direction and the second printing direction being the same. Created.
Specifically, first, in the same manner as in the organic EL element of Example 2-1, a substrate 1 having an anode layer 2 formed on the surface was prepared, and a hole injection transport layer 3 was formed on the surface of the anode layer 2. Formed.
Next, the surface of the obtained hole injecting and transporting layer 3 was coated with a luminescent ink having a concentration of 6.7 wt% of the luminescent composition using a flexographic printing machine (Matsuo Sangyo Co., Ltd.). Was printed and allowed to stand for 1 minute, and then heat treated (fired) at 150 ° C. for 14 minutes, and then the second layer was printed and fired to form the light emitting layer 4. The printing direction when printing the first layer (first printing direction) and the printing direction when printing the second layer (second printing direction) were the same.
Next, in the same manner as in the organic EL element of Example 2-1, the electron injection layer 5 was formed on the surface of the obtained light emitting layer 4, and the cathode layer 6 was formed on the surface of the obtained electron injection layer 5. By doing this, the organic EL element of Example 2-2 was created.

<Example 2-3>
Using a luminescent ink having a concentration of 6.7 wt% of the luminescent composition, the number of times of printing was 3, and the first printing direction, the second printing direction, and the third printing direction were the same, Example 2- 3 organic EL elements were prepared.
The organic EL element of Example 2-3 is the same as the organic EL element of Example 2-2 except that the number of times of printing is different, and thus detailed description of the production method is omitted.

<Example 2-4>
Organic EL of Example 2-4, using a luminescent ink having a concentration of 6.7 wt% of the luminescent composition, with the number of times of printing being twice, and the first and second printing directions being substantially orthogonal. A device was created. That is, the organic EL element of Example 2-4 was created by cross printing.
In addition, since the organic EL element of Example 2-4 is the same as the organic EL element of Example 2-2 except that the printing direction is different, detailed description of the production method is omitted.

<Example 2-5>
Using a luminescent ink having a concentration of 6.7 wt%, the number of times of printing is three times, the first printing direction and the second printing direction are substantially orthogonal, and the second printing direction and the third time. The organic EL elements of Example 2-5 were produced by making the printing directions of the two substantially orthogonal. That is, the organic EL element of Example 2-4 was created by cross printing.
In addition, since the organic EL element of Example 2-5 is the same as the organic EL element of Example 2-2 except that the number of times of printing and the printing direction are different, detailed description of the production method is omitted.

<Comparative example 2>
In the same manner as in the organic EL device of Example 2-1, the mixing ratio (weight mixing ratio) was polymer L: polymer M: polymer H = 0: 10: 0, and the concentration of the luminescent composition was 6.7 wt. % Of luminescent ink was used, and the number of times of printing was set to 1 to produce an organic EL element of Comparative Example 2.

[2-2] Evaluation of organic EL element By applying a direct current voltage to the organic EL element of Example 2-1, the light emitting layer 4 was caused to emit light, and the luminous efficiency (viewing) of the organic EL element of Example 2-1. Sensitivity) was measured. The area of the light emitting portion was 0.25 cm ² .
Luminous efficiency (luminous efficiency) was measured for the organic EL elements of Example 2-2 to Example 2-5 and the organic EL element of Comparative Example 2 in the same manner.
The results are shown in Table 3.

Table 3 shows the printing direction, the film roughness (that is, the roughness of the light-emitting layer 4), the film thickness (that is, the thickness of the light-emitting layer 4), and the current density of Example 2-1 at 10 mA / cm ^2. The luminous efficiency index (luminous efficiency index), which is the luminous efficiency (luminous efficiency) at a current density of 10 mA / cm ² when the luminous efficiency (luminous efficiency) is 100, is shown.
Here, in the printing direction of Table 3, for example, “first time is“ ↓ ”, second time is“ ↓ ”” indicates that the first printing direction and the second printing direction are the same. "First time is" ↓ "and second time is" ← "" indicates that the first printing direction and the second printing direction are substantially orthogonal to each other.

In Comparative Example 2, since a pinhole was generated in the light emitting layer 4 and a leak current was generated, the light emission efficiency could not be measured.
Thereby, when the density | concentration of the luminescent composition was 6.7 wt%, when the polymer L and the polymer H were not mixed with the polymer M, it turned out that a pinhole will generate | occur | produce in the light emitting layer 4. FIG.

From the results of Example 2-1 and Example 2-2 in Table 3, a light-emitting ink having a low concentration of the light-emitting composition was used, and the organic EL device prepared by setting the number of printing to twice (Example 2-2). The organic EL element) has a rough film compared to the organic EL element (organic EL element of Example 2-1) prepared using a luminescent ink with a high concentration of the luminescent composition and the number of times of printing being one. The film thickness was small, the film thickness was large, and the light emission efficiency was high.
Thereby, it turned out that the density | concentration of 6.7 wt% of a luminescent composition is more suitable than the concentration of 10 wt% of a luminescent composition.

Moreover, from the results of Example 2-2 to Example 2-5 in Table 3, the organic EL elements (organic EL elements of Example 2-4 and Example 2-5) prepared by cross printing are in the same direction. It was found that the roughness of the film was small and the luminous efficiency was high as compared with organic EL elements prepared by printing (organic EL elements of Examples 2-2 and 2-3).
Thus, it was found that when the number of times of printing is set to a plurality of times, cross printing is more preferable than printing in the same direction.

[3] Addition of leveling agent for demonstrating the effect of adding a leveling agent to a luminescent ink containing a luminescent composition comprising a low molecular weight polymer, a medium molecular weight polymer and a high molecular weight polymer The experiment was conducted.

[3-1] Preparation of organic EL element A luminescent ink to which a leveling agent was added was prepared, and an organic EL element was prepared using it.
As the leveling agent, a perfluoroalkyl group-containing oligomer, a fluorine-based compound Megafac F-483SF (manufactured by Dainippon Ink & Chemicals, Inc.) was used.
In this example, a luminescent ink having a mixing ratio (weight mixing ratio) of polymer L: polymer M: polymer H = 3: 6: 1 and a concentration of the luminescent composition of 6.7 wt% was prepared. A leveling agent was added to the luminescent ink.
In addition, the luminescent ink created in the present Example is the same as the luminescent ink of Example 1-1 except that the mixing ratio of the polymer L, the polymer M, and the polymer H and the concentration of the luminescent composition are different. Therefore, detailed description of the creation method is omitted.

<Example 3-1>
An organic EL element of Example 3-1 was prepared using a luminescent ink to which a leveling agent was added at 1000 ppm.
Specifically, first, a substrate 1 (glass substrate (25 mm long, 12.5 mm wide)) on which an anode layer 2 (ITO film (thickness 190 nm)) is formed is prepared, and a spin coater is formed on the surface of the ITO film. Apply the hole injection transport layer forming solution under the condition that the press pin (300 rpm) is performed for 3 seconds and the main spin (4500 rpm) is performed for 12 seconds, and then heat treatment is performed at 150 ° C. for 30 minutes. Thus, a hole injection transport layer 3 having a thickness of 35 nm was formed.
Next, on the surface of the obtained hole injecting and transporting layer 3, using a flexographic printing machine (manufactured by Matsuo Sangyo Co., Ltd.), a luminescent ink to which a leveling agent was added at 1000 ppm was applied and allowed to stand for 1 minute. The light emitting layer 4 was formed by heat-processing for 14 minutes at 150 degreeC.
Next, an electron injection layer 5 composed of a bathocuproine layer (20 nm) and a lithium fluoride layer (0.5 nm) was formed on the surface of the obtained light emitting layer 4 by vacuum deposition.
Next, a cathode layer 6 made of an aluminum layer (100 nm) was formed on the surface of the obtained electron injection layer 5 by a vacuum vapor deposition method, thereby producing an organic EL element of Example 3-1.

<Example 3-2>
In the same manner as the organic EL element of Example 3-1, an organic EL element of Example 3-2 was prepared using a luminescent ink added with 100 ppm of a leveling agent.

<Example 3-3>
In the same manner as the organic EL element of Example 3-1, an organic EL element of Example 3-3 was prepared using a luminescent ink to which 1 ppm of a leveling agent was added.

<Comparative Example 3>
In the same manner as in the organic EL device of Example 3-1, the mixing ratio (weight mixing ratio) was polymer L: polymer M: polymer H = 0: 10: 0, and the concentration of the luminescent composition was 6.7 wt%. Yes, an organic EL device of Comparative Example 3 was prepared using a luminescent ink to which a leveling agent was added at 100 ppm.

[3-2] Evaluation of organic EL element By applying a direct current voltage to the organic EL element of Example 3-1, the light emitting layer 4 is caused to emit light, and the luminous efficiency of the organic EL element of Example 3-1 is measured. did. The area of the light emitting portion was 0.25 cm ² .
Luminous efficiency was measured in the same manner for the organic EL elements of Example 3-2 to Example 3-4 and the organic EL element of Comparative Example 3.
The results are shown in Table 4.

Table 4 shows the roughness of the film (that is, the roughness of the light-emitting layer 4), the film thickness (that is, the thickness of the light-emitting layer 4), and the luminous efficiency (visual sensitivity) of the comparative example 3 at a current density of 10 mA / cm ² . The luminous efficiency index (luminous efficiency index), which is the luminous efficiency (luminous efficiency) at a current density of 10 mA / cm ^{2 when} (efficiency) is 100, is shown.

  From the results of Comparative Example 3 in Table 4, it was found that by adding a leveling agent, the generation of pinholes was suppressed and the luminous efficiency could be measured.

Moreover, from the results of Table 4, it was found that the organic EL elements of Example 3-1 to Example 3-3 had higher luminous efficiency than the organic EL element of Comparative Example 3.
Thus, it was found that when the polymer L and the polymer H are mixed with the polymer M, the light emission efficiency is improved.

According to the luminescent composition of the present invention described above, a low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a weight average molecular weight of 100,000 or more. A polymer having at least one of a light-emitting monomer that forms a light-emitting component, a hole-transporting monomer that forms a hole-transporting component, and an electron-transporting monomer that forms an electron-transporting component. It is made up of.
Therefore, the luminescent composition of the present invention has a low molecular weight polymer for improving coating properties and an improved shape retention in addition to the medium molecular weight polymer contained in the conventional luminescent composition. Therefore, the high-performance organic EL device 10 having high coatability and high performance can be formed.

In addition, according to the luminescent composition of the present invention described above, the polymer is composed of two kinds of a tertiary aromatic amine derivative that is a hole transporting monomer and an oxadiazole derivative that is an electron transporting monomer. It is an original copolymer.
That is, since the polymer contained in the luminescent composition is a bipolar polymer having a hole transporting component and an electron transporting component, the driving voltage of the organic EL element 10 can be suppressed and the light emission characteristics can be improved. Can do.

According to the manufacturing method of the organic EL element of the present invention described above, the light emitting layer 4 is formed by the step of printing the light emitting layer 4 by the flexographic printing method using the light emitting ink containing the light emitting composition. It has become.
That is, since the light emitting layer 4 is formed by a flexographic printing method, the area of the organic EL element 10 can be easily increased, and the organic EL element 10 can be manufactured at a low cost.
Moreover, since there is no photolithography process at all in the manufacturing process of the organic EL element 10, the organic EL element 10 can be manufactured by an environment-friendly method with high reproducibility and no development waste liquid.

Moreover, according to the manufacturing method of the organic EL element of this invention demonstrated above, the process of printing the light emitting layer 4 by a flexographic printing system is substantially orthogonal to the 1st printing step printed along one direction, and the one direction. A second printing step for printing along the direction in which the first printing step is performed at least once and the second printing step is performed at least once.
Therefore, since the luminescent ink can be applied thickly without unevenness, a high-performance organic EL element 10 can be manufactured.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist thereof.

  The polymer contained in the luminescent composition may be a single component system as described in (1) above, may be a two component system as described in (2) above, Thus, it may be a ternary system, or may be a quaternary system or more.

  The organic EL element 10 only needs to include at least the anode layer 2, the light emitting layer 4, and the cathode layer 6, and does not necessarily include the hole injection transport layer 3 and the electron injection layer 5.

It is a cross-sectional schematic diagram which shows an example of an organic EL element provided with the light emitting layer formed with the luminescent composition of this invention. It is GPC data which showed the molecular weight distribution of the polymer created in the Example. It is GPC data which showed the molecular weight distribution of the polymer blend created in the Example.

Explanation of symbols

4 Light emitting layer 10 Organic EL device (organic electroluminescence device)

Claims (5)

In a luminescent composition comprising a luminescent component, a hole transport component, and an electron transport component,
A low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer having a weight average molecular weight of 100,000 or more,
The polymer comprises at least one of a light-emitting monomer that forms the light-emitting component, a hole-transport monomer that forms the hole-transport component, and an electron-transport monomer that forms the electron-transport component. A luminescent composition. The luminescent composition according to claim 1,
The polymer is a binary copolymer of a tertiary aromatic amine derivative that is the hole transporting monomer and an oxadiazole derivative that is the electron transporting monomer. Composition. In a luminescent composition comprising a phosphorescent light emitting component, a hole transport component, and an electron transport component,
A low molecular weight polymer having a weight average molecular weight of 3000 to 5000, a medium molecular weight polymer having a weight average molecular weight of 30,000 to 80,000, and a high molecular weight polymer having a weight average molecular weight of 100,000 or more,
The polymer includes a tertiary aromatic amine derivative that is a hole transporting monomer that forms the hole transporting component and an oxadiazole derivative that is an electron transporting monomer that forms the electron transporting component. A luminescent composition characterized by being an original copolymer. In the manufacturing method of an organic electroluminescent element provided with the light emitting layer formed with the luminescent composition as described in any one of Claims 1-3,
A method for producing an organic electroluminescent device, comprising forming the light emitting layer by a step of printing the light emitting layer by a flexographic printing method using a light emitting ink containing the light emitting composition. In the manufacturing method of the organic electroluminescent element of Claim 4,
The process includes
A first printing step for printing along one direction;
A second printing step for printing along a direction substantially orthogonal to the one direction,
The method of manufacturing an organic electroluminescence element, wherein the first printing step is performed at least once and the second printing step is performed at least once.