JPH0963767A - Organic electroluminescence device - Google Patents

Abstract

(57) An object of the present invention is to provide at low cost an organic electroluminescence device which can effectively extract light from a light emitting layer and has high brightness. [1] In an organic electroluminescent device having at least a light emitting layer 3 between electrodes composed of a pair of anodes 5 and cathodes 1 at least one of which is transparent or semi-transparent, from the pair of anodes 5 and cathodes 1 The difference in height is 0.1μ on the outside of the electrode and on the side where the emitted light is emitted.
An organic electroluminescence device comprising a transparent or semi-transparent substrate 7 having a surface with irregularities of m or more and 0.2 mm or less. [2] In an organic electroluminescence device having at least a light emitting layer between electrodes composed of a pair of an anode and a cathode, at least one of which is transparent or semitransparent, a transparent or semitransparent electrode on the side where luminescence is emitted. An organic electroluminescent element having a substrate having a surface on which the electrode is formed, which is different from the surface on which the electrode is formed, and which has unevenness with a height difference of 0.1 μm or more and 0.2 mm or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device (hereinafter, sometimes referred to as an organic EL device).

[0002]

2. Description of the Related Art Inorganic electroluminescent devices (hereinafter, sometimes referred to as inorganic EL devices) using an inorganic phosphor as a light emitting material are used for display devices such as a planar light source as a backlight and a flat panel display. However, a high-voltage alternating current was required to emit light. Recently, Tang et al. Used organic fluorescent dye as a light emitting layer,
An organic EL device having a two-layer structure was produced by laminating this and an organic charge transport compound used for electrophotographic photoreceptors and the like (JP-A-59-194393). Organic E
Compared to inorganic EL devices, L devices are characterized by low voltage drive, high brightness, and the ability to easily emit light of multiple colors. Therefore, many attempts have been made on device structures, organic fluorescent dyes, and organic charge transport compounds. Has been reported [Japanese Journal of Applied Physics (Jp
n. J. Appl. Phys. ) Volume 27, L269 (1988)], [Journal of Applied.
Physics (J. Appl. Phys.) Volume 65,
3610 (1989)].

Heretofore, low-molecular-weight organic fluorescent dyes have been generally used as a material for the light-emitting layer.
Examples of the high molecular weight light emitting material include WO901148, JP-A-3-244630, and Applied Physics Letters (Appl. Phys. Le).
tt. Vol. 58, p. 1982 (1991). In the examples disclosed in WO 9013148, a poly (p-phenylenevinylene) thin film converted into a conjugated polymer is obtained by forming a soluble precursor on an electrode and performing a heat treatment. The disclosed EL element is disclosed. JP-A-3-244630 exemplifies a conjugated polymer which is soluble in a solvent itself and does not require heat treatment. Applied Physics Letters (Appl.
Phys. Lett. 58, 1982 (199)
1 year) also describes a polymer light emitting material that is soluble in a solvent and an organic EL device prepared using the same.

A substrate having a transparent electrode made of an indium-tin oxide film (hereinafter, also referred to as ITO) formed on a substrate of glass or a polymer film is used as a substrate for the organic EL device. Generally, emitted light is taken out through a transparent electrode and a base material. It is considered that the light emission generated in the light emitting layer in the organic EL element is uniformly radiated in all directions. However, when light passes from a base material having a high refractive index to the air having a low refractive index, It is known that total reflection occurs at the interface between the base material and the air, and only a part of the emitted light can be extracted to the outside. The totally reflected light is emitted from the end surface of the substrate. In an organic EL element, which is a flat-type light emitting element, the brightness viewed from the top is practically important, and it is required to increase the proportion of light emitted from the light emitting layer in the direction perpendicular to the plane. On the other hand, in a backlight for a liquid crystal display, a light diffusing plate having stripe-shaped irregularities having a triangular cross section on its surface is used. This is because the light from the cold cathode, which is the light source, is passed through the light guide plate and further through the light diffusion plate, so that the direction of light emission is collected in the front direction (the direction perpendicular to the substrate) to improve the front brightness. It is also known.

However, as a method for increasing the luminous efficiency, the development of materials having high luminous efficiency has been focused so far. Furthermore, the organic EL elements used so far use a flat base material, and a method for effectively extracting light in the front direction has not been known.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic electroluminescent device which can effectively extract light from a light emitting layer and has high brightness at low cost.

[0007]

In view of such circumstances, the inventors of the present invention have made a diligent study in order to effectively extract light from the light emitting layer and improve the brightness at the front, and as a result, have the light emitting layer. The inventors have found that the organic EL element can reduce the rate of total reflection by providing irregularities on the surface of the element on the side where light is extracted, and can improve the utilization efficiency of light from the light emitting layer, leading to the present invention.

That is, the present invention [1] is an organic electroluminescent device having at least a light emitting layer between electrodes composed of a pair of anodes and cathodes, at least one of which is transparent or semi-transparent, and electrodes composed of the pair of anodes and cathodes. The present invention relates to an organic electroluminescence device having a transparent or semi-transparent base material having unevenness having a height difference of 0.1 μm or more and 0.2 mm or less on the surface outside of and on the side where luminescence is emitted. Further, the present invention [2] is an organic electroluminescence device having at least a light emitting layer between at least one transparent or semitransparent pair of electrodes consisting of an anode and a cathode, which is a side on which light is emitted and which is transparent. Alternatively, an organic electroluminescence device having a substrate having a semi-transparent electrode formed thereon, which has unevenness with a height difference of 0.1 μm or more and 0.2 mm or less on another surface different from the surface on which the electrode is formed. It is related.

Further, in the present invention, [3] the light emitting layer has fluorescence in a solid state, and the repeating unit represented by the formula (1) is
The organic electroluminescent device according to [1] or [2], which comprises a polymeric fluorescent substance having a polystyrene-reduced number average molecular weight of 10 ³ to 10 ⁷ in an amount of 50 mol% or more of all repeating units.

Embedded image -Ar-CR = CR'- (1) (wherein Ar has 4 carbon atoms involved in a conjugated bond).
Or more and 20 or less arylene group or heterocyclic compound group, R and R'are each independently hydrogen, carbon number 1 to 20
Alkyl group, C6-20 aryl group, C4
To 20 heterocyclic compounds, a group selected from the group consisting of cyano groups. Hereinafter, the present invention will be described in detail.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The organic EL device of the present invention is an organic electroluminescence device having at least a light emitting layer between electrodes composed of a pair of anodes and cathodes, at least one of which is transparent or semitransparent. And on the outside of the electrode composed of the cathode and on the side where the emitted light is emitted,
It has a transparent or semi-transparent substrate having unevenness with a height difference of 0.1 μm or more and 0.2 mm or less on the surface. In the organic EL device of the present invention, a base material having the irregularities may be attached to the device surface. That is, in the organic EL element of the present invention, a transparent or semitransparent electrode is formed into a film in an organic electroluminescence element having at least a light emitting layer between an electrode composed of a pair of an anode and a cathode, at least one of which is transparent or semitransparent. The height difference of the surface of the substrate is 0.1 μm on the other surface different from the surface on which the electrodes are formed.
The transparent or semi-transparent base material having an unevenness of 0.2 mm or less is bonded to another surface different from the uneven surface.

When a substrate having irregularities is attached to an organic EL element, it is preferable that an air layer is not sandwiched between the surface of the organic EL element and the surface. In addition, it is preferable to use a pressure-sensitive adhesive, an adhesive, or a photocurable adhesive for the bonding, and it is practical to use the pressure-sensitive adhesive. Further, in the case of bonding, it is preferable that the difference in the refractive index between the substrate having unevenness, the bonding agent and the substrate is small, and it is more preferable to use a material having a difference in the refractive index of each material within 0.2, Particularly preferably, it is within 0.1.

Further, in the organic EL device of the present invention, in an organic electroluminescence device having at least a light emitting layer between electrodes composed of a pair of an anode and a cathode, at least one of which is transparent or semitransparent, the side from which light is emitted. And having unevenness with a height difference of 0.1 μm or more and 0.2 mm or less on another surface of the base material on which the transparent or semitransparent electrode is formed, different from the surface on which the electrode is formed. It is a thing.

Here, the shape of the surface irregularities is not particularly limited, but a pyramid shape, a hemispherical shape, a stripe shape with a triangular cross section, or a stripe shape with a semicircular cross section is preferable, and a triangular or semicircular stripe shape. Is more preferable.

Regarding the size of the uneven surface, if it is large,
Since the luminescence looks uneven and is not industrial if it is small, one side or diameter is 0.1 μm or more and 0.2 mm or less, preferably 1 μm, when the unevenness is pyramidal or semicircular.
It is m or more and 0.1 mm or less. In the stripe shape, the length of the stripe is the length of the sheet or film and is not particularly limited, but the repetition cycle is 0.1 μm.
Or more and 0.2 mm or less, preferably 1 μm or more and 0.1.
It is 1 mm or less. At this time, the height of the unevenness is determined by the size and the cycle of the unevenness, and is usually preferably equal to or less than the value of the size and the cycle. The thickness of the polymer sheet or film having an uneven surface is not particularly limited, but is 20 to 300 μm in view of the handling surface and cost of the sheet or film.
Is preferable, and more preferably 70 to 200 μm.

Next, a base material having an uneven surface will be described. In the case of directly processing the base material on which the electrodes are formed, examples of the base material include glass and a transparent or semitransparent polymer material such as a polymer sheet or film. In the case of the polymer material, the polymer material is not limited to one polymer material, and another polymer material may be used to form the uneven surface on the polymer substrate.

The polymer substrate on which the electrode is formed has high heat resistance and is not particularly limited as long as it is transparent or translucent, but is not limited to polycarbonate, polysulfone, polyarylate, polyethersulfone, polyethylene terephthalate, polyethylene. Examples thereof include naphthalate, preferably polycarbonate, polysulfone, polyethylene terephthalate, and polyethylene naphthalate. When forming an uneven surface on a base material on which an electrode is formed, or as a polymer material used for a polymer base material having an uneven surface, polymethyl methacrylate, poly-n-butyl methacrylate, poly-t-butyl methacrylate, Polymethacrylic acid derivatives such as polyglycol methacrylate, polymethyl acrylate, polyacrylic acid derivatives such as polyethyl acrylate, polyvinyl acetate, polyvinyl butyrate, polyoxymethylphenylsilylene,
Examples thereof include polystyrene, polycarbonate, polysulfone, polyarylate, polyether sulfone, polyethylene terephthalate and polyethylene naphthalate. Among these, polymethyl methacrylate, poly-n-butyl methacrylate and poly-t-butyl methacrylate are preferable.

In the case of molding a surface having an uneven surface on a polymer substrate, polycarbonate, polysulfone, polyarylate, cellulose diacetate, cellulose triacetate, polyethersulfone, polyethylene terephthalate, polyethylene naphthalate, etc. are exemplified. Preferred examples include polycarbonate, polysulfone, polyethylene terephthalate and polyethylene naphthalate.

Next, a method for forming irregularities on the surface will be described. As a method for forming the uneven surface, for an inorganic material such as glass, a method of patterning with a photoresist and then performing chemical or vapor phase etching is exemplified. In the case of a polymer material, a metal surface having an uneven surface is pressed under heating to transfer the unevenness, a method of rolling a polymer sheet or a film with a roll having an uneven surface, a polymer having a slit having an uneven shape to a polymer Examples thereof include a method of extruding and casting, a method of casting on an uneven surface to form a film, and a method of photopolymerizing a monomer after forming a film in a pattern to remove an unpolymerized portion. Among these,
For polymer materials, a metal surface having an uneven surface is pressed under heating to transfer the unevenness, a polymer sheet or film is rolled with a roller having an uneven surface, or cast on a surface having an uneven surface. Membrane methods are practical and preferred.

In the organic EL device of the present invention, the light emitting material to be used is not particularly limited, and a low molecular weight light emitting body or a polymer light emitting body can be used, but a polymer light emitting body is preferable, and a conjugated polymer is more preferable. Among the conjugated polymers, those containing an arylene vinylene structure are particularly preferable. Examples of the low molecular weight luminescent material include dyes such as naphthalene derivative, anthracene derivative, perylene derivative, polymethine type, xathene type, coumarin type, cyanine type, metal complex of 8-hydroquinoline and its derivative, aromatic amine, tetraphenylcyclo Pentadiene derivatives, etc., or JP-A-57-5
Known materials described in, for example, 1781 and 59-194393 can be used.

When a polymeric fluorescent substance is used for the light emitting layer used in the organic EL device of the present invention, a polymer having a light emitting group in its side chain can be used, but preferably it contains a conjugated structure in its main chain. Especially polythiophene, poly-
P-phenylene, polyarylene vinylene and its derivatives are preferred. Among them, polyarylene vinylene and its derivatives are preferable. The polyarylene vinylene and its derivatives are preferably polymers containing the repeating unit represented by Chemical formula 2 in an amount of 50 mol% or more of all repeating units. Although it depends on the structure of the repeating unit, it is more preferable that the repeating unit represented by Chemical formula 2 is 70% or more of all the repeating units. The polymeric fluorescent substance is a repeating unit other than the repeating unit represented by Chemical formula 2, a divalent aromatic compound group or a derivative thereof, a divalent heterocyclic compound group or a derivative thereof, or a group obtained by combining them. May be included. Further, the repeating unit represented by Chemical formula 2 and other repeating units may be linked with a non-conjugated unit having an ether group, an ester group, an amide group, an imide group, or the like,
The non-conjugated portion may be contained in the repeating unit.

In the polymeric fluorescent substance, Ar in Chemical formula 2 is an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in a conjugate bond,
For example, a divalent aromatic compound group represented by Chemical formula 3 or a derivative group thereof, a divalent heterocyclic compound group or a derivative group thereof, or a group obtained by combining them can be given.

[0022]

Embedded image (R _{1 to} R ₉₂ each independently represent hydrogen, carbon number 1 to 2
A group selected from the group consisting of an alkyl group having 0, an alkoxy group and an alkylthio group; an aryl group having 6 to 18 carbon atoms and an aryloxy group; and a heterocyclic compound group having 4 to 14 carbon atoms. )

Among these, phenylene group, substituted phenylene group, biphenylene group, substituted biphenylene group, naphthalenediyl group, substituted naphthalenediyl group, anthracene-9,10-diyl group, substituted anthracene-9,10-
A diyl group, a pyridine-2,5-diyl group, a substituted pyridine-2,5-diyl group, a thienylene group or a substituted thienylene group is preferable. More preferably, phenylene group, biphenylene group, naphthalenediyl group, pyridine-2,5-
A diyl group and a thienylene group.

R and R'in formula 2 are other than hydrogen or a cyano group.
When it is a substituent, it has 1 to 20 carbon atoms.
Alkyl groups include methyl, ethyl and propyl
Group, butyl group, pentyl group, hexyl group, heptyl group,
Examples include octyl group, decyl group and lauryl group.
Cyl group, ethyl group, pentyl group, hexyl group, heptyl group
A group and an octyl group are preferable. As an aryl group,
Nyl group, 4-C₁~ C₁₂Alkoxyphenyl group (C ₁~
C₁₂Indicates that the carbon number is 1 to 12. Smells below
The same is true. ), 4-C₁~ C₁₂Alkylphenyl
Group, 1-naphthyl group, 2-naphthyl group and the like.
You.

From the viewpoint of solvent solubility, Ar in Chemical formula 2 is 1
Having one or more groups selected from an alkyl group having 4 to 20 carbon atoms, an alkoxy group and an alkylthio group, an aryl group having 6 to 18 carbon atoms and an aryloxy group, and a heterocyclic compound group having 4 to 14 carbon atoms. Is preferred.

Examples of these substituents are as follows. Examples of the alkyl group having 4 to 20 carbon atoms include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, and a lauryl group. A pentyl group, a hexyl group, a heptyl group, and an octyl group are preferable.
Examples of the alkoxy group having 4 to 20 carbon atoms include a butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, an octyloxy group, a decyloxy group, and a lauryloxy group. , A heptyloxy group and an octyloxy group. Examples of the alkylthio group include a butylthio group, a pentylthio group, a hexylthio group, a heptylthio group, an octylthio group, a decyloxy group, and a laurylthio group. A pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group are preferable.

Examples of the aryl group include phenyl group and 4-C
₁ -C ₁₂ alkoxyphenyl group, 4-C _{1 ~C 12} alkyl phenyl group, 1-naphthyl group, 2-naphthyl groups. Examples of the aryloxy group include a phenoxy group. As the heterocyclic compound group, 2-thienyl group, 2-pyrrolyl group, 2-furyl group, 2-, 3- or 4
-Pyridyl group and the like are exemplified. The number of these substituents is
Although it depends on the molecular weight of the polymeric fluorescent substance and the constitution of the repeating unit, from the viewpoint of obtaining a polymeric fluorescent substance having high solubility, it is more preferable that one or more of these substituents are present per 600 molecular weight.

The polymeric fluorescent substance used in the organic EL device of the present invention may be a random, block or graft copolymer, or a polymer having an intermediate structure between them, such as a block type. It may be a random copolymer. From the viewpoint of obtaining a polymeric fluorescent substance having a high quantum yield of fluorescence, a random copolymer having a block property or a block or graft copolymer is preferable to a completely random copolymer. Further, since the organic EL device of the present invention utilizes light emission from a thin film, the polymeric fluorescent substance used is one having fluorescence in a solid state.

The polymeric fluorescent substance preferably has a molecular weight of 10 ³ to 10 ⁷ in terms of polystyrene, and the degree of polymerization thereof varies depending on the repeating structure and the ratio thereof. From the viewpoint of film formability, the total number of repeating structures is preferably 4 to 10,000, more preferably 5 to 3,000, and particularly preferably 10 to 2,000.

In the case of forming a film from a solution by using these organic solvent-soluble polymeric fluorescent substances at the time of producing an organic EL device, it suffices to remove the solvent by coating the solution and then drying it. In addition, the same method can be applied when a charge transport material or a light emitting material is mixed, which is very advantageous in manufacturing.

The method for synthesizing the polymeric fluorescent substance used in the organic EL device of the present invention is not particularly limited. For example, a dialdehyde compound in which two aldehyde groups are bonded to an arylene group and a methyl halide group in the arylene group are used. An example is the Wittig reaction from a diphosphonium salt obtained from a compound having two bonds and triphenylphosphine.
Another example of a synthesis method is a dehydrohalogenation method from a compound in which two methyl halide groups are bonded to an arylene group. Furthermore, a sulfonium salt decomposition method for obtaining the polymeric fluorescent substance by heat treatment from an intermediate obtained by polymerizing a sulfonium salt of a compound in which two methyl halide groups are bonded to an arylene group with an alkali is exemplified. In any of the synthetic methods, a compound having a skeleton other than the arylene group is added as a monomer, and the structure of the repeating unit contained in the resulting polymeric fluorescent substance can be changed by changing the proportion thereof. You may add and adjust so that the repeating unit shown by 2 may be 50 mol% or more, and may copolymerize. Of these, Wittig
The method by reaction is preferable from the viewpoint of reaction control and yield.

More specifically, a method for synthesizing an arylene vinylene-based copolymer, which is one example of the polymeric fluorescent substance used in the organic EL device of the present invention, will be described. When a polymeric fluorescent substance is obtained by the Wittig reaction, for example, first, a bis (methyl halide) compound, more specifically, 2,5
-Dioctyloxy-p-xylylene dibromide to N,
A phosphonium salt is synthesized by reacting with triphenylphosphine in an N-dimethylformamide solvent, and this is condensed with a dialdehyde compound, more specifically, terephthalaldehyde using, for example, lithium ethoxide in ethyl alcohol. By the Wittig reaction, a polymeric fluorescent substance containing a phenylene vinylene group and a 2,5-dioctyloxy-p-phenylene vinylene group is obtained. At this time, two or more kinds of diphosphonium salts and / or two or more kinds of dialdehyde compounds may be reacted to obtain a copolymer.

When these polymeric fluorescent substances are used as a light emitting material for an organic EL device, the purity thereof affects the light emitting characteristics. Therefore, after the synthesis, purification treatments such as reprecipitation purification and fractionation by chromatography can be performed. preferable.

Regarding the structure of the organic EL device of the present invention,
There is no particular limitation other than the above-mentioned features of the present invention, and a known structure is adopted. An example of the structure of the organic EL element of the present invention is shown in FIGS. In either case, the side from which luminescence is emitted is the anode side, and is an example in which the base material 7 having irregularities on its surface is attached to the outside of the glass plate 6 on which the anode 5 is formed. FIG. 1 shows a case where the base material 7 having irregularities on the surface has a triangular stripe shape in cross section, and FIG. 2 shows a case where the base material 7 having irregularities on the surface has a stripe shape having a semicircular cross section. is there. For example, on both surfaces of the light emitting layer 3 made of the above-mentioned polymeric fluorescent substance, or the light emitting layer 3 made of a mixture of the polymeric fluorescent substance and a charge transport material (meaning a general term for an electron transport material and a hole transport material). An example is a structure having a pair of electrodes. Further, a hole transport layer 4 containing a hole transport material is provided between the light emitting layer 3 and the anode 5. At this time, the hole transport layer 4 is preferably adjacent to the light emitting layer 3. Moreover, the thing which provided the electron carrying layer 2 containing an electron carrying material between the light emitting layer 3 and the cathode 1 is mentioned. At this time, the electron transport layer 2 is preferably adjacent to the light emitting layer 3. Further, a hole transport layer 4 containing a hole transport material is provided between the light emitting layer 3 and the anode 5, and an electron transport layer 2 containing an electron transport material is provided between the light emitting layer 3 and the cathode 1. There are things that consist of. Further, the light emitting layer and the charge transporting layer may each independently be a single layer or a combination of a plurality of layers. Further, for example, a light emitting material other than the polymeric fluorescent substance described below may be mixed and used in the light emitting layer. Further, it is also possible to form a layer in which the polymeric fluorescent substance and / or the charge transport material is dispersed in a polymeric compound.

In the organic EL device of the present invention, known materials can be used as the charge transport material used with the polymeric fluorescent substance, that is, the electron transport material or the hole transport material,
Examples of the hole transport material include, but are not limited to, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, and triphenyldiamine derivatives, and electron transport materials include oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or Examples thereof include its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, tetracyanoanthraquinodimethane or its derivatives, fluorenone derivatives, diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, and metal complexes of 8-hydroxyquinoline or its derivatives. It

Specifically, JP-A-63-70257, JP-A-63-175860, and JP-A-2-1353.
Nos. 59, 2-135361, 2-209
988, 3-37992, 3-152
No. 184 is exemplified. As a hole transport material, a triphenyldiamine derivative, as an electron transport material, an oxadiazole derivative, benzoquinone or its derivative, anthraquinone or its derivative, 8
-A metal complex of hydroxyquinoline or a derivative thereof is preferable, and particularly 4,4'-bis (N
(3-Methylphenyl) -N-phenylamino) biphenyl, 2- (4-biphenylyl) as electron transport material
-5- (4-t-Butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone and tris (8-quinolinol) aluminum are preferred. Of these, either one of the electron transporting compound and the hole transporting compound, or both of them may be used at the same time. These may be used alone or as a mixture of two or more.

When a charge transport layer is further provided between the light emitting layer and the electrode, these charge transport materials may be used to form the charge transport layer. When the charge transporting material is used in a mixture with the light emitting layer, the amount of the charge transporting material varies depending on the kind of the compound to be used. It may be determined appropriately in consideration of the situation. Usually, it is 1 to 40% by weight, more preferably 2 to 30% by weight, based on the light emitting material.

Known luminescent materials that can be used together with the polymeric fluorescent substance of the present invention are not particularly limited. For example, naphthalene derivative, anthracene or its derivative, perylene or its derivative, polymethine type, xanthene type, coumarin type, cyanine type. And the like, a metal complex of 8-hydroxyquinoline or a derivative thereof, an aromatic amine, tetraphenylcyclopentadiene or a derivative thereof, tetraphenylbutadiene or a derivative thereof, and the like can be used. Specifically, known ones such as those described in JP-A-57-51781 and JP-A-59-194393 can be used.

Next, a typical method for producing the organic EL device of the present invention will be described. A pair of electrodes consisting of an anode and a cathode, as a transparent or semitransparent electrode, glass,
A transparent substrate such as a transparent plastic on which a transparent or semitransparent electrode is formed is used. As the material of the anode, a conductive metal oxide film, a translucent metal thin film, or the like is used. Specifically, a film (NESA or the like) formed using conductive glass made of ITO, tin oxide, or the like, gold, platinum, silver, copper, or the like is used. As a manufacturing method, a vacuum evaporation method, a sputtering method, a plating method, or the like is used.

On the anode, a light emitting layer containing the above polymeric fluorescent substance or the polymeric fluorescent substance and a charge transport material as a light emitting material is formed. As a forming method, a melt of these materials,
Spin coating method using a solution or a mixed solution, a casting method, a dipping method, a bar coating method, a coating method such as a roll coating method is exemplified, but a solution or a mixed solution is a spin coating method, a casting method, a dipping method, A method of forming a film by a coating method such as a bar coating method or a roll coating method is particularly preferable.

The thickness of the light emitting layer is preferably 1 nm to
It is 1 μm, more preferably 2 nm to 500 nm. To increase the current density and luminous efficiency, 5 to 200n
The range of m is preferred. When the light emitting layer is thinned by a coating method, in order to remove the solvent, after the light emitting layer is formed, it is heated and dried under reduced pressure or in an inert atmosphere at a temperature of 30 to 300 ° C, preferably 60 to 200 ° C. It is desirable to do.

When the hole transport layer is laminated under the light emitting layer, it is preferable to form the hole transport layer before the light emitting layer is formed by the above film forming method. The film formation method of the hole transport layer is not particularly limited, and may be a vacuum deposition method from a powder state, or a spin coating method after being dissolved in a solution, a casting method, a dipping method, a bar coating method, a roll coating method, or the like. Use a coating method or a coating method such as a spin coating method, a casting method, a dipping method, a bar coating method or a roll coating method after mixing and dispersing a polymer compound and a charge transport material in a solution state or a molten state. You can

The polymer compound to be mixed is not particularly limited, but a compound that does not extremely disturb charge transport is preferable, and a compound that does not strongly absorb visible light is suitably used. For example, poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylenevinylene) or a derivative thereof, poly (2,5-thienylenevinylene) or a derivative thereof, polycarbonate, polyacrylate, Examples thereof include polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride and polysiloxane. From the viewpoint of easy film formation, it is preferable to use a coating method when a polymer compound is used.

The thickness of the hole transport layer is required to be at least such that pinholes are not generated, but if it is too thick, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of the charge transport layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500 n.
m, particularly preferably 5 to 200 nm.

When an electron transport layer is further laminated on the light emitting layer, it is preferable that the electron transport layer is formed on the light emitting layer after the light emitting layer is formed by the above film forming method.

The method for forming the electron transport layer is not particularly limited, but it is a vacuum deposition method from a powder state, or a spin coating method after being dissolved in a solution, a casting method,
A coating method such as a dipping method, a bar coating method, a roll coating method, or a spin coating method, a casting method, a dipping method, a bar coating method in which a polymer compound and a charge transport material are mixed and dispersed in a solution state or a molten state. A coating method such as a coating method or a roll coating method can be used.

The polymer compound to be mixed is not particularly limited, but a compound that does not extremely disturb charge transport is preferable, and a compound that does not strongly absorb visible light is preferably used. For example, poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylenevinylene) or a derivative thereof, poly (2,5-thienylenevinylene) or a derivative thereof, polycarbonate, polyacrylate, Examples thereof include polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride and polysiloxane. From the viewpoint of easy film formation, it is preferable to use a coating method when a polymer compound is used.

The thickness of the electron transport layer needs to be at least such that pinholes are not generated, but if it is too thick, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of the charge transport layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500 n.
m, particularly preferably 5 to 200 nm.

Next, an electrode is provided on the light emitting layer or the electron transporting layer. This electrode becomes an electron injection cathode. The material is not particularly limited, but a material having low ionization energy is desirable. For example, aluminum, indium, magnesium, calcium, lithium, magnesium-silver alloy, magnesium-indium alloy, magnesium-indium alloy, lithium-aluminum alloy,
A lithium-silver alloy, a lithium-indium alloy, a graphite thin film, or the like is used. As a method for manufacturing the cathode, a vacuum evaporation method, a sputtering method, or the like is used.

[0050]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. Here, regarding the number average molecular weight, the number average molecular weight in terms of polystyrene was determined by gel permeation chromatography (GPC) using chloroform as a solvent. Example 1 <Synthesis of polymeric fluorescent substance 1> 2,5-dioctyloxy-
p-Xylylene dibromide was reacted with triphenylphosphine in N, N-dimethylformamide solvent to synthesize a phosphonium salt. 47. The obtained phosphonium salt
75 parts by weight and 6.7 parts by weight of terephthalaldehyde were dissolved in ethyl alcohol. An ethyl alcohol solution containing 5.8 parts by weight of lithium ethoxide was added dropwise to an ethyl alcohol solution of a phosphonium salt and dialdehyde, and polymerized at room temperature for 3 hours. After leaving overnight at room temperature,
The precipitate was separated by filtration, washed with ethyl alcohol, dissolved in chloroform, and ethanol was added thereto to reprecipitate. This was dried under reduced pressure to obtain 8.0 parts by weight of a polymer. This is called polymeric fluorescent substance 1. The repeating units of polymeric fluorescent substance 1 calculated from the charged ratio of the monomers and the molar ratios thereof are shown below.

Embedded image (Molar ratio = 50: 50. Two repeating units are alternately bonded.) The polystyrene reduced number average molecular weight of the polymeric fluorescent substance 1 was 1.0 × 10 ⁴ . The structure of the polymeric fluorescent substance 1 was confirmed by infrared absorption spectrum and NMR.

<Production and Evaluation of Element> Organic EL produced
A schematic diagram of the structure of the device is shown in FIG. An ITO film [anode (transparent electrode) with a thickness of 40 nm was formed by sputtering.
5] was attached to the glass substrate 6 to form a film having a thickness of 50 nm by dipping using a 1.0 wt% chloroform solution of polyvinylcarbazole (hole transport layer 4). Further, a 1.0 wt% toluene solution of polymeric fluorescent substance 1 was spin-coated to form a film having a thickness of 50 nm (light emitting layer 3). Further, this was dried under reduced pressure at 150 ° C. for 1 hour, and then tris (8-quinolinol) aluminum (Alq ₃ ) was used as the electron transport layer 2 in an amount of 0.1 to 0.2.
35 nm was vapor-deposited at a rate of nm / s. A 40 nm thick lithium-aluminum alloy (lithium concentration: 1 wt%) was vapor-deposited thereon as a metal layer of the cathode 1 to produce an organic EL element. The degree of vacuum during vapor deposition is 8 × 10 ^-6 Torr
It was below.

In the obtained organic EL device, as a base material 7 having irregularities on its surface, a product name Lumithrough (Sumitomo Chemical Co., Ltd.) having a UV-curing resin layer lens formed on a polyethylene terephthalate film and having a semicircular cross section Made by Kogyo Co., Ltd., the pitch of the stripe lens is about 110.
μm, lens thickness about 60 μm, polyethylene terephthalate film thickness about 100 μm)
It stuck on the glass substrate 6 of L element using the adhesive material.
A voltage of 12.5 V was applied to the obtained organic EL device, and the result of measurement was that a current having a current density of 75.6 mA / cm ² flowed.
The brightness in the vertical direction was 4220 cd / m ² . Moreover, the result of measuring the angle dependence of the emission intensity is shown in FIG.
The results before bonding (Comparative Example 1) are also shown.

Comparative Example 1 A voltage of 12.5 V was applied to the organic EL device obtained without laminating a base material having irregularities on the surface, and the same measurement as in Example 1 was conducted. Density 75.6 mA / cm
² current flows, brightness in the vertical direction is 3136 cd / m
^{Was 2} . Further, when the angle dependence of the emission intensity was measured, it became as shown in FIG. As described above, the organic EL device of Example 1 showed excellent utilization efficiency of light from the light emitting layer and excellent storage characteristics of light emitting display quality.

[0054]

EFFECT OF THE INVENTION The organic EL device of the present invention can extract light from the light emitting layer with high efficiency in the front direction and exhibits high brightness. Therefore, it is a device such as a planar light source as a backlight or a flat panel display. Can be preferably used as

[Brief description of drawings]

FIG. 1 is a schematic view showing a layer structure of an organic electroluminescence element of the present invention.

FIG. 2 is a schematic view showing a layer structure of the organic electroluminescence element of the present invention.

FIG. 3 is a diagram showing angle dependence of emission intensity.

[Explanation of symbols]

 1 ... Cathode. 2 ... Electron transport layer. 3 ... Light emitting layer. 4 ... Hole transport layer. 5 ... Anode (transparent electrode). 6 ... Glass plate. 7 ... A base material having unevenness on the surface.

Front page continuation (72) Inventor Yoshihiko Tsuchida 6 Kitahara, Tsukuba, Ibaraki Sumitomo Chemical Co., Ltd.

Claims (6)

[Claims] 1. An organic electroluminescence device having at least a light emitting layer between a pair of electrodes consisting of an anode and a cathode, at least one of which is transparent or semitransparent,
The height difference is 0.1 μm or more and 0.2 mm on the outer side of the electrode composed of the pair of anode and cathode and on the side where the emitted light is emitted.
An organic electroluminescence device comprising a transparent or semi-transparent substrate having the following irregularities on its surface. 2. An organic electroluminescence device having at least a light emitting layer between a pair of electrodes consisting of an anode and a cathode, at least one of which is transparent or semitransparent,
The height difference is 0.1 μm or more and 0.1 μm or more on the other surface of the base material on which the light emission is emitted and on which the transparent or semitransparent electrode is formed, which surface is different from the surface on which the electrode is formed. 2m
An organic electroluminescence device having irregularities of m or less. 3. The light emitting layer has fluorescence in a solid state, and the repeating unit represented by the formula (1) is 5 of all repeating units.
^3. The organic electroluminescence device according to claim 1 or 2, which comprises 0% by mol or more and a polymeric fluorescent substance having a polystyrene reduced number average molecular weight of 10 ³ to 10 ⁷ . Embedded image -Ar-CR = CR'- (1) (wherein Ar has 4 carbon atoms involved in a conjugated bond).
Or more and 20 or less arylene group or heterocyclic compound group, R and R'are each independently hydrogen, carbon number 1 to 20
Alkyl group, C6-20 aryl group, C4
To 20 heterocyclic compounds, a group selected from the group consisting of cyano groups. ) 4. The organic electroluminescent device according to claim 1, wherein a layer made of an electron transporting compound is provided between the cathode and the light emitting layer and adjacent to the light emitting layer. . 5. The organic electroluminescence according to claim 1, wherein a layer made of a hole transporting compound is provided between the anode and the light emitting layer adjacent to the light emitting layer. element. 6. A layer comprising an electron transporting compound between a cathode and a light emitting layer adjacent to the light emitting layer, and a hole transporting property adjacent to the light emitting layer between an anode and the light emitting layer. The organic electroluminescence device according to claim 1, wherein a layer made of a compound is provided.