JP2007035643A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element, capable of effectively extracting light from a light-emitting layer and capable of exhibiting high luminance at low cost. <P>SOLUTION: In the organic electroluminescent element, having at least the light-emitting layer between electrodes consisting of a pair of an anode and a cathode of which at least one of them is transparent or translucent, a transparent or translucent base material having a ruggedness of which a height difference is 0.1 μm or larger and 0.2 mm or smaller on the surface thereof is pasted on an outer side of the electrodes consisting of the pair of the anode and the cathode and on the side to which the emitted light is radiated, and an air layer is not pinched between the base material and the element surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element (hereinafter sometimes referred to as an organic EL element).

An inorganic electroluminescence element (hereinafter, sometimes referred to as an inorganic EL element) using an inorganic phosphor as a light emitting material is used for display devices such as a planar light source or a flat panel display as a backlight. High voltage alternating current was necessary to make it.
In recent years, Tang et al. Fabricated an organic EL device having a two-layer structure in which an organic fluorescent dye is used as a light emitting layer and an organic charge transport compound used in an electrophotographic photoreceptor or the like is laminated (Japanese Patent Laid-Open No. Sho 59). -194393). Compared to inorganic EL elements, organic EL elements have the characteristics that light emission of a large number of colors can be easily obtained in addition to low voltage drive and high luminance, so there are many element structures, organic fluorescent dyes, and organic charge transport compounds. An attempt has been reported [Japanese Journal of Applied Physics (Jpn. J. Appl. Phys.), 27, L269 (1988)], [Journal of Applied Physics (J. Appl. Phys.) 65, 3610 (1989)].

Up to now, low molecular weight organic fluorescent dyes have been generally used as the material for the light emitting layer, and as high molecular weight light emitting materials, WO90113148, JP-A-3-244630, Applied Physics. -Letters (Appl. Phys. Lett.), 58, 1982 (1991). In an example of the specification of WO90113148, a poly (p-phenylene vinylene) thin film converted into a conjugated polymer is obtained by forming a soluble precursor on an electrode and performing a heat treatment. An EL device that has been disclosed is disclosed.
Japanese Patent Application Laid-Open No. 3-244630 exemplifies a conjugated polymer having characteristics that it is soluble in a solvent and does not require heat treatment. Applied Physics Letters (Appl. Phys. Lett.), Vol. 58, 1982 (1991) also describes a polymer light-emitting material soluble in a solvent and an organic EL device prepared using the same.

In the organic EL element, a substrate in which a transparent electrode made of an indium-tin oxide film (hereinafter sometimes referred to as ITO) is formed on a substrate of glass or a polymer film is used. It is common to take out through a transparent electrode and a base material. Light emission generated in the light emitting layer in the organic EL element is considered to be emitted uniformly in all directions, but light passes from the base material having a high refractive index into the air having a low refractive index. It is known that total reflection occurs at the interface between the substrate and the air, and only a part of the emitted light can be extracted outside. The totally reflected light is emitted from the end face of the substrate.
In an organic EL element which is a planar light emitting element, luminance viewed from above is practically important, and it is required to increase the ratio of light emitted from the light emitting layer in the vertical direction of the plane.
On the other hand, a backlight for a liquid crystal display uses a light diffusing plate having striped irregularities with a triangular cross section on the surface. This is because light from the cold cathode, which is a light source, is passed through the light guide plate and further through the light diffusing plate, thereby collecting the light emission direction in the front direction (perpendicular to the substrate), thereby improving 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, a conventional organic EL element uses a planar substrate, and a method for effectively extracting light in the front direction has not been known.

  An object of the present invention is to provide an organic electroluminescent device that can effectively extract light from a light emitting layer and has high luminance at low cost.

  In view of such circumstances, the present inventors have taken out the light from the light emitting layer effectively and have made extensive studies to improve the luminance at the front. As a result, the organic EL element having the light emitting layer has a light extraction side. It has been found that providing the unevenness on the surface of the element can reduce the ratio of total reflection and improve the utilization efficiency of light from the light emitting layer, leading to the present invention.

That is, the present invention provides [1] an organic electroluminescent element having at least a light emitting layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, on the outside of the pair of anodes and cathodes. In addition, the present invention relates to an organic electroluminescence device having 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 on the side where light emission is emitted.
Further, the present invention [2] is 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 translucent. Alternatively, an organic electroluminescence device having unevenness with a height difference of 0.1 μm or more and 0.2 mm or less on the other surface different from the surface on which the electrode is formed of a base material on which a translucent electrode is formed It is concerned.

Further, in the present invention, [3] the light emitting layer has fluorescence in a solid state, the repeating unit represented by the formula (1) is 50 mol% or more of all repeating units, and the number average molecular weight in terms of polystyrene is 10 ^{The present invention} relates to the organic electroluminescence device according to [1] or [2], which comprises a polymeric fluorescent substance of ³ to 10 ⁷ .
-Ar-CR = CR'- (1)
(Here, Ar is an arylene group or heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond, R and R ′ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms. And a group selected from the group consisting of an aryl group having 6 to 20 carbon atoms, a heterocyclic compound having 4 to 20 carbon atoms, and a cyano group.)

  Since the organic EL element of the present invention can extract light from the light emitting layer with high efficiency in the front direction and exhibits high luminance, it can be preferably used as a device such as a planar light source as a backlight, a flat panel display or the like.

Hereinafter, the present invention will be described in detail.
The organic EL device of the present invention is an organic electroluminescence device having at least a light-emitting layer between an electrode composed of a pair of anodes and cathodes, at least one of which is transparent or translucent, outside the electrodes composed of the pair of anodes and cathodes. In addition, a transparent or translucent substrate having unevenness with a height difference of 0.1 μm or more and 0.2 mm or less on the surface is provided on the side from which light emission is emitted.
Moreover, the organic EL element of this invention may paste the base material which has this unevenness | corrugation on the element surface. That is, in the organic EL device of the present invention, a transparent or translucent electrode is formed in an organic electroluminescent device having at least a light emitting layer between electrodes composed of a pair of anode and cathode, at least one of which is transparent or translucent. The surface having the irregularities of the transparent or translucent substrate having the irregularities of 0.1 μm or more and 0.2 mm or less on the surface on the other surface different from the surface on which the electrode of the substrate is formed It is bonded with another surface different from the above.

  When bonding an uneven substrate to an organic EL element, it is preferable not to sandwich an air layer between the surface of the organic EL element. Moreover, it is preferable to perform bonding using an adhesive, an adhesive, or a photocurable adhesive, and bonding using an adhesive is practical. Furthermore, when bonding, it is preferable that the difference in the refractive index of the substrate having unevenness, the bonding agent, and the substrate is smaller, and it is more preferable to use a material having a difference in refractive index of each material within 0.2, Particularly preferably, it is within 0.1.

  Furthermore, the organic EL device of the present invention is a side on which light emission is emitted in an organic electroluminescence device having at least a light emitting layer between a pair of anodes and cathodes, at least one of which is transparent or translucent. The other surface of the base material on which the transparent or semitransparent electrode is formed is different from the surface on which the electrode is formed, and has a height difference of 0.1 μm or more and 0.2 mm or less. .

  Here, the shape of the irregularities on the surface 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. .

As for the size of the uneven surface, if it is large, the light emission looks uneven, and if it is small, it is not industrial, so the unevenness is a pyramid or semicircular shape with one side or diameter of 0.1 μm or more and 0.2 mm or less, Preferably they are 1 micrometer 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 period is 0.1 μm or more and 0.2 mm or less, preferably 1 μm or more and 0.1 mm or less. It is. At this time, although the height of the unevenness is determined by the size and period of the unevenness, it is usually preferable to be less than the value of the size and period.
Although there is no restriction | limiting in particular in the thickness of the polymer sheet and film which have an uneven surface, 20-300 micrometers is preferable from the handling surface and cost surface of a sheet | seat or a film, More preferably, it is 70-200 micrometers.

Next, the base material which gives unevenness to the surface will be described.
When the substrate on which the electrode is formed is directly processed, examples of the substrate include glass and a transparent or translucent polymer material such as a polymer sheet or film.
In the case of a polymer material, the polymer material is not limited to one polymer material, and another polymer material may be used to form an uneven surface on the polymer substrate.

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

  In the case where a surface having an uneven surface is molded on a polymer substrate, polycarbonate, polysulfone, polyarylate, cellulose acetate, cellulose acetate, polyethersulfone, polyethylene terephthalate, polyethylene naphthalate, etc. are exemplified, preferably 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 performing chemical or vapor phase etching after patterning with a photoresist is exemplified. In addition, in a polymer material, a metal surface having an uneven surface is pressed under heat to transfer the unevenness, a method of rolling a polymer sheet or film with a roll having an uneven surface, and a slit to a polymer having an uneven shape. Examples include a method of extruding and casting, a method of casting on an uneven surface and forming a film, and a method of removing a non-polymerized portion by photopolymerizing the monomer into a pattern after film formation.
Among these, in 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 film with a roll having an uneven surface, or an uneven surface. The method of casting and forming a film is practical and preferable.

In the organic EL device of the present invention, the light emitting material to be used is not particularly limited, and a low molecular light emitter or a polymer light emitter can be used, but a polymer light emitter is preferable, and a conjugated polymer is more preferable. Among the conjugated polymers, those containing an arylene vinylene structure are particularly preferable.
Examples of low-molecular light emitters include naphthalene derivatives, anthracene derivatives, perylene derivatives, dyes such as polymethine series, xanthene series, coumarin series, and cyanine series, metal complexes of 8-hydroquinoline and its derivatives, aromatic amines, tetraphenylcyclo Pentadiene derivatives and the like, or known ones described in JP-A-57-51781 and 59-194393 can be used.

When using a polymeric fluorescent substance as the light emitting layer used in the organic EL device of the present invention, a polymer having a light emitting group in the side chain can be used, but preferably contains a conjugated structure in the main chain, In particular, polythiophene, poly-p-phenylene, polyarylene vinylene and derivatives thereof are preferable. Of these, polyarylene vinylene and derivatives thereof are preferable.
The polyarylene vinylene and its derivative are preferably a polymer containing the repeating unit represented by the formula (1) in an amount of 50 mol% or more based on the total repeating units. Although it depends on the structure of the repeating unit, the repeating unit represented by the formula (1) is more preferably 70% or more of the entire repeating unit. The polymeric fluorescent substance is obtained by combining a divalent aromatic compound group or derivative thereof, a divalent heterocyclic compound group or derivative thereof, or a combination thereof as a repeating unit other than the repeating unit represented by the formula (1) A group or the like may be included.
In addition, the repeating unit represented by the formula (1) and other repeating units may be linked by a non-conjugated unit having an ether group, an ester group, an amide group, an imide group, etc. Non-conjugated moieties may be included.

In the polymeric fluorescent substance, Ar in the formula (1) is an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond. Examples thereof include an aromatic compound group or a derivative group thereof, a divalent heterocyclic compound group or a derivative group thereof, or a group obtained by combining them.

（Ｒ₁ 〜Ｒ₉₂は、それぞれ独立に、水素、炭素数１〜２０のアルキル基、アルコキシ基及びアルキルチオ基；炭素数６〜１８のアリール基及びアリールオキシ基；並びに炭素数４〜１４の複素環化合物基からなる群から選ばれた基である。）

(R _{1 to} R ₉₂ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 18 carbon atoms; and a complex having 4 to 14 carbon atoms. It is a group selected from the group consisting of ring compound groups.)

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-diyl group, pyridine-2, A 5-diyl group, a substituted pyridine-2,5-diyl group, a thienylene group or a substituted thienylene group is preferred.
More preferred are a phenylene group, a biphenylene group, a naphthalenediyl group, a pyridine-2,5-diyl group, and a thienylene group.

The case where R and R ′ in formula (1) are substituents other than hydrogen or cyano group will be described. Examples of the alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, propyl group, butyl group, and pentyl group. Hexyl group, heptyl group, octyl group, decyl group, lauryl group and the like, and methyl group, ethyl group, pentyl group, hexyl group, heptyl group and octyl group are preferable.
Examples of the aryl group include a phenyl group, a 4-C ₁ -C ₁₂ alkoxyphenyl group (C ₁ -C ₁₂ indicates that the number of carbon atoms is 1 to 12, and the same applies hereinafter), 4-C ₁ -C ₁₂ alkylphenyl group, 1-naphthyl group, 2-naphthyl groups.

  From the viewpoint of solvent solubility, Ar in formula (1) is one or more alkyl groups having 4 to 20 carbon atoms, alkoxy groups and alkylthio groups, aryl groups and aryloxy groups having 6 to 18 carbon atoms, and 4 to 4 carbon atoms. It preferably has a group selected from 14 heterocyclic compound groups.

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, and 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, a lauryloxy group, and the like, such as a pentyloxy group and a hexyloxy group. , A heptyloxy group and an octyloxy group are preferable.
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, and a pentylthio group, a hexylthio group, a heptylthio group, and an octylthio group are preferable.

Examples of the aryl group include a phenyl group, 4-C ₁ ~C ₁₂ alkoxyphenyl group, 4-C ₁ ~C ₁₂ alkyl phenyl group, 1-naphthyl group, 2-naphthyl groups.
A phenoxy group is illustrated as an aryloxy group. Examples of the heterocyclic compound group include a 2-thienyl group, 2-pyrrolyl group, 2-furyl group, 2-, 3- or 4-pyridyl group.
The number of these substituents varies depending on the molecular weight of the polymeric fluorescent substance and the constitution of the repeating unit, but from the viewpoint of obtaining a highly soluble polymeric fluorescent substance, these substituents are one or more per 600 molecular weight. It is more preferable.

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 thereof, for example, a random copolymer having a block property. It may be a polymer. From the viewpoint of obtaining a polymeric fluorescent substance having a high fluorescence quantum yield, a random copolymer having a block property and a block or graft copolymer are preferable to a complete random copolymer.
In addition, since the organic EL element of the present invention utilizes light emission from a thin film, the polymer fluorescent substance having fluorescence in a solid state is used.

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. In general, 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 terms of film formability.

  When forming a film from a solution by using these organic solvent-soluble polymeric fluorescent substances when preparing an organic EL device, it is only necessary to remove the solvent by drying after applying this solution. The same technique can be applied even when a transport material or a light emitting material is mixed, which is very advantageous in production.

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 two halogenated methyl groups are bonded to the arylene group. A Wittig reaction from a diphosphonium salt obtained from the above compound and triphenylphosphine is exemplified.
As another synthesis method, a dehydrohalogenation method from a compound in which two halogenated methyl groups are bonded to an arylene group is exemplified.
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 having two halogenated methyl groups bonded to an arylene group with an alkali is exemplified.
In any of the synthesis methods, a compound having a skeleton other than an arylene group is added as a monomer, and the abundance ratio thereof can be changed to change the structure of the repeating unit contained in the generated polymeric fluorescent substance. The repeating unit represented by (1) may be added and adjusted so as to be 50 mol% or more, and copolymerized.
Among these, the method by Wittig reaction is preferable in terms of reaction control and yield.

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

  When these polymeric fluorescent substances are used as the light emitting material of the organic EL device, the purity affects the light emission characteristics. Therefore, it is preferable to carry out a purification treatment such as reprecipitation purification and fractionation by chromatography after synthesis.

There is no restriction | limiting in particular about the structure of the organic EL element of this invention except having the characteristic of the said this invention, A well-known structure is employ | adopted. Examples of the structure of the organic EL device of the present invention are shown in FIGS. In any case, the side from which light emission is emitted is the anode side, and is an example in which a base material 7 having irregularities on the surface is bonded to the outside of the glass plate 6 on which the anode 5 is formed. FIG. 1 shows a case where the shape of the base material 7 having unevenness on the surface is a stripe shape having a triangular cross section, and FIG. 2 shows a case where the shape of the base material 7 having unevenness on the surface is a stripe shape having a semicircular cross section. is there.
For example, on both sides of the light emitting layer 3 made of the polymer fluorescent material or the light emitting layer 3 made of a mixture of the polymer fluorescent material and a charge transport material (which means a generic name of an electron transport material and a hole transport material). The thing of the structure which has a pair of electrode is mentioned.
Moreover, the thing formed by providing the positive hole transport layer 4 containing a positive hole transport material between the light emitting layer 3 and the anode 5 is mentioned. At this time, the hole transport layer 4 is preferably adjacent to the light emitting layer 3.
Moreover, the thing formed by providing 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. The thing which becomes.
In addition, the light emitting layer and the charge transport layer may each independently be a single layer or a combination of a plurality of layers. Furthermore, for example, a light emitting material other than the polymeric fluorescent substance described below may be mixed and used in the light emitting layer. Moreover, it can also be set as the layer which disperse | distributed this polymeric fluorescent substance and / or charge transport material to the high molecular compound.

  In the organic EL device of the present invention, a known material can be used as the charge transport material used together with the polymeric fluorescent substance, that is, the electron transport material or the hole transport material, and is not particularly limited. Examples include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives and the like, and examples of electron transport materials include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinones or derivatives thereof, naphthoquinones or derivatives thereof, anthraquinones or derivatives thereof. Examples include derivatives, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, 8-hydroxyquinoline or metal complexes of derivatives thereof, and the like.

Specifically, JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-20988, JP-A-3-37992, The thing etc. which are described in the same 3-152184 gazette are illustrated.
The hole transport material is preferably a triphenyldiamine derivative, the electron transport material is preferably an oxadiazole derivative, benzoquinone or a derivative thereof, an anthraquinone or a derivative thereof, or a metal complex of 8-hydroxyquinoline or a derivative thereof. 4,4′-bis (N (3-methylphenyl) -N-phenylamino) biphenyl as the electron transport material, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1, 3,4-oxadiazole, benzoquinone, anthraquinone, and tris (8-quinolinol) aluminum are preferred.
Of these, one or both of an electron transporting compound and a hole transporting compound may be used simultaneously. These may be used singly or in combination of two or more.

When a charge transport layer is further provided between the light-emitting layer and the electrode, the charge transport layer may be formed using these charge transport materials.
In addition, when the charge transport material is mixed with the light emitting layer, the amount of the charge transport material varies depending on the type of the compound used, etc. It may be determined as appropriate in consideration. Usually, it is 1 to 40 weight% with respect to a luminescent material, More preferably, it is 2 to 30 weight%.

  Although it does not specifically limit as a well-known luminescent material which can be used with the polymeric fluorescent substance of this invention, For example, pigment | dyes, such as a naphthalene derivative, anthracene or its derivative (s), perylene or its derivative (s), a polymethine type, a xanthene type, a coumarin type, a cyanine type , Metal complexes of 8-hydroxyquinoline or its derivatives, aromatic amines, tetraphenylcyclopentadiene or its derivatives, tetraphenylbutadiene or its derivatives, and the like can be used. Specifically, known ones such as those described in JP-A-57-51781 and 59-194393 can be used.

Next, a typical method for producing the organic EL element of the present invention will be described. As a pair of electrodes composed of an anode and a cathode, a transparent or translucent electrode in which a transparent or translucent electrode is formed on a transparent substrate such as glass or transparent plastic is used.
As the material for the anode, a conductive metal oxide film, a translucent metal thin film, or the like is used. Specifically, a film (NESA etc.) made 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 deposition method, a sputtering method, a plating method, or the like is used.

  On the anode, the above-described polymeric fluorescent substance or a light-emitting layer containing the polymeric fluorescent substance and a charge transporting material is formed as a luminescent material. Examples of the forming method include spin coating methods, casting methods, dipping methods, bar coating methods, roll coating methods and the like using melts, solutions or mixed solutions of these materials. A method of forming a film by a coating method such as a spin coating method, a casting method, a dipping method, a bar coating method, or a roll coating method is particularly preferable.

The thickness of the light emitting layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm. In order to increase the current density and increase the light emission efficiency, the range of 5 to 200 nm is preferable.
In addition, 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 dried by heating at a temperature of 30 to 300 ° C., preferably 60 to 200 ° C. under reduced pressure or in an inert atmosphere. It is desirable to do.

When a hole transport layer is laminated under the light emitting layer, it is preferable to form the hole transport layer before providing the light emitting layer by the above film forming method.
The method for forming the hole transport layer is not particularly limited, but includes 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, etc. Use a coating method, or a coating method such as a spin coating method, casting method, dipping method, bar coating method, roll coating method after polymer compound and charge transport material are mixed and dispersed in a solution state or a molten state. Can do.

The polymer compound to be mixed is not particularly limited, but those that do not extremely inhibit charge transport are preferable, and those that do not strongly absorb visible light are preferably used.
For example, poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, poly (2,5-thienylene vinylene) or a derivative thereof, polycarbonate, polyacrylate, Examples include polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane. In terms of easy film formation, it is preferable to use a coating method when using a polymer compound.

  The thickness of the hole transport layer needs to be at least such that no pinholes are generated. However, if the thickness is too large, 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 nm, and particularly preferably 5 to 200 nm.

  Further, when an electron transport layer is further laminated on the light emitting layer, it is preferable to form the electron transport layer on the light emitting layer after the light emitting layer is provided by the film forming method described above.

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

The polymer compound to be mixed is not particularly limited, but those that do not extremely inhibit charge transport are preferable, and those that do not strongly absorb visible light are preferably used.
For example, poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, poly (2,5-thienylene vinylene) or a derivative thereof, polycarbonate, polyacrylate, Examples include polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane. In terms of easy film formation, it is preferable to use a coating method when using a polymer compound.

  The thickness of the electron transport layer needs to be at least such that no pinholes are generated. However, if the thickness is too large, 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 nm, and particularly preferably 5 to 200 nm.

  Next, an electrode is provided on the light emitting layer or the electron transport layer. This electrode becomes an electron injection cathode. Although it does not specifically limit as the material, The material with small ionization energy is desirable. For example, aluminum, indium, magnesium, calcium, lithium, magnesium-silver alloy, magnesium-indium alloy, magnesium-indium alloy, lithium-aluminum alloy, lithium-silver alloy, lithium-indium alloy, graphite thin film, or the like is used. As a method for producing the cathode, a vacuum deposition method, a sputtering method, or the like is used.

（モル比＝５０：５０。二つの繰り返し単位は交互に結合している。）
該高分子蛍光体１のポリスチレン換算の数平均分子量は、１．０×１０⁴ であった。該高分子蛍光体１の構造については赤外吸収スペクトル、ＮＭＲで確認した。 Examples of the present invention will be described below, but the present invention is not limited thereto.
Here, for 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 phosphonium salts. 47.75 parts by weight of the obtained phosphonium salt 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 dropped into an ethyl alcohol solution of a phosphonium salt and a dialdehyde and polymerized at room temperature for 3 hours. After standing overnight at room temperature, the precipitate was filtered off, washed with ethyl alcohol, dissolved in chloroform, and ethanol was added thereto to form a precipitate again. 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 unit of the polymeric fluorescent substance 1 calculated from the monomer charge ratio and the molar ratio thereof are shown below.

(Molar ratio = 50: 50. Two repeating units are alternately bonded.)
The number average molecular weight in terms of polystyrene 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.

<Creation and evaluation of element>
A schematic diagram of the structure of the produced organic EL device is shown in FIG.
A glass substrate 6 provided with an ITO film [anode (transparent electrode) 5] with a thickness of 40 nm by sputtering was formed into a film with a thickness of 50 nm by dipping using a 1.0 wt% chloroform solution of polyvinylcarbazole. Hole transport layer 4). Furthermore, a 1.0 wt% toluene solution of polymeric fluorescent substance 1 was used to form a film with a thickness of 50 nm by spin coating (light emitting layer 3). Further, this was dried under reduced pressure for 1 hour 0.99 ° C., as the electron transport layer 2 was 35nm deposited tris (8-quinolinol) aluminum (Alq ₃₎ at a rate of 0.1 to 0.2 nm / s. A lithium-aluminum alloy (lithium concentration: 1 wt%) was deposited as a metal layer of the cathode 1 to a thickness of 40 nm to produce an organic EL device. The degree of vacuum at the time of vapor deposition was 8 × 10 ⁻⁶ Torr or less.

Product name Lumi-Thru (Sumitomo Chemical Co., Ltd.) having an ultraviolet curable resin layer lens with a semicircular cross section formed on a polyethylene terephthalate film as a base material 7 having irregularities on the surface of the organic EL element obtained. And a stripe lens pitch of about 110 μm, a lens thickness of about 60 μm, and a polyethylene terephthalate film thickness of about 100 μm) were bonded onto the glass substrate 6 of the obtained organic EL element using an adhesive.
As a result of applying and measuring 12.5V to the obtained organic EL element, a current with a current density of 75.6 mA / cm ² flowed, and the luminance in the vertical direction was 4220 cd / m ² . Moreover, the result of having measured the angle dependency of the emitted light intensity was shown in FIG. 3 together with the result before bonding (Comparative Example 1).

Comparative Example 1
As a result of applying a voltage of 12.5 V to the organic EL element obtained without bonding a substrate having irregularities on the surface and measuring the same as in Example 1, the current density was 75.6 mA / cm. ² current flowed, and the luminance in the vertical direction was 3136 cd / m ² . Further, when the angle dependency of the emission intensity was measured, it was as shown in FIG.
As described above, the organic EL device of Example 1 exhibited excellent light-emitting display quality storage characteristics with high use efficiency of light from the light-emitting layer.

Schematic which shows the layer structure of the organic electroluminescent element of this invention. Schematic which shows the layer structure of the organic electroluminescent element of this invention. The figure which shows the angle dependence of emitted light 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 substrate having irregularities on the surface.

Claims (7)

There is at least a light-emitting layer between a pair of anodes and cathodes, at least one of which is transparent or semi-transparent, and the height is high on the outside of the pair of anodes and cathodes and on the side from which light emission is emitted. A transparent or translucent substrate having unevenness of 0.1 μm or more and 0.2 mm or less on the surface is bonded using a bonding agent, and an air layer is provided between the substrate and the element surface. An organic electroluminescence device characterized by not being sandwiched. In an organic electroluminescence device having at least a light emitting layer between a pair of anode and cathode electrodes, at least one of which is transparent or translucent, a transparent or translucent electrode is formed on the side from which light is emitted. The other surface of the substrate is different from the surface on which the electrode is formed, and has a height difference of 0.1 μm or more and 0.2 mm or less, and the substrate is a polymer substrate. An organic electroluminescence device characterized by the above. The light emitting layer has fluorescence in a solid state, the repeating unit represented by the formula (1) is 50 mol% or more of all repeating units, and the number average molecular weight in terms of polystyrene is 10 ³ to 10 ⁷ 3. The organic electroluminescence device according to claim 1, further comprising a phosphor.
-Ar-CR = CR'- (1)
(Here, Ar is an arylene group or heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond, R and R ′ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms. And a group selected from the group consisting of an aryl group having 6 to 20 carbon atoms, a heterocyclic compound having 4 to 20 carbon atoms, and a cyano group.) The organic electroluminescent device according to claim 1, 2 or 3, wherein a layer made of an electron transporting compound is provided adjacent to the light emitting layer between the cathode and the light emitting layer. 4. The organic electroluminescence device according to claim 1, wherein a layer made of a hole transporting compound is provided adjacent to the light emitting layer between the anode and the light emitting layer. A layer made of an electron transporting compound adjacent to the light emitting layer between the cathode and the light emitting layer, and a layer made of a hole transporting compound adjacent to the light emitting layer between the anode and the light emitting layer. The organic electroluminescent element according to claim 1, 2 or 3, wherein the organic electroluminescent element is provided. In 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 translucent, light is emitted outside the electrodes composed of the pair of anodes and cathodes. A transparent or semi-transparent substrate having unevenness on the surface with a height difference of 0.1 μm or more and 0.2 mm or less on the side so that an air layer is not sandwiched between the substrate and the element surface The manufacturing method of the organic electroluminescent element characterized by bonding using.

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