JPH10223367A - Organic electric field luminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high brightness even during low voltage driving and enable compactness by providing a plastic-based micro-lens array structure in which an anode, an organic luminous layer, and a cathode are laminated on one plate face and the other face of a substrate provided with a luminous part is protruded on this face side. SOLUTION: To collect rays of light, a protrusion micro-lens array structure 1A is provided on an opposite face of a face of forming a luminous part 2 in which an anode of a substrate 1, an organic luminous layer, and a cathode are laminated. This micro-lens array structure 1A is shaped of shear arc, for example, a fine lens part 1a of 1 to 5000 microns in diameter R is arrays in pitches P of 1 to 5000 microns, and thickness W1 is 100 to 2000 microns. Here, in the micro-lens array structure 1A, one face of the substrate 1 may be plastic- molded or a sheet of the micro-lens array structure 1A additionally manufactured on a glass plate 1B may be laminated. Thereby, the ray of light 3 of a luminous part 2 is collected at a part of the protrusion type micro-lens array structure 1A, and high brightness is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an organic electroluminescent device. More specifically, the present invention relates to an organic electroluminescent device with high brightness.

[0002]

2. Description of the Related Art Recent organic electroluminescent devices have become quite practical due to the development of materials and layer structures such as a hole transport layer and a light emitting layer for improving durability and achieving full color. However, there is a problem that the luminance is reduced when driving at a low voltage to improve the durability or using a color filter or the like for full color. In recent years, dyes having high luminous efficiency and excellent stability have been searched for, but at present, sufficient dyes have not been obtained simply by improving the dyes.

[0003] Further, as a substrate of an organic electroluminescent element,
A glass substrate is usually used because of characteristics such as optical characteristics and mechanical strength. Therefore, there is a limit to the weight reduction and thinning of the organic electroluminescent element, and also in terms of productivity, formability,
There was a problem in workability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic electroluminescent device which realizes high luminance even at low voltage driving. Another object of the present invention is to reduce the weight of the organic electroluminescent device.

[0005]

The organic electroluminescent device according to the present invention is an organic electroluminescent device having an anode, an organic luminescent layer and a cathode laminated on one surface of a substrate, wherein the substrate is made of plastic. It has a micro lens array structure made of.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, by incorporating a plastic microlens array structure into an organic electroluminescent device, a lightweight, high-brightness, low-voltage organic electroluminescent device has been developed. The inventors have found that the present invention can be realized, and arrived at the present invention.

That is, when an ordinary flat substrate is used, the light emitted from the light emitting portion passes through the substrate as it is, whereas when the substrate has a plastic microlens array structure, the light emitted from the light emitting portion is emitted. Is focused on the convex portion of the microlens array structure. Therefore, high luminance can be achieved. In addition, a plastic microlens array structure can reduce the weight.

This microlens array structure is preferably made of a photocurable resin, particularly a photocurable resin obtained by photocuring a photocurable liquid monomer containing a polyfunctional (meth) acrylate compound. In the present specification, “(meth) acrylate” indicates “acrylate and / or methacrylate”. The same applies to “(meth) acryloyl” described below.

Further, the microlens array structure is preferably manufactured by exposure through a mask.

[0010] The substrate according to the present invention can be formed by laminating a microlens array sheet on a glass substrate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the organic electroluminescent device of the present invention will be described in detail with reference to the drawings.

First, a substrate having a plastic microlens array structure according to the present invention will be described with reference to FIGS.

FIGS. 1A to 1C are schematic views illustrating the structure and light-condensing function of a substrate according to the present invention, and FIG. 2 is a perspective view showing an example of a method for forming a microlens array structure. .

The microlens array structure according to the present invention refers to a structure in which minute lens portions 1a having an arc-shaped cross section are arranged in a plane as shown in FIGS. 1 (a) to 1 (c), and more specifically. For example, the diameter (R in FIG. 1A) is 0.1 to 1
The microlens portions 1a of 0000 μm, preferably 1 to 5,000 μm are arranged in parallel at a pitch of 0.1 to 10,000 μm, preferably 1 to 5,000 μm (P in FIG. 1A). is there. This thickness (W _{1 in} FIG. 7A) is 1
0 to 10,000 μm, preferably 100 to 2,000
μm.

The purpose of focusing the emitted light beam is as shown in FIG.
As shown in (a) to (c), the microlens array structure 1A has a convex shape on the side opposite to the surface on which the light emitting portion 2 on which the anode, the organic light emitting layer, and the cathode of the substrate 1 are laminated.

The shape of the lens portion 1a is shown in FIGS.
As shown in (c), the shape is not limited to the one having a semicircular cross section, but may be a convex lens having an arc cross section. In this case, the radius of curvature is 0.05 to 13,000,000 μm, preferably 0.1 to 0.3,000,000 μm. The lens diameter is 0.5 to 3,000,000 μm.
1 to 10,000 μm, preferably 1 to 5,000 μm
Is fine.

In the present invention, as shown in FIGS. 1A and 1B, the substrate 1 itself may be formed of plastic so as to have the microlens array structure 1A on one side. As shown, the substrate 1 may be formed by forming the plastic microlens array structure 1A on the glass plate 1B or by laminating a sheet of the microlens array structure 1A separately manufactured on the glass plate 1B. In this case, the thickness W ₂ of the glass plate 1B is 300 to 5,000 μ
m is preferable.

As shown in FIG. 3, in the case of a flat substrate 11 in a conventional organic electroluminescent device, the plane-emitting light beam 13 emitted from the light emitting section 12 passes through as it is.
It remains diffused. On the other hand, if the substrate 1 according to the present invention has a microlens array structure, FIG.
As shown in (a) to (c), the light beam 3 emitted from the light emitting unit 2
Is condensed at the portion of the convex microlens array structure 1A, and as a result, high brightness of the organic electroluminescent element is achieved.

In the present invention, the microlens array structure is formed of a plastic, particularly preferably a photocurable resin.

The photocurable resin can be obtained by photocuring a photocurable liquid monomer composition containing a photocurable liquid monomer, a photopolymerization initiator, and the like.

The photocurable liquid monomer is not particularly limited as long as it is polymerized and cured by light irradiation to form a transparent polymer, and is not particularly limited.
Acrylate-based compounds are suitable. Among them, triethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, 2,2-bis [4-
(Meth) acryloyloxyphenyl] propane, 2,
2-bis [4- (2- (meth) acryloyloxyethoxy)] phenylpropane, p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-
Polyfunctional (meth) acrylates such as bis [β- (meth) acryloyloxyethylthio] diphenyl sulfone, trimethylolpropane tri (meth) acrylate, urethane acrylate, epoxy acrylate, and monofunctional copolymerizable with these monomers Mixtures with monomers, and mixtures of these polyfunctional (meth) acrylate compounds with addition-polymerizable polythiols are preferred. The monofunctional monomer includes, for example, methyl (meth) acrylate and benzyl (meth) acrylate, and the polythiol includes, for example, pentaerythritol tetrakis (β-thiopropionate), tris [2- ( β-thiopropionyloxy) ethyl] isocyanurate.

Among these, monomers that form polymers having a refractive index (to air) of 1.50 or more, preferably 1.55 or more, particularly preferably 1.58 or more are selected.

Known photopolymerization initiators can be used for curing these photocurable liquid monomers, and two or more of them may be used in combination. Examples of the photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, trimethylbenzoylphenylphosphinic acid methyl ester, 1-hydroxycyclohexylphenyl ketone, benzophenone,
And diphenoxybenzophenone.

When photocuring and thermal curing are used in combination for the purpose of rapidly completing curing, a known thermal curing agent such as benzoyl peroxide, diisopropylperoxycarbonate, t-butylperoxy (2-ethylhexanoate) is used. A polymerization initiator can be added.

[0025] If necessary, an antioxidant, an ultraviolet absorber, a coloring agent, and the like can be added to the photocurable liquid monomer composition.

In order to form a microlens array structure made of a photocurable resin by photocuring, for example,
The photocurable liquid monomer composition can be poured into a plate-shaped mold having a microlens array structure in part, and then exposed. More specifically,
Between the microlens array-shaped plate and the flat plate,
The photocurable liquid monomer composition is poured, and light is irradiated from the side of the flat plate to perform photocuring. A microlens array structure is formed on the microlens array-shaped plate side of the photocurable resin molded product obtained by photocuring (hereinafter, referred to as “microlens array structure”).
This method is called "mold transfer method". ).

In this case, as shown in FIG. 2, a photo-curable liquid monomer is formed by using a negative mask pattern 4 in which only a portion 4A corresponding to the lens portion forming portion transmits light instead of a microlens array plate. By exposing the composition 5, a microlens array shape having a smaller lens portion 5A can be formed. That is, by using such a negative mask pattern 4, more light is applied to only the lens 5A forming portion of the photocurable liquid monomer composition 5 than the other portions, so that this portion is convex as described later. The lens 5A can be formed into a convex shape (hereinafter, this method may be referred to as a "partial light irradiation method"). As a method of partially irradiating using the negative mask pattern 4, exposure is performed through the negative mask pattern 4 in the first stage, and further, the entire surface is exposed (exposure excluding the mask pattern 4) in the second stage. Alternatively, a two-step exposure method of performing exposure from the back side) or a method of performing simultaneous exposure from the mask pattern 4 side and the back side may be used.

The negative type mask pattern used in the partial light irradiation method can be obtained by an appropriate method such as a photographing method, a vapor deposition method, and printing. As the substrate on which the mask pattern is to be placed, a glass plate is preferable, but a polymer film or paper may be used, or they may be bonded to a hard transparent material such as glass. The mask surface on which the pattern is drawn may be arranged on the inner surface of the injection mold or on the outer surface.However, in order to obtain good transferability of the pattern, the inner side, that is, the photocurable liquid Preferably, it is arranged on the surface in contact with the monomer composition. In this case, it is desirable to use a chromium vapor deposition mask made of glass in consideration of recycling of the mask so as not to be affected by the photocurable liquid monomer composition.

Curing shrinkage during photopolymerization of the photocurable liquid monomer composition proceeds with an increase in the degree of polymerization due to light irradiation. Therefore, when partial light irradiation is performed through the negative type mask pattern, the light-irradiated unmasked portion first cures and is affected by the curing shrinkage, and thus the masked light is not irradiated or light-irradiated. The low-volume part is hollow. That is, the unmasked portion forms a convex protrusion. The shape of the convex portion is spherical or aspherical (spherical-like shape) because the light goes around the masked portion by the diffraction phenomenon when the irradiation light passes through the mask.
Lens section.

Therefore, by partially irradiating light,
After forming the surface irregularities, complete the curing by removing the negative mask pattern and irradiating the entire surface with light,
A final microlens array structure can be obtained. Alternatively, a material such as glass that transmits light to the mold on the side opposite to the negative-type mask pattern through the photocurable liquid monomer composition can be used to irradiate light from the entire surface to complete curing. In this case, the formation of unevenness on one side and the curing of the entire surface can be performed simultaneously.

In both the mold transfer method and the partial light irradiation method, a light source for light irradiation is appropriately selected according to the characteristic wavelength of the photocurable liquid monomer composition and the photopolymerization initiator. Can be. A light source for light irradiation is generally used in the form of parallel light or scattered light using an ultraviolet light source such as a high-pressure mercury lamp, a metal halide lamp, or a short arc lamp, but a laser or the like is used in combination with a photosensitizer. It is also possible to use visible and infrared light sources.

At the time of light irradiation, the entire poured mold may be heated in order to complete the curing promptly, and the curing may be promoted by adding a thermal polymerization initiator.

Further, in order to further reduce optical distortion, treatment such as annealing by slight heating after curing may be performed. Further, a surface treatment such as a hard coat and an antireflection coat can be performed.

Next, the structure of the organic electroluminescent device of the present invention using such a substrate having a plastic microlens array structure will be described with reference to FIGS.

4 to 6 are schematic sectional views showing examples of the structure of the organic electroluminescent device of the present invention. In the figures, 1 is a substrate, 6 is an anode, 7 is an organic light emitting layer, and 7a is a hole transport layer. , 7b are an electron transport layer, 7c is a hole injection layer, 8 is a cathode, 10, 10A,
10B is an organic electroluminescent element.

The substrate 1 serves as a support for the organic electroluminescent device, and is required to have excellent properties such as optical properties, heat resistance, surface accuracy, mechanical strength, light weight, and gas barrier properties.

In the present invention, as this substrate 1, as shown in FIGS. 1A to 1C, a plastic microlens array structure or a laminate of a glass plate and a microlens array structure having excellent characteristics. Is used.

The substrate may be provided with a dense silicon oxide film or the like on at least one side for the purpose of further enhancing gas barrier properties.

The anode 6 formed on the substrate 1 plays a role of injecting holes into the organic light emitting layer 7. This anode 6 is usually made of aluminum, gold, silver, platinum, nickel,
Metals such as palladium and platinum, metal oxides such as oxides of indium and / or tin, metal halides such as copper iodide, carbon black, or conductive materials such as poly (3-methylthiophene), polypyrrole, and polyaniline It is preferably formed of indium tin oxide, such as a polymer. The formation of the anode 6 is usually performed by a sputtering method,
It is often performed by a vacuum deposition method or the like. Fine metal particles such as silver, fine particles such as copper iodide, carbon black,
When conductive metal oxide fine particles, conductive polymer fine powder, or the like is used, the anode 6 can be formed by dispersing it in an appropriate binder resin solution and applying it on the substrate 1. When using a conductive polymer,
The anode 6 can also be formed by forming a thin film directly on the substrate 1 by electrolytic polymerization or by coating a conductive polymer on the substrate 1 (Appl. Phys. Let.).
t. 60, 2711, 1992). The anode 6 can be formed by laminating different materials.

The thickness of the anode 6 varies depending on whether transparency is required. When transparency is required, it is desirable that the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 5 to 100.
0 nm, preferably about 10 to 500 nm. If the anode 6 may be opaque, it may be made of the same material as the substrate 1. Further, different conductive materials can be laminated on the anode 6.

The organic light emitting layer 7 formed on the anode 6
It is made of a material that efficiently transports and recombines holes injected from the anode 6 and electrons injected from the cathode 8 between the electrodes to which an electric field is applied, and emits light efficiently by the recombination. Normally, as shown in FIG. 5, the organic light-emitting layer 7 is of a function-separated type in which the organic light-emitting layer 7 is divided into a hole transport layer 7a and an electron transport layer 7b (Appl. Phys. Lett., 51, 913
1987).

Function-separated type organic electroluminescent device 1 shown in FIG.
At 0A, the material of the hole transport layer 7a is the anode 6
It is necessary that the material has a high hole injection efficiency and a material capable of efficiently transporting the injected holes. For that purpose, it is required that the ionization potential is small, the hole mobility is large, the stability is further improved, and impurities serving as traps during production or use are hardly generated.

As such a hole transporting material, for example, an aromatic diamine compound linked to a tertiary aromatic amine unit such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane (Japanese Patent Laid-Open Publication No. 1959-19439
No. 3), 4,4′-bis [N- (1-naphthyl)-
N-phenylamino] aromatic amines containing two or more tertiary amines represented by biphenyl and having two or more condensed aromatic rings substituted by nitrogen atoms (JP-A-5-234681); Aromatic triamines having a starburst structure in derivatives (US Pat. No. 4,92
Aromatic diamines such as N, N'-diphenyl-N, N'-bis (3-methylphenyl) biphenyl-4,4'-diamine (U.S. Pat. No. 4,764,62)
No. 5), α, α, α ′, α′-tetramethyl-α, α ′
-Bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084), a triphenylamine derivative which is sterically asymmetric as a whole molecule (JP-A-4-129271), bienyl In which a plurality of aromatic diamino groups are substituted on a group (JP-A-4-17539)
No. 5), an aromatic diamine in which a tertiary aromatic amine unit is linked by an ethylene group (JP-A-4-264189), an aromatic diamine having a styryl structure (JP-A-Hei-4).
(Japanese Patent Application Laid-Open No. 4-290466), a compound in which an aromatic tertiary amine unit is linked by a thiophene group (JP-A-4-304466).
JP-A-4-308688), a benzylphenyl compound (JP-A-4-364153), and a fluorene group of 3
Tertiary amine compound (JP-A-5-239455), bisdipyridylaminobiphenyl (JP-A-5-3473)
20634), N, N, N-triphenylamine derivatives (JP-A-6-1972), and aromatic diamines having a phenoxazine structure (JP-A-7-138562).
JP, JP-A-7-252474, a hydrazone compound (JP-A-2-311591), a silazane compound (U.S. Pat. No. 4,950,950), and a silanamin derivative ( JP-A-6-49079), phosphamine derivatives (JP-A-6-25659), and quinacridone compounds. These compounds may be used alone or, if necessary, in combination of two or more.

In addition to the above compounds, the hole transport layer 7
As a material of a, polyvinyl carbazole or polysilane (Appl. Phys. Lett., Vol. 59, 2760)
P. 1991), polyphosphazene (JP-A-5-3)
No. 10949), polyamide (JP-A-5-3109)
No. 49), polyvinyl triphenylamine (Japanese Patent Application Laid-Open No. 7-53953), a polymer having a triphenylamine skeleton (Japanese Patent Application Laid-Open No. 4-133065), and a polymer in which triphenylamine units are linked by a methylene group or the like. (S
Synthetic Metals, 55-57, 41
63, 1993), polyamines containing aromatic amines (J. Polym. Sci., Poly).
m. Chem. Ed. , 21, 969, 1983.
) Can be used.

The hole transporting layer 7a is formed on the anode 6 by coating these hole transporting materials by a coating method or a vacuum evaporation method.

In the case of the coating method, one or more of the hole transporting materials and, if necessary, additives such as a binder resin or a coating property improving agent which do not trap holes are added and dissolved in a solvent. Then, a coating solution is prepared, applied to the anode 6 by a method such as spin coating, and dried to form an organic hole transport layer 7a. In this case, examples of the binder resin include polycarbonate, polyarylate, and polyester. Since a large amount of the binder resin decreases the hole mobility, a small amount is desirable.
It is preferably at most 50% by weight.

On the other hand, in the case of the vacuum evaporation method, the hole transporting material is put into a crucible provided in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ^-4 Pa by a suitable vacuum pump. Is heated to evaporate the hole transporting material, and the hole transporting layer 7a is formed on the anode 6 on the substrate 1 opposed to the crucible.
To form

When the hole transport layer 7a is formed in this manner, a metal complex and / or a metal salt of an aromatic carboxylic acid (JP-A-4-320484), a benzophenone derivative and a thiobenzophenone derivative are further used as acceptors. (JP-A-5-295361), fullerenes (JP-A-5-331458) and the like are doped at a concentration of 10 ⁻³ to 10% by weight to generate holes as free carriers, thereby reducing the amount of holes. Voltage driving can be enabled.

The thickness of the hole transport layer 7a is usually 10 to 3
00 nm, preferably 30 to 100 nm. In order to uniformly form such a thin hole transport layer,
Generally, it is preferable to employ a vacuum deposition method.

In order to further improve the hole injection efficiency and to improve the adhesion of the entire organic layer to the anode 6,
As shown in FIG. 6, a hole injection layer 7c is also formed between the hole transport layer 7a and the anode 6. As the material used for the hole injection layer 7c, a material having a low ionization potential, high conductivity, and capable of forming a thermally stable thin film on the anode 6 is preferable. A phthalocyanine compound or a porphyrin compound (Japanese Patent Application Laid-Open No. 57-51781, JP-A-63-29569).
By interposing such a hole injection layer 7c, it is possible to obtain the effect that the initial drive voltage of the device is reduced and at the same time the voltage rise when the device is continuously driven with a constant current is suppressed. The conductivity of the hole injection layer 7c can also be improved by doping the acceptor similarly to the hole transport layer 7a.

The thickness of the hole injection layer 7c is usually 2 to 10
0 nm, preferably 5 to 50 nm. In order to uniformly form such a thin hole injection layer, it is generally preferable to employ a vacuum evaporation method.

The electron transport layer 7b formed on the hole transport layer 7a is a compound capable of efficiently transporting electrons from the cathode in the direction of the hole transport layer 7a between electrodes to which an electric field is applied. It consists of.

The electron transporting compound used for the electron transporting layer 7b needs to be a compound having a high electron injection efficiency from the cathode 8 and capable of efficiently transporting the injected electrons. For that purpose, it is required that the compound has a high electron affinity, high electron mobility, excellent stability, and hardly generates impurities serving as traps during production or use.

Materials satisfying such conditions include aromatic compounds such as tetraphenylbutadiene (Japanese Unexamined Patent Publication No.
And metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP-A-59-1943).
No. 93), cyclopentadiene derivatives (Japanese Unexamined Patent Publication No.
289675), perinone derivatives (JP-A 2-2)
No. 89676), oxadiazole derivatives (Japanese Patent Application Laid-Open No. 2-216991), and bisstyrylbenzene derivatives (Japanese Patent Application Laid-Open Nos. 1-245087 and 2-222448).
No. 4), perylene derivatives (JP-A-2-189890)
JP-A-3-7991), coumarin compounds (JP-A-2-191694 and JP-A-3-792), rare-earth complexes (JP-A-1-256584), and distyrylpyrazine derivatives (JP-A-Heisei 2). 252793)),
p-phenylene compound (JP-A-3-33183), thiadiazolopyridine derivative (JP-A-3-372)
No. 92), pyrrolopyridine derivatives (JP-A-3-37)
293), naphthyridine derivatives (JP-A-3-20
3982) and the like.

Electron transport layer 7b using these compounds
Can generally simultaneously fulfill the role of transporting electrons and the role of providing light emission when holes and electrons recombine.

When the hole transporting layer 7a has a light emitting function, the electron transporting layer 7b may only play the role of transporting electrons.

For the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, doping a fluorescent dye for laser such as coumarin using an aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Ph.
ys. 65, 3610, 1989). In the present invention, the above-mentioned organic electron transporting material is used as a host material to dope various fluorescent dyes by 10 ^-3 to 10 mol%. In addition, the light emitting characteristics of the device can be further improved.

The thickness of the electron transporting layer 7b is usually 10 to 2
00 nm, preferably 30 to 100 nm.

The electron transporting layer can be formed in the same manner as the hole transporting layer, but usually a vacuum evaporation method is used.

The organic light emitting layer 7 of the single-layer type which does not perform the function separation as shown in FIG.
-Phenylene vinylene) (Nature, 347, 5)
39, 1990 et al.), Poly [2-methoxy-5-
(2-ethylhexyloxy) -1,4-phenylenevinylene] (Appl. Phys. Lett., Vol. 58,
1982, 1991, etc.), poly (3-alkylthiophene) (Jpn. J. Appl. Phys. 30, vol.
L1938, 1991, etc.) or a system in which a light emitting material and an electron transfer material are mixed with a polymer such as polyvinyl carbazole (Applied Physics, vol. 61, p. 1044, 19).
1992).

The cathode 8 plays a role of injecting electrons into the organic light emitting layer 7. As the material used for the cathode 8, it is possible to use the material used for the anode 6, but for efficient electron injection, a metal having a low work function is preferable, and tin, magnesium, indium, calcium,
Suitable metals such as aluminum and silver or alloys thereof are preferred. The thickness of the cathode 8 is usually about the same as that of the anode 6.

For the purpose of protecting the cathode made of a low work function metal, a metal layer having a high work function and being stable to the atmosphere can be further laminated on the cathode to increase the stability of the device. Metals such as aluminum, silver, nickel, chromium, gold, and platinum are used for the metal layer for this purpose.

FIGS. 4 to 6 show an example of an element main body employed in the present invention. The present invention is applied to an element main body having the following layer structure other than the illustrated one. can do.

Anode / hole transport layer / electron transport layer / interface layer / cathode, anode / hole transport layer / electron transport layer / other electron transport layer / cathode, anode / hole transport layer / electron transport layer / others Electron transport layer / interface layer / cathode, anode / hole injection layer / hole transport layer / electron transport layer / interface layer /
Cathode, anode / hole injection layer / hole transport layer / electron transport layer / other electron transport layer / cathode In the above layer structure, the interface layer is for improving the contact between the cathode and the organic layer, and is aromatic. Diamine compounds (JP-A-6-267658), quinacridone compounds (JP-A-6-330031), naphthacene derivatives (JP-A-6-330032), organic silicon compounds (JP-A-6-325871), organic compounds Phosphorus compounds (Japanese Patent Application Laid-Open No. Hei 6-325872) and compounds having an N-phenylcarbazole skeleton (Japanese Patent Application No. Hei 6-199562)
No.), N-vinylcarbazole polymer (Japanese Patent Application No. 6-20)
0942) and the like. The thickness of the interface layer is usually 2 to 100 nm, preferably 5 to 30 n.
m. Instead of providing the interface layer, a region containing 50% by weight or more of the material for the interface layer may be provided near the cathode interface between the organic light emitting layer and the electron transport layer.

The other electron transporting layer is further formed on the electron transporting layer in order to further improve the luminous efficiency of the organic electroluminescent device. Is easy to inject electrons from the cathode,
It is required that the ability to transport electrons is further increased. As such an electron transporting material, an oxadiazole derivative (Appl. Phys. Lett., Vol. 55, 1489)
1989, etc.) and a system in which they are dispersed in a resin such as polymethyl methacrylate (PMMA) (Appl. Phys.
s. Lett. 61, 2793, 1992),
Phenanthroline derivatives (JP-A-5-331559), n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like. The thickness of the other electron transporting layer is usually 5 to 200 nm, preferably 1 to 200 nm.
0-100 nm.

The organic electroluminescent device of the present invention can be applied to any of a single device, a device having a structure arranged in an array, and a device having a structure in which an anode and a cathode are arranged in an XY matrix. be able to.

[0067]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist.

Example 1 0.1 part by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator and 100 parts by weight of 4,4'-bis (β-methacryloyloxyethylthio) diphenylsulfone and benzophenone 0.02 parts by weight was uniformly stirred and mixed. This composition was poured into a mold composed of a microlens array-shaped metal plate in which hemispherical concave portions having a diameter of 1 mm are arranged at a pitch of 1 mm, and a flat glass plate provided via a 1 mm-thick silicon spacer. . Then, curing was performed by irradiating ultraviolet light as scattered light for 3 minutes from a high-pressure mercury lamp having an output of 80 mW / cm ² 50 cm above the glass plate. After curing, the mold was released and the cured product was annealed at 120 ° C. for 1 hour to obtain a plastic sheet having a convex microlens array structure on one side and a smooth surface on one side. The lens diameter, the radius of curvature of the lens portion, the pitch of the lens portion, the thickness, the refractive index, and the specific gravity of the microlens array sheet are as shown in Table 1.

The microlens array sheet was used as a substrate, and ITO (indium tin oxide) was provided on the smooth surface side.
At a low temperature to a thickness of 0.1 μm by sputtering. Next, using an etching solution of 6N hydrochloric acid (50 ° C.),
The O film was processed into a stripe shape having a width of 2 mm. This ITO
The substrate was subjected to UV / O ₃ cleaning. After that, it is installed in a vacuum evaporation apparatus, and evacuated using an oil diffusion pump equipped with a liquid nitrogen trap until the degree of vacuum in the apparatus becomes 10 ⁻⁴ Pa or less. Copper phthalocyanine shown in Chemical Formula 1 below was formed on a substrate to a thickness of 20 nm. At this time, the deposition rate was 0.3 nm / sec.

[0070]

Embedded image

Next, as an organic hole transporting material,
N, N′-diphenyl-N, N ′-(α-naphthyl) -1,1′-biphenyl-4,4′-diamine shown in (1) is placed in a ceramic crucible and heated with a tantalum wire heater around the crucible. And vapor deposition. At this time, the temperature of the crucible was controlled in the range of 160 to 170 ° C. The degree of vacuum at the time of vapor deposition was 10 ⁻⁴ Pa, the vapor deposition time was 3 minutes and 10 seconds, and the film thickness was 60 n.
m of the organic hole transport layer was obtained.

[0072]

Embedded image

Next, as a material for the electron transporting layer,
Aluminum 8-hydroxyquinoline complex Al
Using (C ₉ H ₆ NO) ₃ , vapor deposition was performed on the organic hole transport layer in the same manner. The temperature of the crucible at this time is 2
The temperature was controlled in the range of 30 to 270 ° C. The degree of vacuum during evaporation is 2
× 10 ^-6 torr, the deposition time was 3 minutes and 30 seconds, and the thickness of the obtained electron transport layer was 75 nm.

[0074]

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On the substrate on which the hole injection layer, the hole transport layer and the electron transport layer were formed, an alloy electrode of magnesium and silver (Mg:
(Ag = 10: 1.5 (atomic ratio)) was formed by vapor deposition to a film thickness of 40 nm by a dual simultaneous vapor deposition method. Vapor deposition was performed using a molybdenum board with a degree of vacuum of 2 ×.
The deposition was performed at 10 ⁻⁴ Pa and a deposition time of 4 minutes and 20 seconds to obtain a glossy film. Further, aluminum was deposited to a thickness of 40 nm as a protective layer.

When a DC voltage of 6 V was applied using the ITO electrode side of the obtained organic electroluminescent device as a positive electrode and the MgAg alloy film side as a cathode, a current of 4 mA / cm ² flowed to emit light. The luminance at that time was measured, and the results are shown in Table 1.

Example 2 A lens diameter and a lens portion shown in Table 1 were obtained in the same manner as in Example 1 except that a mold for a microlens array in which hemispherical concave portions having a diameter of 2 mm were arranged at a pitch of 2 mm was used. A microlens array sheet having a radius of curvature, a lens portion pitch, a thickness, a refractive index, and a specific gravity was obtained. An organic electroluminescent device was manufactured in the same manner, and the luminance was measured. The results are shown in Table 1.

Example 3 To 100 parts by weight of p-bis (β-methacryloyloxyethylthio) xylylene was added 2,4,6
0.1 parts by weight of trimethylbenzoyldiphenylphosphine oxide and 0.02 parts by weight of benzophenone were added, and the mixture was stirred and mixed uniformly. A negative mask pattern (a chrome vapor-deposited mask on a 1.5 mm thick glass plate) having a light transmitting portion with a diameter of 10 μm at a pitch of 20 μm as shown in 4 of FIG. And placed in a mold made of a transparent glass plate placed via a 1 mm thick silicon spacer. 8mW / output power 50cm above and below this mold
Among the high-pressure mercury lamps of cm ² , curing was performed by irradiating ultraviolet rays as scattered light from above through a negative mask pattern for 1 minute, and then simultaneously irradiating from above and below for 11 minutes. Thereafter, the demolded cured product is annealed at 120 ° C. for 1 hour, and a microlens array sheet having a convex surface on one side and having a lens diameter, a lens radius of curvature, a lens pitch, a thickness, a refractive index, and a specific gravity shown in Table 1 shown in Table 1. I got An organic electroluminescent device was manufactured in the same manner as in Example 1 except that this sheet was used as a substrate, and the luminance thereof was measured. The results are shown in Table 1.

Example 4 A lens diameter, a lens radius of curvature and a lens pitch shown in Table 1 were obtained in the same manner as in Example 3 except that a negative mask pattern having light transmitting portions having a diameter of 50 μm at a pitch of 80 μm was used. , A thickness, a refractive index and a specific gravity of a microlens array sheet were obtained. Except for using this sheet as a substrate, an organic electroluminescent device was manufactured in the same manner as in Example 1,
The luminance was measured and the results are shown in Table 1.

Example 5 A lens diameter, a lens radius of curvature, and a lens pitch shown in Table 1 were obtained in the same manner as in Example 3 except that a negative mask pattern having a light transmitting portion having a diameter of 100 μm at a pitch of 110 μm was used. , A thickness, a refractive index and a specific gravity of a microlens array sheet were obtained. An organic electroluminescent device was manufactured in the same manner as in Example 1 except that this sheet was used as a substrate, and the luminance thereof was measured. The results are shown in Table 1.

Example 6 A microlens array sheet was prepared in the same manner as in Example 3, and this sheet was coated on a 1000 μm-thick glass plate with the photocurable liquid monomer composition used in Example 3. On top of each other.
A laminated substrate having a lens diameter, a lens radius of curvature, a lens pitch, a thickness, a refractive index, and a specific gravity shown in Table 1 was manufactured. An organic electroluminescent device was manufactured in the same manner as in Example 1 except that this laminated substrate was used, and its luminance was measured. The results are shown in Table 1.

Example 7 In Example 3, after photo-curing, the chromium vapor deposition mask glass and the silicon spacer were removed.
A laminated substrate having a lens diameter, a lens radius of curvature, a lens pitch, a thickness, a refractive index, and a specific gravity shown in Table 1 in which a microlens array layer was laminated on a glass plate having a thickness of 1000 μm was manufactured. Example 1 except that this laminated substrate was used.
An organic electroluminescent device was manufactured in the same manner as in Example 1 and the luminance thereof was measured. The results are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that a glass plate having no smooth microlens array structure was used on both sides (thickness, refractive index and specific gravity are as shown in Table 1). Thus, an organic electroluminescent device was manufactured, and its luminance was measured. The results are shown in Table 1.

Comparative Example 2 100, parts by weight of p-bis (β-methacryloyloxyethylthio) xylylene was added with 2,4,6-
0.1 parts by weight of trimethylbenzoyldiphenylphosphine oxide and 0.02 parts by weight of benzophenone were uniformly stirred and mixed. This composition was poured into a mold of optically polished glass sandwiching a silicon spacer of 1 mm in thickness, and irradiated with ultraviolet rays for 5 minutes between metal halide lamps having an output of 80 W / cm ² above and below at a distance of 40 cm from the glass surface. The mold was removed, and an annealing treatment was performed at 120 ° C. for 1 hour.
The cured product thus formed without forming the microlens array structure was cut into a 25 mm × 75 mm glass slide to obtain a sheet having the thickness, refractive index and specific gravity shown in Table 1. An organic electroluminescent device was prepared in the same manner as in Example 1 except that this sheet was used as a substrate, and its luminance was measured. The results are shown in Table 1.

[0085]

[Table 1]

[0086]

As described above in detail, according to the organic electroluminescent device of the present invention, the light-collecting action of the substrate having the microlens array structure enables the high-luminance organic electroluminescent device without changing the driving voltage or the dye material. A light-emitting element can be realized. Therefore, the organic electroluminescent device of the present invention is an industrially extremely useful technique for providing a high-brightness, low-voltage flat panel display or the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a structure and a light condensing function of a substrate according to the present invention.

FIG. 2 is a perspective view illustrating an example of a method for forming a microlens array structure.

FIG. 3 is a schematic diagram illustrating a light beam emitted from a conventional substrate.

FIG. 4 is a schematic sectional view showing one embodiment of the organic electroluminescent device of the present invention.

FIG. 5 is a schematic sectional view showing another embodiment of the organic electroluminescent device of the present invention.

FIG. 6 is a schematic sectional view showing another embodiment of the organic electroluminescent device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Lens part 1A Microlens array structure 1B Glass plate 2 Light emitting part 3 Emitted light 4 Negative mask pattern 5 Photocurable liquid monomer composition 6 Anode 7 Organic light emitting layer 7a Hole transport layer 7b Electron transport layer 7c Hole Injection layer 8 Cathode 10, 10A, 10B Organic electroluminescent device

Claims (5)

[Claims] 1. An organic electroluminescent device in which an anode, an organic light emitting layer and a cathode are stacked on one plate surface of a substrate, wherein the substrate has a plastic microlens array structure. Electroluminescent device. 2. The organic electroluminescent device according to claim 1, wherein the microlens array structure is made of a photocurable resin. 3. The organic electroluminescent device according to claim 2, wherein the photo-curable resin is a photo-curable resin obtained by photo-curing a photo-curable liquid monomer containing a polyfunctional (meth) acrylate compound. 4. The microlens array structure is manufactured by exposure through a mask.
4. The organic electroluminescent device according to any one of items 3 to 3. 5. The organic electroluminescent device according to claim 1, wherein the substrate is formed by laminating a microlens array sheet on a glass substrate.