WO2011093120A1

WO2011093120A1 - Organic electroluminescene element and lighting device

Info

Publication number: WO2011093120A1
Application number: PCT/JP2011/050251
Authority: WO
Inventors: 恭雄當間; 邦雅檜山; 健夫荒井
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2010-01-26
Filing date: 2011-01-11
Publication date: 2011-08-04
Also published as: JP5655795B2; JPWO2011093120A1

Abstract

Disclosed are an electroluminescence element and a lighting device, wherein the electroluminescence element is formed by stacking an organic electroluminescence layer, comprising a transparent electroconductive layer and an electron transport layer, and an opposing electrode in sequence upon a transparent substrate. The transparent substrate comprises oxide nanoparticles with an average diameter between 1nm-20nm and a plastic upon at least one side of the transparent substrate; and further comprises a light-diffusion layer wherein an application fluid whereto a light-diffusing filler with an average particle diameter between 0.1µm-0.7µm is added to a composite material is coated, dried, and hardened, the post-hardening refraction thereof being between 1.65-1.80, inclusive, and the thickness of the electron transport layer is between 40-200nm.

Description

ORGANIC ELECTROLUMINESCENT ELEMENT AND LIGHTING DEVICE

The present invention relates to an organic electroluminescence element and a lighting device using the element.

There is an electroluminescence display (ELD) as a light-emitting electronic display device. As a component of ELD, an inorganic electroluminescent element and an organic electroluminescent element are mentioned. Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements. The organic electroluminescence device has a configuration in which a light emitting layer containing a compound that emits light (an organic compound thin film containing a fluorescent organic compound) is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer, It is an element that emits light by utilizing light emission (fluorescence / phosphorescence) when excitons (excitons) are generated by recombination and the excitons are deactivated. Usually, in order to utilize this light emission, a transparent conductive layer such as ITO is used for at least one of the electrodes sandwiching the organic compound thin film, and the transparent conductive layer is further supported by a transparent substrate such as glass.

Organic EL devices can emit light at a low voltage of several volts to several tens of volts, are self-luminous, have a wide viewing angle, high visibility, and are thin-film, completely solid-state devices that save space. It is attracting attention from the viewpoint of portability.

However, in the organic electroluminescence device for practical use in the future, it is desired to develop an organic electroluminescence device that emits light efficiently and with high luminance with low power consumption.

As one of the problems to be solved in order to improve the performance in the future, the organic electroluminescence device has a problem that the light extraction efficiency (the ratio of the energy coming out of the substrate to the emitted energy) is low. That is, the light emission of the light emitting layer is not directional and dissipates in all directions, so there is a large loss when guiding light forward from the light emitting layer, and there is a problem that the display screen becomes dark due to insufficient light intensity. .

The light emitted from the light emitting layer uses only the light emitted in the forward direction, but the light extraction efficiency (light emission efficiency) in the forward direction derived from multiple reflection based on classical optics is 1 / 2n ² . It can be approximated, and is almost determined by the refractive index n of the light emitting layer. If the refractive index of the light emitting layer is about 1.7, the light emission efficiency from the organic EL part is simply about 20%. The remaining light propagates in the area direction of the light emitting layer (spray in the lateral direction) or disappears at the metal electrode facing the transparent electrode with the light emitting layer interposed therebetween (absorption in the backward direction).

A variety of methods have been studied as methods for improving the light extraction efficiency.

For example, a method of forming a layer containing scattering particles and a low refractive index layer in a matrix having the same refractive index as that of the transparent electrode between the transparent electrode layer and the transparent body, and improving the light extraction efficiency by the light scattering effect ( For example, see Patent Document 1). This is a method using an inorganic compound such as titania as a high refractive index matrix, and there is no description of a light scattering layer made of a resin containing oxide nanoparticles and a light scattering filler in a resin matrix. Moreover, there was no description about the method of improving light extraction efficiency using a light-scattering layer with respect to the organic electroluminescent layer which shows the light distribution luminance characteristic which changes with light emission wavelengths.

On the other hand, a method of increasing the overall brightness by suppressing the brightness in the front direction of the element and increasing the brightness at an angle of 50 to 70 degrees is disclosed (for example, see Patent Document 2). However, since this method has a high luminance at a specific angle of 50 to 70 degrees, it is not suitable for a lighting device or the like that requires the same luminance in all directions, such as a light bulb. In addition, there is a problem that the light spectrum observed in the front direction and the oblique direction are different, and the color changes depending on the observation angle. In order to solve such a problem, a method is disclosed in which a selective reflection layer is formed on the light emission side and a change in color is suppressed by reflection of light of a specific wavelength (see, for example, Patent Document 3). However, this method improves the change in color depending on the viewing angle, but the luminance is reduced by the selective reflection layer, and this is used for an organic light emitting layer having different light distribution luminance characteristics depending on the emission wavelength. In such a case, the disadvantage that the brightness at a specific angle is high cannot be improved.

In addition, by using an organic light-emitting layer having different light distribution luminance characteristics depending on the emission wavelength, and providing a light-transmitting light collecting plate with unevenness on the surface of the light-transmitting substrate, the front luminance is increased. Although a method (see, for example, Patent Document 4) is disclosed, although high luminance is obtained by this method, a change in color depending on an observation angle and a variation in luminance occur. Therefore, as an organic EL element for white illumination, It was insufficient.

Japanese Patent No. 4186847 Japanese Patent No. 4350996 JP 2009-231257 A JP 2006-278137 A

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electroluminescent device that greatly improves light extraction efficiency and has small color change and luminance variation depending on an observation angle, and the device. It is in providing the used illuminating device.

As a result of intensive studies on the above problems, the inventors of the present invention have an average particle size of 0.1 μm or more and 0.7 μm in an organic-inorganic composite material having a refractive index of 1.65 or more and 1.80 or less (hereinafter referred to as composite material). High light extraction efficiency, which was difficult in the prior art, by forming an organic light-emitting layer with different light distribution luminance characteristics depending on the emission wavelength on a transparent substrate on which a light-scattering layer containing the following light-scattering filler was formed And the suppression of changes in color and brightness depending on the observation angle.

Therefore, the present invention is achieved by the following configuration.

1. In an organic electroluminescence device in which a transparent conductive layer, an organic electroluminescence layer having an electron transport layer, and a counter electrode are sequentially laminated on a transparent substrate, the transparent substrate is an oxide having an average particle diameter of 1 nm to 20 nm on at least one surface. An organic-inorganic composite material composed of nanoparticles and a resin material precursor, and having a refractive index of 1.65 to 1.80 after curing, has an average particle size of 0.1 μm to 0 μm. An organic layer characterized in that it has a light scattering layer obtained by coating, drying and curing a coating solution to which a light-scattering filler of 7 μm is added, and the thickness of the electron transport layer is 40 to 200 nm Electroluminescence element.

2. 2. The organic electroluminescence device according to 1 above, wherein a difference in refractive index between the composite material of the light scattering layer and the light scattering filler is 0.2 to 0.3.

3. 3. An illuminating device using the organic electroluminescence element as described in 1 or 2 above.

According to the present invention, it is possible to obtain an organic electroluminescence element that is excellent for white illumination, with significantly improved light extraction efficiency compared to the prior art, small changes in color depending on the observation angle, and variations in luminance.

Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

Embodiments of an organic electroluminescence element (also referred to as an organic EL element) and a lighting device of the present invention will be described in detail below, but the contents described below are representative examples of the embodiment of the present invention. As long as the gist is not exceeded, it is not limited to these contents.

[Transparent substrate]
The organic EL device of the present invention is a composite having an oxide nanoparticle having an average particle diameter of 1 nm or more and 20 nm or less and a resin on at least one surface of a transparent substrate, and having a refractive index of 1.65 or more and 1.80 or less. The material has a light scattering layer containing a light scattering filler having an average particle size of 0.1 μm or more and 0.7 μm or less, and an electron transport layer having a film thickness of 40 nm or more and 200 nm or less. To do.

The transparent substrate is not particularly limited as long as it has high light transmittance. For example, a glass substrate, a resin substrate, a resin film, etc. are preferably mentioned in terms of excellent hardness as a base material and ease of film formation on the surface, but from the viewpoint of lightness and flexibility It is preferable to use a transparent resin film.

The transparent resin film that can be preferably used as the transparent substrate in the present invention is not particularly limited, and the material, shape, structure, thickness and the like can be appropriately selected from known ones. For example, polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, modified polyester, polyethylene (PE) resin films, polypropylene (PP) resin films, polystyrene resin films, polyolefin resin films such as cyclic olefin resins, Vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, polyamide resin Examples include films, polyimide resin films, acrylic resin films, triacetyl cellulose (TAC) resin films, and the like, but wavelengths in the visible range (380 to 78). If the resin film transmittance of 80% or more in nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

In the present invention, the refractive index of the transparent resin film is preferably 1.50 or more, more preferably 1.60 or more and 1.80 or less.

In the present invention, the thickness of the transparent resin film is preferably 50 μm or more and 250 μm or less, and more preferably 75 μm or more and 200 μm or less.

The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesion of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment.

Also, examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, epoxy copolymer and the like. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

The light scattering layer preferably has a small difference in refractive index from the transparent substrate, preferably a composite material having a refractive index of 1.65 or more and 1.80 or less, and more preferably a refractive index of 1.65 or more and 1.75. The following is more preferable.

The composite material referred to in the present invention refers to a composite of a resin, which is an organic material, and an inorganic material such as oxide nanoparticles. A so-called polymer nanocomposite material or polymer in which oxide nanoparticles are dispersed in the resin. Hybrid materials are preferably used.

Hereinafter, the composite material will be described in more detail.

The resin used for the composite material according to the present invention is not particularly limited, but it is preferable to use a curable resin in view of cost and convenience when forming the layer. The curable resin used in the present invention can be cured by any of ultraviolet and electron beam irradiation or heat treatment, and is mixed with oxide nanoparticles in an uncured state and then cured. As long as it forms a transparent resin composition, it can be used without particular limitation, and examples thereof include silicone resins, epoxy resins, vinyl ester resins, acrylic resins, allyl ester resins, and the like. The curable resin may be an actinic ray curable resin that is cured by being irradiated with ultraviolet rays or electron beams, or may be a thermosetting resin that is cured by heat treatment. Such types of resins can be preferably used, and acrylic resins can be particularly preferably used.

<Acrylic resin>
Examples of the raw material component of the acrylic resin include monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, fluorene acrylate, and N-vinylpyrrolidone. Alternatively, urethane (meth) acrylate, polyester (meth) acrylate, polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, isocyanuric acid modified di (or tri) Examples include polyfunctional monomers such as acrylate.

In the present invention, it is preferable to use a trifunctional or higher polyfunctional acrylate compound and a trifunctional or higher polyfunctional urethane acrylate compound.

<Oxide nanoparticles>
The oxide nanoparticles used in the composite material of the present invention are not particularly limited as long as the refractive index of the composite material can be adjusted to a target value, and absorption, emission, fluorescence, etc. occur in the wavelength region to be used. It is preferable to select and use those not present. In the present invention, the composite material formed in the organic EL element has a high light extraction effect due to its high transparency. Therefore, the oxide nanoparticles used in the present invention are 1 nm or more and 20 nm or less. Preferably there is. When the average particle size is less than 1 nm, it is difficult to disperse the particles and the desired performance may not be obtained. On the other hand, when the average particle diameter exceeds 20 nm, the resulting composite material layer may become turbid depending on the difference in refractive index, resulting in a decrease in transparency, and the oxide nanoparticles acting as an optical scatterer. Therefore, the average particle diameter is preferably 20 nm or less because the contribution to the adjustment of the target refractive index is small. Here, the average particle diameter refers to the volume average value of the diameter (sphere converted particle diameter) when each particle is converted into a sphere having the same volume.

The refractive index of the oxide nanoparticles used in the present invention is preferably higher than that of the resin, and the refractive index is preferably 1.6 or more and 2.5 or less.

As oxide nanoparticles, the elements constituting the oxide are Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb. 1 selected from the group consisting of Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and rare earth metals Metal oxide nanoparticles that are seeds or two or more metals can be used. Specifically, for example, titanium oxide (titania), zinc oxide, aluminum oxide (alumina), zirconium oxide, hafnium oxide, niobium oxide. Tantalum oxide, magnesium oxide, barium oxide, indium oxide, tin oxide, lead oxide, and double oxides composed of these oxides, lithium niobate, potassium niobate, lithium tantalate Um, magnesium aluminum oxide in (MgAl ₂ O ₄₎ or the like of the particles and composite particles, the refractive index are those satisfying 1.6.

Further, rare earth oxides can also be used as the metal oxide nanoparticles, specifically, scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, Examples also include terbium oxide, dysprosium oxide, holmium oxide, erbium oxide, thulium oxide, ytterbium oxide, and lutetium oxide.

In the present invention, particularly titanium oxide and zirconium oxide can be preferably used.

As a method for preparing oxide nanoparticles, it is possible to obtain fine particles by spraying and firing the raw material of oxide nanoparticles in a gas phase. Furthermore, a method of preparing particles using plasma, a method of ablating raw material solids with a laser or the like to make fine particles, a method of oxidizing evaporated metal gas to prepare fine particles, and the like can be suitably used. Further, as a method for preparing in the liquid phase, it is possible to prepare a dispersion of oxide nanoparticles dispersed almost as primary particles by using a sol-gel method using an alkoxide or chloride solution as a raw material. Alternatively, it is possible to obtain a dispersion having a uniform particle size by using a reaction crystallization method utilizing a decrease in solubility.

Although there is no restriction | limiting in particular about the filling rate to resin, When filling an oxide nanoparticle of 20 nm or less into resin, when ensuring moldability (fluidity, there is no crack), it is preferable that it is 30 volume% or less. . On the other hand, in order to change the optical physical properties (refractive index) by filling the oxide nanoparticles, a certain filling rate is required, so 5 volume% or more, further 10 volume% or more is preferable. The volume fraction of the oxide nanoparticles here is expressed by the formula (x / a) / when the specific gravity of the oxide nanoparticles is a, the content is x grams, and the total volume of the composite material produced is Y milliliters. It is obtained by Y × 100. The content of oxide nanoparticles can be determined by observing a semiconductor crystal image with a transmission electron microscope (TEM) (information on the semiconductor crystal composition can also be obtained by local elemental analysis such as EDX) or given resin composition It can be calculated from the contained mass of a predetermined composition obtained by elemental analysis of ash contained in the product and the specific gravity of crystals of the composition.

<Surface treatment agent>
Since it is necessary to mix the oxide nanoparticles with the resin uniformly, the oxide nanoparticles are preferably subjected to a surface treatment in order to increase the affinity with the resin. For the bonding between the necessary surface treating agent and the particle surface, the following introduction methods are conceivable, but not limited to them.

A. Physical adsorption (secondary binding activator treatment)
B. Utilization reaction of surface chemical species (covalent bond with surface hydroxyl group)
C. Surface introduction and reaction of active species (introduction of active sites such as radicals and graft polymerization, high energy ray irradiation and graft polymerization)
D. Resin coating (encapsulation, plasma polymerization)
E. Deposition immobilization (deposition of sparingly soluble organic acid salts)
Further specific examples are as follows.

(1) Silane coupling agent A condensation reaction or a hydrogen bond between a silanol group and a hydroxyl group on the particle surface is used. Examples include vinylsilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, and the like. Trimethylmethoxysilane, dimethyldimethoxysilane, methyltrimethoxy Silane, hexamethyldisilazane and the like are preferably used.

(2) Other coupling agents Titanate, aluminate, and zirconate coupling agents are also applicable. Further, zircoaluminate, chromate, borate, stannate, isocyanate and the like can be used. A diketone coupling agent can also be used.

(3) Surface adsorbents Alcohols, nonionic surfactants, ionic surfactants, carboxylic acids, amines and the like are applicable.

(4) Resin-based surface treatment After introducing active species to the particle surface by the methods (1) to (3) above, a method of providing a polymer layer on the surface by graft polymerization, or adsorbing a pre-synthesized polymer dispersant to the particle surface , There is a method of combining. In order to provide a polymer layer more firmly on the particle surface, graft polymerization is preferred, and grafting at a high density is particularly preferred.

<Production method of composite material>
In producing the composite material of the present invention, first, a resin containing fine particles (a molten state when a thermoplastic resin is used and an uncured state when a curable resin is used) is prepared. A composite material turns into a desired layer by apply | coating etc. on a base material.

In particular, when a curable resin is used as the resin, it may be prepared by mixing the curable resin dissolved in an organic solvent and the fine particles according to the present invention, or in a monomer solution that is one of the raw materials of the curable resin. It may be prepared by adding and mixing the fine particles according to the present invention and then polymerizing them. Alternatively, it may be prepared by melting an oligomer in which a monomer is partially polymerized or a low molecular weight polymer, and adding and mixing the fine particles according to the present invention thereto.

Examples of the organic solvent used herein include lower alcohols having about 1 to 4 carbon atoms, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as methyl acetate and ethyl acetate, hydrocarbons such as toluene and xylene, and the like. However, it is not particularly limited as long as it has a boiling point lower than that of the monomer and is compatible with these monomers.

In particular, in the present invention, a method of polymerizing after adding the fine particles according to the present invention to a monomer solution is preferable, and in particular, a highly viscous solution in which the monomer and the fine particles according to the present invention are mixed is given a share while cooling. Are preferably mixed. At this time, it is also important to adjust the viscosity so that the dispersion of the fine particles according to the present invention in the curable resin is optimized. Examples of the method for adjusting the viscosity include adjustment of the particle diameter, surface state, and addition amount of the fine particles according to the present invention, addition of a solvent and a viscosity modifier, and the fine particles according to the present invention are surface-modified depending on the structure. Since it is easy, an optimal kneading state can be obtained.

In the case of compounding by giving a share, the fine particles according to the present invention can be added in a powder or agglomerated state. Or it is also possible to add in the state disperse | distributed in the liquid. When adding in the state disperse | distributed in the liquid, it is preferable to deaerate after mixing.

In the case of adding in a dispersed state in the liquid, it is preferable to add the aggregated particles after dispersing them into the primary particles. Various dispersing machines can be used for dispersion, but a bead mill is particularly preferable. There are various kinds of beads, but those having a small size are preferable, and those having a diameter of 0.001 to 0.5 mm are particularly preferable.

The fine particles according to the present invention are preferably added in a surface-treated state. However, it is also possible to use a method such as an integral blend in which a surface treatment agent and fine particles are added at the same time to form a composite with a curable resin. Is possible.

《Light scattering filler》
The present invention provides a light-scattering filler having an average particle size of 0.1 μm or more and 0.7 μm or less in a composite material comprising oxide nanoparticles having a refractive index of 1.65 or more and 1.80 or less and a resin as a light scattering layer. One of the characteristics is to contain.

A light-scattering filler is a filler that has the function of multiple scattering of light that has entered the light-scattering layer. In the present invention, the light-scattering filler is particularly effective for light having different light distribution luminance characteristics depending on the emission wavelength. The particle size is preferably 0.1 μm or more and 0.7 μm or less in view of general scattering. If it is less than 0.1 μm, the effect is small because the intensity of scattered light is low with respect to all wavelengths, and if it exceeds 0.7 μm, the scattering intensity increases with light of all wavelengths. The desired effect cannot be obtained because it cannot be utilized well. In the present invention, when the luminance in the oblique direction of the short wavelength light is higher as the alignment luminance characteristic in the light emitting layer, the effect of uniformizing the color and luminance depending on the observation angle can be obtained by scattering blue light more strongly. Therefore, the particle size of the light scattering filler is more preferably 0.2 μm or more and 0.5 μm or less.

Further, the refractive index of the light scattering filler is preferably 0.01 or more so that the difference in refractive index from the composite material to be added is obtained, and is preferably 0.5 or less. In order to utilize the difference in scattering intensity depending on the wavelength of the present invention, it is particularly preferable that the refractive index difference with the composite material is 0.2 or more and 0.3 or less.

As the light-scattering filler used in the present invention, a known filler made of inorganic or polymer can be used. Examples of inorganic compounds include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, And calcium phosphate. Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Of these, the optical filler used in the present invention is preferably silica or acrylic resin from the viewpoint of the difference in refractive index from the composite material. Further, the addition amount of these light scattering fillers is preferably 1% by mass or more and 30% by mass or less, but may be adjusted according to the degree of light scattering.

In addition, the light scattering filler can be in any shape such as a sphere, needle shape, flat plate shape, etc., and further, the dispersibility in the resin can be improved by performing the same surface treatment as the above-mentioned inorganic nanoparticles. It is.

The film thickness of the light scattering layer of the present invention is preferably about 1 to 10 μm, more preferably 2 to 7 μm, as long as it can improve the light extraction efficiency by the light scattering filler and improve the angle dependency of chromaticity and luminance. preferable.

The light scattering layer of the present invention may be formed on at least one surface of the transparent substrate, and may be formed on the light incident side surface or the emission side surface with respect to the transparent substrate. It may be formed on both sides. When the light scattering layer is formed on both surfaces of the transparent substrate, it is preferable to appropriately adjust the addition amount of the light scattering filler so that the scattering intensity does not become too strong due to both light scattering layers. When the light scattering layer is formed only on one side of the transparent substrate, a resin layer not containing a light scattering filler is formed on the opposite surface, and one surface is warped when handled as a transparent substrate. It is preferable not to cause so-called curling. Furthermore, a layer having a function as a barrier coat layer or a hard coat layer can also be formed. As the resin layer not containing this light-scattering filler, if the difference in refractive index with the transparent base material is large, deterioration of light extraction due to interface reflection occurs. Therefore, the refractive index is the same as or slightly higher than that of the transparent base material. Preferably it is low.

In addition, when the light scattering layer of the present invention is formed on the surface on the light incident side with respect to the transparent substrate, a transparent conductive layer is formed thereon, so that a smoothing layer is formed on the light scattering layer. It is preferable to form. As the smoothing layer, it is only necessary to obtain a smoothness that does not cause a short circuit when a transparent conductive layer or an organic light emitting layer is formed on the surface, and a general resin can be used. Therefore, it is preferable to use a matrix resin for the light scattering layer.

<Formation of light scattering layer>
The light scattering layer used in the organic electroluminescence device of the present invention is formed on the transparent substrate by means such as coating. As a coating method, it can coat by well-known methods, such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, and an inkjet method.

The light scattering layer can be produced by a method such as curing by ultraviolet rays and heat, film formation by drying, curing by chemical reaction, or the like. When an ultraviolet curable resin is used, a light source for curing by a photocuring reaction to form a cured film layer can be used without limitation as long as it is a light source that generates ultraviolet rays. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. The irradiation conditions vary depending on individual lamps, irradiation of active rays, usually 5 ~ 500mJ / cm ^2, but preferably 5 ~ 150mJ / cm ^2, particularly preferably 20 ~ 100mJ / cm ^2.

[Layer structure of organic electroluminescence element]
One feature of the present invention is that an organic electroluminescence layer is formed on a transparent substrate having the light scattering layer having a high refractive index.

The organic electroluminescence layer as used herein refers to an anode buffer layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, a cathode buffer layer, or a portion between a transparent conductive layer and a counter electrode. Refers to the layer formed.

Although the organic electroluminescence layer of the present invention varies depending on the constituent materials, its refractive index is usually about 1.7. The film thickness of the organic electroluminescence layer is usually 0.05 μm or more and 0.5 μm or less, and preferably 0.1 μm or more and 0.2 μm or less in terms of light emission efficiency and stability.

In the present invention, it is preferable to form the film thickness of the electron transport layer in the organic electroluminescence layer in the range of 40 nm or more and 200 nm or less in order to improve the light extraction efficiency.

It is known that the light emission luminance characteristics in the light emitting layer are changed by changing the thickness of the electron transport layer in the organic electroluminescence layer. For example, in the case of an organic EL device that emits white light using three colors of red, green, and blue or other combinations in the light emitting layer as in the present invention, the emission luminance of each wavelength is adjusted by adjusting the film thickness of the electron transport layer, In addition, the luminance of the emitted light can be changed according to the outgoing angle.

In the present invention, the luminance ratio in an appropriate angle direction from the normal direction of the substrate is preferably larger in blue than in red or green, and in order to obtain such light distribution luminance characteristics, the film of the electron transport layer is used. The thickness is preferably 40 nm or more and 200 nm or less, and particularly preferably 50 nm or more and 100 nm or less. Here, when the thickness of the electron transport layer is less than 40 nm, the light distribution of each color becomes uniform, and the extraction efficiency of blue light having a particularly low emission luminance is lowered, which is not preferable. Further, even when the thickness of the electron transport layer exceeds 200 nm, the light distribution of each wavelength is made uniform, and the luminous efficiency is lowered due to the increase in the distance between the transparent conductive layer and the light emitting point. It is not preferable.

Regarding the above light distribution luminance characteristics, for example, when the light emission of the organic electroluminescence layer produced using a smooth substrate that does not cause light scattering or the like is observed, the luminance or chromaticity of the emitted light varies depending on the angle at which it is observed. Can be confirmed.

The transparent conductive layer of the present invention refers to a layer made of a transparent and conductive compound and acting as an electrode. The transparent conductive layer has a refractive index of 1.8 or more and 2.1 or less when a metal oxide material such as ITO is used by vapor deposition or sputtering. When the film thickness t2 of the transparent conductive layer is 0.05 μm or more and 0.15 μm or less and is formed by coating using metal nanowires or the like, the refractive index is 1.6 or more and 1.8 or less, and the film thickness t2 is Generally, it is 0.1 μm or more and 1 μm or less.

In the present invention, in order to efficiently move the light emitted from the organic electroluminescence layer to the light scattering layer, the refractive index of the transparent conductive layer is preferably close to 1.7. Therefore, the transparent conductive layer of the present invention is preferably formed by applying metal nanowires such as silver nanowires together with a conductive polymer material, and preferably has a refractive index of 1.6 or more and 1.8 or less. The film thickness is preferably 0.1 μm or more and 0.5 μm or less.

[Measurement method of refractive index]
In the present invention, a commonly used method can be used as a method for measuring the refractive index. For example, it can be obtained from the measurement result of the spectral reflectance of a spectrophotometer (such as U-4000 type manufactured by Hitachi, Ltd.) for a sample in which each layer is coated alone. After roughening the back surface, light absorption treatment is performed with a black spray to prevent light reflection on the back surface, and the reflectance in the visible light region (400 to 700 nm) is measured under the condition of regular reflection at 5 degrees. Can be obtained.

[Measurement method of film thickness]
In the present invention, a commonly used method can be used as a method of measuring the film thickness of each layer constituting the organic EL element. For example, the cross section of the organic EL element produced by laminating each layer can be obtained by photographing with a scanning electron microscope and measuring the film thickness.

[Transparent conductive layer]
As the transparent conductive layer in the organic EL device of the present invention, a material having a work function (4 eV or more) of a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material for forming the transparent conductive layer is preferably used. . Specific examples of such electrode substances include metals such as Au, and conductive light-transmitting materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, a material such as IDIXO (In ₂ O ₃ —ZnO) that can form an amorphous light-transmitting conductive film may be used. In the present invention, the transparent conductive layer is preferably used as an anode. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. The sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 50 to 200 nm.

In addition, the transparent conductive layer can be used in combination with other resins having a relatively low refractive index while having high conductivity, and contains metal nanowires that can be expected to improve light extraction efficiency due to the light scattering effect. It is preferable. Furthermore, since the strength of the transparent conductive layer is increased by the network structure of the metal nanowire and the durability of the organic EL element is improved, it is preferable to use the metal nanowire for the transparent conductive layer.

When using a metal nanowire in the present invention, in order to form a long conductive path with one metal nanowire and to express an appropriate light scattering property, the average length is preferably 3 μm or more. It is preferably 3 to 500 μm, particularly preferably 3 to 300 μm. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is small from a transparency viewpoint, On the other hand, the larger one is preferable from an electroconductive viewpoint. In the present invention, the average diameter of the metal nanowire is preferably 10 to 300 nm, and more preferably 30 to 200 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

There is no restriction | limiting in particular as a metal composition of the metal nanowire which concerns on this invention, Although it can comprise from the 1 type or several metal of a noble metal element and a base metal element, noble metals (for example, gold, platinum, silver, palladium, rhodium, (Iridium, ruthenium, osmium, etc.) and at least one metal belonging to the group consisting of iron, cobalt, copper, and tin is preferable, and at least silver is more preferable from the viewpoint of conductivity.

Moreover, in order to achieve both conductivity and stability (sulfurization and oxidation resistance of metal nanowires and migration resistance), it is also preferable that silver and at least one metal belonging to a noble metal other than silver are included. When the metal nanowire according to the present invention includes two or more kinds of metal elements, for example, the metal composition may be different between the inside and the surface of the metal nanowire, or the entire metal nanowire has the same metal composition. May be.

As a manufacturing method of Ag nanowire, Adv. Mater. , 2002, 14, 833-837; Chem. Mater. 2002, 14, 4736-4745, etc., as a method for producing Co nanowires, such as JP 2006-233252, etc. as a method for producing Au nanowires, and JP 2002-266007, etc., as a method for producing Cu nanowires. Reference can be made to Japanese Unexamined Patent Publication No. 2004-149871. In particular, Adv. Mater. And Chem. Mater. The method for producing Ag nanowires reported in (1) can be easily produced in an aqueous system, and since the conductivity of silver is the highest among metals, it is preferable as the method for producing metal nanowires according to the present invention. Can be applied.

In the present invention, the metal nanowires come into contact with each other to form a three-dimensional conductive network, exhibiting high conductivity, and allowing light to pass through the window of the conductive network where no metal nanowire exists. In addition, the light from the organic light emitting layer can be efficiently extracted by the scattering effect of the metal nanowires. If the metal nanowire is installed in the electrode part on the side close to the organic light emitting layer part, this scattering effect can be used more effectively, and this is a more preferable embodiment.

Also, by mounting metal nanowires, highly conductive electrodes can be completed by coating. Therefore, even if unevenness due to particles exists on the surface of the composite material layer, the unevenness can be relaxed, and the possibility of damaging the light emitting layer can be eliminated.

In the present invention, the refractive index of the transparent conductive layer is preferably 1.5 or more and 2.0 or less, more preferably 1.6 or more and 1.9 or less.

In the present invention, as described above, by optimizing the balance of the refractive index and thickness of the transparent conductive layer, organic electroluminescence layer, and transparent resin film, not only the conventionally known light extraction efficiency is improved. The film physical properties of the organic electroluminescence device having a fine film structure can be greatly improved.

[Organic electroluminescence device]
The preferable specific example of the layer structure of an organic electroluminescent element is shown below.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer preferably contains at least two kinds of light emitting materials having different emission colors, and a single layer or a light emitting layer comprising a plurality of light emitting layers A unit may be formed. The hole transport layer also includes a hole injection layer and an electron blocking layer.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

The structure of the light emitting layer according to the present invention is not particularly limited as long as the contained light emitting material satisfies the above requirements.

Also, there may be a plurality of layers having the same emission spectrum or emission maximum wavelength.

It is preferable to have a non-light emitting intermediate layer between each light emitting layer.

In the present invention, the total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in the field of this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.

The film thickness of each light emitting layer is preferably adjusted in the range of 1 to 50 nm, more preferably in the range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

For the production of the light emitting layer, a light emitting material or a host compound, which will be described later, is formed by forming a film by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, an ink jet method, or the like. it can.

In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.

In the present invention, the light emitting layer preferably contains a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emits light from the light emitting material.

As the host compound contained in the light emitting layer of the organic EL device according to the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.

As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. Moreover, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.

The host compound used in the present invention may be a conventionally known low molecular compound or a high molecular compound having a repeating unit, and a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). )But it is good.

As the known host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable. Here, the glass transition point (Tg) is a value determined by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579 No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. No. 2002-302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, and the like.

Next, the light emitting material will be described.

As the light-emitting material according to the present invention, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound or a phosphorescent compound) is used.

In the present invention, a phosphorescent material is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.), and the phosphorescence quantum yield is 0 at 25 ° C. A preferred phosphorescence quantum yield is 0.1 or more, although it is defined as 0.01 or more compounds.

The phosphorescent quantum yield can be measured by the method described in Spectra II, page 398 (1992 version, Maruzen) of Experimental Chemistry Lecture 4 of the 4th edition. The phosphorescence quantum yield in a solution can be measured using various solvents. However, when a phosphorescent material is used in the present invention, the phosphorescence quantum yield (0.01 or more) is achieved in any solvent. Just do it.

There are two types of light emission of the phosphorescent material. In principle, the carrier recombination occurs on the host compound to which the carrier is transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent material. Energy transfer type to obtain light emission from the phosphorescent light emitting material, and another one is that the phosphorescent light emitting material becomes a carrier trap, and recombination of carriers occurs on the phosphorescent light emitting material, and light emission from the phosphorescent light emitting material is obtained. Although it is a trap type, in any case, the excited state energy of the phosphorescent material is required to be lower than the excited state energy of the host compound.

The phosphorescent light-emitting material can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, and is preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferably, an iridium compound, an osmium compound, or a platinum compound (platinum complex compound), or a rare earth complex, and most preferably an iridium compound.

Fluorescent light emitters can also be used for the organic electroluminescence device according to the present invention. Representative examples of fluorescent emitters (fluorescent dopants) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Examples thereof include dyes, perylene dyes, stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

Conventionally known dopants can also be used in the present invention. For example, International Publication No. 00/70655 pamphlet, JP-A Nos. 2002-280178, 2001-181616, 2002-280179, 2001 -181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671, 2001-345183, 2002 No. 324679, International Publication No. 02/15645, JP 2002-332291, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572, JP 002-117978, 2002-338588, 2002-170684, 2002-352960, WO01 / 93642, JP2002-50483, 2002-1000047 No. 2002-173684, No. 2002-359082, No. 2002-17584, No. 2002-363552, No. 2002-184582, No. 2003-7469, No. 2002-525808. JP2003-7471, JP2002-525833A, JP2003-31366A, 2002-226495, 2002-234894, 2002-233506, 2002-2417. No. 1, No. 2001-319779, No. 2001-319780, No. 2002-62824, No. 2002-1000047, No. 2002-203679, No. 2002-343572, No. 2002-203678. Gazettes and the like.

In the present invention, at least one light emitting layer may contain two or more kinds of light emitting materials, and the concentration ratio of the light emitting materials in the light emitting layer may vary in the thickness direction of the light emitting layer.

《Middle layer》
In the present invention, a case where a non-light emitting intermediate layer (also referred to as an undoped region) is provided between the light emitting layers will be described.

In the case of having a plurality of light emitting layers, the non-light emitting intermediate layer is a layer provided between the light emitting layers.

The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 to 20 nm, and more preferably in the range of 3 to 10 nm to suppress interaction such as energy transfer between adjacent light emitting layers, and This is preferable because a large load is not applied to the voltage characteristics.

The material used for the non-light emitting intermediate layer may be the same as or different from the host compound of the light emitting layer, but may be the same as the host material of at least one of the adjacent light emitting layers. preferable.

The non-light-emitting intermediate layer may contain a non-light-emitting layer, a compound common to each light-emitting layer (for example, a host compound), and each common host material (where a common host material is used) Including the case where the physicochemical characteristics such as phosphorescence emission energy and glass transition point are the same, and the case where the molecular structure of the host compound is the same, etc.) The barrier is reduced, and the effect of easily maintaining the injection balance of holes and electrons even when the voltage (current) is changed can be obtained. Furthermore, by using a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer, device fabrication, which is a major problem in conventional organic EL device fabrication, is achieved. Complexity can also be eliminated.

In the case of using the organic EL element in the present invention, the host material is responsible for carrier transportation, and therefore a material having carrier transportation ability is preferable. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance between injection and transport of holes and electrons, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material.

On the other hand, in order to optimally adjust the injection balance of holes and electrons, it is also preferable that the non-light emitting intermediate layer functions as a blocking layer described later, that is, a hole blocking layer and an electron blocking layer. It is done.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

An injection layer is a layer provided between an electrode and an organic layer in order to reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
The blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film as described above. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and their forefront of industrialization” (published by NTT Corporation on November 30, 1998). There is a hole blocking (hole blocking) layer.

In a broad sense, the hole blocking layer has a function of an electron transport layer and is composed of a hole blocking material having a function of transporting electrons and having a remarkably small ability to transport holes, while transporting electrons. By blocking holes, the recombination probability of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed. The hole blocking layer is preferably provided adjacent to the light emitting layer.

On the other hand, the electron blocking layer, in a broad sense, has a function of a hole transport layer, and is made of a material having a function of transporting holes while having a remarkably small ability to transport electrons, while transporting holes. By blocking electrons, the probability of recombination of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transporting layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 to 30 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has either hole injection or transport or electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and also two described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

Also, JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. it can. The thickness of the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm, preferably 5 to 200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use a hole transport layer having a high p property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq ₃ ), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) Aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg Metal complexes replaced with Cu, Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Further, the distyrylpyrazine derivatives exemplified as the material of the light emitting layer can also be used as the electron transport material, and inorganic semiconductors such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer. It can be used as an electron transport material.

The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. The electron transport layer may have a single layer structure composed of one or more of the above materials.

It is also possible to use an electron transport layer having a high n property doped with impurities. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be produced.

《Counter electrode》
The counter electrode of the present invention refers to an electrode facing the transparent conductive layer. In the present invention, since the transparent conductive layer is mainly used as an anode, the following cathode can be used as the counter electrode. As the cathode, a material having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

In addition, a transparent or semi-transparent cathode can be produced by producing a conductive transparent material on the cathode after the metal is produced with a thickness of 1 nm to 20 nm on the cathode. An element in which both the anode and the cathode are transmissive can be manufactured.

[Method for manufacturing organic electroluminescence element]
The organic electroluminescence element of the present invention can be produced by sequentially forming a composite material layer, a transparent conductive layer, an organic electroluminescence layer, and a counter electrode on a transparent substrate.

<< Formation of transparent conductive layer >>
In the present invention, a transparent conductive layer can be formed using a desired electrode substance on a transparent substrate on which a light scattering layer is formed. For example, when ITO (indium oxide added with tin) is used as the electrode material, the transparent conductive layer can be formed by a method such as vapor deposition or sputtering. In addition, a transparent conductive layer can be formed from a material containing metal nanowires, a conductive polymer, or a transparent conductive metal oxide by a liquid phase film forming method such as a coating method or a printing method.

In the present invention, from the viewpoint of improving productivity, improving electrode quality such as smoothness and uniformity, and reducing environmental burden, a liquid conductive film forming method such as a coating method or a printing method is applied to a transparent conductive layer containing metal nanowires. It is preferable to form by. As coating methods, roll coating method, bar coating method, dip coating method, spin coating method, casting method, die coating method, blade coating method, bar coating method, gravure coating method, curtain coating method, spray coating method, doctor coating method Etc. can be used. As the printing method, a letterpress (letter) printing method, a stencil (screen) printing method, a lithographic (offset) printing method, an intaglio (gravure) printing method, a spray printing method, an ink jet printing method, and the like can be used. In addition, as necessary, physical surface treatment such as corona discharge treatment or plasma discharge treatment can be applied to the surface of the releasable substrate as a preliminary treatment for improving the adhesion and coating properties.

<< Formation of organic electroluminescence layer >>
In the present invention, an anode buffer layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, a layer formed between all or part of the cathode buffer layer and formed between the transparent conductive layer and the cathode. It is called an organic electroluminescence layer. As an example of a method for producing this organic electroluminescence layer, a method for producing an organic electroluminescence layer comprising a hole injection layer / a hole transport layer / a light emitting layer / a hole blocking layer / an electron transport layer will be described.

An organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are organic electroluminescence element materials, is formed on a transparent substrate on which a transparent conductive layer is formed.

As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are particularly preferable. Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C., a degree of vacuum of 10 ⁻⁶ to 10 ⁻² Pa, and a vapor deposition rate of 0.01 to It is desirable to select appropriately within the range of 50 nm / second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

<Formation of cathode>
After forming the above organic electroluminescence layer, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm. Is provided.

The desired organic electroluminescence element is obtained by the above steps. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

It is also possible to reverse the production order to produce a cathode, an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode in this order. When a DC voltage is applied to the multicolor liquid crystal display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

[Use]
The surface light emitter and the light emitting panel according to the present invention can be used as a display device, a display, and various light emitting sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. Although it is not limited to this, it can be effectively used for a backlight of a liquid crystal display device combined with a color filter and a light source for illumination.

[Lighting device]
The organic electroluminescent material according to the present invention can also be applied to an organic EL element that emits substantially white light as a lighting device. A plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing. The combination of a plurality of emission colors may include three emission maximum wavelengths of the three primary colors of blue, green, and blue, or two using the relationship of complementary colors such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

In addition, a combination of light emitting materials for obtaining a plurality of emission colors includes a combination of a plurality of phosphorescent or fluorescent materials (light emitting dopants), a light emitting material that emits fluorescent or phosphorescent light, and the light emission. Any combination of a dye material that emits light from the material as excitation light may be used, but in the white organic EL device according to the present invention, a method of combining a plurality of light-emitting dopants is preferable.

As a layer structure of the organic EL element for obtaining a plurality of emission colors, a method of having a plurality of emission dopants in one emission layer, a plurality of emission layers, and an emission wavelength of each emission layer. Examples thereof include a method in which different dopants are present, and a method in which minute pixels emitting light of different wavelengths are formed in a matrix.

In the white organic EL device according to the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

The light emitting material used for the light emitting layer is not particularly limited. For example, in the case of a backlight in a liquid crystal display element, the platinum complex according to the present invention is known so as to be suitable for the wavelength range corresponding to the CF (color filter) characteristics. Any one of the light emitting materials may be selected and combined to be whitened.

Thus, in addition to the display device and the display, the white light-emitting organic EL element is used as a liquid crystal display as a kind of lamp such as various light-emitting light sources and lighting devices, home lighting, interior lighting, and exposure light source. It is also useful for display devices such as device backlights.

In addition, backlights such as clocks, signboard advertisements, traffic lights, light sources such as optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processing machines, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

Hereinafter, although an example is given and the present invention is explained, the present invention is not limited to this.

Example 1
<< Production of Composite Material (Organic / Inorganic Composite Material) 1 >>
(Preparation of zirconia particles)
To a zirconium salt solution in which 2600 g of zirconium oxychloride octahydrate is dissolved in 40 l (liter) of pure water, 340 g of 28% ammonia water and 20 l of dilute ammonia water in pure water are added with stirring to obtain a zirconia precursor. A slurry was prepared.

Next, an aqueous sodium sulfate solution in which 400 g of sodium sulfate was dissolved in 5 l of pure water was added to the zirconia precursor slurry while stirring.

Next, this mixture was dried in the atmosphere at 120 ° C. for 24 hours using a dryer to obtain a solid.

Next, the solid was pulverized with an automatic mortar or the like and then baked at 500 ° C. for 1 hour in the air using an electric furnace. This fired product is put into pure water, stirred to form a slurry, washed using a centrifuge, sufficiently removed the added sodium sulfate, dried in a drier, and zirconia particles 1 was prepared. As a result of TEM observation, the average particle size was 5 nm. XRD confirmed that the particles were ZrO ₂ crystals.

(Surface treatment for zirconia particles)
While adding 10 g of the above-mentioned zirconia particles to 100 ml of toluene containing 2 g of phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical) and 0.1 g of methacryloxypropyltrimethoxysilane, while dispersing using 0.03 mm zirconia beads under nitrogen After heating to 100 ° C. to obtain a uniform dispersion, it was heated to reflux for 5 hours under nitrogen as it was to obtain a toluene dispersion of surface-treated zirconia particles.

(Particle dispersion in resin)
70 ml of curable resin monomer (fluorene acrylate) and 30 ml of the above surface-treated zirconia dispersion (amount that gives a desired refractive index) are mixed, 0.4 g of Irgacure 184 is added as a polymerization initiator and dissolved, and composite material 1 is dissolved. Obtained.

(Composite material evaluation)
The obtained composite material 1 was applied onto a smooth glass substrate so as to have a dry film thickness of 1 μm, and cured by irradiating with ultraviolet rays to prepare a sample in which a thin film layer was formed. As a result of measuring this sample with a spectrophotometer (such as U-4000 type manufactured by Hitachi, Ltd.), the refractive index was 1.75.

Further, the thin film layer was observed with a scanning electron microscope, and the spherical equivalent particle diameter of each particle was obtained from the projected area of 200 particles of zirconia nanoparticles, and the average value was obtained. As a result, the average particle diameter of the zirconia nanoparticles dispersed in the thin film was 6 nm.

<< Production and Evaluation of Composite Material 2 >>
The composite material 2 was produced by changing the addition amount of the dispersion liquid of the zirconia particles 1 to 10% by volume in the same manner as the production of the composite material 1. The refractive index and the average particle diameter of the zirconia nanoparticles were measured by the same method as for the composite material 1. As a result, the refractive index was 1.65, and the average particle diameter of the zirconia nanoparticles was 6 nm.

<< Production and Evaluation of Composite Material 3 >>
In the same manner as the preparation of the zirconia particles 1 described above, the concentration of the sodium sulfate aqueous solution during particle formation was adjusted to prepare zirconia particles 2 having an average particle diameter of 25 nm. Then, the composite material 3 which mixed 30 volume% of dispersion liquids of the zirconia particle 2 with the method similar to preparation of the composite material 1 was produced. The refractive index and the average particle diameter of the zirconia nanoparticles were measured by the same method as for the composite material 1. As a result, the refractive index was 1.72, and the average particle diameter of the dispersed zirconia nanoparticles was 28 nm.

<< Production and Evaluation of Composite Material 4 >>
A composite material 4 in which titania nanoparticles were dispersed was produced in the same manner as the production method of the composite material 1. The obtained resin monomer solution in which titania nanoparticles were dispersed was applied on a smooth glass substrate so as to have a dry film thickness of 1 μm, cured by irradiation with ultraviolet rays, and evaluated in the same manner as in the composite material 1. . As a result, the refractive index was 1.74, and the average particle diameter of the dispersed titania nanoparticles was 18 nm.

<< Production and Evaluation of Composite Material 5 >>
In the method for producing the composite material 4, the amount of titania nanoparticles added was adjusted, and the composite material 5 was produced. The obtained resin monomer solution in which titania nanoparticles were dispersed was applied on a smooth glass substrate so as to have a dry film thickness of 1 μm, cured by irradiation with ultraviolet rays, and evaluated in the same manner as in the composite material 1. . As a result, the refractive index was 1.80, and the average particle diameter of the dispersed titania nanoparticles was 18 nm.

<< Evaluation of Comparative Resin A >>
A resin monomer solution in which a polymerization initiator is dissolved in a curable resin monomer (fluorene acrylate) is applied on a smooth glass substrate so as to have a dry film thickness of 1 μm, and cured by irradiation with ultraviolet rays. A sample on which a thin film layer was formed was prepared. As a result of evaluating the obtained sample by the same method, it was resin which does not contain the inorganic nanoparticle whose refractive index is 1.61.

Table 1 shows the evaluation results of the above thin film layers.

<< Preparation of transparent substrate 1 >>
The composite material 1 described above was applied to both sides of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index: 1.75) so that the dry film thickness would be 3 μm, respectively, and then irradiated with ultraviolet rays. Cured.

<< Preparation of transparent substrate 2 >>
The composite material 1 is applied to one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index 1.75) so that the dry film thickness is 3 μm and cured by irradiating with ultraviolet rays. Let this side be the surface. Furthermore, after adding 20% by mass of silica particles KE-P30 (average particle size 0.3 μm) manufactured by Nippon Shokubai Co., Ltd. to the composite material 1, ultrasonic dispersion is performed to obtain a resin solution 1A containing a light scattering filler. It was prepared, applied to the back surface of the PEN film so that the dry film thickness was 3 μm, and cured by irradiation with ultraviolet rays.

<< Preparation of transparent substrate 3 >>
The above-mentioned composite material 2 is applied to one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index: 1.75) so as to have a dry film thickness of 3 μm and cured by irradiating with ultraviolet rays. Let this side be the surface. Furthermore, after adding 20% by mass of silica particles KE-P30 (average particle size 0.3 μm) manufactured by Nippon Shokubai Co., Ltd. to the composite material 2, ultrasonic dispersion is performed to obtain a resin solution 2A containing a light scattering filler. It was prepared, applied to the back surface of the PEN film so that the dry film thickness was 3 μm, and cured by irradiation with ultraviolet rays.

<< Preparation of transparent substrate 4 >>
The composite material 3 described above is applied to one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index 1.75) so that the dry film thickness is 3 μm and cured by irradiating with ultraviolet rays. Let this side be the surface. Furthermore, after adding 20% by mass of silica particles KE-P30 (average particle size 0.3 μm) manufactured by Nippon Shokubai Co., Ltd. to the composite material 3, ultrasonic dispersion is performed to obtain a resin solution 3A containing a light scattering filler. It was prepared, applied to the back surface of the PEN film so that the dry film thickness was 3 μm, and cured by irradiation with ultraviolet rays.

<< Preparation of transparent substrate 5 >>
On one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index 1.75), the above-mentioned comparative resin A is applied so as to have a dry film thickness of 3 μm and irradiated with ultraviolet rays. Cured. Furthermore, after adding 20% by mass of silica particles KE-P30 (average particle size: 0.3 μm) manufactured by Nippon Shokubai Co., Ltd. to Comparative Resin A, ultrasonic dispersion is performed to obtain a resin solution AA containing a light scattering filler. Was applied to the surface opposite to the side where the comparative resin A for PEN film was applied so that the dry film thickness was 3 μm, and cured by irradiating with ultraviolet rays.

<< Preparation of transparent substrate 6 >>
After adding 20% by mass of silica particles KE-P30 (average particle size 0.3 μm) manufactured by Nippon Shokubai Co., Ltd. to the composite material 4, ultrasonic dispersion is performed to prepare a resin solution 4A containing a light scattering filler. This was applied to one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index 1.75) so as to have a dry film thickness of 5 μm, and cured by irradiating with ultraviolet rays. Further, the composite material 4 was further applied as a smoothing layer so that the dry film thickness was 4 μm, and cured by irradiating with ultraviolet rays. Thereafter, the composite material 4 was applied to the opposite surface of the PEN film so as to have a dry film thickness of 4 μm, and cured by irradiation with ultraviolet rays.

<< Preparation of transparent substrate 7 >>
After adding 20% by mass of silica particles SO-E2 (average particle size 0.5 μm) manufactured by Admatechs Co., Ltd. to the composite material 4, ultrasonic dispersion is performed to prepare a resin solution 4B containing a light scattering filler. In the production of the transparent substrate 6, the transparent substrate 7 was produced in the same manner except that the resin solution 4A was changed to the resin solution 4B.

<< Preparation of transparent substrate 8 >>
After adding 20% by mass of PMMA particles XX-1973Z (average particle size 0.1 μm) manufactured by Sekisui Chemical Co., Ltd. to the composite material 4, ultrasonic dispersion is performed to prepare a resin solution 4C containing a light scattering filler. In the production of the transparent substrate 6, the transparent substrate 8 was produced in the same manner except that the resin solution 4A was changed to the resin solution 4C.

<< Preparation of transparent substrate 9 >>
After adding 20% by mass of silica particles SO-E3 (average particle size: 1.0 μm) manufactured by Admatex Co., Ltd. to the composite material 4, ultrasonic dispersion is performed to prepare a resin solution 4D containing a light scattering filler. In the production of the transparent substrate 6, the transparent substrate 9 was produced in the same manner except that the resin solution 4A was changed to the resin solution 4D.

<< Preparation of transparent substrate 10 >>
After adding 20% by mass of silica particles RX-50 (average particle size 0.04 μm) manufactured by Nippon Aerosil Co., Ltd. to composite material 4, ultrasonic dispersion was performed to prepare resin solution 4E containing a light scattering filler. In the production of the transparent substrate 6, the transparent substrate 10 was produced in the same manner except that the resin solution 4A was changed to the resin solution 4E.

<< Preparation of transparent substrate 11 >>
After adding 20% by mass of alumina particles AO-802 (average particle size 0.7 μm) manufactured by Admatechs Co., Ltd. to composite material 2, ultrasonic dispersion is performed to prepare resin solution 2B containing a light scattering filler. This was applied to one side of a 125 μm thick biaxially stretched PEN film (manufactured by Teijin DuPont; refractive index 1.75) so as to have a dry film thickness of 5 μm, and cured by irradiating with ultraviolet rays. Further, the composite material 2 was further applied as a smoothing layer so that the dry film thickness was 4 μm, and cured by irradiating with ultraviolet rays. Thereafter, the composite material 2 was applied to the opposite surface of the PEN film so as to have a dry film thickness of 4 μm, and cured by irradiation with ultraviolet rays.

<< Preparation of transparent substrate 12 >>
After adding 20% by mass of silica particles KE-P30 (average particle size 0.3 μm) to the composite material 5, ultrasonic dispersion is performed to prepare a resin solution 5A containing a light-scattering filler, which has a thickness of 125 μm. A biaxially stretched PEN film (manufactured by Teijin DuPont Co., Ltd .; refractive index 1.75) was applied to a dry film thickness of 5 μm and cured by irradiating with ultraviolet rays. Further, the composite material 5 was further applied as a smoothing layer so that the dry film thickness was 4 μm, and cured by irradiating with ultraviolet rays. Thereafter, the composite material 5 was applied to the opposite surface of the PEN film so as to have a dry film thickness of 4 μm, and was cured by irradiation with ultraviolet rays.

<< Production of Organic EL Element 1 >>
100 nm of ITO (indium tin oxide; refractive index 1.85) was formed on one surface of the transparent substrate 1 and patterned. The transparent substrate 1 provided with the ITO transparent electrode was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes. On top of this, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS, Bayer, Baytron P Al 4083) to 70% with pure water is spun at 3000 rpm for 30 seconds. Then, the substrate was dried at a substrate surface temperature of 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 30 nm.

This substrate was transferred to a glove box in accordance with JIS B 9920 under a nitrogen atmosphere, with a measured cleanliness of class 100, a dew point temperature of −80 ° C. or lower, and an oxygen concentration of 0.8 ppm. A coating solution for a hole transport layer was prepared as follows in a glove box, and applied with a spin coater under conditions of 1500 rpm and 30 seconds. This substrate was dried by heating at a substrate surface temperature of 150 ° C. for 30 minutes to provide a hole transport layer. The film thickness was 20 nm when it apply | coated and measured on the conditions with the board | substrate prepared separately.

(Coating liquid for hole transport layer)
Monochlorobenzene 100g
Poly-N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) benzidine (ADS254BE: manufactured by American Die Source)
0.5g
Subsequently, the light emitting layer coating liquid was prepared as follows, and it apply | coated on 2000 rpm and the conditions for 30 seconds with the spin coater. Furthermore, it heated at the substrate surface temperature of 120 degreeC for 30 minutes, and provided the light emitting layer. When the coating was performed under the same conditions on a separately prepared substrate and measured, the film thickness was 40 nm. Of the following light emitting layer compositions, HA showed the lowest Tg, which was 132 ° C.

(Light emitting layer coating solution)
Butyl acetate 100g
HA 1g
DA 0.11g
DB 0.002g
DC 0.002g
Subsequently, the coating liquid for electron carrying layers was prepared as follows, and it apply | coated on the conditions of 1500 rpm and 30 seconds with a spin coater. Furthermore, it heated for 30 minutes at the substrate surface temperature of 120 degreeC, and provided the electron carrying layer. The film thickness was 30 nm when it applied and measured on the conditions prepared with the board | substrate prepared separately.

(Coating liquid for electron transport layer)
2,2,3,3-tetrafluoro-1-propanol 100g
ET-A 0.75g
Next, the substrate provided up to the electron transport layer was moved to a vapor deposition machine without being exposed to the atmosphere, and the pressure was reduced to 4 × 10 ⁻⁴ Pa. Note that potassium fluoride and aluminum were each placed in a tantalum resistance heating boat and attached to a vapor deposition machine.

First, a resistance heating boat containing potassium fluoride was energized and heated to provide a 3 nm electron injection layer made of potassium fluoride on the substrate. Subsequently, a resistance heating boat containing aluminum was energized and heated, and a cathode having a thickness of 100 nm made of aluminum was provided at a deposition rate of 1 to 2 nm / second.

When the cross section of the obtained organic EL element 1 was observed with a scanning electron microscope, the thickness of the organic electroluminescence layer was 0.12 μm, and the thickness of the transparent conductive layer was 0.1 μm.

<< Production of Organic EL Element 2 >>
An ITO transparent conductive layer, an organic electroluminescence layer, and a cathode were formed by the same method as the production of the organic EL element 1. At that time, only the coating condition of the electron transport layer was changed, and the film thickness of the electron transport layer was adjusted to 70 nm.

<< Production of Organic EL Element 3 >>
An ITO transparent conductive layer, an organic electroluminescence layer, a cathode, and a light extraction member are formed on the surface of the transparent substrate 2 in the same manner as in the production of the organic EL element 1, and the organic electroluminescence layer is arranged in an almost equivalent manner according to the emission wavelength. An organic EL element 3 having light luminance characteristics was produced.

<< Production of Organic EL Element 4 >>
An ITO transparent conductive layer, an organic electroluminescence layer, a cathode, and a light extraction member are formed on the surface of the transparent substrate 2 in the same manner as the production of the organic EL element 2, and the light distribution luminance of the organic electroluminescence layer varies depending on the emission wavelength. An organic EL element 4 having characteristics was produced.

<< Preparation of organic EL elements 5-14 >>
An ITO transparent conductive layer, an organic electroluminescence layer, a cathode, and a light extraction member were formed on the surfaces of the transparent substrates 3 to 12 in the same manner as in the production of the organic EL element 2, and organic EL elements 5 to 14 were produced.

<< Preparation of organic EL elements 15-17 >>
An ITO transparent conductive layer, an organic electroluminescence layer, and a cathode were formed on the surface of the transparent substrate 6 by the same method as the production of the organic EL element 2. At that time, only the coating conditions of the electron transport layer were changed, and the film thickness of the electron transport layer was adjusted to the value shown in Table 2, to obtain organic EL elements 15 to 17.

<< Evaluation of organic EL elements >>
[External extraction quantum efficiency]
With respect to the produced organic EL element, the external extraction quantum efficiency (%) when a constant current of ^2.5 mA / cm ² was passed was measured under an inert gas atmosphere. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used. The obtained results are shown in Table 2 as relative values when the measured value of the organic EL element 1 is 100.

[Light distribution luminance characteristics]
The produced organic EL device is set in a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing), and the organic EL device emits light and changes the angle with respect to the normal direction, and the luminance and spectral spectrum at each tilt angle. Were measured, and light distribution luminance characteristics in red of wavelength 620 nm, green of wavelength 525 nm, and blue of wavelength 458 nm were obtained. When the front luminances of red, green, and blue in the normal direction are each 1, the relative luminances of red, green, and blue in directions inclined by 30 degrees, 45 degrees, and 60 degrees with respect to the normal direction And is shown in Table 2. When the relative luminance value is in the range of 0.95 to 1.05, changes in luminance and chromaticity are not visually recognized, and it is favorable as white illumination.

The obtained results are shown in Table 2.

In Table 2, the refractive index of the matrix resin is the refractive index of the cured film of the composite material used for each light scattering layer, to which no light scattering layer filler is added. Moreover, the refractive indexes of the used silica, PMMA, and alumina are 1.45, 1.49, and 1.76, respectively.

From Table 2, it can be seen that the organic electroluminescence device having the configuration of the present invention has a high external extraction quantum efficiency, a small luminance and color change depending on the observation angle, and is excellent as white illumination.

Example 2
The organic EL element 8 of the present invention produced in Example 1 was covered with a glass case to obtain a lighting device. The glass cover was filled with nitrogen gas, and a water capturing agent was provided in the glass cover on the side opposite to the light emitting surface.

The lighting device according to the present invention has high luminous efficiency and can be used as a thin lighting device that emits white light with a long light emission lifetime.

Example 3
The organic EL element 8 of the present invention produced in Example 1 was covered with a transparent barrier film (transparent resin film coated with a silicon dioxide film) to obtain a flexible lighting device. The illuminating device according to the present invention can be used as a thin illuminating device that emits white light having a long emission life while maintaining high luminous efficiency even with some bending motion.

Claims

In an organic electroluminescence device in which a transparent conductive layer, an organic electroluminescence layer having an electron transport layer, and a counter electrode are sequentially laminated on a transparent substrate, the transparent substrate is an oxide having an average particle diameter of 1 nm to 20 nm on at least one surface. An organic-inorganic composite material composed of nanoparticles and a resin material precursor, and having a refractive index of 1.65 to 1.80 after curing, has an average particle size of 0.1 μm to 0 μm. An organic layer characterized in that it has a light scattering layer obtained by coating, drying and curing a coating solution to which a light-scattering filler of 7 μm is added, and the thickness of the electron transport layer is 40 to 200 nm Electroluminescence element.
2. The organic electroluminescence device according to claim 1, wherein the refractive index difference between the composite material of the light scattering layer and the light scattering filler is 0.2 to 0.3.
An illuminating device using the organic electroluminescence element according to claim 1 or 2.