JP2014199274A - Laminate and organic electroluminescent device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate that has increased durability, has increased light extraction efficiency, and contributes to the suppression of the occurrence of stains and unevenness.SOLUTION: The laminate has, in this order, a substrate, a light diffusion layer containing light diffusion particles and a binder containing a (meth)acrylate resin, and a flattening layer containing a binder containing a (meth)acrylate resin, wherein the degree of polymerization of the light diffusion layer is 30 to 65% inclusive, and the degree of polymerization of the flattening layer is at least 50%.

Description

  The present invention relates to a laminate and an organic electroluminescent device.

  An organic electroluminescent device has a structure having an organic light emitting layer between a pair of electrodes, is a self-luminous display device, and is expected for use in displays and illumination. For example, an organic electroluminescent display has advantages in display performance such as higher visibility than conventional CRTs and LCDs and no viewing angle dependency. In addition, there is an advantage that the display can be made lighter and thinner. On the other hand, in addition to the advantages that organic electroluminescence lighting can be reduced in weight and thickness, it has the potential to realize illumination in a shape that could not be realized by using a flexible substrate. Yes.

  In order to improve the light extraction efficiency, an organic electroluminescence device having a light extraction member made of a laminate having a substrate, a light diffusion layer, and a planarization layer in this order is known (for example, Patent Documents 1 to 3). The light diffusing layer is a layer containing light diffusing particles having an average particle size of micron order and a binder. Light emitted from the organic light emitting layer side is scattered by the light diffusing particles and diffused to the light extraction side, thereby The extraction efficiency can be improved. The planarization layer is provided to flatten the surface when the surface of the light diffusion layer has an uneven shape, and serves to facilitate the subsequent steps such as the electrode formation process.

JP 2012-155177 A JP 2009-76452 A JP 2012-221604 A

However, in an organic electroluminescent device, when a (meth) acrylic resin obtained by polymerizing a (meth) acrylate monomer is used as a binder for the light diffusion layer, the light extraction efficiency is reduced and there are many dark portions on the light emitting surface. There is a problem in that it is undesirable in appearance because it causes a brightness difference with a brightly shining portion and is visually recognized as spots or unevenness. This spot / unevenness is more noticeable when driving for a long time.
The inventors of the present invention have studied the solution of the above problem and found that the degree of polymerization of the light diffusion layer and the planarization layer is related.
According to the study by the present inventors, since there are light diffusing particles in the light diffusing layer, when the degree of polymerization is too high when the (meth) acrylate monomer undergoes volume shrinkage due to polymerization, the light diffusing particles and the binder It was found that stress was generated at the interface of the film and the film became brittle, and a gap was formed between the light diffusing particles and the binder, so that the light extraction efficiency was lowered, and the above-mentioned spots and unevenness appeared.
On the other hand, since the planarization layer on the light diffusion layer does not contain light diffusion particles, the film does not become brittle even when the degree of polymerization increases. Further, the planarization layer needs to have a sufficiently high degree of polymerization so that it can withstand plasma and sputter damage when an anode such as ITO is formed thereon, and further, patterning by photolithography. When the degree of polymerization of the planarization layer is too low, the process resistance of patterning by photolithography is low, or the ITO surface becomes rough due to damage during film formation of an anode such as ITO, and the above-mentioned spots and unevenness appear over time. .
In order to increase the degree of polymerization of the planarizing layer, heating or UV irradiation may be performed even after the light diffusing layer / planarizing layer is formed. At this time, the light diffusing layer as the base further undergoes polymerization, causing spots and unevenness. However, it becomes even more prominent when driven for a long time.

Therefore, an organic electroluminescent device that has high light extraction efficiency and no spots or unevenness on the light emitting surface is desired.
An object of this invention is to provide the laminated body which contributes to durability improvement, the improvement of light extraction efficiency, and suppression of generation | occurrence | production of a spot and nonuniformity. Another object of the present invention is to provide an organic electroluminescent device that has high durability, high light extraction efficiency, and no spots or unevenness.

  Means for solving the problems are as follows.

[1]
A laminate having a substrate, a light diffusion layer containing a binder containing (meth) acrylic resin and light diffusing particles, and a planarization layer containing a binder containing (meth) acrylic resin in this order, A laminate in which the diffusion layer has a polymerization degree of 30% to 65% and the planarization layer has a polymerization degree of 50% or more.
[2]
The laminate according to [1], wherein the light diffusion particles in the light diffusion layer have an average particle size of 0.5 μm to 10 μm.
[3]
The laminate according to [1] or [2], wherein the volume shrinkage of the binder in the light diffusion layer is 2% or less.
[4]
The light diffusion layer is formed from a composition for forming a light diffusion layer containing a (meth) acrylate monomer, a light diffusion particle, and a polymerization initiator,
The planarization layer is formed from a planarization layer-forming composition containing a (meth) acrylate monomer and a polymerization initiator,
The blending ratio of the polymerization initiator in the composition for forming a light diffusion layer is 3% by mass or less with respect to the (meth) acrylate monomer,
The laminated body in any one of [1]-[3] whose compounding ratio of the polymerization initiator in the composition for planarization layer formation is 3 mass% or less with respect to a (meth) acrylate type monomer.
[5]
The laminate according to any one of [1] to [4], wherein the light diffusion particles are crosslinked (meth) acrylic resin particles.
[6]
The said light-diffusion layer and the said planarization layer are laminated bodies in any one of [1]-[5] containing the titanium oxide microparticles | fine-particles which carried out the photocatalyst inactivation processing further.
[7]
[1] to [6] The organic electroluminescent device having the laminated body according to any one of [1] to [6] and a first electrode, an organic light emitting layer, and a second electrode in this order on the planarization layer side of the laminated body. .

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body which contributes to durability improvement, the improvement of light extraction efficiency, and suppression of generation | occurrence | production of a spot and nonuniformity can be provided. In addition, according to the present invention, it is possible to provide an organic electroluminescence device that has high durability, high light extraction efficiency, and no spots or unevenness.

It is a schematic diagram which shows an example of the laminated body of this invention. It is a schematic diagram which shows an example of the organic electroluminescent apparatus of this invention.

(Laminate)
The laminate of the present invention is a laminate having a substrate, a binder containing (meth) acrylic resin and a light diffusing layer containing light diffusing particles, and a planarizing layer containing a binder in this order. The degree of polymerization of the layer is 30% or more and 65% or less, and the degree of polymerization of the planarizing layer is 50% or more.
FIG. 1 is a schematic view showing an example of a laminate of the present invention. The laminated body 10 in FIG. 1 has a light diffusion layer 2 and a planarizing layer 3 on a substrate 1.

<Light diffusion layer>
The light diffusion layer of the laminate of the present invention contains at least a binder containing (meth) acrylic resin and light diffusion particles.

<< Binder >>
The binder of the light diffusion layer contains a (meth) acrylic resin. The “(meth) acrylic resin” is a concept including both “acrylic resin” and “methacrylic resin”. The (meth) acrylic resin also includes acrylate / methacrylate derivatives, particularly acrylate / methacrylate (co) polymers. The same applies to “(meth) acrylate monomers” and the like.
The (meth) acrylic resin is preferably formed by polymerizing a (meth) acrylate monomer.
The repeating unit of the (meth) acrylic resin is not particularly limited. The (meth) acrylic resin preferably has a repeating unit derived from a (meth) acrylic acid ester monomer as a repeating unit.
The binder of the light diffusion layer is preferably a material having a large refractive index from the viewpoint of light extraction efficiency. The refractive index of the binder is preferably in the range of 1.4 to 1.9, more preferably 1.5 to 1.85, and still more preferably 1.55 to 1.80. If the refractive index of a binder is the said range, the quantity of the below-mentioned titanium oxide fine particle added for refractive index adjustment can be decreased. It is preferable to add a small amount of titanium oxide fine particles because the titanium oxide fine particles are unlikely to be scattered or absorbed and the strength of the film is easily maintained.

The volume shrinkage ratio of the binder of the light diffusion layer is preferably 2% or less, and more preferably 1% or less.
Here, the volumetric shrinkage of the binder means the rate of change of the volume of the binder (polymer) after curing with respect to the binder (monomer) before polymerization.
When the volume shrinkage of the binder is 2% or less, it is preferable because no gap is generated between the light diffusion particles and the binder, the light extraction efficiency is improved, and spots and unevenness are hardly generated.

<< light diffusion particles >>
The light diffusing particles are not particularly limited as long as they can diffuse light, and can be appropriately selected according to the purpose. The light diffusing particles may be organic particles, inorganic particles, or two or more kinds. These particles may be contained.

Examples of organic particles include (meth) acrylic resin particles (for example, polymethyl methacrylate particles, cross-linked polymethyl methacrylate particles, acrylic-styrene copolymer particles), melamine particles, polycarbonate particles, polystyrene particles, cross-linked polystyrene particles, poly Examples include vinyl chloride particles, benzoguanamine-melamine formaldehyde particles, and the like.
Examples of inorganic particles include ZrO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , and the like. Among these, TiO ₂ , ZrO ₂ , ZnO, and SnO ₂ are particularly preferable.

As the light diffusing particles, crosslinked resin particles are preferable in terms of solvent resistance and dispersibility in the binder, and crosslinked (meth) acrylic resin particles are particularly preferable.
It can be confirmed that the light diffusing particles are crosslinked resin particles by dispersing in a solvent, for example, toluene and checking the difficulty of dissolution of the resin particles.

The average particle diameter of the light diffusion particles is preferably 0.5 μm to 10 μm, more preferably 0.5 μm to 6 μm, and still more preferably 1 to 3 μm. If the average particle diameter of the light diffusing particles is 10 μm or less, most of the light does not scatter forward, and the ability to convert the angle of light by the light diffusing particles does not decrease. On the other hand, if the average particle diameter of the light diffusing particles is 0.5 μm or more, it does not become smaller than the wavelength of visible light, Mie scattering does not change to the Rayleigh scattering region, and the wavelength dependence of the scattering efficiency of the light diffusing particles The chromaticity of the organic electroluminescent device hardly changes, the backscattering does not become strong, and the light extraction efficiency is improved.
The average particle diameter of the light diffusing particles can be measured by an apparatus using a dynamic light scattering method such as Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., or by image processing of an electron micrograph.

The refractive index of the light diffusing particles is not particularly limited and can be appropriately selected according to the purpose, but is preferably 1.0 to 3.0, more preferably 1.2 to 1.6, and 1.3. -1.5 is more preferable. When the refractive index is less than 1.0 and more than 3.0, light diffusion (scattering) becomes too strong, and the light extraction efficiency may be lowered.
The refractive index of the light diffusing particles is determined by measuring the refractive index of the refractive liquid using, for example, an automatic refractive index measuring device (KPR-2000, manufactured by Shimadzu Corporation), and then using a precision spectrometer (GMR-1DA, Inc.). (Manufactured by Shimadzu Corporation).

  The content of the light diffusion particles in the light diffusion layer is preferably 30% by volume or more and 66% by volume or less, more preferably 40% by volume or more and 60% by volume or less, and particularly preferably 45% by volume or more and 55% by volume or less. When the content is 30% by volume or more, there is a high probability that the light incident on the light diffusion layer is scattered by the light diffusion particles, and the ability to convert the light angle of the light diffusion layer is increased. The light extraction efficiency can be improved without increasing the thickness of the light source. Further, it is preferable not to increase the thickness of the light diffusing layer because this leads to cost reduction, the variation in the thickness of the light diffusing layer is reduced, and the scattering effect in the light emitting surface is less likely to occur. On the other hand, when the content is 66% by volume or less, the binder of the light diffusing layer sufficiently covers the light diffusing particles, and no cavities are formed inside, so that the physical strength of the light diffusing layer is high. .

  The light diffusion layer may contain components other than the binder and the light diffusion particles.

<< Titanium oxide fine particles >>
The light diffusion layer preferably has a refractive index equal to or higher than that of the organic light emitting layer (for example, 1.8 or higher) in order to efficiently extract light emitted from the organic light emitting layer side. In order to increase the refractive index of the light diffusion layer, nanoparticles mainly composed of titanium oxide can be used. That is, the light diffusion layer preferably contains titanium oxide fine particles, and particularly preferably contains titanium oxide fine particles subjected to photocatalytic inactivation treatment.
The titanium oxide fine particles subjected to the photocatalytic deactivation treatment are not particularly limited as long as they do not have photocatalytic activity, and can be appropriately selected according to the purpose. (1) The surface of the titanium oxide fine particles is made of alumina, silica, and zirconia. Examples include titanium oxide fine particles coated with at least one kind, and (2) titanium oxide fine particles formed by coating a resin on the coated surface of the titanium oxide fine particles coated in (1). Examples of the resin include polymethyl methacrylate (PMMA).

  Confirmation that the photocatalytically inactivated titanium oxide fine particles do not have photocatalytic activity can be performed by, for example, a methylene blue method.

The titanium oxide fine particles in the photocatalyst-inactivated titanium oxide fine particles are not particularly limited and can be appropriately selected according to the purpose. The crystal structure is mainly composed of rutile, a rutile / anatase mixed crystal, and anatase. It is preferable that there is a rutile structure as a main component.
The titanium oxide fine particles may be compounded by adding a metal oxide other than titanium oxide.
The metal oxide that can be combined with the titanium oxide fine particles is preferably at least one metal oxide selected from Sn, Zr, Si, Zn, and Al.
The amount of the metal oxide added to titanium is preferably 1 mol% to 40 mol%, more preferably 2 mol% to 35 mol%, still more preferably 3 mol% to 30 mol%.

The primary average particle diameter of the titanium oxide fine particles is preferably 1 nm to 30 nm, more preferably 1 nm to 25 nm, and still more preferably 1 nm to 20 nm. If the primary average particle size exceeds 30 nm, the dispersion may become cloudy and sedimentation may occur. If the primary average particle size is less than 1 nm, the crystal structure is not clear and becomes nearly amorphous, and changes such as gelation over time. Will happen.
The primary average particle diameter can be measured, for example, by calculation from a half-value width of a diffraction pattern measured by an X-ray diffractometer or statistical calculation from a diameter of an electron microscope (TEM) image.
The shape of the titanium oxide fine particles is not particularly limited and may be appropriately selected according to the purpose. For example, a rice grain shape, a spherical shape, a cubic shape, a spindle shape, or an indefinite shape is preferable. The titanium oxide fine particles may be used alone or in combination of two or more.

The photocatalyst-inactivated titanium oxide fine particles have a refractive index of 2.2 or more and 3.0 or less, more preferably 2.2 or more and 2.8 or less, and further preferably 2.2 or more and 2.6 or less. If the refractive index is 2.2 or more, the refractive index of the light diffusion layer can be effectively increased, and if the refractive index is 3.0 or less, the photocatalyst-inactivated titanium oxide fine particles can be obtained. This is preferable because there is no inconvenience such as coloring.
Here, it is difficult to measure the refractive index of fine particles having a high refractive index (1.8 or more) and an average primary particle diameter of about 1 to 100 nm, as in the case of the titanium oxide fine particles. The refractive index can be measured. A resin material having a known refractive index is doped with the titanium oxide fine particles, and a coating film is formed on the Si substrate or the quartz substrate with the resin material in which the titanium oxide fine particles are dispersed. The refractive index of the coating film is measured with an ellipsometer, and the refractive index of the titanium oxide particles can be determined from the volume fraction of the resin material and the titanium oxide particles that constitute the coating film.

  The content of the photocatalyst-inactivated titanium oxide fine particles is 10% by volume to 30% by volume, more preferably 10% by volume to 25% by volume, and more preferably 10% by volume to 20% by volume with respect to the binder. Is more preferable. When the content is 10% by volume or more, the action of increasing the refractive index of the binder is large and the light extraction effect is high, and when it is 30% by volume or less, Rayleigh scattering does not become strong and the light extraction effect is improved. Therefore, it is preferable.

<Composition for forming light diffusion layer>
The light diffusion layer includes a (meth) acrylate monomer serving as a binder including a (meth) acrylic resin and a light diffusion particle, and is formed from a composition for forming a light diffusion layer including titanium oxide fine particles as necessary. Is preferred.
The composition for forming a light diffusion layer may contain components other than the above components, and examples of the components include a polymerization initiator and a solvent.

<< Polymerization initiator >>
The composition for forming a light diffusion layer preferably contains a polymerization initiator. As said polymerization initiator, a thermal polymerization initiator, a photoinitiator, etc. are mentioned, A photoinitiator is preferable.
The polymerization initiator is preferably a compound that generates a radical or an acid by light and / or heat irradiation, and more preferably a compound that generates a radical or an acid by light.
The photopolymerization initiator preferably has a maximum absorption wavelength of 400 nm or less. Thus, the handling can be performed under a white light by setting the absorption wavelength to the ultraviolet region. A compound having a maximum absorption wavelength in the near infrared region can also be used.

  The compound that generates radicals refers to a compound that generates radicals by irradiation with light and / or heat, and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. A known polymerization initiator or a compound having a bond with a small bond dissociation energy can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.

  Examples of the compound that generates radicals include conventionally known organic peroxide compounds, thermal radical polymerization initiators such as azo polymerization initiators, organic peroxide compounds (JP-A No. 2001-139663, etc.), amine compounds ( JP-B-44-20189), metallocene compounds (described in JP-A-5-83588, JP-A-1-304453, etc.), hexaarylbiimidazole compounds (US Pat. No. 3,479,185, etc.) Description), radical photopolymerization of disulfone compounds (JP-A-5-239015, JP-A-61-166544, etc.), organic halogenated compounds, carbonyl compounds, organic boric acid compounds, phosphine oxide compounds, phosphonate compounds, etc. Agents. The radical generator is more preferably a phosphine oxide compound or a phosphonate compound, particularly preferably an acyl phosphine oxide, an acyl phosphonate, or the like. Specifically, bis (2,4,6-trimethylbenzoyl)- It is phenylphosphine oxide.

  Specific examples of the organic halogenated compounds include Wakabayashi et al., “Bull. Chem. Soc Japan”, 42, 2924 (1969), US Pat. No. 3,905,815, 27830, M.M. P. Hutt, “J. Heterocyclic Chemistry”, Vol. 1 (No. 3), (1970) ”and the like, and in particular, an oxazole compound substituted with a trihalomethyl group: an s-triazine compound. More preferable examples include s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring.

  Examples of the carbonyl compound include, for example, “Latest UV Curing Technology”, pages 60 to 62 [published by Technical Information Association, 1991], paragraphs [0015] to [0016] of JP-A-8-134404, Examples include the compounds described in paragraph numbers [0029] to [0031] of Kaihei 11-217518. Further, benzoin compounds such as acetophenone, hydroxyacetophenone, benzophenone, thioxan, benzoin ethyl ether, benzoin isobutyl ether, benzoic acid ester derivatives such as ethyl p-dimethylaminobenzoate, ethyl p-diethylaminobenzoate, benzyldimethyl Examples include ketal and acylphosphine oxide.

  Examples of the organic borate compound include, for example, Japanese Patent Nos. 2764769 and 2002-116539, and Kunz, Martin, “Rad. Tech'98. Proceeding April 19-22, 1998, Chicago”. And the organic borates described in the above. For example, the compounds described in paragraphs [0022] to [0027] of JP-A-2002-116539 can be mentioned. Examples of other organic boron compounds include JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-7-306527, and JP-A-7-292014. Specific examples include organoboron transition metal coordination complexes.

Next, a photoacid generator that can be used as a photopolymerization initiator will be described in detail.
Examples of the photoacid generator include known compounds such as photoinitiators for photocationic polymerization, photodecolorants for dyes, photochromic agents, or known photoacid generators used in microresists, and the like. And the like. Examples of the photoacid generator include organic halogenated compounds, disulfone compounds, onium compounds, and the like. Among these, organic halogenated compounds and disulfone compounds are particularly preferable. Specific examples of the organic halogen compound and the disulfone compound are the same as those described for the compound generating the radical.

  Examples of the onium compounds include diazonium salts, ammonium salts, iminium salts, phosphonium salts, iodonium salts, sulfonium salts, arsonium salts, selenonium salts, and the like, for example, paragraph numbers [0058] to JP-A-2002-29162. And the compounds described in [0059].

  As the acid generator, an onium salt is particularly preferably used, and among them, a diazonium salt, an iodonium salt, a sulfonium salt, and an iminium salt are preferable from the viewpoint of photosensitivity at the start of photopolymerization, material stability of the compound, and the like.

  Specific examples of the onium salt include, for example, an amylated sulfonium salt described in paragraph [0035] of JP-A-9-268205, and paragraphs [0010] to [0011] of JP-A-2000-71366. A diaryl iodonium salt or a triarylsulfonium salt described in JP-A-2001-288205, a sulfonium salt of thiobenzoic acid S-phenyl ester described in JP-A-2001-288205, a paragraph number in JP-A-2001-133696 Examples include the onium salts described in [0030] to [0033].

  Other examples of the photoacid generator include organic metal / organic halides described in JP-A-2002-29162, paragraphs [0059] to [0062], and photoacids having an o-nitrobenzyl type protecting group. Examples thereof include compounds such as a generator and a compound that generates photosulfonic acid to generate sulfonic acid (such as iminosulfonate).

A polymerization initiator may be used independently and may use 2 or more types together.
The addition amount of the polymerization initiator is preferably 3% by mass or less, more preferably 1 to 2.5% by mass, and more preferably 1.5 to 2.2% by mass with respect to the (meth) acrylate monomer serving as the binder. % Is more preferable. If the addition amount of the polymerization initiator is 3% by mass or less, the degree of polymerization does not become too high in the light diffusion layer, and stress does not occur at the interface between the light diffusion particles and the binder, so the film does not become brittle, Since there is no gap between the diffusing particles and the binder, the light extraction efficiency is improved, and no spots or unevenness occur.

<< solvent >>
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alcohols, ketones, esters, amides, ethers, ether esters, aliphatic hydrocarbons, halogenated carbons. Hydrogen etc. are mentioned. Specifically, alcohol (for example, methanol, ethanol, propanol, butanol, benzyl alcohol, ethylene glycol, propylene glycol, ethylene glycol monoacetate, etc.), ketone (for example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, etc.), ester ( For example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl formate, propyl formate, butyl formate, ethyl lactate, etc.), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methyl chloroform), aromatic Group hydrocarbons (eg benzene, toluene, xylene, ethylbenzene etc.), amides (eg dimethylformamide, dimethylacetamide, n-methylpyrrolidone etc.), ether (E.g. dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, etc.), ether alcohols (such as 1-methoxy-2-propanol, ethyl cellosolve, methyl carbinol and the like) and the. These may be used individually by 1 type and may use 2 or more types together. Among these, aromatic hydrocarbons and ketones are preferable, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone are more preferable, and toluene and xylene are particularly preferable.

<Formation of light diffusion layer>
The light diffusion layer is formed of a light diffusion layer forming composition.
The light diffusion layer is a composition for forming a light diffusion layer on a substrate, for example, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a micro gravure coating method, It can be prepared by applying by a known thin film forming method such as an extrusion coating method and drying, irradiating with light and / or heat. Preferably, curing by light irradiation is advantageous from the viewpoint of rapid curing. Furthermore, after the photocuring treatment, it is also preferable to perform a heat treatment to stop the curing (polymerization reaction) of the diffusion layer by the photopolymerization initiator. In this case, the heating temperature is preferably 60 ° C to 105 ° C, more preferably 70 ° C to 100 ° C, and still more preferably 70 ° C to 90 ° C.

  The light source for light irradiation may be any wavelength near the wavelength (absorption wavelength) at which the photopolymerization initiator reacts. When the absorption wavelength is in the ultraviolet region, each light source can be an ultrahigh pressure, high pressure, medium pressure, low pressure mercury lamp, A chemical lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, sunlight, etc. are mentioned. Various available laser light sources having a wavelength of 350 nm to 420 nm may be irradiated as a multi-beam. When the absorption wavelength is in the infrared region, examples of the light source include a halogen lamp, a xenon lamp, and a high-pressure sodium lamp. Various available laser light sources having a wavelength of 750 nm to 1,400 nm may be converted into multi-beams for irradiation. .

In the case of radical photopolymerization by light irradiation, it can be carried out in air or in an inert gas, but the oxygen concentration was reduced as much as possible in order to shorten the induction period of radical polymerizable monomer polymerization or shorten the irradiation time. An atmosphere is preferable. The oxygen concentration range is preferably 0 to 1,000 ppm, more preferably 0 to 800 ppm, and still more preferably 0 to 600 ppm. Irradiation intensity of ultraviolet irradiation is ^preferably from ^{0.1mW / cm 2 ~200mW / cm 2} , irradiation amount on the coating film ^{surface, 100mJ / cm 2 ~100,000mJ / cm} 2 are preferred, 100 mJ / cm ^{2 to} 50,000 mJ / cm ² is more preferable, and 100 mJ / cm ^{2 to} 20,000 mJ / cm ² is particularly preferable. When the light irradiation amount is less than 100 mJ / cm ² , the light diffusion layer is not sufficiently cured, and may be dissolved when a planarizing layer is applied on the light diffusion layer, or may be collapsed during substrate cleaning. . On the other hand, when the light irradiation amount exceeds 100,000 mJ / cm ² , the polymerization of the light diffusion layer proceeds excessively, the surface is yellowed, the transmittance is lowered, and the light extraction efficiency may be lowered. Moreover, 15 to 70 degreeC is preferable, as for the temperature in a light irradiation process, 20 to 60 degreeC is more preferable, and 25 to 50 degreeC is especially preferable. When the temperature is less than 15 ° C, it may take time to cure the light diffusion layer by photopolymerization. When the temperature exceeds 70 ° C, the photopolymerization initiator itself is affected and cannot be photopolymerized (cured). Sometimes.

The average thickness of the light diffusion layer is preferably 1 μm to 10 μm, more preferably 2 μm to 8 μm, and particularly preferably 3 μm to 6 μm. When the average thickness is 1 μm or more, sufficient light diffusion is obtained, and light extraction efficiency is improved. When the average thickness is 10 μm or less, light scattering is not excessively increased, and light extraction efficiency is improved.
The average thickness of the light diffusion layer can be determined, for example, by cutting a part of the light diffusion layer and measuring it with a scanning electron microscope (S-3400N, manufactured by Hitachi High-Tech Co., Ltd.).

The refractive index of the layer obtained by removing light diffusing particles from the light diffusing layer is preferably 1.7 to 2.2, more preferably 1.7 to 2.1, and still more preferably 1.7 to 2.0. When the refractive index of the layer obtained by removing light diffusing particles from the light diffusing layer is 1.7 or more, the light extraction efficiency is improved, and when it is 2.2 or less, the photocatalytic inertness in the binder in the light diffusing layer is increased. Since the amount of the treated titanium oxide fine particles is not too large, scattering does not become too strong and the light extraction efficiency is improved.
The refractive index of the layer obtained by removing light diffusing particles from the light diffusing layer is preferably equal to or higher than the refractive index of the light emitting layer in the organic electroluminescent layer.

It is preferable that the light emission surface of the light diffusion layer is flat or has a flattening layer on the light emission surface of the light diffusion layer. Thereby, even if it increases the density of light-diffusion particle | grains, the increase in backscattering can be suppressed. Moreover, foreign matter adhesion is prevented by flattening.
Examples of the method for flattening the light emitting surface of the light diffusion layer include a method of laminating a planarization layer forming composition obtained by removing light diffusion particles from a light diffusion layer forming composition on a cured light diffusion layer. Is mentioned.

<Planarization layer>
The laminated body of this invention has a planarization layer.
The planarizing layer preferably has a composition that does not contain the light diffusing particles in the light diffusing layer, and can be formed in the same manner as the light diffusing layer.
There is no restriction | limiting in particular in the average thickness of the said planarization layer, Although it can select suitably according to the objective, 1 micrometer-10 micrometers are preferable, 2 micrometers-8 micrometers are more preferable, and 3 micrometers-6 micrometers are especially preferable. If the average thickness of the flattening layer is less than 1 μm, the surface of the protruding original light diffusion layer cannot be flattened, and if it exceeds 10 μm, the light extraction ability decreases due to light absorption of the flattening layer. May end up.
The total average thickness of the light diffusion layer and the planarization layer is preferably 2 μm to 15 μm, more preferably 3 μm to 14 μm, and particularly preferably 5 μm to 12 μm. If the total average thickness is 2 μm or more, sufficient diffusion and planarization can be achieved, and if it is 15 μm or less, absorption in the planarization layer and excessive diffusion in the light diffusion layer do not occur, and light extraction efficiency is improved. .
The refractive index of the planarizing layer is preferably 1.7 to 2.2, more preferably 1.7 to 2.1, and still more preferably 1.7 to 2.0. If the refractive index of the planarization layer is 1.7 or more, total reflection at the interface between the planarization layer and the barrier layer or the transparent electrode layer does not increase, and the light extraction efficiency is improved. If present, the amount of titanium oxide fine particles subjected to the photocatalytic inactivation treatment in the binder in the planarizing layer is not too large, so that light scattering does not become too strong and the light extraction efficiency is improved.
The planarization layer preferably has a refractive index equal to or higher than that of the light diffusion layer.

<Degree of polymerization of light diffusion layer and planarization layer>
In the laminate, the polymerization degree of the light diffusion layer is 30% or more and 65% or less, and the polymerization degree of the planarization layer is 50% or more. More preferably, the degree of polymerization of the light diffusion layer is 35% or more and 60% or less, and the degree of polymerization of the planarization layer is 60% or more, and the degree of polymerization of the light diffusion layer is 40% or more and 55% or less. Further, it is more preferable that the degree of polymerization of the planarizing layer is 65% or more and 75% or less.
Here, the degree of polymerization of the light diffusion layer is the degree of polymerization of the polymerizable compound in the light diffusion layer containing a polymer of a polymerizable compound having a double bond, preferably the degree of polymerization of the (meth) acrylate monomer. is there. The degree of polymerization of the planarizing layer is the degree of polymerization of the polymerizable compound in the planarizing layer containing a polymer of a polymerizable compound having a double bond, preferably the degree of polymerization of the (meth) acrylate monomer. is there.
The degree of polymerization is determined by the amount of double bonds measured by transmission IR. About the polymerization degree of a planarization layer, apply | coating the planarization layer to Si substrate, respectively, IR spectrum is measured with a Fourier-transform infrared spectrophotometer (NICOLET 4700: The product made from Thermo Scientific), 960-1000 (cm < ^- >). ¹ ) Calculate the integrated value of the intensity of the peak due to the double bond found in ¹ ). At this time, the measurement was performed before and after the polymerization. The integrated intensity value before the polymerization was I _b , and the polymerization after the polymerization was I _a , and the degree of polymerization was ((I _b −I _a ) / I _b ) * 100 [%] It was.
About the polymerization degree of a light-diffusion layer, it superposes | polymerizes by apply | coating a diffused layer to Si substrate, and apply | coating a planarization layer on it. Thereafter, only the planarization layer was removed by dry etching or reverse sputtering, and then the IR spectrum was measured with a Fourier transform infrared spectrophotometer (NICOLET 4700: manufactured by Thermo Scientific), and 960-1000 (cm ⁻ It calculates an integrated value I _a of the intensity of the peak due to the double bonds found in ^1). Further, a diffusion layer is applied to the Si substrate, measurement is performed without performing a polymerization treatment, and an integrated value I _b of the peak intensity due to double bonds is calculated in the same manner. The degree of polymerization was ((I _b −I _a ) / I _b ) * 100 [%].
When the polymerization degree of the light diffusion layer is less than 30%, the polymerization of the binder becomes insufficient and a film cannot be formed, or peeling occurs due to poor adhesion between the substrate and the light diffusion layer.
On the other hand, when the polymerization degree of the light diffusion layer is larger than 65%, voids are generated at the interface between the light diffusion particles and the binder, and the light extraction efficiency is lowered.
When the degree of polymerization of the flattening layer is less than 50%, the polymerization of the binder becomes insufficient, the durability to patterning by photolithography becomes low, the ITO surface becomes rough due to damage during ITO film formation, and after ITO film formation In the cleaning process, peeling occurs or when an element is formed, spots and unevenness appear with time.

<Board>
The laminate of the present invention has a substrate.
The shape, structure, size, material and the like of the substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape. A single-layer structure or a laminated structure may be used, and the size may be appropriately selected according to the size of the light extraction member.

There is no restriction | limiting in particular as a material of the said board | substrate, According to the objective, it can select suitably, For example, inorganic materials, such as a yttria stabilized zirconia (YSZ) and glass (an alkali free glass, soda-lime glass, etc.), polyethylene Examples thereof include polyester resins such as terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate, polyimide resin (PI), polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and styrene-acrylonitrile copolymer. These may be used individually by 1 type and may use 2 or more types together. Among these, a polyester resin is preferable, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable from the viewpoint of applicability with a roll.
The surface of the substrate is preferably subjected to a surface activation treatment in order to improve adhesion with the light diffusion layer provided thereon. Examples of the surface activation treatment include glow discharge treatment and corona discharge treatment.

The substrate may be appropriately synthesized or a commercially available product may be used.
There is no restriction | limiting in particular as thickness of the said board | substrate, According to the objective, it can select suitably, 10 micrometers or more are preferable and 50 micrometers or more are more preferable.
The refractive index of the substrate is preferably 1.3 to 1.8, more preferably 1.4 to 1.7, and still more preferably 1.4 to 1.6. When the refractive index of the substrate is less than 1.3, the difference in refractive index between the substrate and the light diffusing layer becomes large, and when light from the light diffusing layer is incident, Fresnel reflection becomes strong, and light extraction efficiency is increased. If it exceeds 1.8, the difference in refractive index between the substrate and air (light exit side) becomes large, Fresnel reflection becomes strong, and the light extraction efficiency may be lowered.

  The laminate of the present invention can be used as a light extraction member. Since the laminated body and light extraction member of the present invention can improve the light extraction efficiency, it is particularly preferable to use it for an organic electroluminescent device.

(Organic electroluminescent device and organic electroluminescent device manufacturing method)
The organic electroluminescent device of the present invention includes the laminate of the present invention, and the first electrode, the organic light emitting layer, and the second electrode in this order on the planarizing layer side of the laminate.
In a preferred first embodiment, the organic electroluminescent device of the present invention is a substrate, an organic electroluminescent layer between the first electrode, the second electrode, and the first electrode and the second cathode on the substrate. And
The substrate is the laminate of the present invention,
In the sealing plate, at least the first electrode, the second electrode, the organic electroluminescent layer, and the light diffusion layer are sealed. In addition, it is preferable that the first electrode, the second electrode, the organic electroluminescent layer, the planarizing layer, and the light diffusion layer are sealed in a sealing plate.
In a preferred second embodiment, the organic electroluminescent device of the present invention includes a substrate, an organic electroluminescent layer on the substrate, a first electrode, a second electrode, and the first electrode and the second cathode. And
The substrate is the laminate of the present invention,
A barrier layer is provided between the first electrode and the planarization layer or the light diffusion layer.
The method for producing an organic electroluminescent device of the present invention comprises a step of applying a light diffusing layer forming composition on a substrate and forming a light diffusing layer,
A planarization layer forming step of applying a planarization layer forming composition obtained by removing light diffusing particles from the light diffusion layer forming composition onto the light diffusion layer, and forming a planarization layer; According to other steps.
The light diffusion layer forming step is performed within 24 hours after the addition of the polymerization initiator to the light diffusion layer forming composition,
The composition for forming a light diffusion layer and the composition for forming a planarized layer are formed such that the planarizing layer forming step is performed within 24 hours after adding a polymerization initiator to the composition for forming a planarized layer. As the polymerization proceeds, the viscosity gradually changes, which is preferable in that it can prevent abnormal film thickness after coating and insufficient curing.

-Organic electroluminescent layer-
The organic electroluminescent layer has at least a light emitting layer. Examples of the functional layer other than the light emitting layer include a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, a hole injection layer, and an electron injection layer.

The organic electroluminescent layer preferably has a hole transport layer between the anode and the light emitting layer, and preferably has an electron transport layer between the cathode and the light emitting layer. Furthermore, a hole injection layer may be provided between the hole transport layer and the anode, or an electron injection layer may be provided between the electron transport layer and the cathode.
In addition, a hole transporting intermediate layer (electron blocking layer) may be provided between the light emitting layer and the hole transporting layer, and an electron transporting intermediate layer (hole blocking layer) is provided between the light emitting layer and the electron transporting layer. Layer) may be provided. Each functional layer may be divided into a plurality of secondary layers.

  These functional layers including the light emitting layer can be suitably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods.

--- Light emitting layer--
The light-emitting layer receives holes from an anode, a hole injection layer, or a hole transport layer when an electric field is applied, receives electrons from a cathode, an electron injection layer, or an electron transport layer, and recombines holes and electrons. It is a layer having a function of providing a field to emit light.
The light emitting layer includes a light emitting material. The light emitting layer may be composed of only a light emitting material, or may be a mixed layer of a host material and a light emitting material (in the latter case, the light emitting material may be referred to as a “light emitting dopant” or “dopant”). The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, and two or more kinds may be mixed. The host material is preferably a charge transport material. The host material may be one type or two or more types. Furthermore, the light emitting layer may contain a material that does not have charge transporting properties and does not emit light.

  The thickness of the light emitting layer is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 2 nm to 500 nm, and more preferably 3 nm to 200 nm from the viewpoint of external quantum efficiency, More preferably, the thickness is 5 nm to 100 nm. Moreover, the said light emitting layer may be 1 layer, or may be two or more layers, and each layer may light-emit with a different luminescent color.

--- Luminescent material ---
As the light emitting material, any of a phosphorescent light emitting material, a fluorescent light emitting material and the like can be suitably used.
The light emitting material has an ionization potential difference (ΔIp) and an electron affinity difference (ΔEa) of 1.2 eV>ΔIp> 0.2 eV and / or 1.2 eV>ΔEa> with the host compound. A dopant satisfying the relationship of 0.2 eV is preferable from the viewpoint of driving durability.
The light emitting material in the light emitting layer is contained in an amount of 0.1% by mass to 50% by mass with respect to the total compound mass generally forming the light emitting layer in the light emitting layer. From the viewpoint, the content is preferably 1% by mass to 50% by mass, and more preferably 2% by mass to 50% by mass.

<Phosphorescent material>
In general, examples of the phosphorescent material include complexes containing a transition metal atom or a lanthanoid atom.
The transition metal atom is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum. Rhenium, iridium, and platinum are more preferable, and iridium and platinum are more preferable.

  Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .

  The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, as phosphorescent materials, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1, WO05 / 19373A2, WO2004 / 108857A1, WO2005 / 042444A2, WO2005 / 042550A1, JP2001-247859, JP2002-302671, JP2002-117978, JP2003-133074, JP2002-1235076, JP2003-123982, JP2002-170684, EP121257, JP2002-226495, JP2002-2002 34894, JP 2001-247659, JP 2001-298470, JP 2002-173675, JP 2002-203678, JP 2002-203679, JP 2004-357791, JP 2006-93542, JP 2006-261623, Examples thereof include phosphorescent compounds described in JP-A-2006-256999, JP-A-2007-19462, JP-A-2007-84635, JP-A-2007-96259, and the like. Among these, Ir complex, Pt complex, Cu complex, Re complex, W complex, Rh complex, Ru complex, Pd complex, Os complex, Eu complex, Tb complex, Gd complex, Dy complex, and Ce complex are preferable, and Ir complex , A Pt complex, or a Re complex is more preferable, and an Ir complex, a Pt complex, or a Re complex including at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond is further included. In view of luminous efficiency, driving durability, chromaticity, etc., an Ir complex, a Pt complex, or an Re complex containing a tridentate or higher polydentate ligand is particularly preferable.

  Specific examples of the phosphorescent material include the following compounds, but are not limited thereto.

<Fluorescent material>
The fluorescent light emitting material is not particularly limited and may be appropriately selected depending on the purpose. For example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin , Pyran, perinone, oxadiazole, aldazine, pyridine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compound, condensed polycyclic aromatic compound (anthracene, Phenanthroline, pyrene, perylene, rubrene, or pentacene), metal complexes of 8-quinolinol, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene Polyphenylene polymer compounds such as polyphenylene vinylene, organic silane, or their derivatives can be mentioned.

---- Host material ---
As the host material, a hole-transporting host material having excellent hole-transporting property (may be described as a hole-transporting host) and an electron-transporting host compound having excellent electron-transporting property (described as an electron-transporting host) May be used).

<Hole-transporting host material>
Examples of the hole transporting host material include the following materials. Pyrrole, indole, carbazole, azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone Hydrazone, stilbene, silazane, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole), aniline copolymer, thiophene oligomer, Examples thereof include conductive polymer oligomers such as polythiophene, organic silanes, carbon films, or derivatives thereof.
Among these, indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, thiophene derivatives, and those having a carbazole group in the molecule are preferred, and compounds having a t-butyl substituted carbazole group are more preferred.

<Electron transporting host material>
Examples of the electron transporting host material include pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluoreni Heterocyclic tetracarboxylic anhydrides such as redenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, naphthaleneperylene, phthalocyanines, or derivatives thereof (may form condensed rings with other rings), 8-quinolinol derivatives And various metal complexes represented by metal complexes having metal phthalocyanine, benzoxazole or benzothiazole as a ligand. Among these, a metal complex compound is preferable from the viewpoint of durability, and a metal complex having a ligand having at least one nitrogen atom, oxygen atom, or sulfur atom coordinated to a metal is more preferable. Examples of the metal complex electron transporting host include Japanese Patent Application Laid-Open No. 2002-235076, Japanese Patent Application Laid-Open No. 2004-214179, Japanese Patent Application Laid-Open No. 2004-221106, Japanese Patent Application Laid-Open No. 2004-221665, and Japanese Patent Application Laid-Open No. 2004-221068. And compounds described in JP-A No. 2004-327313.

  Specific examples of the hole transporting host material and the electron transporting host material include the following compounds, but are not limited thereto.

--- Hole injection layer, hole transport layer-
The hole injection layer or the hole transport layer is a layer having a function of receiving holes from the anode or the layer on the anode side and transporting them to the cathode side. The hole injecting material and hole transporting material used for these layers may be a low molecular compound or a high molecular compound. Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, Etc. are preferred.

The hole injection layer or the hole transport layer may contain an electron accepting dopant. As the electron-accepting dopant introduced into the hole injection layer or the hole transport layer, an inorganic compound or an organic compound can be used as long as it has an electron accepting property and oxidizes an organic compound.
Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, and metal oxides such as vanadium pentoxide and molybdenum trioxide. In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
These electron-accepting dopants may be used alone or in combination of two or more. The amount of the electron-accepting dopant varies depending on the type of the material, but is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 40% by mass with respect to the hole transport layer material. 1 mass% to 30 mass% is particularly preferable.

  The hole injection layer or the hole transport layer may have a single layer structure composed of one or more of the materials described above, or a multilayer structure composed of a plurality of layers having the same composition or different compositions. Also good.

--Electron injection layer, electron transport layer--
The electron injection layer or the electron transport layer is a layer having a function of receiving electrons from the cathode or a layer on the cathode side and transporting them to the anode side. The electron injection material and the electron transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, the layer containing the like are preferable.

The electron injection layer or the electron transport layer may contain an electron donating dopant. The electron-donating dopant introduced into the electron-injecting layer or the electron-transporting layer is not limited as long as it has an electron-donating property and has a property of reducing an organic compound. Alkali metals such as Li and alkaline earths such as Mg Metals, transition metals including rare earth metals, reducing organic compounds, and the like are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds.
These electron donating dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-donating dopant changes with kinds of material, 0.1 mass%-99 mass% are preferable with respect to electron carrying layer material, 1.0 mass%-80 mass% are still more preferable. 0 mass%-70 mass% is especially preferable.

  The electron injection layer or the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or a multilayer structure composed of a plurality of layers having the same composition or different compositions. Good.

--Hole blocking layer, electron blocking layer--
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the cathode side. .
On the other hand, the electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing to the anode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the anode side. .
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like. As an example of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be used.
The thickness of the hole blocking layer and the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. The hole blocking layer and the electron blocking layer may have a single-layer structure made of one or more of the materials described above, or a multilayer structure made up of a plurality of layers having the same composition or different compositions. Also good.

--- Electrode--
The organic electroluminescent device includes a transparent electrode and a reflective electrode, that is, an anode and a cathode. In view of the properties of the organic electroluminescent element, at least one of the anode and the cathode is preferably transparent.
Usually, the anode only needs to have a function as an electrode for supplying holes to the organic compound layer, and the cathode only needs to have a function as an electrode for injecting electrons into the organic compound layer. The shape, structure, size, and the like are not particularly limited, and can be appropriately selected from known electrode materials according to the use and purpose of the light-emitting element. As a material which comprises an electrode, a metal, an alloy, a metal oxide, an electroconductive compound, or a mixture thereof etc. are mentioned suitably, for example.

  There is no restriction | limiting in particular as said electrode, Although it can select suitably according to the objective, It is preferable to comprise the said reflecting metal and the translucent metal as said translucent member in the anode and cathode.

  Specific examples of the material constituting the anode include, for example, tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO). ) Conductive metal oxides, metals such as gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, Examples thereof include organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  Examples of the material constituting the cathode include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium. Examples include alloys, lithium-aluminum alloys, magnesium-silver alloys, indium, and rare earth metals such as ytterbium. These may be used singly or in combination of two or more from the viewpoint of achieving both stability and electron injection. Among these, alkali metals and alkaline earth metals are preferable from the viewpoint of electron injection properties, and materials mainly composed of aluminum are preferable from the viewpoint of excellent storage stability. The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  There is no restriction | limiting in particular about the formation method of the said electrode, According to a well-known method, it can carry out. For example, a material constituting the electrode from a wet method such as a printing method, a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. In consideration of the suitability, the film can be formed on the substrate according to an appropriately selected method. For example, when ITO is selected as the anode material, it can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. When a metal or the like is selected as the cathode material, one or more of them can be formed simultaneously or sequentially according to a sputtering method or the like.

  In addition, when patterning is performed when forming the electrode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. It may be performed by sputtering or the like, or may be performed by a lift-off method or a printing method.

-Barrier layer-
There is no restriction | limiting in particular as said barrier layer, What is necessary is just to select suitably according to the objective, The organic layer consisting of an organic material alone, or the inorganic layer consisting of an inorganic material may be single, but the organic layer consisting of an organic material And a multilayer structure in which an inorganic layer made of an inorganic material is laminated.
Examples of the inorganic materials, for example _{SiNx, SiON, SiO 2, Al} 2 O 3, etc. TiO ₂ and the like.
Examples of the organic material include a silicone polymer, an epoxy polymer, an acrylic polymer, and a urethane polymer.

There is no restriction | limiting in particular as a formation method of the said barrier layer, According to material, it can select suitably, For example, the apply | coating method, CVD method, a vacuum evaporation method, a sputtering method etc. are mentioned.
The barrier layer has a refractive index (average refractive index in the case of a multilayer structure) of preferably 1.7 or more, and more preferably 1.8 to 2.2. When the refractive index of the barrier layer is less than 1.7, the total reflection of light from the organic electroluminescent layer increases at the interface between the transparent electrode and the barrier layer, and the light extraction efficiency may decrease.
As for the optical properties of the barrier layer, the light transmittance is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.
The average thickness of the barrier layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 5 μm, and still more preferably 0.2 μm to 3 μm. . When the average thickness of the barrier layer is less than 0.1 μm, the sealing function for preventing the permeation of oxygen and moisture in the atmosphere may be insufficient, and when it exceeds 10 μm, the light transmittance decreases. When transparency is impaired, and when an inorganic material is used in a single layer, barrier properties such as cracking due to a stress difference and separation from an adjacent layer may be impaired.

-Sealing plate-
The sealing plate may have a size, shape, structure, or the like that can enclose a laminate including the transparent electrode, the reflective electrode, the organic electroluminescent layer, the planarizing layer, and the light diffusion layer. If there is no restriction | limiting in particular, it can select suitably according to the objective.
A water absorbent or an inert liquid is sealed in a space between the sealing can and the transparent electrode, the reflective electrode, the organic electroluminescent layer, the planarizing layer, and the light diffusing layer. May be.
The moisture absorbent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, Examples thereof include calcium chloride, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide.
The inert liquid is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paraffins, liquid paraffins; fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether; chlorine System solvents, silicone oils and the like.

  Here, FIG. 2 is a schematic view showing an example of the organic electroluminescent device of the present invention. The organic electroluminescent device 20 of FIG. 2 includes a transparent electrode 4, an organic layer on a planarization layer 3 of a laminate (light extraction member) having a light diffusion layer 2 and a planarization layer 3 on a substrate 1. The light-emitting layer 5 and the reflective electrode 6 are included, and the light diffusion layer 2, the planarizing layer 3, the transparent electrode 4, the organic light-emitting layer 5, and the reflective electrode 6 are sealed with a sealing can 7.

The organic electroluminescent device can be configured as a device capable of displaying in full color.
As a method for making the organic electroluminescent device of a full color type, for example, as described in “Monthly Display”, September 2000, pages 33 to 37, the three primary colors (blue (B), A three-color light emission method in which a layer structure that emits light corresponding to green (G) and red (R) is arranged on a substrate, a white light that divides white light emission by a layer structure for white light emission into three primary colors through a color filter layer And a color conversion method in which blue light emission by a layer structure for blue light emission is converted into red (R) and green (G) through a fluorescent dye layer are known.
In this case, it is preferable to appropriately adjust the laser power and thickness for each pixel of blue (B), green (G), and red (R).
In addition, a planar light source having a desired emission color can be obtained by using a combination of a plurality of layer structures having different emission colors obtained by the above method. For example, a white light-emitting light source combining blue and yellow light-emitting elements, a white light-emitting light source combining blue (B), green (G), and red (R) organic electroluminescent elements.

  The organic electroluminescent device is, for example, a lighting device, a computer, an on-vehicle display, an outdoor display, a home device, a business device, a home appliance, a traffic display, a clock display, a calendar display, a luminescence. It can be suitably used in various fields including cent screens, audio equipment and the like.

Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the examples and comparative examples described below, the average thickness of the light diffusion layer, the average thickness of the planarization layer, and the refractive index of the binder were measured as follows.

<Average thickness of light diffusion layer and planarization layer>
The average thickness of the light diffusion layer and the planarization layer can be determined, for example, by cutting out a part of the light diffusion layer or the planarization layer and using a scanning electron microscope (S-3400N, manufactured by Hitachi High-Tech Co., Ltd.). .

<Measurement of refractive index>
The refractive index of the binder constituting the light diffusing layer and the planarizing layer (the refractive index of the layer obtained by removing the light diffusing particles from the light diffusing layer and the planarizing layer) is about the wavelength of light on the Si substrate or the quartz substrate. The refractive index can be obtained by depositing the binder to a thickness and measuring the binder on the deposited substrate with an ellipsometer.

  Titanium oxide dispersion coated with alumina and zirconia on the surface (dispersion of titanium oxide nanoparticles with an average diameter of 15 nm, refractive index 2.45) "Material name: Titanium oxide dispersed toluene, trade name: Highly transparent titanium oxide slurry HTD For “−760T”, the presence or absence of photocatalytic activity was measured as follows. As a result, it was found that the photocatalytic activity was suppressed and it was equivalent to zirconium oxide particles having no photocatalytic effect.

<Measurement of photocatalytic activity>
The photocatalytic activity is measured using a known “methylene blue method” as a general method. The "methylene blue method" is a photocatalyst by placing a methylene blue aqueous solution in a quartz tube, doping each particle into it, measuring the transmittance before light irradiation, irradiating with light, and confirming the change in the transmittance of the methylene blue aqueous solution. Activity was measured quantitatively.

<Production of organic electroluminescent device>
-Preparation of binder (planarization layer forming material)-
Titanium oxide dispersion coated with alumina and zirconia on the surface (dispersion of titanium oxide nanoparticles with an average diameter of 15 nm, refractive index 2.45) "Material name: Titanium oxide dispersed toluene, trade name: Highly transparent titanium oxide slurry HTD -760T "35 g, acrylate monomer (resin material)" Material name: fluorene derivative, product name: Ogsol EA-0200 "(volume shrinkage ratio 1% or less) 10 g, and toluene 8.5 g were stirred with a roller mixer and a stirrer. Then, it was further dissolved by ultrasonic waves (sonifier) to obtain a binder forming material.
Since the obtained binder forming material becomes the forming material of the flattening layer as it is, it may be hereinafter referred to as the flattening layer forming material.

-Production of light diffusion layer forming material-
Light diffusion particles (cross-linked acrylic particles having an average diameter of 1.5 μm, refractive index of 1.49) “Material name: EX-150” (4.2 g) and toluene (14 g) were stirred with a stirrer in 19 g of the obtained binder-forming material. Then, the light diffusing particles were sufficiently dispersed in the binder forming material with ultrasonic waves, and further stirred with a stirrer to obtain a light diffusing layer forming material having a light diffusing particle content of 40% by volume.

  Next, a polymerization initiator (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide) is added to the produced planarization layer forming material and light diffusion layer forming material in the amounts shown in Table 1 (mass with respect to the acrylate monomer). Ratio) was added and stirred thoroughly.

-Production of light extraction member-
Next, a glass substrate (manufactured by Corning, Eagle XG, refractive index 1.51) is placed in a cleaning container, subjected to ultrasonic cleaning in a neutral detergent, and then ultrasonically cleaned in pure water, at 120 ° C. for 120 minutes. Heat drying was performed.
A light diffusion layer forming material was applied to a glass substrate using a wire bar, and then UV irradiation (365 nm) was performed for 1 minute in a nitrogen atmosphere to cure, thereby preparing a light diffusion layer having an average thickness of 5 μm.
Next, a planarizing layer forming material is applied on the light diffusion layer using a wire bar, and cured by UV irradiation to form a planarizing layer having an average thickness of 5 μm, and a light extraction member (laminate) is produced. did. In addition, when the organic electroluminescent device was assembled, the light diffusion layer and the planarization layer were applied so as to fit in the sealing plate.
Thereafter, the produced light extraction member was subjected to ultrasonic cleaning in the order of isopropyl alcohol (IPA) and pure water, and dried at 120 ° C. for 2 hours.

Next, the produced light extraction member was washed in the US (water 20 minutes) (peeling of the light extraction layer (consisting of the light diffusion layer and the planarizing layer) before film formation of the anode can occur here), and then flattened. An ITO (Indium Tin Oxide) film having a thickness of 100 nm was formed on the conversion layer with a metal mask using a sputter film forming machine to form a first electrode (anode).
The laminate having the first electrode prepared by the above method is washed in the US (water 20 minutes) {the anode can be peeled off before the organic layer is formed here}, and then on the first electrode by a vacuum deposition apparatus. , HAT-CN is 10 nm (hole injection layer), α-NPD is 500 nm (hole transport layer), CBP (85%) and Ir (ppy) ₃ (15%) are co-deposited to 30 nm on the light emitting layer Further, triphenylene 10 nm (hole blocking layer) was laminated thereon, and Alq 40 nm (electron injection layer) was laminated thereon, whereby an organic layer was obtained. Next, LiF is deposited as a buffer layer on the electron injection layer so as to have a thickness of 1 nm, and aluminum is deposited as an electrode layer (second electrode) on the buffer layer so as to have a thickness of 100 nm. Obtained.

--Sealing--
Next, a desiccant was affixed to the produced laminate in a nitrogen gas atmosphere, and the organic layer side of the substrate was sealed with a sealing glass can in which a sealing material was applied to the installation surface with the substrate. Thus, an organic electroluminescence device was produced.

[Evaluation]
About the produced organic electroluminescent device, the degree of polymerization of the light diffusion layer and the planarizing layer, the presence or absence of peeling of the light extraction layer before the anode film formation, the presence or absence of peeling of the anode before the organic layer formation, light The removal efficiency, the appearance unevenness and the presence or absence of spots were evaluated. The results are shown in Table 1.

<Measurement of degree of polymerization>
The degree of polymerization of the light diffusion layer and the leveling layer were measured by transmission IR.
About the polymerization degree of a planarization layer, apply | coating the planarization layer to Si substrate, respectively, IR spectrum is measured with a Fourier-transform infrared spectrophotometer (NICOLET 4700: The product made from Thermo Scientific), 960-1000 (cm < ^- >). ¹ ) Calculate the integrated value of the intensity of the peak due to the double bond found in ¹ ). At this time, the measurement was performed before and after the polymerization. The integrated intensity value before the polymerization was I _b , and the polymerization intensity was I _a , and the degree of polymerization was ((I _b −I _a ) / I _b ) * 100 [%] It was.
About the polymerization degree of a light-diffusion layer, it superposes | polymerizes by apply | coating a diffused layer to Si substrate, and apply | coating a planarization layer on it. Thereafter, only the planarization layer was removed by dry etching or reverse sputtering, and then the IR spectrum was measured with a Fourier transform infrared spectrophotometer (NICOLET 4700: manufactured by Thermo Scientific), and 960-1000 (cm ⁻ It calculates an integrated value I _a of the intensity of the peak due to the double bonds found in ^1). Further, a diffusion layer is applied to the Si substrate, measurement is performed without performing a polymerization treatment, and an integrated value I _b of the peak intensity due to double bonds is calculated in the same manner. The degree of polymerization was ((I _b −I _a ) / I _b ) * 100 [%].

<Measurement of external quantum yield>
The external quantum yield was measured using an external quantum efficiency measurement device “C9920-12” manufactured by Hamamatsu Photonics Co., Ltd., by applying a constant DC current to each organic electroluminescence device to emit light.

<Evaluation method of change with time of organic electroluminescence device>
The change with time of the organic electroluminescent device was evaluated by visual observation of the light emitting surface. Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a direct current was applied to each element to drive it at a luminance of 1000 cd / m 2 and drive at a temperature of 20 ° C. and a humidity of 60%. Generation | occurrence | production and the generation | occurrence | production of the nonuniformity and the spot on the external appearance after leaving for 100 hours were confirmed visually.

<The evaluation method of the state in manufacture of an organic electroluminescent apparatus>
The surface of the light diffusion layer and the planarization layer was visually observed for each film forming process, thereby confirming surface irregularities and peeling.

From the results of Table 1, it was found that Examples 1 to 3 all had high external quantum efficiency, and the results obtained by the method for evaluating changes over time of the organic electroluminescent device were also good.
In Comparative Examples 1 and 2, the degree of polymerization of the diffusion layer was increased as compared with Examples 1 and 2 by increasing the amount of the polymerization initiator added to the diffusion layer. Although peeling of the light extraction layer and the anode was not observed, unevenness and spots were observed after 100 hours.
In Comparative Example 3, the addition amount of the polymerization initiator in the diffusion layer was reduced, but the polymerization degree of the diffusion layer was low, and peeling of the light extraction layer was observed before the anode film formation.
Further, the refractive index of the binder upon curing is 1.8, the refractive index of the diffusing fine particles is 1.49, and the refractive index difference is sufficiently large, so that even a thin film can obtain sufficient diffusion for light extraction.
In addition, since toluene is used as a solvent, resin particles must have sufficient solvent resistance. However, in this respect, the combination of the materials is resistant to the solvent, and the dispersion deterioration (aggregation, etc.) due to changes over time is also very high. Are better.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Light diffusing layer 3 Flattening layer 4 Transparent electrode 5 Organic light emitting layer 6 Reflecting electrode 7 Sealing can 10 Laminate 20 Organic electroluminescent device

Claims (7)

  A laminate having a substrate, a light diffusion layer containing a binder containing (meth) acrylic resin and light diffusing particles, and a planarization layer containing a binder containing (meth) acrylic resin in this order, A laminate in which the diffusion layer has a polymerization degree of 30% to 65% and the planarization layer has a polymerization degree of 50% or more.   The laminate according to claim 1, wherein an average particle diameter of the light diffusion particles in the light diffusion layer is 0.5 μm to 10 μm.   The laminate according to claim 1 or 2, wherein the volume shrinkage of the binder in the light diffusion layer is 2% or less. The light diffusion layer is formed from a composition for forming a light diffusion layer containing a (meth) acrylate monomer, a light diffusion particle, and a polymerization initiator,
The planarizing layer is formed from a composition for forming a planarizing layer containing a (meth) acrylate monomer and a polymerization initiator,
The blending ratio of the polymerization initiator in the composition for forming a light diffusion layer is 3% by mass or less with respect to the (meth) acrylate monomer,
The laminated body as described in any one of Claims 1-3 whose compounding ratio of the polymerization initiator in the composition for planarization layer formation is 3 mass% or less with respect to a (meth) acrylate type monomer.   The laminate according to any one of claims 1 to 4, wherein the light diffusion particles are crosslinked (meth) acrylic resin particles.   The laminate according to any one of claims 1 to 5, wherein the light diffusion layer and the planarization layer further include titanium oxide fine particles subjected to photocatalytic inactivation treatment.   The organic electroluminescent device which has a 1st electrode, an organic light emitting layer, and a 2nd electrode in this order on the planarization layer side of the laminated body as described in any one of Claims 1-6, and this laminated body. .