JP4186688B2 - Electroluminescence element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroluminescence (EL) element, and more particularly to an electroluminescence element having high light extraction efficiency from an electroluminescence layer.
[0002]
[Prior art]
As shown in FIG. 4A, the electroluminescence element used in the EL display has at least a transparent substrate 5, a transparent electrode layer (anode) 3, an electroluminescence layer 2, and a cathode 1. In this electroluminescence element, holes injected from the transparent electrode layer 3 serving as the anode and electrons injected from the cathode 1 are recombined in the electroluminescence layer 2, and the emission center is excited by the recombination energy to emit light. It has a light emission principle.
[0003]
In the organic EL display, it is preferable that the light emitted from the electroluminescence layer 2 is efficiently extracted to the transparent substrate 5 side. However, as shown in FIG. The light is totally reflected at the interface between the air 5 and the air 7 and mainly travels while being totally reflected in the plane direction inside the transparent substrate 2. The light extraction efficiency extracted from the transparent substrate 2 by the guided light 12 (the ratio of the light generated in the electroluminescence layer 2 extracted outside the electroluminescence element) is as low as about 20%.
[0004]
To solve such a problem, as shown in FIG. 5, a low refractive index layer 4 is provided on the electroluminescent layer 2 side of the transparent substrate 5, and the light 11 having a large emission angle is refracted by the low refractive index layer 4, thereby It has been studied to reduce generation and improve light extraction efficiency. For example, Patent Document 1 below describes an electroluminescence element having a low refractive index layer having a refractive index of 1.01 to 1.3 formed by a silica airgel film technique.
[0005]
[Patent Document 1]
JP 2002-278477 A (paragraph numbers 0010 to 0012)
[0006]
[Problems to be solved by the invention]
By providing the low refractive index layer 4 between the transparent electrode layer 3 and the transparent substrate 5 as described in JP-A-2002-278477, total reflection at the interface between the transparent substrate 5 and the air layer 7 is reduced. However, in the same issue, the total reflection at the interface between the transparent electrode layer 3 and the low refractive index layer 4 is not improved. Rather, the provision of the low refractive index layer 4 has a problem that the total reflection amount at the interface between the transparent electrode layer 3 and the low refractive index layer 4 increases.
[0007]
An object of the present invention is to provide an electroluminescence device in which total reflection at the light extraction side interface of the transparent electrode layer is reduced in addition to the interface with the air layer of the transparent substrate, and the light extraction efficiency is sufficiently improved. And
[0008]
[Means for Solving the Problems]
The electroluminescence device of the first invention (invention 1) is an electroluminescence device comprising a cathode, an electroluminescence layer, a transparent electrode layer, a low refractive index layer, and a translucent material arranged in this order. Is a matrix having a refractive index of 1.1 to 1.5 and having a refractive index lower than that of the transparent body, Contains particles that scatter light from the electroluminescent layer, and prevents the material in the low refractive index layer from diffusing to the transparent electrode layer side between the low refractive index layer and the transparent electrode layer. A barrier layer is provided.
[0009]
When light scattering particles are contained in the low refractive index layer in this way, total reflection of light incident from the electroluminescence layer through the transparent electrode layer and the barrier layer to the interface between the barrier layer and the low refractive index layer is reduced. To do.
[0010]
The reason is considered as follows. That is, when light enters the interface between the barrier layer and the low refractive index layer from the electroluminescence layer through the transparent electrode layer and the barrier layer, the light is totally reflected at the interface. . In this total reflection, a phenomenon occurs in which part of light oozes out to the low refractive index layer side from the interface. That is, the electric field and magnetic field of incident light exist even on the low refractive index layer side from the interface.
[0011]
Since there is a particle that scatters the soaked light in the vicinity of the interface in the low refractive index layer, a part of the light oozed out to the low refractive index layer side is scattered by the particle, and it is no longer a transparent electrode. After scattering without returning to the total reflection light in the layer, it diffuses into the low refractive index layer directly or after being reflected by, for example, an aluminum reflective film of the cathode. In this way, by including the light scattering particles in the low refractive index layer, the reflectance of total reflection decreases, and more light enters the low refractive index layer side from the transparent electrode layer, As a result, the light extraction efficiency of the electroluminescence element is improved.
[0012]
In addition to using scattering particles, controlled irregularities such as forming a periodic structure such as a grating or a planar photonic crystal to refract light, forming a microlens or the like to refract light, and the like can be used as a transparent electrode layer. There are also proposals to improve the extraction rate by providing it with a transparent substrate, but these all take time to form, and also fill the unevenness to flatten the surface of the transparent electrode layer on the electroluminescent layer side This is industrially disadvantageous because it may be difficult to do.
[0013]
In the electroluminescent element of the first invention (invention 1), a barrier layer is provided between the low refractive index layer and the transparent electrode layer. For this reason, even if an easily diffusible substance such as a low molecular weight component such as a residual monomer or moisture exists in the low refractive index layer, this substance is prevented from diffusing to the transparent electrode layer side. And the substance is prevented from affecting the electroluminescent layer.
[0014]
The electroluminescence device of the second invention (invention 2) is an electroluminescence device comprising a cathode, an electroluminescence layer, a transparent electrode layer, a low refractive index layer, and a translucent material arranged in this order. A particle-containing layer comprising a matrix and particles that scatter light from the electroluminescent layer dispersed in the matrix is provided between the refractive index layer and the matrix is equivalent to the low refractive index layer. And a barrier layer is provided between the particle-containing layer and the transparent electrode layer to prevent the substance in the particle-containing layer from diffusing to the transparent electrode layer side. It is characterized by this.
[0015]
In the present specification, “equivalent refractive index” means that the difference between one refractive index and the other refractive index is 0.3 or less, preferably 0.2 or less, particularly preferably 0.1 or less. That means.
[0016]
At the interface of the scattering particle-containing layer provided between the barrier layer and the low refractive index layer, the particle-containing layer side interface of the barrier layer is caused by the light scattering action of the particles in the particle-containing layer in the same manner as described above. To reduce the total reflection of light. That is, when total reflection occurs at the interface between the barrier layer and the particle-containing layer, the light that has leached into the particle-containing layer at the time of total reflection is scattered by the particles in the particle-containing layer and extracted to the particle-containing layer side. As a result, the amount of light entering the particle-containing layer without being totally reflected at the interface of the barrier layer on the particle-containing layer side after being reflected directly from the barrier layer or by an aluminum reflective film of the cathode, for example, increases.
[0017]
Since the matrix of the particle-containing layer and the low refractive index layer have the same refractive index, total reflection hardly occurs at the interface between the particle-containing layer and the low refractive index layer. As a result, most of the light that enters the particle-containing layer from the transparent electrode layer and reaches the interface between the particle-containing layer and the low-refractive index layer enters the low-refractive index layer as it is. In this way, the light extraction efficiency from the electroluminescence element is improved.
[0018]
That is, the second invention takes out the totally reflected light in the barrier layer or the barrier layer and the transparent electrode layer by the particle-containing layer, and further refracts the light into the transparent substrate perpendicularly by the low refractive index layer. Suppresses total reflection at the air layer interface of the substrate. Thereby, the light extraction rate is improved. Note that with only a simple scattering layer, it is physically equivalent to simply moving a part of the light source to the scattering nucleus, and the total reflection amount at the air layer interface of the transparent substrate is hardly reduced, and light extraction is performed. The rate improvement is hardly expected.
[0019]
In the electroluminescence element of the second invention (invention 2), a barrier layer is provided between the particle-containing layer and the transparent electrode layer. For this reason, even if an easily diffusible substance such as a low molecular weight component such as a monomer or moisture is present in the particle-containing layer, this substance is prevented from diffusing to the transparent electrode layer side. The substance is prevented from affecting the luminescent layer.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments. 1 and 2 are cross-sectional views each showing an electroluminescence element according to an embodiment of the present invention.
[0021]
FIG. 1 (a) shows an electroluminescence device according to an embodiment of the first invention (invention 1). The cathode 1, the electroluminescence layer 2, the transparent electrode layer 3, the barrier layer 10, and the particle-containing low refractive index. A layer 4 ′ and a light-transmitting substrate 5 such as a glass substrate are stacked in this order.
[0022]
The light from the electroluminescence layer 2 is reflected as it is or reflected by the cathode 1, passes through the electroluminescence layer 2, exits to the transparent electrode layer 3 side, and then passes through the barrier layer 10, the low refractive index layer 4 ′ and the substrate 5. To be taken out.
[0023]
Since the low refractive index layer 4 ′ is provided, the light that has entered the low refractive index layer 4 ′ through the barrier layer 10 from the transparent electrode layer 3 side is incident on the substrate at an incident angle near to the substrate surface of the substrate 5. 5 and the low refractive index layer 4 ′, the total reflection at the air layer side interface of the substrate 5 is reduced.
[0024]
In one aspect (first aspect) of this embodiment, the barrier layer 10 has a high refractive index equal to or higher than that of the transparent electrode layer 3.
[0025]
In this first embodiment, since the low refractive index layer 4 ′ contains particles, total reflection at the interface between the barrier layer 10 and the low refractive index layer 4 ′ is reduced as follows, and the light extraction efficiency is reduced. Will improve.
[0026]
That is, when the light 11 is incident from the electroluminescence layer 2 through the transparent electrode layer 3 and the barrier layer 10 to the interface between the barrier layer 10 and the low refractive index layer 4 ′ at an incident angle larger than the critical angle, the light 11 Is totally reflected at the interface. In this total reflection, a phenomenon occurs in which a part of light oozes toward the low refractive index layer 4 ′ side from the interface. That is, the electric field and magnetic field of incident light exist even on the low refractive index layer 4 ′ side from the interface. It is known that the reach distance of the penetrating light is 500 to 600 nm in the direction perpendicular to the transparent electrode when the transparent electrode layer thickness is 100 nm and the refractive index of the low refractive index layer 4 ′ is 1.3. Yes.
[0027]
In the vicinity of the interface in the low-refractive index layer 4 ', there are particles that scatter the soaked light, so that part of the light that has oozed out on the low-refractive index layer 4' side is scattered by the particles. Then, after scattering without returning to the total reflection light in the transparent electrode layer 3, it is diffused directly or after being reflected by, for example, an aluminum reflection film of the cathode, and then diffused into the low refractive index layer 4 ′. Thus, by including the light scattering particles in the low refractive index layer 4 ′, the total reflection light is reduced, and more light passes from the transparent electrode layer 3 through the barrier layer 10, and the low refractive index layer 4. As a result, the light extraction efficiency of the electroluminescent element is improved.
[0028]
Next, the preferable structure of the board | substrate 5 and each layer 1-4 ', 10 is demonstrated.
[0029]
A: About the substrate
The substrate has a refractive index in the range of 1.4 to 1.9, preferably 1.45 to 1.70, more preferably 1.47 to 1.65, and most preferably 1.48 to 1.60. Things are used. This refractive index is an average refractive index in the entire depth direction determined by an ellipsometer measurement based on ASTM D-542, and is represented by a value with respect to sodium D line (589.3 nm) at 23 ° C. As the substrate having such a refractive index, a transparent substrate made of a general-purpose material can be used. For example, various types of shot glass such as BK7, SF11, LaSFN9, BaK1, and F2, synthetic fused silica glass, optical crown glass, low expansion borosilicate glass, sapphire, soda glass, alkali-free glass, polymethyl methacrylate, and cross-linked Acrylic resin such as acrylate, aromatic polycarbonate resin such as bisphenol A polycarbonate, styrene resin such as polystyrene, amorphous polyolefin resin such as polycycloolefin, polyester resin such as epoxy resin and polyethylene terephthalate, polysulfone such as polyethersulfone Examples thereof include synthetic resins such as resins and polyetherimide resins. Of these, shot glass such as BK7 and BaK1, synthetic fused silica glass, optical crown glass, low expansion borosilicate glass, soda glass, alkali-free glass, acrylic resin, aromatic polycarbonate resin, and amorphous polyolefin resin are preferable. BK7 shot glass, synthetic fused silica glass, optical crown glass, low expansion borosilicate glass, soda glass, alkali-free glass, acrylic resin, aromatic polycarbonate resin, and polyethersulfone resin are particularly preferable. Note that a film such as an antireflection film, a polarizing film, or a retardation film, a film, or the like may be formed on the light extraction side of these substrates as necessary.
[0030]
The thickness of the substrate is usually 0.1 to 10 mm. The lower limit of the substrate thickness is preferably 0.2 mm, more preferably 0.3 mm, from the viewpoint of mechanical strength and gas barrier properties. On the other hand, the upper limit value of the thickness of the substrate is preferably 5 mm and more preferably 3 mm from the viewpoints of lightness, compactness, and light transmittance.
[0031]
The transmittance of the laminated substrate is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more at a sodium D-line wavelength (589.3 nm).
[0032]
B: Particle-containing low refractive index layer 4 ′
The particle-containing low refractive index layer 4 ′ is obtained by dispersing particles in a low refractive index matrix. As this matrix, a fluoride resin such as silica and cyclic Teflon, magnesium fluoride, or a porous material or composite thereof is preferable, and porous silica is particularly preferable. If necessary, an organic component may be introduced into silica to make it hydrophobic, impart flexibility, prevent cracks, and the like.
[0033]
It is important that the refractive index of this matrix is lower than the refractive index of the transparent substrate, but 1.1 to 1.5 It is. In particular, about 1.2 to 1.35 is preferable. If the refractive index is too low, the mechanical strength of the film tends to be insufficient. If it is too high, the total amount of reflected light increases and the extraction rate decreases.
[0034]
As particles to be contained in the particle-containing low refractive index layer 4 ′, silica, colloidal silica, titania, zirconia, ITO (indium tin oxide), ATO (antimony tin oxide), alumina, and the like are preferable. In particular, it is preferable that light absorption in the visible region is as small as possible and that the refractive index difference with the low refractive index layer 4 ′ is as large as possible. In order to contain the particles in the matrix, it may be added to the raw material liquid in the step (1) of preparing the raw material liquid described later.
[0035]
The particle size and shape can be used as long as they have a function of scattering light, but those that cause Mie scattering are particularly preferable. Therefore, the particle size is an optical size, and the wavelength of light to be scattered is λ. In this case, it is preferably larger than 1 / 10λ. If the particle diameter is too large, it is not preferable because a problem is likely to occur in the flatness of the low refractive index film. Moreover, too small particles are not preferable because they have a small scattering effect and increase the refractive index of the low refractive index layer matrix. For the above reasons, it is desired that the physical particle diameter is such that 60% or more by weight ratio in all particles is in the range of 30 to 400 nm, preferably 40 to 200 nm, and most preferably 60 to 120 nm.
[0036]
The content of the particles in the solid film is preferably about 1 to 40% by volume, particularly about 5 to 20% by volume. If the particle content is too small, a sufficient scattering effect cannot be obtained. If the amount is too large, the concealment effect becomes high, and the rate at which light can be extracted decreases.
[0037]
The thickness of the particle-containing low refractive index layer 4 ′ is preferably about 100 to 1000 nm, particularly about 300 to 700 nm.
[0038]
If this layer is too thin, the scattering layer thickness will be small with respect to the leaching distance, and the scattering effect will be insufficient. If it is too thick, there is no problem with the scattering effect, but it is disadvantageous in terms of flattening and crack prevention. The reason why it is desirable that the transparent electrode side interface of the particle-containing low refractive index layer is flat is that the transparent electrode film formed by the vacuum method reflects the unevenness of the base as it is. The electric field in the electroluminescent layer needs to be kept uniform. If the transparent electrode has irregularities, the electric field becomes non-uniform and causes deterioration of the EL pigment, which easily causes defects such as dark spots. The problem of becoming.
[0039]
The porous silica film is formed by the following process, for example. (1) a step of preparing a raw material liquid for forming a porous silica film, (2) a step of applying the raw material liquid on a substrate to form a primary film, and (3) a high molecular weight of the applied primary film. A step of forming an intermediate film, (4) a step of bringing a water-soluble organic solvent into contact with the intermediate film to form a porous silica film, and (5) a step of drying the porous silica film. Hereinafter, each step will be described.
[0040]
(1) A step of preparing a raw material liquid for forming a porous silica film;
The raw material liquid for forming the porous silica film is a hydrous organic solution containing a raw material compound that is mainly composed of alkoxysilanes and can be increased in molecular weight by hydrolysis reaction and dehydration condensation reaction.
[0041]
The water-containing organic solution that is a raw material liquid contains alkoxysilanes, a hydrophilic organic solvent, water, and a catalyst that is added as necessary.
[0042]
Examples of alkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, tetraisopropoxysilane, tetra (n-butoxy) silane, and the like, trimethoxysilane, triethoxysilane, and methyl. Trialkoxysilanes such as trimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dialkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, bis (Trimethoxysilyl) methane, bis (triethoxysilyl) methane, 1,2-bis (trimethoxysilyl) ethane, 1,2-bis (triethoxysilyl) ethane, 1,4-bis (tri Toxylsilyl) benzene, 1,4-bis (triethoxysilyl) benzene, 1,3,5-tris (trimethoxysilyl) benzene and the like, in which two or more trialkoxysilyl groups are bonded, 3- Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, An alkyl group substituted on a silicon atom, such as 3-carboxypropyltrimethoxysilane, has a reactive functional group, and may be a partial hydrolyzate or oligomer.
[0043]
Among these, tetramethoxysilane, tetraethoxysilane, trimethoxysilane, triethoxysilane, tetramethoxysilane, or tetraethoxysilane oligomer is particularly preferable. In particular, tetramethoxysilane oligomers are most preferably used because of their reactivity and controllability of gelation.
[0044]
Furthermore, monoalkoxysilanes having 2 to 3 hydrogen, alkyl groups, or aryl groups on silicon atoms can be mixed with the alkoxysilanes. By mixing monoalkoxysilanes, the resulting porous silica membrane can be hydrophobized to improve water resistance. Examples of monoalkoxysilanes include triethylmethoxysilane, triethylethoxysilane, tripropylmethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, diphenylmethylmethoxysilane, diphenylmethylethoxysilane, and the like. The mixing amount of monoalkoxysilanes is desirably 70 mol% or less of the total alkoxysilanes. If the mixing amount exceeds 70 mol%, gelation may not occur.
[0045]
Further, fluorinated alkyls such as (3,3,3-trifluoropropyl) trimethoxysilane, (3,3,3-trifluoropropyl) triethoxysilane, pentafluorophenyltrimethoxysilane, pentafluorophenyltriethoxysilane When an alkoxysilane having a group or a fluorinated aryl group is used in combination, excellent water resistance, moisture resistance, stain resistance and the like may be obtained.
[0046]
In this raw material solution, the oligomer may be a cross-linked or cage molecule (such as silsesquioxane). Practically, as the upper limit of the degree of condensate contained in the water-containing organic solution, the transparency of the solution is preferably in the range of 90 to 100% as the light transmittance at a wavelength of 400 nm, 23 ° C. and an optical path length of 10 mm, for example. Used. The lower limit of the light transmittance of the solution is preferably 92% or more, more preferably 95% or more.
[0047]
In addition, when applying the above-described raw material liquid, it is necessary that a certain degree of high molecular weight (that is, a state in which condensation has progressed to some extent) has already been achieved. It is preferable that high molecular weight is achieved to such an extent that insoluble matter cannot be formed. The reason is that if there are visible insolubles in the raw material solution before coating, large surface irregularities can be surely produced and the film quality is lowered.
[0048]
As the organic solvent, those having the ability to mix alkoxysilanes constituting the raw material liquid, water, and a hydrophilic organic compound having a boiling point of 80 ° C. or higher, which will be described later, are preferably used. Usable organic solvents include alcohols such as monohydric alcohols having 1 to 4 carbon atoms, dihydric alcohols having 1 to 4 carbon atoms, polyhydric alcohols such as glycerin and pentaerythritol; diethylene glycol, ethylene glycol monomethyl ether, ethylene Glycol dimethyl ether, 2-ethoxyethanol, propylene glycol monomethyl ether, propylene glycol methyl ether acetate and the like, ethers or esterified products of the above alcohols; ketones such as acetone and methyl ethyl ketone; formamide, N-methylformamide, N-ethylformamide, N , N-dimethylformamide, N, N-diethylformamide, N-methylacetamide, N-ethylacetamide, N, N-dimethylacetamide, N, N-di Tylacetamide, N-methylpyrrolidone, N-formylmorpholine, N-acetylmorpholine, N-formylpiperidine, N-acetylpiperidine, N-formylpyrrolidine, N-acetylpyrrolidine, N, N′-diformylpiperazine, N, N Amides such as' -diformylpiperazine and N, N'-diacetylpiperazine; Lactones such as γ-butyrolactone; Ureas such as tetramethylurea and N, N'-dimethylimidazolidine; Dimethylsulfoxide and the like . These water-soluble organic solvents may be used alone or as a mixture. Among these, preferable organic solvents in terms of film-forming properties (particularly volatile) on the substrate include acetone, methyl ethyl ketone, monohydric alcohols having 1 to 4 carbon atoms, and the like. Among these, methanol, ethanol, n-propanol, isopropyl alcohol, and acetone are more preferable, and methanol or ethanol is most preferable.
[0049]
A hydrophilic organic compound having a boiling point of 80 ° C. or higher has a hydrophilic functional group such as a hydroxyl group, a carbonyl group, an ether bond, an ester bond, a carbonate bond, a carboxyl group, an amide bond, a urethane bond, or a urea bond in the molecular structure. It is an organic compound. The hydrophilic organic compound may have a plurality of hydrophilic functional groups among them in the molecular structure. The boiling point here is a boiling point under a pressure of 760 mmHg. When a hydrophilic organic compound having a boiling point of less than 80 ° C. is used, the porosity of the porous silica film may be extremely reduced. Preferable examples of the hydrophilic organic compound having a boiling point of 80 ° C. or higher include alcohols having 3 to 8 carbon atoms, polyhydric alcohols having 2 to 6 carbon atoms, and phenols. More preferred hydrophilic organic compounds include alcohols having 3 to 8 carbon atoms, diols having 2 to 8 carbon atoms, triols having 3 to 8 carbon atoms, and tetraols having 4 to 8 carbon atoms. More preferable hydrophilic organic compounds include alcohols having 4 to 7 carbon atoms such as n-butanol, isobutyl alcohol, t-butyl alcohol, n-pentanol, cyclopentanol, n-hexanol, cyclohexanol, benzyl alcohol, C2-C4 diols such as ethylene glycol, propylene glycol, 1,4-butanediol, C3-C6 triols such as glycerol and trishydroxymethylethane, C4 such as erythritol and pentaerythritol -5 tetraols. In this hydrophilic organic compound, if the number of carbon atoms is too large, the hydrophilicity may decrease too much.
[0050]
A catalyst is mix | blended as needed. Examples of the catalyst include substances that promote the hydrolysis and dehydration condensation reactions of the alkoxysilanes described above. Specific examples include acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, oxalic acid and maleic acid; amines such as ammonia, butylamine, dibutylamine and triethylamine; bases such as pyridine; Lewis such as acetylacetone complex of aluminum Acids; and the like.
[0051]
Examples of the metal species of the metal chelate compound used as the catalyst include titanium, aluminum, zirconium, tin, and antimony. Specific examples of the metal chelate compound include the following.
[0052]
Examples of aluminum complexes include di-ethoxy mono (acetylacetonato) aluminum, di-n-propoxy mono (acetylacetonato) aluminum, di-isopropoxy mono (acetylacetonato) aluminum, di-n-butoxy. Mono (acetylacetonato) aluminum, di-sec-butoxy mono (acetylacetonato) aluminum, di-tert-butoxy mono (acetylacetonato) aluminum, monoethoxy bis (acetylacetonato) aluminum, mono-n -Propoxy bis (acetylacetonato) aluminum, monoisopropoxy bis (acetylacetonato) aluminum, mono-n-butoxy bis (acetylacetonato) aluminum, mono-sec-butoxy bi (Acetylacetonato) aluminum, mono-tert-butoxy bis (acetylacetonato) aluminum, tris (acetylacetonato) aluminum, diethoxy mono (ethylacetoacetate) aluminum, di-n-propoxy mono (ethylacetoacetate) ) Aluminum, diisopropoxy mono (ethyl acetoacetate) aluminum, di-n-butoxy mono (ethyl acetoacetate) aluminum, di-sec-butoxy mono (ethyl acetoacetate) aluminum, di-tert-butoxy mono (Ethyl acetoacetate) aluminum, monoethoxy bis (ethyl acetoacetate) aluminum, mono-n-propoxy bis (ethyl acetoacetate) aluminum, monoisoprop Xy-bis (ethyl acetoacetate) aluminum, mono-n-butoxy bis (ethyl acetoacetate) aluminum, mono-sec-butoxy bis (ethyl acetoacetate) aluminum, mono-tert-butoxy bis (ethyl acetoacetate) Examples thereof include aluminum chelate compounds such as aluminum and tris (ethylacetoacetate) aluminum.
[0053]
Titanium complexes include triethoxy mono (acetylacetonato) titanium, tri-n-propoxy mono (acetylacetonato) titanium, triisopropoxy mono (acetylacetonato) titanium, tri-n-butoxy mono (acetyl). Acetonato) titanium, tri-sec-butoxy mono (acetylacetonato) titanium, tri-tert-butoxy mono (acetylacetonato) titanium, diethoxy bis (acetylacetonato) titanium, di-n-propoxy bis (Acetylacetonato) titanium, diisopropoxy bis (acetylacetonato) titanium, di-n-butoxy bis (acetylacetonato) titanium, di-sec-butoxy bis (acetylacetonato) titanium, di-tert -Butoxy bis (ace Ruacetonate) titanium, monoethoxy tris (acetylacetonato) titanium, mono-n-propoxy tris (acetylacetonato) titanium, monoisopropoxy tris (acetylacetonato) titanium, mono-n-butoxy tris (acetyl) Acetonato) titanium, mono-sec-butoxy-tris (acetylacetonato) titanium, mono-tert-butoxy-tris (acetylacetonato) titanium, tetrakis (acetylacetonato) titanium, triethoxy mono (ethylacetoacetate) titanium , Tri-n-propoxy mono (ethyl acetoacetate) titanium, triisopropoxy mono (ethyl acetoacetate) titanium, tri-n-butoxy mono (ethyl acetoacetate) titanium, tri-sec-butyl Xy mono (ethyl acetoacetate) titanium, tri-tert-butoxy mono (ethyl acetoacetate) titanium, diethoxy bis (ethyl acetoacetate) titanium, di-n-propoxy bis (ethyl acetoacetate) titanium, diiso Propoxy bis (ethyl acetoacetate) titanium, di-n-butoxy bis (ethyl acetoacetate) titanium, di-sec-butoxy bis (ethyl acetoacetate) titanium, di-tert-butoxy bis (ethyl acetoacetate) Titanium, monoethoxy tris (ethyl acetoacetate) titanium, mono-n-propoxy tris (ethyl acetoacetate) titanium, monoisopropoxy tris (ethyl acetoacetate) titanium, mono-n-butoxy tris (ethyl acetoacetate) Acetate) titanium, mono-sec-butoxy tris (ethyl acetoacetate) titanium, mono-tert-butoxy tris (ethyl acetoacetate) titanium, tetrakis (ethyl acetoacetate) titanium, mono (acetylacetonate) tris (ethyl aceto) Acetate) titanium, bis (acetylacetonato) bis (ethylacetoacetate) titanium, tris (acetylacetonato) mono (ethylacetoacetate) titanium and the like.
[0054]
In addition to these catalysts, weak alkaline compounds such as basic catalysts such as ammonia may be used. In this case, it is preferable to adjust silica concentration, organic solvent species, etc. as appropriate. Moreover, when preparing a water-containing organic solution, it is preferable not to increase the catalyst concentration in a solution rapidly. Specific examples include a method of mixing alkoxysilanes and a part of an organic solvent, then mixing water, and finally mixing the remaining organic solvent and base.
[0055]
In particular, hydrochloric acid that is highly volatile and easy to remove and Lewis acids such as acetylacetone complex of aluminum are preferable. The addition amount of the catalyst is usually 0.001-1 mol, preferably 0.01-0.1 mol, with respect to 1 mol of alkoxysilanes. When the addition amount of the catalyst exceeds 1 mol, a precipitate composed of coarse gel particles is generated, and a uniform porous silica film may not be obtained.
[0056]
The raw material liquid for forming the porous silica film of the present invention is formed by blending the above-mentioned raw materials. The blending ratio of the alkoxysilanes is preferably 10 to 60% by weight and more preferably 20 to 40% by weight with respect to the whole raw material liquid. When the compounding ratio of alkoxysilanes exceeds 60% by weight, the porous silica film may be broken during film formation. On the other hand, when the compounding ratio of alkoxysilanes is less than 10% by weight, the hydrolysis reaction and the dehydration condensation reaction are extremely slow, and the film formability may be deteriorated (film unevenness).
[0057]
Water is blended 0.01 to 10 times, preferably 0.05 to 7 times, more preferably 0.07 to 5 times the weight of the alkoxysilane to be used. When the blending amount of water is less than 0.01 times the weight of the alkoxysilanes, the degree of progress of hydrolysis condensation reaction becomes insufficient, and the film may become cloudy. On the other hand, when the amount of water exceeds 10 times the weight of the alkoxysilanes, the surface tension of the raw material liquid becomes extremely large, and the film formability may deteriorate (liquid repelling, etc.).
[0058]
Water is necessary for hydrolysis of alkoxysilanes, and is important from the viewpoint of improving the film forming property of the target porous silica film. Therefore, when the preferable amount of water is defined by the molar ratio with respect to the amount of alkoxide groups, the amount of water is 0.1 to 1.6 mol times, especially 0.3 to 1.2 mol times the amount of 1 mol of alkoxide groups in alkoxysilane In particular, the amount is preferably 0.5 to 0.7 mole times.
[0059]
Water may be added at any time after the alkoxysilanes are dissolved in an organic solvent, but it is desirable to add water after sufficiently dispersing the alkoxysilanes, catalyst and other additives in the solvent. Most preferred.
[0060]
The purity of the water to be used may be one that has undergone either or both of ion exchange and distillation. When the porous silica film of the present invention is used in an application field that particularly dislikes minute impurities such as semiconductor materials and optical materials, a porous silica film with a higher purity is required, and thus distilled water is further ion-exchanged. It is desirable to use ultrapure water. In this case, for example, water passed through a filter having a pore size of 0.01 to 0.5 μm may be used.
[0061]
When a hydrophilic organic compound having a boiling point of 80 ° C. or higher is used in the water-containing organic solution, the content of the hydrophilic organic compound having a boiling point of 80 ° C. or higher is equal to the total content of the organic solvent and the hydrophilic organic compound having a boiling point of 80 ° C. or higher. On the other hand, it is important that the amount is not more than a specific amount. The content of the hydrophilic organic compound having a boiling point of 80 ° C. or higher with respect to the total content is 90% by weight or less, preferably 85% by weight or less.
[0062]
If the blending ratio of the hydrophilic organic compound having a boiling point of 80 ° C. or higher is too small, the porosity of the porous silica film becomes extremely small, and it may be difficult to achieve a low refractive index of the porous silica film. In general, the total content of the organic solvent and the hydrophilic organic compound having a boiling point of 80 ° C. or higher is preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 60% by weight or more. On the other hand, when the blending ratio of the hydrophilic organic compound exceeds 90% by weight of the total content, the coating film may become cloudy during the film formation or the porous silica film may be broken. Therefore, the content of the hydrophilic organic compound having a boiling point of 80 ° C. or higher in the water-containing organic solution is 30% to 90% by weight, particularly 50% to 85% by weight, particularly 60% to 85% by weight of the total content. % Or less is preferable.
[0063]
The atmospheric temperature in the preparation of the coating liquid and the mixing order are arbitrary, but in order to obtain a uniform structure formation in the coating liquid, water is preferably mixed last. Moreover, in order to suppress the extreme hydrolysis and condensation reaction of silicon alkoxide in the coating solution, the coating solution should be adjusted at a temperature range of 0 to 60 ° C., particularly 15 to 40 ° C., particularly 15 to 30 ° C. Is preferred.
[0064]
At the time of liquid preparation, the stirring operation of the coating liquid is arbitrary, but it is more preferable to stir with a stirrer for each mixing.
[0065]
Further, after the coating solution is prepared, the solution is preferably aged in order to hydrolyze and dehydrate and condense silicon alkoxides. During this aging period, it is preferable that the hydrolyzed condensate of silicon alkoxides to be generated is in a more uniformly dispersed state in the coating solution, and therefore it is preferable to stir the solution.
[0066]
The temperature during the aging period is arbitrary, and in general, it may be heated at room temperature or continuously or intermittently. Among them, it is preferable to perform rapid heat aging in order to form a three-dimensional nanoporous structure by a hydrolytic condensate of silicon alkoxides. Further, when heat aging is performed, heat aging immediately after adjusting the coating solution is preferable, and within 15 days after adjusting the coating solution, more preferably within 12 days, particularly within 3 days, and particularly within 1 day, it is preferable to start heating aging.
[0067]
Specifically, accelerated aging is preferably performed at 40 to 70 ° C. for 1 to 5 hours. At that time, in order to obtain a uniform porous structure, stirring is preferably performed. In particular, accelerated aging for 2 to 3 hours at a temperature in the vicinity of 60 ° C. is preferable from the viewpoint of porosity.
[0068]
The viscosity of the raw material liquid is 0.1 to 1000 centipoise, preferably 0.5 to 500 centipoise, more preferably 1 to 100 centipoise, and it is preferable from the viewpoint of production to use a raw material liquid having a viscosity in this range.
[0069]
(2) A step of forming a primary film from a raw material liquid;
The primary film is formed by applying a water-containing organic solution, which is a raw material liquid, on a substrate. Examples of the substrate include semiconductors such as silicon and germanium, compound semiconductors such as gallium-arsenic and indium-antimony, substrates such as ceramics and metals, and transparent substrates such as glass substrates and synthetic resin substrates.
[0070]
When the porous silica film of the present invention is formed on a substrate, the properties of the substrate surface may affect the properties of the porous silica film. Therefore, not only the cleaning of the substrate surface but also the surface treatment of the substrate may be performed in some cases. Examples of the substrate surface cleaning include immersion treatment in acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, alkalis such as aqueous sodium hydroxide, and mixed liquids having oxidizing properties such as hydrogen peroxide and concentrated sulfuric acid, hydrochloric acid, and ammonia. It is done. In particular, from the viewpoint of adhesion to a porous silica film, it is more preferable to perform a surface treatment with acids such as sulfuric acid and nitric acid on a silicon substrate and a transparent glass substrate.
[0071]
Examples of means for applying the raw material liquid include a casting method in which the raw material liquid is extended onto the substrate using a bar coater, an applicator or a doctor blade, a dip method in which the substrate is immersed in the raw material liquid, and a spin coating method. Well known. Of these means, the casting method and the spin coating method are preferably employed because the raw material liquid can be uniformly applied.
[0072]
When the raw material liquid is applied by the casting method, the casting speed is 0.1 to 1000 m / min, preferably 0.5 to 700 m / min, and more preferably 1 to 500 m / min.
[0073]
The rotation speed in the place where the raw material liquid is applied and formed by the spin coating method is 10 to 100,000 rotations / minute, preferably 50 to 50,000 rotations / minute, and more preferably 100 to 10,000 rotations / minute.
[0074]
In the dip coating method, the substrate may be dipped in the coating solution and pulled up at an arbitrary speed. The pulling speed at this time is preferably 0.01 to 50 mm / sec, more preferably 0.05 to 30 mm / sec, and particularly preferably 0.1 to 20 mm / sec. Although there is no restriction | limiting in the speed | rate which immerses a board | substrate in a coating liquid, It may be preferable to immerse a board | substrate in a coating liquid at a speed | rate comparable as a raising speed | rate. The substrate may be immersed for an appropriate time until the substrate is immersed in the coating solution and pulled up. The duration is usually 1 second to 48 hours, preferably 3 seconds to 24 hours, more preferably 5 seconds to 12 hours. It's time. The atmosphere during coating may be air or an inert gas such as nitrogen or argon, and the temperature is usually 0 to 60 ° C., preferably 10 to 50 ° C., more preferably 20 to 40 ° C. The humidity is usually 5 to 90%, preferably 10 to 80%, more preferably 15 to 70%. Since the dip coating method has a lower drying speed than the spin coating method, there is a tendency to form a stable film with less distortion by the sol-gel reaction after coating. Therefore, the film structure may be preferably controlled by the surface treatment of the substrate.
[0075]
The film forming temperature is 0 to 100 ° C., preferably 10 to 80 ° C., more preferably 20 to 70 ° C.
[0076]
(3) A process in which the applied film is polymerized to form an intermediate film;
The applied film has a high molecular weight, and an intermediate film is formed. This reaction is called a so-called sol-gel method, and the elementary reaction consists of two elementary reactions, a hydrolysis reaction of alkoxysilanes and a dehydration condensation reaction between silanol groups generated by the hydrolysis reaction.
[0077]
The hydrolysis reaction is caused by adding water, but the water can be added as an aqueous alcohol solution or as water vapor without being particularly limited. If water is added rapidly, depending on the type of alkoxysilane, the hydrolysis reaction and the dehydration condensation reaction occur too quickly, and precipitation may occur. Therefore, in order to prevent such precipitation, take sufficient time to add water, make the alcohol solvent coexist in a state where water is added uniformly, and add water at a low temperature. It is preferable to use means such as inhibiting the reaction alone or in combination.
[0078]
As the hydrolytic condensation reaction of alkoxysilanes by the sol-gel method proceeds, the condensation product of alkoxysilanes gradually increases in molecular weight. In the hydrolysis-condensation reaction, phase separation that may be caused by a change in phase equilibrium may occur. In the present invention, the composition of the raw material liquid, the alkoxysilanes used, and the hydrophilic organic compound having a boiling point of 80 ° C. or higher The degree of hydrophilicity is controlled so that phase separation occurs on the nanometer scale. As a result, the separated phase of the hydrophilic organic compound is formed on the substrate while being held in the gel network of the alkoxysilane condensate, thereby forming an intermediate film.
[0079]
For this reason, it is important to control the hydrophilicity of a hydrophilic organic compound having a boiling point of 80 ° C. or higher. When the hydrophilic organic compound is represented by a relative dielectric constant, it is preferably 10 to 20, more preferably 13 to 19 can be defined.
[0080]
From the viewpoint of balancing the degree of hydrophilicity, it is desirable that the water-containing organic solution that is the raw material liquid contains an organic solvent (specifically, methanol, ethanol, etc.) having a relative dielectric constant of 23 or more. In particular, when the weight ratio of the organic solvent having a relative dielectric constant of 23 or more and the hydrophilic organic compound having a boiling point of 80 ° C. or more (weight of the organic solvent / weight of the hydrophilic organic compound) is in the range of 5/5 to 2/8. Furthermore, the desired phase separation behavior is achieved. The weight ratio is most preferably 4/6 to 2/8.
[0081]
(4) Forming a porous silica film by bringing a water-soluble organic solvent into contact with the intermediate film (extraction process);
By bringing a water-soluble organic solvent into contact with the intermediate film, the hydrophilic organic compound in the intermediate film is extracted and removed, and water in the intermediate film is removed. The water present in the intermediate film is not only dissolved in the organic solvent but also adsorbed on the inner wall of the film constituent material. Therefore, in order to effectively remove the water in the intermediate film, the organic solvent Control the water content in it. Therefore, the content of water in the organic solvent is 0 to 10% by weight, preferably 0 to 5% by weight, and more preferably 0 to 3% by weight. If the dehydration is not sufficiently performed, the pores may collapse and disappear or become smaller in the subsequent heating or drying process of the film.
[0082]
As the means for extracting and removing the hydrophilic organic compound in the intermediate film, for example, immersing the intermediate film in a water-soluble organic solvent, washing the surface of the intermediate film with a water-soluble organic solvent, Examples thereof include spraying a water-soluble organic solvent on the surface and spraying water-soluble organic solvent vapor on the surface of the intermediate film. Of these, dipping means and cleaning means are preferred. Although the contact time between the intermediate film and the water-soluble organic solvent can be set in the range of 1 second to 24 hours, the upper limit of the contact time is preferably 12 hours and more preferably 6 hours from the viewpoint of productivity. On the other hand, the lower limit of the contact time is preferably 10 seconds and more preferably 30 seconds because the hydrophilic organic compound having a boiling point of 80 ° C. or higher and water must be sufficiently removed.
[0083]
(5) A step of drying the porous silica membrane;
The drying step is performed for the purpose of removing volatile components remaining in the porous silica membrane and / or for the purpose of promoting the hydrolysis condensation reaction of alkoxysilanes. The drying temperature is 20 to 500 ° C., preferably 30 to 400 ° C., more preferably 50 to 350 ° C., and the drying time is 1 minute to 50 hours, preferably 3 minutes to 30 hours, more preferably 5 minutes to 15 hours. The drying method can be performed by a known method such as blow drying or drying under reduced pressure, and may be combined. It should be noted that since the drying is too strong and the volatile components are removed rapidly, cracks are generated in the porous silica film, so that a gentle drying method such as blow drying is preferable. After the blast drying, vacuum drying for the purpose of sufficiently removing volatile components can be added.
[0084]
This drying step can be used in place of the extraction step described above. That is, the step of removing the hydrophilic organic compound having a boiling point of 80 ° C. or higher from the intermediate film formed in the step (3) is not limited to the extraction step (4), but the drying step described here. Can be implemented.
[0085]
The method for producing a laminated substrate capable of removing the hydrophilic organic compound in such a drying step includes a raw material compound mainly composed of alkoxysilanes that cause a hydrolysis reaction and a dehydration condensation reaction, and a hydrophilic organic compound having a boiling point of 80 ° C. or higher. A step of forming a primary film by applying a water-containing organic solution comprising a substrate, a step of forming an intermediate film by causing a hydrolysis reaction and a dehydration condensation reaction of the water-containing organic solution forming the primary film, Contacting the intermediate film with a catalytic substance that promotes hydrolysis and dehydration condensation reaction to form a dense layer in the surface layer region of the intermediate film; and drying the intermediate film to obtain the boiling point of 80 ° C. It can be specified by a configuration including at least a step of forming the porous silica film by removing the hydrophilic organic compound.
[0086]
C: About the barrier layer 10
As described above, the particle-containing low refractive index layer 4 ′ is preferably formed by hydrolysis of alkoxysilanes. In the formed particle-containing low refractive index layer 4 ′, an alkoxysilane monomer or Oligomers or low molecular weight substances such as solvents, water, and catalysts may remain. In the assembly process of the EL element, a low molecular weight substance or a mobile substance may enter from the outside and remain. This low molecular weight substance has diffusibility and may affect the electroluminescence layer through the transparent electrode layer 3.
[0087]
The barrier layer 10 prevents the diffusion of such substances and protects the transparent electrode layer and the electroluminescence layer.
[0088]
The barrier layer 10 has a high refractive index equal to or higher than that of the transparent electrode layer 3 in the first mode of this embodiment. For this reason, light incident on the barrier layer 10 from the transparent electrode layer 3 is not totally reflected. As a constituent material of the barrier layer 10 in this case, ZrO ₂ TiO ₂ , Al ₂ O ₃ , CeO ₂ , TiN, Ta ₂ O ₃ , Ta ₂ O ₅ , SiO _x N _y , SiN, SiO _x , SnO ₂ , Sb ₂ O ₅ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ Or a mixture thereof. Any material can be used as long as it is visible and has little or no absorption and has a dense film structure, and an inorganic compound as a main component is particularly preferable. This barrier layer is formed, for example, by vapor deposition. The thickness of the barrier layer 10 in this case is not particularly limited, but is preferably 20 nm or more, preferably 50 nm or more, particularly 100 nm or more in order to sufficiently exhibit the barrier characteristics, and to suppress light absorption. In particular, it is preferably 1000 nm or less, particularly 400 nm or less.
[0089]
In the second aspect of the embodiment of FIG. 1, the barrier layer 10 has a low refractive index less than that of the transparent electrode layer 3, and is extremely thin with a thickness of 500 nm or less, particularly 300 nm or less, particularly preferably 200 nm or less. Have At the interface between the low refractive index barrier layer 10 and the transparent electrode layer 3, light from the transparent electrode layer 3 side may be totally reflected. However, since the layer thickness is small, from the interface at the time of total reflection. The leaching region reaches not only the barrier layer 10 but also the particle-containing low refractive index layer 4 ′, and the leaching light is scattered by the particles in the low refractive index layer 4 ′. 'Being taken out inside. When the layer thickness is larger than the above upper limit value, the leaching light does not reach the particle-containing low refractive index layer, so that the extraction rate does not increase.
[0090]
As a constituent material of the ultra-thin barrier layer 10 having a low refractive index, MgF ₂ , Fluoride materials such as NaF, SiO ₂ Or various porous materials such as nanoporous silica, or a mixture thereof. Also in this case, in order to prevent diffusion, the lower limit value of the thickness of the barrier layer is preferably 50 nm or more, particularly 100 nm or more if it can be 20 nm or more.
[0091]
D: About transparent electrode layer 3
The transparent electrode layer 3 functions as an anode of the electroluminescence element. As the transparent electrode layer 3, a composite oxide thin film such as indium oxide added with tin (commonly referred to as ITO) and zinc oxide added with aluminum (commonly referred to as AZO) is preferably used. . In particular, ITO is preferable.
[0092]
The transparent electrode layer 3 is formed by a vacuum film formation process such as vapor deposition or sputtering. The larger the light transmittance in the visible light wavelength region of the formed transparent electrode, the better, for example, 50 to 99%. A preferred lower limit is 60%, more preferably 70%. The electrical resistance of the transparent electrode is preferably as small as the sheet resistance, but usually 1 to 100Ω / □ (= 1 cm). ² The upper limit is preferably 70Ω / □, and more preferably 50Ω / □. Further, the thickness of the transparent electrode is usually 10 to 500 nm as long as the above-described light transmittance and surface resistance value are satisfied, and the lower limit is preferably 50 nm and more preferably 100 nm from the viewpoint of conductivity. On the other hand, from the viewpoint of light transmittance, the upper limit is preferably 300 nm, and more preferably 200 nm. Such a transparent electrode is formed in a pattern necessary as an electrode of an electroluminescence element by a photolithography method or the like.
[0093]
The transparent electrode layer 3 can also be formed by a coating method.
[0094]
E: About the electroluminescence layer 2
The electroluminescence layer 2 is formed of a material that exhibits a light emission phenomenon when an electric field is applied. The material includes activated zinc oxide ZnS: X (where X is Mn, Tb, Cu). , Sm, etc.), CaS: Eu, SrS: Ce, SrGa. ₂ S ₄ : Ce, CaGa ₂ S ₄ : Ce, CaS: Pb, BaAl ₂ S ₄ : Conventionally used inorganic EL materials such as Eu, aluminum complexes of 8-hydroxyquinoline, aromatic amines, organic EL materials of low molecular dyes such as anthracene single crystals, poly (p-phenylene vinylene), poly Conventionally used are conjugated polymer organic EL materials such as [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene], poly (3-alkylthiophene), and polyvinylcarbazole. Organic EL materials can be used. The thickness of the electroluminescence layer is usually 10 to 1000 nm, preferably 30 to 500 nm, more preferably 50 to 200 nm. The electroluminescent layer can be formed by a vacuum film formation process such as vapor deposition or sputtering.
[0095]
F: About cathode 1
The cathode 1 is provided so as to face the transparent electrode layer 3 described above and to sandwich the electroluminescence layer 2. The cathode 1 is made of aluminum, tin, magnesium, indium, calcium, gold, silver, copper, nickel, chromium, palladium, platinum, magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy, or the like. In particular, it is preferable to form with aluminum. If the thickness of the cathode is too thin, reflectivity and conductivity are insufficient. On the other hand, if it is too thick, problems such as separation of the cathode from the electroluminescence layer due to residual stress occur. From this viewpoint, the thickness of the cathode is usually 10 to 1000 nm, preferably 30 to 500 nm, and more preferably 50 to 300 nm. The cathode can be formed by a vacuum film formation process such as vapor deposition or sputtering.
[0096]
G: About other layers
A hole injection layer and a hole transport layer can be further laminated between the electroluminescence layer 2 and the transparent electrode layer 3, and an electron injection layer and an electron are interposed between the electroluminescence layer 2 and the cathode 1. A transport layer can be further laminated. Moreover, you may apply well-known layers other than these.
[0097]
An embodiment of the second invention (claim 2) will be described with reference to FIG.
[0098]
In this embodiment, a barrier layer 10, a particle-containing low refractive index layer 4 ′, and a low refractive index layer 4 not containing particles are provided between the transparent electrode layer 3 and the substrate 5. The matrix components of the low refractive index layer 4 and the particle-containing low refractive index layer 4 ″ have the same refractive index. The difference between the refractive index of the low refractive index layer 4 and the refractive index of the matrix component of the particle-containing refractive index layer 4 ″ is 0.3 or less, preferably 0.2 or less, particularly preferably 0.1 or less. is there.
[0099]
The other structure of the electroluminescent element of FIG. 2 is the same as that of FIG. 1, and the same code | symbol has shown the identical part. The barrier layer 10 may be either the first aspect or the second aspect of the embodiment of FIG.
[0100]
The low refractive index layer 4 in FIG. 2 can be the same as the matrix component (composition other than particles) of the low refractive index layer 4 ′. The matrix component of the low refractive index layer 4 ″ can be the same as the matrix component of the low refractive index layer 4 ′. The matrix component of the particle-containing low refractive index layer 4 ″ is preferably the same composition as the low refractive index layer 4, but may be different.
[0101]
The difference in refractive index between the matrix component of the low refractive index layer 4 ″ and the low refractive index layer 4 is 0.3 or less, particularly preferably 0.2 or less, particularly preferably 0.1 or less.
[0102]
The thickness of the low-refractive index layer 4 is considered from the bleed distance at the time of total reflection at the interface, and if it is too thin, the leached light penetrates without being refracted into the substrate, and the rate of exiting as it is increases. There is a problem that the effect of improving the light extraction rate is insufficient. On the other hand, if the film is too thick, it is difficult to flatten the film surface, and cracks are liable to occur due to problems of residual strain and its strain absorption capability. It is preferable that it is 100-1000 nm, especially 300-700 nm. The thickness of the particle-containing low refractive index layer 4 '' is preferably 100 to 1000 nm, particularly 300 to 700 nm.
[0103]
As shown in FIG. 3 described later, an air layer (void) may be provided in place of the low refractive index layer 4 that does not contain particles, only for a top emission type element in which the substrate 5 is disposed on the cathode 1 side. In this case, the refractive index of the air layer is 1.0. Also, regarding the thickness, the problem of flattening of the film and cracks are solved, so that the upper limit is not particularly limited.
[0104]
The preferred particles of the particle-containing low refractive index layer 4 ″ and the preferred content thereof are the same as those of the particle-containing low refractive index layer 4 ′.
[0105]
In the electroluminescent device of FIG. 2 configured as described above, when the barrier layer 10 has the high refractive index equal to or higher than that of the transparent electrode layer 3, the barrier layer 10 and the low refractive index are as follows. Total reflection at the interface with the index layer 4 ″ is reduced.
[0106]
That is, when light is incident from the electroluminescence layer 2 through the transparent electrode layer 3 and the barrier layer 10 to the interface between the barrier layer 10 and the particle-containing low refractive index layer 4 '' at an incident angle larger than the critical angle, Light is totally reflected at the interface. In this total reflection, a phenomenon occurs in which a part of light oozes out from the interface toward the particle-containing low refractive index layer 4 ″ in the same manner as in the case of FIG. That is, the electric field and magnetic field of the incident light exist on the particle-containing low refractive index layer 4 ″ side from the interface.
[0107]
In the vicinity of the interface in the particle-containing low-refractive index layer 4 ″, there is a particle that scatters the leached light. The portion is scattered by the particles and diffuses directly or indirectly into the particle-containing low refractive index layer 4 ″ without returning to the total reflection light on the barrier layer 10 side. Thus, by including the light scattering particles in the particle-containing low refractive index layer 4 ″, the reflectivity of total reflection is reduced, and more light is transmitted from the barrier layer 10 to the particle-containing low refractive index layer 4. It will enter the '' side.
[0108]
Since the matrix of the particle-containing low refractive index layer 4 ″ and the low refractive index layer 4 have the same refractive index, total reflection is performed at the interface between the particle-containing low refractive index layer 4 ″ and the low refractive index layer 4. Does not occur. As a result, light that enters the particle-containing low refractive index layer 4 ″ from the transparent electrode layer and reaches the interface between the particle-containing low refractive index layer 4 ″ and the low refractive index layer 4 is almost as it is. Enter layer 4. In this way, the light extraction efficiency from the electroluminescence element is improved.
[0109]
Also in the embodiment of FIG. 2, the second mode of the embodiment of FIG. 1, that is, the barrier layer 10 may have a low refractive index and a very thin film thickness. Also in this case, the light extraction efficiency is improved as in the second embodiment.
[0110]
The above embodiment is a bottom emission type element in which light is emitted from the substrate 5. However, in the present invention, the cathode 1 is formed on the substrate and a transparent protective cover is provided instead of the substrate 5. It may be an element.
[0111]
FIG. 3 shows an element according to the embodiment of the top emission type in the embodiment of FIG. 1, in which a cathode 1 is formed on a substrate 5, and an electroluminescence layer 2 and a transparent electrode layer are sequentially formed thereon. 3, a barrier layer 10 and a particle-containing low refractive index layer 4 ′ are formed, and a protective cover 6 is formed on the particle-containing low refractive index layer 4 ′. Optically, this protective cover serves as the substrate in the embodiment of FIG. As the material of the protective cover 6, any material that is transparent and can be flattened can be used. In addition to various glass and resin materials used for the substrate, a transparent coating material having no self-supporting property, such as UV or heat. Examples thereof include a curable acrylic resin and a sol-gel reaction material (silicate material). The thickness of the protective cover 6 is preferably about 10 to 1000 μm, particularly about 100 to 200 μm. In this case, the substrate 5 does not necessarily need to be transparent.
[0112]
FIG. 3 shows a top emission type element in which the substrate 5 is arranged on the cathode 1 side in the embodiment of FIG. 1, but a top emission type element in which the substrate 5 is arranged on the cathode 1 side in FIG.
[0113]
【Example】
Hereinafter, Reference Examples 1 and 2 and Comparative Examples 1 and 2 corresponding to Examples will be described. In Reference Examples 1 and 2 and Comparative Examples 1 and 2 below, the cathode and the electroluminescence layer are not formed, a fluorescent dye layer is formed on the transparent electrode layer, and the fluorescent dye layer is irradiated with excitation light. The fluorescence was taken out from the substrate side.
[0114]
<Reference Example 1 (corresponding to the embodiment of FIG. 1)>
A surface of a glass substrate having a thickness of 0.7 mm and a plane size of 75 mm square made of non-alkali glass AN100 manufactured by Asahi Glass Co., Ltd. was degreased by immersing it in 0.1 N nitric acid for about 1 hour, and then washed with pure water Dry in an oven at 60 ° C.
[0115]
Meanwhile, a small amount of acid catalyst (aluminum acetylacetonate) was added to 30 wt% of MS51 (tetramethoxysilane oligomer) manufactured by Mitsubishi Chemical Co., Ltd. The fine particles were added together with a surfactant, stirred at 60 ° C. for 3 hours, and left to mature for one week.
[0116]
This is coated on the glass substrate 1 with a dip coater, dried for 15 minutes, immersed in methanol for 5 minutes, pulled up, dried for 5 minutes, heated in a 150 ° C. oven for 15 minutes, and then the particle-containing low refractive index layer 4 ′. Got.
[0117]
The film thickness of the particle-containing low-refractive index layer 4 ′ is 600 nm, and the refractive index of the low-refractive index film formed of only a matrix material (material excluding fine particles) is measured with a sopra ellipsometer. It was 1.27 at 550 nm.
[0118]
Zirconium oxide was vapor-deposited on the low refractive index layer 4 ′ to form a barrier layer 10 having a thickness of 300 nm. On top of that, ITO was sputtered at a thickness of 1000 mm to form a transparent electrode layer 3 and further AlQ3 (fluorescent dye tris (8-hydroxyquinolide) aluminum) was deposited at a thickness of 1000 mm.
[0119]
The back surface of this laminate is irradiated with excitation light having a wavelength of 400 nm or less, and the extracted light intensity of 420 to 750 nm is measured with a detector placed in the direction of an emission angle of 45 degrees on the surface, and the emission energy integrated at all wavelengths is obtained. It was. A fluorescence spectral luminance meter manufactured by Hitachi, Ltd. was used for the measurement.
[0120]
<Comparative Example 1 (corresponding to the conventional example of FIG. 5)>
Except that the titania fine particles were not added to the coating solution for forming the low refractive index layer in Reference Example 1, a fluorescent element having a layer structure corresponding to FIG. went.
[0121]
The amount of light extracted in Reference Example 1 was 170% of the amount of light extracted in Comparative Example 1.
[0122]
<Comparative example 2 (equivalent to the conventional example of FIG. 4)>
An electroluminescent element was produced in the same manner as in Comparative Example 1 except that the low refractive index layer 4 was omitted and the layer configuration shown in FIG.
[0123]
The amount of light taken out in Comparative Example 2 was 91% of Comparative Example 1.
[0124]
<Reference Example 2 (corresponding to the embodiment of FIG. 2)>
The low refractive index layer 4 having a thickness of 500 nm is formed using the coating liquid containing no titania fine particles of Comparative Example 1, and the 600 nm thick particles containing the titania fine particle-containing coating liquid of Reference Example 1 are formed thereon. A low refractive index layer 4 ″ was formed.
[0125]
Zirconium oxide was deposited thereon to form a barrier layer 10 having a thickness of 300 nm. On top of that, ITO was sputtered at a room temperature of 1000 mm to form a transparent electrode layer 3, and further AlQ3 was deposited at a thickness of 1000 mm.
[0126]
When the same extracted light amount measurement was performed for Reference Example 2, it was 190% of Comparative Example 1.
[0127]
【The invention's effect】
As described above, according to the present invention, the light extraction efficiency of the electroluminescence element can be remarkably improved. According to the present invention, the light extraction rate of an electroluminescent element can be improved widely regardless of inorganic or organic. In particular, since the optical functional layer is provided on the light emitting layer side with respect to the transparent substrate on the emission side, an improvement in the light extraction rate can be achieved without causing deterioration in resolution and bleeding between pixels. In addition, the transparent electrode layer and the electroluminescence layer can be protected by the barrier layer, so that deterioration of the electroluminescence pigment and generation of dark spots can be suppressed, and the lifetime of the element can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electroluminescence element according to an embodiment.
FIG. 2 is a cross-sectional view of an electroluminescence element according to an embodiment.
FIG. 3 is a cross-sectional view of an electroluminescence element according to an embodiment.
FIG. 4 is a cross-sectional view of an electroluminescence element according to a conventional example.
FIG. 5 is a cross-sectional view of an electroluminescence element according to a conventional example.
[Explanation of symbols]
1 Cathode
2 Electroluminescence layer
3 Transparent electrode layer
4 Low refractive index layer
4 ', 4''particle-containing low refractive index layer
5 Glass substrate
6 Protective cover
10 Barrier layer

Claims (7)

In the electroluminescence device in which the cathode, the electroluminescence layer, the transparent electrode layer, the low refractive index layer, and the light transmitting body are arranged in this order,
The low refractive index layer includes a matrix having a refractive index of 1.1 to 1.5 and a refractive index lower than that of the translucent material , and particles that scatter light from the electroluminescent layer;
An electroluminescence device, wherein a barrier layer is provided between the low refractive index layer and the transparent electrode layer to prevent a substance in the low refractive index layer from diffusing to the transparent electrode layer side. In the electroluminescence device in which the cathode, the electroluminescence layer, the transparent electrode layer, the low refractive index layer, and the light transmitting body are arranged in this order,
Between the transparent electrode layer and the low refractive index layer, a particle-containing layer comprising a matrix and particles that scatter light from the electroluminescence layer dispersed in the matrix is provided,
The matrix has a refractive index equivalent to the low refractive index layer;
An electroluminescence device, wherein a barrier layer is provided between the particle-containing layer and the transparent electrode layer to prevent a substance in the particle-containing layer from diffusing to the transparent electrode layer side.   3. The electroluminescent device according to claim 1, wherein the refractive index of the barrier layer is equal to or higher than the refractive index of the transparent electrode layer.   3. The electroluminescent device according to claim 1, wherein the barrier layer has a thickness of 50 to 400 nm.   5. The electroluminescent element according to claim 4, wherein the barrier layer has a thickness of 100 to 200 nm.   6. The electroluminescent element according to claim 1, wherein the light transmitting body is a transparent substrate.   6. The electroluminescent element according to claim 1, wherein the cathode is formed on a transparent substrate, and the light transmitting body is a protective cover.

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