JP4140541B2 - Electroluminescence element - Google Patents

Description

  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.

  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.

  In the 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 7 and the air 7 and travels while being totally reflected in the surface direction inside the transparent substrate 2. There is also guided light that is totally reflected at the interface between the transparent electrode layer and the transparent substrate and proceeds in the plane direction inside the transparent electrode or inside the transparent electrode and the electroluminescent layer. This guided light is absorbed and attenuated inside the device. Therefore, it is not taken out (Non-Patent Documents 1 and 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%.

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.
JP 2002-278477 A (paragraph numbers 0010 to 0012) Chutinan et al. "Spring Materials Society Preliminary Proceedings" 2003 27P-A-16 Fujita et al. "Spring Materials Society Preliminary Proposal" 2003 29-YN-13

  As described in JP-A-2002-278477, by providing the low refractive index layer 4 between the transparent electrode layer 3 and the transparent substrate 5, total reflection at the interface with the air layer 7 of the transparent substrate 5 is reduced. However, in the publication, 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.

  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

Electroluminescent device according to the reference example, the cathode, the electroluminescent layer, a transparent electrode layer, and the translucent body is the electroluminescent device comprising disposed in this order, between the transparent electrode layer and the translucent member, the low refractive A leaching light diffusing layer containing particles that scatter light is provided in a matrix made of an index material.

  In this way, when a leaching light diffusion layer containing particles that scatter light is provided in a matrix made of a low refractive index material between the transparent electrode layer and the transparent body, an electroluminescence layer, a transparent electrode layer And the total reflection amount of the light incident on the interface of the low refractive index layer is reduced.

  The reason is considered as follows. That is, light is incident at an incident angle larger than the critical angle at the interface with the leaching light diffusion layer containing particles that scatter light from the electroluminescence layer through the transparent electrode layer into the matrix made of the low refractive index material. When incident, this light is totally reflected at the interface. However, as shown in FIG. 1B, which will be described later, during this total reflection, a part of light oozes out to the low refractive index layer side (layer side made of a low refractive index material) from the interface. A phenomenon occurs (this leaching light may be called evanescent wave or near-field light). That is, the electric field and magnetic field of incident light exist even on the low refractive index layer side from the interface.

  Using this leaching phenomenon, the low refractory layer leached out by allowing particles of different refractive index from the matrix made of low refractive index material to exist within the light bleed distance (depth). Part of the light is scattered by the particles and is no longer returned to the totally reflected light in the transparent electrode layer, but after being scattered, or after being reflected directly or by a cathode, for example, an aluminum reflective film, diffuses into the low refractive index layer. It becomes like this. In this way, by including particles that scatter light (hereinafter sometimes referred to as “light scattering particles”) in the low refractive index layer that is in contact with the transparent electrode layer, the reflectance of total reflection is reduced. A lot of light enters from the transparent electrode layer to the low refractive index layer side. As a result, the light extraction efficiency of the electroluminescence element is improved. Other than using light scattering particles, between the transparent electrode layer and the low refractive index layer, between the transparent electrode layer and the transparent body (glass substrate), or between the transparent electrode layer and the EL light emitting layer. There are also proposals to provide controlled irregularities such as forming a grating, a planar photonic crystal, and a microlens, but all of these are laborious and costly to form, which is disadvantageous industrially.

The electroluminescent device of the present invention (Claim 1 ) is an electroluminescent device comprising a cathode, an electroluminescent layer, a transparent electrode layer, a low refractive index layer, and a translucent material arranged in this order. A leachable light diffusion layer containing particles that scatter light in a matrix made of a low refractive index material is provided between the refractive index layer and the matrix of the leachable light diffusion layer. The refractive index is equal to the refractive index of the refractive index layer and lower than the refractive index of the transparent electrode layer.

  In the present specification, “equivalent refractive index” means that the difference between one refractive index and the other refractive index is less than 0.3, preferably 0.2 or less, particularly preferably 0.1 or less. That means. The refractive index “low” may be “low” to such an extent that a difference in measurement occurs, but in practice it exceeds 0.1, preferably exceeds 0.2, more preferably 0.3. More preferably, the difference is 0.4 or more, and particularly preferably 0.5 or more.

  At the interface of the leaching light diffusion layer provided between the transparent electrode layer and the low refractive index layer, the transparent electrode layer is formed by the light scattering action of the leaching light diffusion layer containing particles in the same manner as described above. The total reflection of the light that has oozed out to the low refractive layer side is reduced. That is, when total reflection occurs at the interface between the transparent electrode layer and the leaching light diffusion layer, the light leached into the particle-containing leaching light diffusion layer at the time of total reflection is reflected in the particle-containing leaching light diffusion layer. Scattered by the particles 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 transparent electrode layer on the particle-containing layer side after being reflected directly from the transparent electrode layer or by an aluminum reflective film of the cathode, for example, increases.

  The matrix of the particle-containing leaching light diffusing layer and the low refractive index layer have the same refractive index, and therefore, total reflection hardly occurs at the interface between the particle-containing leaching light diffusing layer and the low refractive index layer. As a result, most of the light entering the particle-containing leached light diffusing layer from the transparent electrode layer and reaching the interface between the particle-containing leached light diffusing layer and the low refractive index layer is directly converted into the low refractive index layer. enter in. In this way, the light extraction efficiency from the electroluminescence element is improved.

That is, according to the present invention, a part of the total reflected light that is normally confined in the transparent electrode layer by the light scattering particle-containing exuded light diffusing layer is used by utilizing the exudation that occurs during total reflection. By taking out the light and making it enter perpendicularly into the transparent substrate by the low refractive index layer and making it refracted (incident at an angle where the amount of total reflection is small), the total reflection at the air layer interface of the transparent substrate is suppressed. Thereby, the light extraction efficiency is remarkably improved.
In a simple scattering layer (a layer in which scattering particles are dispersed in a range where the leaching light does not reach, and only light scattering that does not participate in light extraction) is physically performed, light that is not simply totally reflected. Moves to the low refractive index layer and only functions to scatter this light, so that total reflection at the air layer interface of the transparent substrate is hardly reduced, and improvement in light extraction efficiency can hardly be expected.

  According to the present invention, the light extraction efficiency of the electroluminescence element can be significantly improved. According to the present invention, the light extraction efficiency of electroluminescent elements can be improved widely regardless of inorganic light-emitting materials and organic light-emitting materials.

Hereinafter, the present invention will be described in more detail with reference to embodiments. 1 and 2 are cross-sectional views showing a reference example and an electroluminescence element according to an embodiment of the present invention, respectively .

FIG. 1A shows an electroluminescence element according to a reference example . The cathode 1, the electroluminescence layer 2, the transparent electrode layer 3, the light scattering particle-containing seepage light diffusion layer 4 ′, and the light transmission of a glass substrate or the like. The substrates 5 are stacked in this order.

  The light from the electroluminescence layer 2 is reflected as it is or reflected by the cathode 1 and passes through the electroluminescence layer 2 and is emitted to the transparent electrode layer 3 side. Thereafter, the light scattering particle-containing leachable light diffusion layer 4 ′ and the substrate 5 are emitted. Taken out through.

  In this electroluminescence element, the light scattering particle-containing seepage light diffusion layer 4 ′ is provided, so that the light that has entered the light scattering particle-containing seepage light diffusion layer 4 ′ from the transparent electrode layer 3 side is incident on the substrate 5. The light enters the interface between the substrate 5 and the light diffusing particle-containing exuded light diffusing layer 4 ′ at an incident angle close to perpendicular to the substrate surface, and the total reflection at the air layer side interface of the substrate 5 is reduced.

  In this embodiment, since the light scattering particle-containing leaching light diffusion layer 4 ′ contains particles, the light scattering particle-containing leaching light diffusion layer 4 ′ of the transparent electrode layer 3 and The total reflection at the interface decreases, and the light extraction efficiency is improved.

  That is, the transparent electrode layer 3 and the low refractive index layer from the electroluminescence layer 2 through the transparent electrode layer 3 (in this case, a case where the light scattering particle-containing seepage light diffusion layer 4 ′ is not provided) is considered. When the light 11 is incident on the interface 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 part of light oozes out to the low refractive index layer side from the interface. That is, the electric field and magnetic field of the incident light ooze out from the interface between the transparent electrode layer 3 and the low refractive index layer to the low refractive index layer side. When the transparent electrode layer has a thickness of 100 nm and the refractive index of the light scattering particle-containing exuded light diffusion layer 4 ′ is 1.3, the reach distance of the seepage light is 500 to 600 nm in the direction perpendicular to the transparent electrode. It is known. Normally, the light that has oozed out to the low refractive index layer side returns to the transparent electrode layer 3 side after total reflection.

  In the present invention, a light-scattering particle-containing leachable light diffusion layer 4 ′ which is also a low refractive index layer is provided at a position where leachable light exists in the vicinity of the interface between the transparent electrode layer 3 and the low refractive index layer. By adopting such a structure, particles (particles having a refractive index different from that of the low refractive index layer) scatter the light that has penetrated into the low refractive index layer in the vicinity of the interface between the transparent electrode layer 3 and the low refractive index layer. become.

  That is, a part of the light that has oozed out to the light diffusion layer 4 ′ side is scattered by the particles, and is no longer returned to the total reflected light in the transparent electrode layer 3. The light enters the protruding light diffusion layer 4 ′ side (transferred or taken in). Light that has entered the light diffusion layer 4 ′ side that has penetrated into the light scattering particles is scattered and diffused by the light scattering particles, or after being reflected directly or after being reflected by, for example, an aluminum reflecting film of the cathode 1, The leaching light diffuses into the light diffusion layer 4 ′.

  In this way, the reflectance of total reflection is reduced by the light scattering particle-containing seepage light diffusing layer 4 ′, and more light is oozed out of the transparent electrode layer 3 and contains light scattering particles 4 ′. As a result, the light extraction efficiency of the electroluminescence element is improved.

  Next, the preferable structure of the board | substrate 5 and each layer 1-4 'is demonstrated.

A: Substrate The substrate has a refractive index 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. Those in the range of 60 are used.

  When the refractive index of the substrate exceeds 1.9, the difference in refractive index between the substrate and air is large, so that the total reflection amount here becomes large. Since the thickness of the substrate normally exceeds 100 μm, especially in the case of EL display applications, if the total reflection here is large, the amount of light that has been totally reflected once returns to the diffusion layer and is scattered again and emitted. This is not preferable because emission light is mixed between pixels having a size of 100 μm square or less, and a phenomenon such as pixel bleeding and color bleeding is generated.

  Also, if the refractive index of the substrate exceeds 1.9, the reflection of external light on the substrate surface becomes large, which is also not preferable because it reduces the resolution of the display.

  When the refractive index of the substrate is less than 1.4, there is no material suitable as a self-supporting transparent substrate material, which is not preferable.

  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.

  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.

  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).

B: Light-scattering particle-containing oozing light diffusion layer The particle-containing light-scattering particle-containing oozing light diffusion layer 4 ′ is obtained by dispersing particles in a low refractive index matrix. As this matrix, fluoride resins such as silica and cyclic Teflon, magnesium fluoride, and the like are 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.

  It is important that the refractive index of this matrix is lower than the refractive index of the transparent electrode layer 3, and preferably the refractive index of the matrix is lower than that of the transparent substrate 5. As described above, the “low refractive index material” in the present invention means a material having a refractive index lower than that of the transparent electrode layer 3 (preferably a material having a refractive index lower than that of the transparent substrate 5).

  The refractive index of the matrix is specifically 1.1 to less than 1.9, preferably 1.1 to 1.6, particularly 1.2 to 1.5, and more preferably about 1.2 to 1.35. If the refractive index is too low, the mechanical strength of the film tends to be insufficient. If it is too high, the amount of total reflected light on the light exit side of the light-scattering particle-containing seepage light diffusion layer 4 ′ increases, and the light extraction efficiency decreases.

  The light scattering particles contained in the light scattering particle-containing exuded light diffusion layer 4 ′ include silica (refractive index 1.46), colloidal silica (refractive index 1.3 to 1.4 varies depending on production conditions), Titania (refractive index: 2.4 to 2.7, depending on crystal form), zirconia (refractive index: 2.0), ITO (indium tin oxide) (refractive index 1.9), ATO (antimony tin oxide) (refractive Preferably 1.9) and alumina (refractive index 1.8). In particular, it is preferable that light absorption in the visible region is as small as possible (that is, colorless and transparent) and that the refractive index difference with the matrix of the light-scattering particle-containing leached light diffusion layer 4 ′ is as large as possible.

  The difference in refractive index is the difference in refractive index between the matrix and the dispersed light scattering particles, and it does not matter which refractive index is higher. Examples of the particles having a refractive index smaller than that of the matrix include fine bubbles. In order to suppress the wavelength dependency of the scattering rate, fine bubbles may be desirable. Usually, particles having a refractive index larger than that of the matrix are often used. The difference in refractive index between the matrix and the light scattering particles is 0.1 or more, preferably 0.3 or more, more preferably 0.5 or more, and still more preferably 0.9 or more. The upper limit of the refractive index difference is not in principle, but is usually about 1.5 in view of easily available materials.

  In order to form a light diffusing particle-containing leached light diffusion layer in which such light scattering particles are dispersed in the matrix, for example, in the step (1) of preparing a raw material liquid described later, the light scattering particles are added to the raw material liquid You just have to.

  The size and shape of the particles must have a function of diffusing the seepage light, that is, preventing the seepage light from returning to the transparent electrode side and scattering and diffusing to the light extraction side (translucent side). The amount of leaching light (leaching distance) substantially exists from the interface (the interface between the transparent electrode layer and the low refractive index layer) to the low refractive index layer side from about 100 to 600 nm. Therefore, it is necessary to have a diameter that can exist in this range and has a function of diffusing light.

  The light-scattering particles are preferably those that cause Mie scattering. Therefore, the particle size is 1 / 20λ when the wavelength of light to be scattered (usually 400 to 700 nm because it is visible light) is λ as the optical size. Preferably, it is desired to be larger than 1 / 10λ. In addition, it is not preferable that the particle diameter of the light scattering particles is too large because a problem is likely to occur in the flatness of the light diffusion layer containing the light scattering particles. If a problem arises in the flatness of the light diffusing layer containing the light scattering particles, the electric field in the EL light-emitting layer becomes non-uniform, and problems such as a decrease in luminance and lifetime of the device are likely to occur. In addition, particles that are too small are not preferable because they have a small scattering effect and also increase the refractive index of the light diffusing layer-containing light diffusion layer matrix. For the above reasons, the physical particle diameter is 20 to 400 nm, preferably 40 to 200 nm, most preferably 60% or more (sometimes referred to as “60% weight particle diameter”) in terms of the weight ratio (weight percentage) of the particles. Is desirably in the range of 60 to 120 nm.

  In the present invention, the measurement of the 60% weight particle diameter of the light scattering particles is carried out as follows.

[1] Cross-sectional observation of the diffusion layer was performed with FIB-SEM.
FIB (focused ion beam) is an abbreviation for focused ion beam processing observation apparatus, and “FB-2000A” manufactured by Hitachi, Ltd. was used as the apparatus. The section processing conditions are as follows.
(1) A sputtered Pt (platinum) film was formed before FIB processing.
(2) A W (tungsten) film was locally formed at the corresponding location before the cross section was prepared by FIB.
(3) A hole for observation (about 20 μ × 30 μ square) was made with FIB, and the surface used for observation was finished by lowering the ion beam current. The ion species was Ga ⁺ and the ion beam acceleration voltage was 30 kV.

  SEM observation was performed with “S4100” manufactured by Hitachi, Ltd. The observation condition was an acceleration voltage of 5.0 kV, and an image was taken of the observation surface of the hole made by FIB with an inclination of about 80 degrees from the sample film vertical direction (equivalent to observing the film cross section from almost the front). The magnification was × 10000.

The cross-sectional observation image was observed as follows.
Twenty random images of 20 μ width in the surface direction of the sample film were collected from the sample film, and the particle diameter of the observed particles in the image was observed. When the particle cross-sectional shape is irregular, the particle diameter of the particle is regarded as the particle diameter when the particle is regarded as a particle having a circular cross section having substantially the same area.
For each of the particles observed here, the particle size is converted to a weight assuming that the cube of the particle size is proportional to the weight of the particle, and the range of 60% by weight or more of all particles in terms of the particle size conversion defined above is derived. It was.
When the particles were aggregated and formed into a lump, this was handled as a single particle (basically, measurement by this method was adopted).

  When the above method could not be applied because the sample film was fragile or the particle shape was difficult to understand with SEM or TEM, the particle size was measured using the following means.

[2] In preparing the coating liquid before forming the sample film, the particle suspension was passed through a particle size distribution meter to measure the particle size distribution.
As the particle size distribution meter, MICROTEC particle size distribution model “9230 UPA” manufactured by Nikkiso Co., Ltd. was used. The solvent for suspending the particles is not particularly limited as long as the particles can be suspended. However, when titania particles are dispersed in a silicate solution to form a film by a sol-gel method, an alcohol solvent is desirable.
From the measured particle size distribution, data of particle diameter, frequency and cumulative ratio can be obtained. From this data, it was assumed that the particle diameter was approximately the diameter of a spherical particle, and the range of the 60% weight particle diameter was derived in the same manner as described above.

  The thickness of the oozing-out light diffusion layer is preferably at least twice the average particle diameter of the light scattering particles. Thus, by setting the particle diameter of the light scattering particles and the thickness of the leaching light diffusion layer, the light scattering particles exhibit a scattering effect efficiently.

  The average particle diameter of the light scattering particles is a value that is 50% by volume by measuring the particle size distribution by the method shown above (FIB-SEM, if not applied, measuring the particle size distribution of the particle dispersion before coating). Was used.

  The content of light scattering particles in the light scattering particle-containing leaching light diffusion layer 4 ′ is preferably about 1 to 40% by volume, particularly about 5 to 20% by volume. When the light scattering particle content is too small, a sufficient scattering effect cannot be obtained. When the amount is too large, the concealment effect becomes high, and the rate at which light can be extracted decreases.

  The thickness of the light scattering particle-containing exuded light diffusion layer 4 'is preferably about 100 to 1000 nm, particularly about 300 to 700 nm. Needless to say, this is based on the assumption that the light-scattering particle-containing exuded light diffusion layer 4 ′ is positioned within the reach of the exuded light. Although it depends on the film thickness and wavelength of the light diffusion layer 4 ′ that oozes out the light scattering particles, the light scattering particles are usually present within 1 μm (1000 nm), preferably 600 nm from the surface of the transparent electrode layer 3. It is preferable to provide a protruding light diffusion function, and it is one of preferred embodiments that 1/3 or more of the light scattering particles are disposed within 600 nm from the surface of the transparent electrode layer 3.

  If this light scattering particle-containing leaching light diffusion layer 4 'is too thin, the scattering layer thickness (abundance of particles in the leaching part) will be small with respect to the light leaching distance, and the scattering effect will be insufficient. It becomes. If it is too thick, there is no problem with scattering, but it is disadvantageous in terms of flattening and crack prevention.

  The transparent electrode layer 3 side interface of the light scattering particle-containing exuded light diffusion layer 4 ′ is preferably flat because the vacuum method is applied on the light scattering particle-containing exuded light diffusion layer 4 ′. This is because the transparent electrode layer 3 formed by (which means a vacuum deposition method or the like) reflects the unevenness of the foundation almost as it is.

  That is, in order to generate uniform and stable light, it is desirable to keep the electric field in the electroluminescence layer as uniform as possible. If the transparent electrode layer 3 has large irregularities, the electric field becomes non-uniform and the EL becomes uneven. This is because problems such as deterioration of the dye and the occurrence of defects such as dark spots are likely to occur.

The porous silica film as the matrix of the light scattering particle-containing exuded light diffusion layer 4 ′ is formed by the following steps (1) to (5), for example.
(1) Step of preparing a raw material liquid for forming a porous silica film
(2) A process of forming the primary film by applying the raw material liquid onto the substrate
(3) Process in which the applied primary film is made high molecular weight to form an intermediate film
(4) A step of forming a porous silica film by bringing a water-soluble organic solvent into contact with the intermediate film
(5) Step of drying the porous silica membrane

Hereinafter, each step will be described.
However, since the purpose is to form a low refractive index film, in the present invention, the method for forming the low refractive index layer 4 is not particularly limited to this manufacturing method as long as the requirements are satisfied. For example, a porous film (mesoporous film) produced by a manufacturing process as shown in the following document can also be used as long as the film requirements are satisfied.
JP2002-278477
USP Pat.No.US6592764B1 (BLOCK COPOLYMER PROCESSING FOR MESOSTRUCTURED INORGANIC
OXIDE MATERIALS Inventors; Galen D. Stucky et al.)
ULVAC Technical Bulletin No.57, September 2002, pages 34-36
IDW2002 Proceedings 1163-1166
Application of Low Refractive Materials for Optical Windows of Displays T. Nakayama
Et al.ULVAC

(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.

  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.

  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.

  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.

  Furthermore, monoalkoxysilanes having 2 to 3 hydrogen, alkyl groups, or aryl groups on a silicon atom 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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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 appropriately adjust the silica concentration, the organic solvent species, and the like. 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.

  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.

  The raw material liquid for forming the porous silica film is formed by blending the above-described 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).

  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.).

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  In the present invention, in order to form the light scattering particle-containing exuded light diffusion layer 4 ′, a predetermined amount of light scattering particles is blended in the raw material liquid prepared as described above.

(2) forming a primary film from the 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.

  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.

  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.

  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.

  When the raw material liquid is applied and formed by the spin coating method, the rotation speed is 10 to 100,000 rotations / minute, preferably 50 to 50,000 rotations / minute, and more preferably 100 to 10,000 rotations / minute.

  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.

  The film forming temperature is 0 to 100 ° C., preferably 10 to 80 ° C., more preferably 20 to 70 ° C.

(3) a step 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.

  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.

  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.

  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.

  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.

(4) A step of forming a porous silica membrane by bringing a water-soluble organic solvent into contact with the intermediate membrane (extraction step);
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.

  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.

(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 film and / or for the purpose of promoting the hydrolysis and 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.

  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) described above, but the drying step described here. Can be implemented.

  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.

C: About the transparent electrode layer 3 The transparent electrode layer 3 acts as an anode of an electroluminescent element. As the transparent electrode layer 3, indium oxide added with tin (commonly called ITO), zinc oxide added with aluminum (commonly called AZO), zinc oxide added with indium (commonly called IZO). A complex oxide thin film is preferably used. In particular, ITO is preferable.

  The transparent electrode layer 3 is formed by a vacuum film formation process such as vapor deposition or sputtering. The transparent electrode layer 3 can also be formed by a coating method.

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 value, but is usually 1 to 100Ω / □ (= 1 cm ² ), and the upper limit is preferably 70Ω / □, more preferably 50Ω / □.

  In addition, the thickness of the transparent electrode is preferably 0.01 to 10 μm as long as the light transmittance and the surface resistance value described above are satisfied, and its lower limit is preferably 0.03 μm (30 nm) from the viewpoint of conductivity. 0.05 μm (50 nm) is more preferable. On the other hand, from the viewpoint of light transmittance, the upper limit is preferably 1 μm, and more preferably 0.5 μm. Such a transparent electrode is formed in a pattern necessary as an electrode of an electroluminescence element by a photolithography method or the like.

D: 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 (provided that X Is an activation element such as 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, low molecular dye organic EL materials such as anthracene single crystals, poly (p-phenylene vinylene), poly [ 2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene], poly (3-alkylthiophene), polyvinyl carbonate Conventionally used organic EL materials such as conjugated polymer organic EL materials such as rubazole 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 electroluminescence layer can be formed by a vacuum film formation process such as vapor deposition or sputtering, or a coating process using chloroform or the like as a solvent.

E: Cathode The cathode 1 is provided so as to face the transparent electrode layer 3 described above and sandwich the electroluminescence layer 2 therebetween. 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. The thickness of the cathode is usually 10 to 1000 nm, preferably 30 to 500 nm, more preferably 50 to 300 nm. The cathode can be formed by a vacuum film formation process such as vapor deposition or sputtering.

F: 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 between the electroluminescence layer 2 and the cathode 1. Further, an electron injection layer and an electron transport layer can be further laminated. Moreover, you may apply well-known layers other than these.

Next, an embodiment of claim 1 will be described with reference to FIG.

  In this embodiment, a low refractive index layer 4 containing no particles is provided between the transparent electrode layer 3 and the substrate 5, and light scattering is performed between the low refractive index layer 4 and the transparent electrode layer 3. A particle-containing leaching light diffusing layer 4 '' is provided. The matrix components of the low refractive index layer 4 and the light scattering particle-containing leaching light diffusing layer 4 '' preferably have substantially the same refractive index. Note that the difference between the refractive index of the low refractive index layer 4 and the refractive index of the matrix component of the light scattering particle-containing exuded light diffusion layer 4 ″ is less than 0.3, preferably 0.2 or less, particularly preferably. Is 0.1 or less.

  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 low refractive index layer 4 in FIG. 2 can be the same as the matrix component (composition other than particles) of the light scattering particle-containing exuded light diffusion layer 4 ′ in FIG. 1, and the formation process is also light scattering. Except for not using particles, the process is the same as that for forming the light-scattering particle-containing leached light diffusion layer 4 ″ described above. The matrix component of the light scattering particle-containing exuding light diffusion layer 4 '' may be the same as the matrix component of the light scattering particle-containing exuding light diffusion layer 4 'shown in FIG. The matrix component of the light scattering particle-containing exuded light diffusion layer 4 ″ preferably has the same composition as the low refractive index layer 4, but may be different.

  The thickness of the low refractive index layer 4 is preferably from 100 to 1000 nm, particularly from 300 to 700 nm, from the viewpoint of the seepage distance during total reflection at the interface, and the flattening of the film and the prevention of cracks. The thickness of the light scattering particle-containing exuded light diffusion layer 4 ″ is preferably 100 to 1000 nm, particularly 300 to 700 nm.

  As for the low-refractive index layer 4 that does not contain particles only in the mode of FIG. 3 (top emission type) described later, even if this layer is an air layer (void), there is no problem in the device configuration. The refractive index is 1.0. Regarding the thickness, the problem of flattening of the film and cracks are solved, so that the upper limit is not particularly limited.

  The preferred light scattering particles of the light scattering particle-containing leaching light diffusion layer 4 ″ and the preferred content thereof are the same as those of the light scattering particle-containing leaching light diffusion layer 4 ′. The outgoing light diffusing layer 4 '' can be formed in the same manner as the leached light diffusing layer 4 'containing light scattering particles.

  In the electroluminescence element configured as described above, the total reflection amount at the interface between the transparent electrode layer 3 and the light scattering particle-containing oozing light diffusion layer 4 '' is reduced as follows.

  That is, when light is incident from the electroluminescence layer 2 through the transparent electrode layer 3 to the interface between the transparent electrode layer 3 and the light diffusing particle-containing exuded light diffusion layer 4 ″ at an incident angle larger than the critical angle, This light is totally reflected at the interface. In this total reflection, a phenomenon occurs in which a part of the light oozes out from the interface to the light diffusing particle 4 ″ side from the interface, just as in the case of FIG. 1B. That is, the electric field and magnetic field of the incident light exist from the interface to the side of the light diffusing layer 4 ″ that oozes out the light scattering particles.

  In the vicinity of the interface in the light scattering particle-containing exuded light diffusion layer 4 ″, there are particles that scatter the exuded light. A part of the light leached into the particle is scattered by the light scattering particles, and the particle-containing light-scattering particle-containing leaching light diffusion layer 4 ′ is directly or indirectly returned to the totally reflected light on the transparent electrode layer 3 side. 'Become spread inside. In this way, by adding the light scattering particles to the light scattering particle-containing leaching light diffusing layer 4 '', the reflectance of the total reflection is reduced, and more light is scattered from the transparent electrode layer 3. The contained leaching light diffusing layer 4 '' side enters.

  Since the matrix of the light scattering particle-containing exuded light diffusion layer 4 ″ and the low refractive index layer 4 have substantially the same refractive index, the light scattering particle-containing exuded light diffusion layer 4 ″ and the low refractive index are low in refraction. Total reflection does not occur at the interface with the rate layer 4. As a result, the light scattering particle containing seepage light diffusion layer 4 ″ enters from the transparent electrode layer 3 and reaches the interface between the light scattering particle containing seepage light diffusion layer 4 ″ and the low refractive index layer 4. The light that has entered the low refractive index layer 4 almost as it is. In this way, the light extraction efficiency from the electroluminescence element is improved.

  In the embodiment shown in FIGS. 1 and 2, the substrate 5 is provided on the outermost layer when viewed from the electroluminescence layer 2, but the substrate is provided outside the cathode and is the outermost layer when viewed from the electroluminescence layer. May be provided with a protective cover.

  FIG. 3 shows an embodiment having such a configuration in the embodiment of FIG. 1, in which a cathode 1 is formed on a substrate 5, and an electroluminescent layer 2, a transparent electrode layer 3, and light scattering particles are sequentially formed thereon. A contained leaching light diffusing layer 4 ′ is formed, and a protective cover 6 is formed on the leached light diffusing layer 4 ′ containing light scattering particles. While the embodiment of FIG. 1 is referred to as a bottom emission organic EL, the embodiment of FIG. 3 may be referred to as a top emission organic EL. As the material of the protective cover 6, any material can be used as long as it is transparent and can be flattened. In addition to various glasses and resin materials used for the substrate, a transparent coating material having no self-supporting property, for example, UV or Examples thereof include thermosetting acrylic resins and sol-gel reaction materials (silicate materials). 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 is not necessarily transparent, and in this embodiment, the protective cover performs the optical function of the transparent substrate in the embodiment of FIG.

  FIG. 3 shows the substrate 5 arranged on the cathode 1 side in the embodiment of FIG. 1, but the substrate 5 may be arranged on the cathode 1 side similarly in FIG.

  Furthermore, in the present invention, since the guided light in the transparent electrode layer is extracted using the light scattering phenomenon, the wavelength dependency of the scattering rate is actively used to improve the extraction efficiency of a specific color, The lifetime of the luminescent dye of that color can be increased.

  For example, by devising the particle size and particle refractive index of light-scattering particles, using Rayleigh scattering, or by using Mie and Rayleigh scattering together, it is possible to secure blue with a sufficient scattering rate. It becomes possible to take out more efficiently.

  In addition, if a material whose refractive index suddenly increases in the vicinity of blue in the visible light region, such as titania, is selected for the composition of light scattering particles, blue can be extracted more efficiently than other colors. Is possible.

  On the other hand, for example, when bubbles having a size corresponding to particles are dispersed, the refractive index of air hardly changes depending on the wavelength, so it is used for the purpose of suppressing the wavelength dependence of the light extraction efficiency. be able to.

  In white or full-color electroluminescent elements, generally the brightness of the short wavelength side dye is low, or the brightness half-life is short when the same brightness is emitted. Therefore, for example, if the blue extraction rate can be improved, there is no need for a design that increases the area of the blue pixel, which leads to an improvement in luminance per area, and the current flowing to the blue pixel can be reduced, so that the lifetime can be improved. It becomes. Even in a white light source application, it is possible to minimize the width of deviation from white in timekeeping by improving the blue extraction rate and lifetime.

  In the top emission type shown in the embodiment of FIG. 3, it is necessary to form a transparent electrode layer and a light scattering particle-containing leaching light diffusion layer after forming the electroluminescence layer. In this case, since the electroluminescence layer may have lower emission luminance due to crystallization or deterioration at a high temperature of 100 ° C. or higher, the processing temperature for forming the light extraction layer is 150 ° C. or lower, preferably 120 ° C. Hereinafter, it is more preferably 100 ° C. or lower. The atmospheric pressure is also preferably a normal pressure.

  Therefore, in this embodiment, when the low refractive index layer is formed of a porous silica material, for example, a high boiling hydrophilic organic compound as in the porous silica film forming step of the above (1) to (5) is used as a template. A film forming process that makes the film porous at a low temperature is preferable.

  As another method, a low refractive index layer and a light scattering particle-containing oozing light diffusion layer are formed in this order on another transparent substrate such as a plastic film in advance, and this optical film is formed on the transparent electrode. It is also possible to attach to a light extraction film. In the case of pasting, the light scattering particle-containing oozing light diffusion layer also serves as an adhesive layer or an adhesive layer. In this case, a process that requires heating, an organic solvent, etc. can be completed during film production, so that the light-scattering particle-containing seepage light diffusion layer can be formed without damaging the electroluminescence layer. This is a preferred method for this embodiment.

  As the base material for the plastic film, any transparent and flexible base material can be suitably used. For example, PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate) film, PES (polyethersulfone) film, PC (polycarbonate) film, APO (amorphous polyolefin, cyclic polyolefin) film, etc. can be suitably used. It is not limited.

  You may substitute this base material as a protective cover in FIG. Further, the base film can be provided with functional layers such as a gas barrier layer, an antireflection layer, and a circular deflector layer mainly on the light emission side, if necessary.

  If necessary, a low refractive index layer is first formed on this film. When the substrate is a plastic film, it is difficult to process at a high temperature exceeding 200 ° C. when forming a porous silica film thereon. Therefore, a film synthesis method as described in the present invention can be suitably used.

  Hereinafter, Reference Examples 1 to 6 and Comparative Examples 1 to 6 corresponding to Examples will be described. In Reference Examples 1 to 6 and Comparative Examples 1 to 6 below, the cathode and the electroluminescence layer are not formed, a fluorescent dye layer is formed on the transparent electrode layer, and excitation light is emitted to the fluorescent dye layer. Irradiated from the side, fluorescence was extracted from the substrate side.

<Reference Example 1 (corresponding to the embodiment of FIG. 1)>
The surface of a 0.7 mm thick, 75 mm square glass substrate made of non-alkali glass AN100 manufactured by Asahi Glass Co., Ltd. was degreased by immersing it in 0.1N nitric acid for about 1 hour, washed with pure water, 60 Dry in oven.

  On the other hand, a small amount of acid catalyst (aluminum acetylacetonate) is added to MS51 (tetramethoxysilane oligomer) 30 wt%, BtOH 50 wt%, demineralized water 8 wt%, MeOH 12 wt% manufactured by Mitsubishi Chemical Corp. Silica fine particles having a diameter in the range of 70 to 150 nm and an average particle diameter of 120 nm were added so as to be 10% by weight of MS51, stirred at 60 ° C. for 3 hours, and left to mature for one week.

  This is coated on the glass substrate 1 with a dip coater, dried for 15 minutes, then immersed in methanol for 5 minutes, pulled up, dried for 5 minutes, heated in an oven at 150 ° C. for 15 minutes, and light scattering particle-containing leached light A diffusion layer 4 ′ was obtained. At the time of dip coating, a protective film was applied to the back surface and peeled off after coating, so that a coating film was formed only on one side.

  The obtained light-scattering particle-containing exuded light diffusion layer 4 ′ was observed to have a thickness of 600 nm and a structure in which the light-scattering particles overlapped in approximately five steps.

  When the refractive index of the matrix portion of the light diffusion layer 4 ′ containing the light scattering particles containing the light scattering particles was measured by an Sopra ellipsometer, it was 1.27 at a wavelength of 550 nm. Refractive index measurement was also performed on a prism coupler model 2010 manufactured by Metricon Inc., USA. When measured with a laser having a wavelength of 633 nm, the refractive index was 1.29.

  In the following, refractive index measurement was carried out with a sopra ellipsometer based on principle D542. If the refractive index of the matrix portion of a meso (nano) porous material or particle dispersion material is difficult to measure with an ellipsometer, Refractive index measurement was performed at 25 ° C. using a prism coupler model 2010 with a laser having a wavelength of 633 nm.

Regarding the film thickness, the film thickness of the deposited film or the sputtered film was confirmed by time management from a calibration curve or by a crystal oscillation type film thickness meter. The film thickness of the coating film was measured by measuring the level difference by scratching the optical interference film thickness meter or the film. The thickness of a thick substrate such as a glass substrate was measured with a micro caliper or the like.
Moreover, the average particle diameter was measured by FIB-SEM method.

  In addition, the content of the light scattering particles in the formed light scattering particle-containing leached light diffusion layer 4 ′ was 7% by volume.

  The transparent electrode layer 3 is formed by sputtering ITO at a thickness of 1000 mm on this light scattering particle-containing leached light diffusion layer 4 ′, and further ALQ3 (aluminum quinoline complex: a dye emitting green fluorescence) is formed at a thickness of 1000 mm. Vapor deposited. The refractive index of the ITO layer was measured and found to be 1.9.

  Irradiate the back surface (fluorescent dye deposition side) of this laminate with excitation light having a wavelength of 400 nm or less, and measure the extraction light intensity of 420 to 750 nm with a detector installed in the direction of an emission angle of 45 degrees on the surface of the glass substrate side. The emission energy integrated over all wavelengths was determined. A fluorescence spectroluminance meter F-4500 manufactured by Hitachi, Ltd. was used for the measurement.

  The amount of light taken out was found to be 170% relative to 100% in the case of Comparative Example 1 below.

<Comparative Example 1 (corresponding to the conventional example of FIG. 5)>
A fluorescent light-emitting device having a layer structure corresponding to FIG. 5 was produced in exactly the same manner as in Reference Example 1 except that silica fine particles were not added to the coating solution for forming the light-diffusing layer containing the light-scattering particles. The same amount of extracted light was measured.

  The amount of light taken out in Comparative Example 1 was set to 100%.

<Comparative example 2 (equivalent to the conventional example of FIG. 4)>
A fluorescent light-emitting device was manufactured in the same manner as in Comparative Example 1 except that the light-scattering particle-containing seepage light diffusion layer 4 ′ was omitted and the layer configuration shown in FIG. went.

  The amount of light taken out in Comparative Example 2 was 91% of Comparative Example 1.

<Reference Example 2 (corresponding to the embodiment of FIG. 2)>
A low refractive index layer 4 having a thickness of 500 nm is formed using the coating liquid containing no silica fine particles of Comparative Example 1, and light scattering having a thickness of 600 nm using the silica fine particle-containing coating liquid of Reference Example 1 is formed thereon. A particle-containing leaching light diffusion layer 4 ″ was formed.

  An ITO transparent electrode layer 3 was formed thereon. In the same manner as in Reference Example 1, a film was formed by room temperature sputtering. The film thickness was 1000 mm. Similarly, ALQ3 was deposited with a thickness of 1000 mm.

  When the same extracted light amount measurement was performed for Reference Example 2, it was 190% of Comparative Example 1.

<Reference Example 3>
A glass substrate was prepared in the same manner as in Reference Example 1. The coating solution was prepared as follows. A small amount of an acid catalyst (aluminum acetylacetonate) was added to 30 wt% of MS51 (tetramethoxysilane oligomer) manufactured by Mitsubishi Chemical, 50 wt% of butyl alcohol, 8 wt% of demineralized water, and 12 wt% of methanol. At this time, titania particles having an average particle diameter of 200 nm (60% weight particle diameter is 160 to 220 nm) were dispersed in butyl alcohol in advance so that the weight percentage in the finished particle-containing layer was 8 wt%. The weight percentage in the particle-containing layer was measured in the same manner as that for obtaining the particle size distribution in the film. Volume conversion by weight was performed by examining the density of particles and matrix. The density when the matrix is a porous body was calculated from obtaining the refractive index by obtaining the X-ray reflectivity or obtaining the refractive index. The mixture was stirred at 60 ° C. for 3 hours and left to mature for one week.

  This was coated on a glass substrate in the same manner as in Reference Example 1 to form a film. The thickness of the formed light-scattering particle-containing leachable light diffusion layer was 500 nm, and the refractive index of the matrix portion was measured and found to be 1.40. The light scattering particle content was 4% by volume.

  In this state, the amount of light transmitted in the direction perpendicular to the substrate was measured, and the ratio of the amount of scattered light was examined by comparing the amount of light transmitted in the direction perpendicular to the glass substrate described in Reference Example 1. For the measurement of the light transmittance, a UV-visible spectrophotometer HP8453 type manufactured by Hured Packard was used.

  Further, in order to confirm that the surface itself was smooth (not a scattering surface), the surface roughness was measured with a stylus type surface roughness meter. A P-15 type manufactured by KLA-Tencor Corporation was used for the measurement. When measured by scanning 0.5 μm, Ra = 4 nm.

  The amount of scattering loss with respect to the light transmission amount of this laminate was 39% at a wavelength of 450 nm and 28% at a wavelength of 550 nm.

  The laminated body was sputtered with ITO at room temperature in the same manner as in Reference Example 1 to form a transparent electrode layer having a thickness of 1000 mm. Further, samples each having a green fluorescent dye ALQ3 (8-hydroxyquinoline aluminum) and a blue fluorescent dye PPD (phenantylphenylenediamine) formed thereon by vapor deposition at a thickness of 1000 mm were prepared.

  Using this laminate, the fluorescence intensity was measured in the same manner as in Reference Example 1. However, the peak fluorescence intensity in the direction of 30 ° (outgoing angle 30 °) from the vertical direction on the outgoing side of the glass substrate was measured. Samples deposited with ALQ3 were measured for peak fluorescence intensity at a wavelength of 550 nm, and samples deposited with PPD were measured for peak fluorescence intensity at a wavelength of 450 nm.

The light extraction quantity measured in this way is shown as a relative value with respect to 100% in the case of Comparative Example 3 below. The light extraction quantity is as follows. A significant improvement in the extraction efficiency with respect to the green color was confirmed.
ALQ3 (green) deposition sample: 190% (550 nm)
PPD (blue) vapor deposition sample: 240% (450 nm)

<Comparative Example 3>
Except that titania particles were not added to the coating liquid in Reference Example 3, prototypes of fluorescent light emitting devices were manufactured in the same manner, and the same extracted light amount was measured, and the extracted light amount was set to 100%. In addition, when the surface roughness was measured in the same manner as in Reference Example 3, it was Ra = 2 nm.

<Reference Example 4>
Mitsubishi Engineering Plastics polycarbonate resin 7020AD2 was dissolved in methylene chloride to produce titania particles (titanium dioxide) having a particle size of 200 nm (60% weight particle size is 150 to 220 nm) in a particle-containing layer in a weight percentage of 10 wt% ( 3 volume%). This was coated with a solvent by a dip coater on a glass substrate prepared in the same manner as in Reference Example 1, and then dried at room temperature to obtain a light scattering particle-containing leached light diffusion layer.

  The thickness of the formed light-scattering particle-containing leachable light diffusion layer was 600 nm, and the refractive index of the matrix portion was measured to be 1.59. In addition, when the surface roughness was measured in the same manner as in Reference Example 3, it was Ra = 4 nm.

  Using this substrate, an ITO film and a dye layer were formed in the same manner as in Reference Example 3, and the fluorescence intensity was further measured. However, the fluorescence intensity in the direction of 30 ° from the vertical direction on the emission side of the glass substrate was measured.

  The amount of light taken out was found to be 170% (550 nm) relative to 100% in the case of the following Comparative Example 4.

<Comparative example 4>
Except that the titania particles were not added in the above Reference Example 4, a fluorescent light emitting device was manufactured in the same manner, the same extracted light amount was measured, and the measured extracted light amount was set to 100%. Further, when the surface roughness was measured in the same manner as in Reference Example 3, it was Ra = 2 nm.

<Reference Example 5>
In Reference Example 4, the element was formed in the same manner as in Reference Example 4 except that the thickness of the light-scattering particle-containing leached light diffusion layer was 1000 nm, and the amount of light was measured. The relative value with respect to the amount of light was 150% (550 nm).

<Comparative Example 5>
In Reference Example 4, an element was formed and light quantity was measured in the same manner as in Reference Example 4 except that the thickness of the light-scattering particle-containing leached light diffusion layer was 2700 nm (though the thickness was not limited to this reference example) The thickening was achieved by repeating the coating process a plurality of times if necessary.) However, in the case of Comparative Example 4, the relative value with respect to the extracted light amount was 80% (550 nm). This result is considered to be due to the light-scattering particle-containing oozing light diffusion layer becoming too thick and opaque.

<Reference Example 6>
After forming a silica vapor deposition film with a thickness of 200 mm as an anchor coat / barrier coat film on a PET film 125 (μm thickness) manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., a light scattering particle-containing leaching light diffusion in the same manner as in Reference Example 4. A layer was formed. In addition, adhesion of this film and the ITO surface was possible by making it adhere to the glass substrate with ITO before this light-scattering particle containing oozing-out light-diffusion layer dried completely.

  An ITO film and an ALQ3 layer were formed in the same manner as in Reference Example 3 on the light-scattering particle-containing leachable light diffusion layer of this film and further evaluated.

  The thickness of the light-scattering particle-containing exuded light diffusion layer was 600 nm, and the refractive index of the matrix portion was measured to be 1.59. Further, when the surface roughness was measured with a stylus type surface roughness meter (P-15, manufactured by KLA-Tencor Corporation), Ra = 4 nm.

  Using this substrate, the fluorescence intensity was measured in the same manner as in Reference Example 3. The peak fluorescence intensity in the direction of 30 ° (outgoing angle 30 °) from the vertical direction on the outgoing side of the glass substrate was measured.

  The amount of light taken out was found to be 160% (550 nm) relative to the case of Comparative Example 6 below as 100%.

  From this result, it can be seen that improvement in extraction efficiency is expected even when the top emission type is used as an optical film for extracting light.

<Comparative Example 6>
Except that the titania particles were not added in Reference Example 6 above, a fluorescent light emitting device was manufactured in the same manner, and the same extracted light amount was measured. The measured extracted light amount was set to 100%. When the surface roughness of the surface before forming the transparent conductive film was measured with a stylus type surface roughness meter (P-15, manufactured by KLA-Tencor Corporation), Ra = 3 nm.

It is sectional drawing of the electroluminescent element which concerns on a reference example . It is sectional drawing of the electroluminescent element which concerns on embodiment. It is sectional drawing of the electroluminescent element which concerns on a reference example . It is sectional drawing of the electroluminescent element which concerns on a prior art example. It is sectional drawing of the electroluminescent element which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cathode 2 Electroluminescent layer 3 Transparent electrode layer 4 Low refractive index layer 4 ', 4''Light-scattering particle containing oozing light diffusion layer 5 Glass substrate 6 Protective cover

Claims (6)

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 leachable light diffusing layer containing particles that scatter light in a matrix made of a low refractive index material is provided. The electroluminescence device according to claim 1, wherein a matrix of the layers has a refractive index which is equal to a refractive index of the low refractive index layer and lower than a refractive index of the transparent electrode layer. Oite to claim 1, of the particles that scatter light, electroluminescent elements, wherein the weight percentage of particles having a particle diameter of 20~400nm is 60% or more. According to claim 1 or 2, electroluminescent device, wherein the thickness of the light diffusion layer heading該浸is more than twice the average particle size of the particles that scatter light. In any one of claims 1 to 3, more than one-third of the particles for scattering light are electroluminescent device characterized in that it is arranged within 600nm from the surface of the transparent electrode layer. In any one of claims 1 to 4, electroluminescent device, wherein the light transmitting member is a transparent substrate. In any one of claims 1 to 4, the cathode is formed on a transparent substrate, an electroluminescent element, wherein the transparent body is a protective cover.

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