JP2013025900A - Substrate for electronic device, and organic led element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for electronic device exhibiting a high light extraction efficiency to the outside and a high productivity, and to provide an organic LED element using the same.SOLUTION: In the substrate for electronic device and the organic LED element using the same, a translucent substrate, at least one convex structure providing on the translucent substrate and having a height of 5-100 μm, a coating layer covering the translucent substrate and the convex structure, and a translucent electrode layer provided on the coating layer are laminated. The refraction index of the coating layer is higher than those of the translucent substrate and the convex structure.

Description

  The present invention relates to a substrate for an electronic device such as a light emitting element, and an organic LED element using the same.

  In recent years, research and development of new light emitting devices such as a plasma display panel (PDP), a field emission display (FED), an organic LED element, and an inorganic EL element have been advanced. Among these, an organic LED element (Organic Light Emitting Diode) has attracted attention as one of the next generation light emitting elements. This has a structure in which an organic layer is sandwiched between electrodes, and as a mechanism of light emission, first, holes and electrons are injected from each electrode by applying a voltage between the electrodes, and then these. Are combined in the organic layer, and the light emitting material in the organic layer is excited. Thereafter, light generated in the process from the excited state to the ground state of the luminescent material is extracted. Specific applications include displays, backlights, and lighting.

  However, in the organic LED element, although the light emission efficiency of the element itself is improved, when light is extracted from the element to the outside, light is reflected at the interface of each member on the optical path, etc. Since the light extraction efficiency to the light source is reduced, improvement thereof has been demanded.

  For example, in Patent Document 1, a glass fired film having a refractive surface higher than that of the glass plate on the surface of the glass plate on which the transparent conductive film is formed, and a transparent conductive film The glass substrate for organic EL elements in which is formed is described. In such a glass substrate for an organic EL element, light from the organic EL element is scattered at an uneven interface formed on the surface of the glass plate so as to increase the light extraction efficiency to the outside.

JP 2010-198797 A

  However, the surface roughness of the concavo-convex surface formed on the glass plate surface in the above-mentioned Patent Document 1 is 0.05 to 2 μm, and the glass plate surface is merely provided with a gentle slope that causes slight scattering. Absent. For this reason, the light extraction efficiency to the outside has not been sufficiently improved.

  Moreover, in patent document 1, in order to form an uneven surface on the glass plate surface, a part of the glass plate surface is ground and removed by a sandblast method or the like, and processing takes time. There was a problem.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an electronic device substrate having high light extraction efficiency to the outside and high productivity.

  In order to solve the above problems, the present invention provides a translucent substrate, a convex structure that is provided on the translucent substrate and has a height of 5 μm or more and less than 100 μm, and the translucent substrate. And a covering layer covering the convex structure, and a translucent electrode layer provided on the covering layer, the refractive index of the covering layer is the translucent substrate, and Provided is an electronic device substrate characterized by having a refractive index higher than that of the convex structure.

  The present invention relates to a substrate for an electronic device in which a translucent substrate, a convex structure, a coating layer, and a translucent electrode layer are laminated. In the electronic device substrate of the present invention, since the convex structure of 5 μm or more and less than 100 μm is disposed on the light-transmitting substrate, the uneven portion having a large difference in height is formed at the interface portion between the coating layer and the convex structure. Is formed. For this reason, the light totally reflected at the interface portion is reduced, and the amount of light that can enter the translucent substrate is increased. Therefore, the light extraction efficiency to the outside can be increased. Moreover, since the said uneven | corrugated | grooved part is the structure which has arrange | positioned the convex structure on the translucent board | substrate, it can manufacture easily and it becomes possible to raise productivity.

Explanatory drawing of 1st Embodiment which concerns on this invention Explanatory drawing of the interface part of the convex structure and coating layer in 1st Embodiment which concerns on this invention Explanatory drawing about the modification of 1st Embodiment which concerns on this invention Explanatory drawing about the modification of 1st Embodiment which concerns on this invention Explanatory drawing about the modification of 1st Embodiment which concerns on this invention Explanatory drawing about 2nd Embodiment which concerns on this invention Explanatory drawing about the modification of 2nd Embodiment which concerns on this invention Explanatory drawing of the simulation model in the Example which concerns on this invention

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments are not departed from the scope of the present invention. Various modifications and substitutions can be made.

[First Embodiment]
An electronic device substrate according to the present invention will be described with reference to FIG.

  1 is a top view of the electronic device substrate according to the present invention, and the convex structure is also shown in the drawing so that the arrangement of the convex structure becomes clear (FIGS. 3 to 7). Was also shown). Moreover, the lower figure shows an AA ′ cross-sectional view. As shown in the figure below, the electronic device substrate of the present invention is formed by laminating a translucent electrode layer 1, a coating layer 2, a convex structure 3, and a translucent substrate 4 in order from the top in the figure. . In addition, when using the board | substrate for electronic devices of this invention for an organic LED element, for example, an organic layer (light emitting layer) and an electrode are further laminated | stacked on the translucent electrode layer in a figure. In this case, light from the light emitting layer passes through each member from the translucent electrode layer 1 to the translucent substrate 4 and is extracted from the lower surface of the translucent substrate 4.

Then, the refractive index _{n 2} of the cover layer 2 has a refractive index _{n 3} of the convex structures 3, to be higher than the refractive index _{n 4} of the translucent substrate 4, _i.e., n _{4 <n} 2, _{n 3} <it is configured to satisfy a relation n _2.

  Here, when light travels from a material having a high refractive index to a material having a low refractive index, if the incident angle is larger than the critical angle, the incident light is totally reflected without passing through the boundary surface. For this reason, as shown in FIG. 2A, in the case where there is no convex structure 3 and only the portion where the coating layer 2 and the light transmitting substrate 4 are in direct contact, the light A1 having an incident angle B1 larger than the critical angle. Is totally reflected at the interface as shown by C1. On the other hand, when the convex structure 3 having a predetermined height is arranged on the translucent substrate 4 as in the present invention, the above-described structure with respect to the horizontal plane as shown in FIG. When the light A2 having the same angle as the light A1 is seen at the interface with the convex structure 3, the incident angle B2 is equal to or less than the critical angle and can enter the translucent substrate 4 without being totally reflected. . For this reason, by arranging the convex structure 3 on at least a part of the translucent substrate 4, it is possible to extract the light having the incident angle, and the light extraction efficiency can be improved. In addition, although the amount is smaller than light having an incident angle with respect to the horizontal plane larger than the critical angle, there is also light having an incident angle with respect to the horizontal plane that is less than the critical angle. In contrast, when the light passes through the convex structure 3, the light may be totally reflected at the interface portion, and the light enters the translucent substrate 4 more easily without passing through the convex structure 3. For this reason, it is preferable to arrange a part of the coating layer 2 so as to be in direct contact with the translucent substrate 4.

The critical angle can be derived from Snell's law, and is specifically expressed by the following equation.
θ _m = sin ⁻¹ (n _A / n _B )
In the formula, θ _m represents a critical angle, and n _A and n _B represent a refractive index (n _B > n _A ). According to the above formula, when the difference between the refractive indexes n _A and n _B is small, the critical angle approaches 90 degrees, and thus total reflection is difficult to occur. Accordingly, total reflection can be further suppressed by arranging the refractive index difference between adjacent layers to be small. Therefore, the refractive index _n 2 ~n ₄ of each member described above and the refractive index _{n 1} of the light-transmitting electrode layer _1, n 3 _{<n 2} and _{n 4 -0.2 ≦ n 3 ≦ n} 4 +0. 2 and n ₁ −0.2 ≦ n ₂ ≦ n ₁ +0.2 are more preferably satisfied. Further, it is particularly preferable to satisfy the relationship of n ₃ <n ₂ and n ₄ −0.1 ≦ n ₃ ≦ n ₄ +0.1 and n ₁ −0.1 ≦ n ₂ ≦ n ₁ +0.1.

  In the present invention, as described above, total reflection at the interface between the coating layer 2 and the convex structure 3 is less likely to occur than other interface portions due to the effect of the shape. Therefore, even if the refractive index difference between the two is large, the light extraction efficiency does not decrease so much. For this reason, the material is selected so that there is no difference in refractive index between the translucent electrode layer 1 and the covering layer 2, or between the convex structure 3 and the translucent substrate 4. It is particularly preferred.

  Details of each member will be described below.

(Translucent electrode layer 1)
The translucent electrode layer is required to have a translucency of 80% or more because it is necessary to extract light from the light emitting layer adjacent thereto to the outside. In addition, a high work function is required to inject many holes. Specifically, ITO (Indium Tin Oxide), SnO ₂ , ZnO, IZO (Indium Zinc Oxide), AZO (ZnO—Al ₂ O ₃ : zinc oxide doped with aluminum), GZO (ZnO—Ga ₂ O ₃ : Materials such as zinc oxide doped with gallium), Nb-doped TiO ₂ , and Ta-doped TiO ₂ are used. The thickness of the translucent electrode layer is preferably 100 nm or more.

  The method for forming the translucent electrode layer will be described by taking the case where ITO is used as a material as an example. First, ITO is formed with good uniformity on the entire translucent substrate after the coating layer is formed by sputtering or vapor deposition. Next, an ITO pattern is formed on the formed ITO film by photolithography and etching. The ITO pattern obtained thereby becomes a translucent electrode layer. In the case of photolithography, for example, a phenol novolac resin can be used as a resist. Etching may be either wet etching or dry etching. For example, the etching can be performed using a mixed aqueous solution of hydrochloric acid and nitric acid. Furthermore, as the resist stripper, for example, monoethanolamine can be used.

(Coating layer 2)
As the coating layer, a material (base material) having a high light transmittance and having a higher refractive index than the convex structure and the light-transmitting substrate is used as described above. Specific examples of the base material include glass, crystallized glass, translucent resin, and translucent ceramic. Examples of the glass material include soda lime glass, borosilicate glass, alkali-free glass, and quartz glass. The glass composition is not particularly limited as long as it is a material having a desired refractive index. However, because of the high refractive index glass for the base material, one or more components of P ₂ O ₅ , SiO ₂ , B ₂ O ₃ , GeO ₂ , and TeO ₂ are selected as the network former. You may do it. Further, as a high refractive index _{components, TiO 2, Nb 2 O 5} , WO 3, Bi 2 O 3, La 2 O 3, Gd 2 O 3, Y 2 O 3, ZrO 2, ZnO, BaO, PbO, and Sb One or more components of ₂ O ₃ may be selected. Furthermore, in order to adjust the characteristics of the glass, alkali oxides, alkaline earth oxides, fluorides, and the like may be added within a range that does not affect the refractive index.

Therefore, as a glass system constituting the base material, for example, B ₂ O ₃ —ZnO—La ₂ O ₃ system, P ₂ O ₅ —B ₂ O ₃ —R ′ ₂ O—R ”O—TiO ₂ —Nb are used. ₂ O ₅ —WO ₃ —Bi ₂ O ₃ system, TeO ₂ —ZnO system, B ₂ O ₃ —Bi ₂ O ₃ system, SiO ₂ —Bi ₂ O ₃ system, SiO ₂ —ZnO system, B ₂ O ₃ — ZnO-based, P ₂ O ₅ —ZnO-based, etc. Here, R ′ represents an alkali metal element, and R ″ represents an alkaline-earth metal element. In addition, the above material system is only an example, and if it is the structure which satisfy | fills the said conditions, the material to be used will not be restricted especially.

  The color of light emission can be changed by adding a colorant to the base material. As the colorant, transition metal oxides, rare earth metal oxides, metal colloids, and the like can be used alone or in combination.

  A coating layer covers the uneven | corrugated | grooved part formed of the convex structure, and planarizes the surface. That is, it is provided so as to cover the translucent substrate and the convex structure, and is in contact with both members. Therefore, the thickness is determined according to the height of the convex structure and is not limited, but the thickness is preferably 10 μm or more and 150 μm or less, and more preferably 15 μm or more and 100 μm or less. preferable. As a means for forming such a coating layer, various known film forming means such as a sol-gel method, a vapor deposition method, and a sputtering method can be employed. However, the coating layer is preferably produced by the frit paste method, since it is preferable to form the film having the above-described thickness uniformly and rapidly over a large area. As a specific procedure of the frit paste method, first, glass powder having a particle size of 1 to 10 μm, which is a base material, is mixed with an additive such as a resin, a solvent, a filler, a surfactant, etc., and dispersed uniformly. To make a frit paste. Thereafter, the prepared frit paste is placed on a light-transmitting substrate on which a convex structure is formed by coating, printing, or the like, and fired at a desired temperature to form a coating layer.

  The resin is used to support the glass powder and filler in the coating film after screen printing. Specific examples include ethyl cellulose, nitrocellulose, acrylic resin, vinyl acetate, butyral resin, melamine resin, alkyd resin, and rosin resin. There are ethyl cellulose and nitrocellulose as main agents. Butyral resin, melamine resin, alkyd resin, and rosin resin are used as additives for improving the strength of the coating film. The binder removal temperature during firing is 350 ° C. to 400 ° C. for ethyl cellulose and 200 ° C. to 300 ° C. for nitrocellulose.

  The solvent is used to dissolve the resin and adjust the viscosity required for printing. The solvent preferably has a boiling point of 200 ° C to 230 ° C. Blend to adjust viscosity, solid content ratio, drying speed. Specific examples include ether solvents (butyl carbitol (BC), butyl carbitol acetate (BCA), diethylene glycol di-n-butyl ether, dipropylene glycol butyl ether, tripropylene glycol butyl ether due to the suitability for drying the paste during screen printing. , Butyl cellosolve), alcohol solvents (α-terpineol, pine oil, dawanol), ester solvents (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), phthalate ester solvents (DBP) (Dibutyl phthalate), DMP (dimethyl phthalate), DOP (dioctyl phthalate)). Mainly used are α-terpineol and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate). DBP (dibutyl phthalate), DMP (dimethyl phthalate), and DOP (dioctyl phthalate) also function as a plasticizer.

  Further, as an additive, a surfactant may be used for viscosity adjustment and frit dispersion promotion. A silane coupling agent may be used to modify the frit surface.

  In the present embodiment, the number of coating layers is one, but a plurality of layers may be provided.

(Convex structure 3)
At least one convex structure is provided on the translucent substrate so as to cover a part thereof. The height of the convex structure is configured to be 5 μm or more and less than 100 μm from the surface of the translucent substrate. This is because if it is lower than 5 μm, the light extraction efficiency cannot be sufficiently increased, and if it is 100 μm or more, the light extraction efficiency is not effective. Further, when the thickness is 100 μm or more, the coating layer is also thickened accordingly, which is not preferable from the viewpoint of increasing the manufacturing cost. In addition, as long as the said range is satisfied, the convex structure of different height can also be mixed.

  Here, the shape of the convex structure is not limited, and may be various shapes such as a triangular prism, a cone, a triangular pyramid, and a hemisphere. However, it is preferable to have an inclined surface having an inclination angle of 5 degrees or more and less than 45 degrees, and it is particularly preferable to have an inclined surface of 10 degrees to 40 degrees. By having an inclined surface in such a range, the light extraction efficiency can be further increased, which is preferable. In addition, the inclination angle here means the angle made between the surfaces of the translucent substrate.

And the form which has a curved surface in a structure can use it preferably as a convex structure since an inclination angle changes continuously in the surface and can have a surface of the inclination angle of the above-mentioned range.
Specifically, the convex structure is particularly preferably a hemispherical shape. Here, the sphere includes various sphere shapes such as a true sphere and an oblate sphere. The hemisphere here is not limited to the half sphere itself, but includes a shape composed of a part of various spheres such as a one-third sphere.

  Further, the number of the convex structures is not limited, but it is preferable to provide a plurality of convex structures because the light extraction efficiency is increased. In the case of providing a plurality, they are arranged on the translucent substrate 4 randomly or regularly. Specifically, triangular prisms can be arranged in parallel as shown in FIG. 1 or can be arranged so as to have a cross-beam shape by overlapping a part as shown in FIG. Further, hemispherical shapes can be arranged alternately and regularly as shown in FIG. 4, or those having a curved surface (spherical surface) as shown in FIG. 5 can be randomly arranged.

  The shape of the convex structure provided on the same substrate is not limited to one type. For example, a convex structure having a different shape such as a hemispherical shape and a triangular prism shape may be provided at the same time. It can also be arranged at the same time.

  For the convex structure, a material (base material) having a high light transmittance and a lower refractive index than that of the coating layer is used. As the specific base material, glass, crystallized glass, translucent resin, translucent ceramics, etc. can be used in the same manner as the coating layer, and the refractive index is selected from these materials so as to satisfy a predetermined relationship. Is done. Examples of the glass material include soda lime glass, borosilicate glass, alkali-free glass, and quartz glass. The glass composition is not particularly limited as long as it is a material having a desired refractive index.

  The convex structure is also preferably formed by a frit paste method in order to uniformly and quickly form a structure having a height as described above over a large area. As in the case of the coating layer, raw materials are mixed to produce a frit paste. Next, the convex structure 3 can be formed by disposing a frit paste on a light-transmitting substrate by coating and printing in a desired range and baking it at a desired temperature. The shape is mainly controlled by the amount of paste applied and the firing temperature / time.

(Translucent substrate 4)
As the light-transmitting substrate, a material having high visible light transmittance is used. Specific examples of the material having high transmittance include a glass substrate and a plastic substrate. Examples of the material of the glass substrate include inorganic glass such as alkali glass, non-alkali glass, and quartz glass.

  Examples of the material for the plastic substrate include fluorine-containing polymers such as polyester, polycarbonate, polyether, polysulfone, polyethersulfone, polyvinyl alcohol, and polyvinylidene fluoride.

  The thickness of the translucent substrate only needs to be selected to have sufficient strength to protect the device. Specifically, for example, when glass is used, 0.1 mm to 2.0 mm is preferable. However, when the thickness is too thin, the strength is lowered. When the thickness is too thick, the place of use is limited by the size and weight of the device.

In addition, when producing a convex structure and a coating layer with a glass frit, the problem of distortion, etc. may arise. For this reason, the thermal expansion coefficient of the translucent substrate is preferably 50 × 10 ⁻⁷ / ° C. or more. More preferably, it is 70 × 10 ⁻⁷ / ° C. or more, and more preferably 80 × 10 ⁻⁷ / ° C. or more. In accordance with this, the convex structure and the coating layer have an average coefficient of thermal expansion at 100 to 300 ° C. of 60 to 110 × 10 ⁻⁷ / ° C. and a glass transition temperature of 400 to 550 ° C. It is preferable that

Moreover, the barrier layer which consists of one or more layers can also be formed in the surface of the side in which the convex structure of a translucent board | substrate or a coating layer is provided. This is because, when a glass substrate containing an alkali component is used as the light-transmitting substrate, the alkali component in the glass substrate diffuses, affecting the characteristics of the convex structure and the scattering material in the coating layer. This is to prevent this. As the barrier layer, a thin film containing at least one of oxygen and silicon such as a silicon oxide film, a silicon nitride film, an indium oxide film, or the like is preferable.
[Second Embodiment]
A second embodiment will be described with reference to FIG. As shown in FIG. 6, the present embodiment includes a scattering material 5 in the convex structure 3 in the first embodiment. This will be described below.

  Examples of the scattering substance include bubbles, precipitated crystals, material particles different from the base material, and phase separation glass. Here, air bubbles refer to those in which air or gas is dispersed in the base material. The particles are solid small substances, such as fillers, ceramics and glass. Moreover, phase-separated glass means the glass comprised by two or more types of glass layers.

  A specific method for adding the scattering material will be described below.

First, the case where bubbles are used as the scattering material will be described. When the convex structure is formed by the frit paste method, by adjusting the firing conditions, a scattering material composed of bubbles can be contained in the convex structure. Specifically, when the glass particles arranged on the substrate are heated, first, the glass particles start to be fused. When the glass particles are fused to each other, the gap existing between the glass particles is deformed by the softening of the glass, thereby forming a closed space in the glass. As the temperature is further increased, the softening and flow of the glass proceed, and the closed space becomes spherical bubbles. Further, not only the gap but also gas generated during heating may be present in the glass as bubbles. Since the viscosity of the glass is as high as about 10 ^7.6 poise at the softening temperature, if the size of the bubbles is several μm or less, the glass does not float and remains in the convex structure. Since the glass is softened on the outermost surface of the glass, the dent caused by the gap between the glass particles is smoothed. Therefore, by adjusting the material composition so as to generate small bubbles and selecting the firing conditions, it is possible to adjust the smoothness of the surface of the convex structure and the degree of distribution of the scattering material in the convex structure. it can.

  Next, a case where a precipitated crystal is used as the scattering material will be described. This is a method of precipitating crystals inside the convex structure by using glass that is easily crystallized as a raw material when the convex structure is manufactured. If the size of the crystal at this time is 0.1 μm or more, it can function as a scattering material. For this reason, by appropriately selecting the firing conditions, it is possible to precipitate crystals inside the structure while suppressing the precipitation of crystals on the surface of the structure. Specifically, firing at a temperature about 60 ° C. to 100 ° C. higher than the glass transition temperature can be considered. When the temperature is too high, crystals are deposited even on the outermost surface of the convex structure, which is not preferable because the smoothness of the outermost surface is impaired. Therefore, the firing temperature is more preferably 60 to 80 ° C. higher than the glass transition temperature, and further preferably 60 to 70 ° C. By such a technique, while bubbles and precipitated crystals are present as scattering substances in the glass phase, they can be suppressed from occurring on the outermost surface of the convex structure.

  In addition, when material particles other than the base material are used as the scattering material, a convex structure having the scattering material is formed by adding and forming these materials in the raw material of the convex structure in advance. can do. The material is not limited as long as it has a predetermined particle size and refractive index according to the desired degree of scattering and the like. For example, oxides, oxynitrides, nitrides, sulfides, oxysulfides, halides, aluminate chlorides, inorganic phosphor powders such as halophosphates, and the like, or glass powders can be preferably used as the scattering material.

  As shown in FIG. 7, the scattering material can be contained in the coating layer. However, when added to the coating layer in contact with the translucent electrode layer, it is not preferable that the scattering material protrude from the surface. That is, it is preferable that the scattering material exists inside the coating layer and does not exist on the surface of the coating layer in contact with the translucent electrode layer. This is because if the scattering material protrudes from the surface of the coating layer, a short circuit between the electrodes may occur when the translucent electrode layer is formed on the upper surface. Moreover, it is also because a flat translucent electrode layer cannot be produced unless the surface of the coating layer is smooth.

  Further, in any case, the scattering material is preferably selected so that the difference (Δn) from the refractive index of the base material is 0.05 or more in at least a part of the emission spectrum range of the light emitting layer. In particular, in order to obtain sufficient scattering characteristics, the difference in refractive index (Δn) is 0.05 or more over the entire emission spectrum range (430 nm to 650 nm) or the entire visible wavelength range (360 nm to 830 nm). It is more preferable. The particle size of the scattering material is preferably 0.05 μm or more and 3 μm or less. When the particle size is less than 0.05 μm, the wavelength dependency of scattering increases, and it becomes difficult to control the color. When the particle size is larger than 3 μm, the scattering effect is weakened and it is difficult to smooth the surface of the coating layer. Moreover, it is preferable that the density | concentration of a scattering material is 50 volume% or less. When it is more than 50% by volume, it becomes difficult to smooth the surface of the coating layer.

  Here, the case where the scattering material is included in the convex structure or the coating layer has been described, but the scattering material may be included in the convex structure and the coating layer at the same time.

  The configuration of the present invention has been described with reference to the embodiment.

  The substrate for electronic devices of the present invention can be made into a light emitting element such as an organic LED element and an inorganic EL element by further arranging a light emitting layer and an electrode on the translucent electrode layer. These light-emitting elements using the substrate for electronic devices of the present invention can have high light extraction efficiency from the light-emitting layer and high brightness. Further, since the productivity is high, the cost can be reduced.

  Specific examples will be described below, but the present invention is not limited to these examples.

  In this example, a simulation was performed on the relationship between the height of the convex structure 3 and the light extraction efficiency.

  Specifically, a simulation was performed using the model shown in FIG. The upper diagram of FIG. 8 shows a cross-sectional view of the model used in the simulation. The organic LED element used in the model is formed on the translucent substrate 4 with the convex structure 3, the covering layer 2, and the translucent electrode layer. 1. An organic layer (light emitting layer) 6 and a reflective electrode 7 are provided.

  And the perspective view of the convex structure 3 is shown in the lower figure of FIG. As shown in this figure, the convex structure 3 is a triangular prism having a bottom surface with an isosceles triangle, and a plurality of the convex structures 3 are arranged in parallel so that one of the side surfaces is in contact with the translucent substrate. Here, the adjacent triangular prisms are arranged at regular intervals, and the coating layer 2 is in contact with the light-transmitting substrate 4 at the portions.

  In this example, a change in the light extraction efficiency when the height a of each convex structure 3 was changed was simulated. Since the width of each convex structure 3, that is, b in the lower diagram of FIG. 8, is fixed to 200 μm, the angle c of the inclined surface also changes according to the height a. The interval between adjacent triangular prisms, that is, d in the lower diagram of FIG. 8 was 10 μm.

  Here, the refractive index of the convex structure 3 and the translucent substrate 4 was 1.54. The refractive index of the coating layer 2 was 2.00, and the region from the upper end of the convex structure 3 to 15 μm above was filled and flattened. Furthermore, the refractive index of the translucent electrode layer 1 was 2.00, and the refractive index of the organic layer (light emitting layer) was 2.00. The calculation was performed by setting the emission wavelength from the organic layer to 550 nm and dividing the light beam of 1000 lm into 100,000 light beams.

  The results are shown in Table 1. In Table 1, cases where the height is 0 μm, 1.75 μm, 3.49 μm, and 100 μm are also shown as reference examples. The “light extraction efficiency (%)” in the table indicates the percentage of light that can be extracted to the outside out of the light emitted from the organic layer. The same applies to Tables 2 and 3.

これによれば、参照例として示した０μｍ、１．７５μｍ、３．４９μｍの場合、光取り出し効率が２５％程度に過ぎず、高さを変化させても、光取り出し効率にはほとんど変化がみられない。これに対して、８．７５μｍ〜８３．９１μｍでは、高さの増加に伴い光取り出し効率が向上することが分かる。ただし、参照例として示すように、高さを１００μｍにすると、光取り出し効率は低下する。以上のように、凸状構造物の高さを本発明の範囲内にすることにより、高い光取り出し効率が得られる。

According to this, in the case of 0 μm, 1.75 μm, and 3.49 μm shown as the reference example, the light extraction efficiency is only about 25%, and even if the height is changed, the light extraction efficiency hardly changes. I can't. On the other hand, in 8.75 micrometers-83.91 micrometers, it turns out that light extraction efficiency improves with the increase in height. However, as shown as a reference example, when the height is set to 100 μm, the light extraction efficiency decreases. As described above, by setting the height of the convex structure within the range of the present invention, high light extraction efficiency can be obtained.

  In Example 2, the same conditions as in Example 1 except that a scattering material having a particle size of 0.4 μm and a refractive index of 1.7 was added in the coating layer 2 so that the concentration was 0.4 vol%. A simulation was performed. The results are shown in Table 2. Here, as a reference example, a case where the height is 100 μm is also shown.

これによると被覆層２内に散乱物質を添加することによって、光取り出し効率を更に高めることが可能であることが分かる。また、凸状構造物の高さと光取り出し効率の関係についても、実施例１と同様の傾向を示すことがわかる。従って、この場合も凸状構造物の高さを本発明の範囲内にすることによって、高い光取り出し効率が得られることが分かる。

According to this, it is understood that the light extraction efficiency can be further increased by adding a scattering material in the coating layer 2. Moreover, it turns out that the tendency similar to Example 1 is shown also about the relationship between the height of a convex structure, and light extraction efficiency. Therefore, in this case as well, it is understood that high light extraction efficiency can be obtained by setting the height of the convex structure within the range of the present invention.

  In this example, a simulation was performed in the same manner as in Example 1 except that a scattering material having a particle size of 1 μm and a refractive index of 1.95 was added to the inside of the coating layer 2 so that the concentration was 42 vol%. . The results are shown in Table 3. Here, the case where the height is 100 μm is also shown as a reference example.

本実施例においては、散乱物質の添加量を実施例２の場合よりも更に増やしたものであり、光取り出し効率が更に向上していることが分かる。また、凸状構造物の高さと光取り出し効率の関係についても、実施例１、２と同様の傾向を示した。つまり、この結果からも凸状構造物の高さを本発明の範囲内にすることによって、高い光取り出し効率が得られることが分かる。

In this example, the amount of the scattering material added was further increased as compared with Example 2, and it can be seen that the light extraction efficiency is further improved. Moreover, the tendency similar to Example 1, 2 was shown also about the relationship between the height of a convex structure, and light extraction efficiency. That is, it can be seen from this result that high light extraction efficiency can be obtained by setting the height of the convex structure within the range of the present invention.

DESCRIPTION OF SYMBOLS 1 Translucent electrode layer 2 Covering layer 3 Convex structure 4 Translucent substrate 5 Scattering substance

Claims (4)

A translucent substrate;
A convex structure provided at least one on the translucent substrate and having a height of 5 μm or more and less than 100 μm;
The translucent substrate, and a coating layer covering the convex structure;
And a transparent electrode layer provided on the coating layer,
The substrate for an electronic device, wherein a refractive index of the covering layer is higher than a refractive index of the translucent substrate and the convex structure. The electronic device substrate according to claim 1, wherein a scattering material is included in the convex structure and / or in the coating layer. The electronic device substrate according to claim 1, wherein the convex structure and / or the coating layer is produced by a frit paste method. An organic LED element using the electronic device substrate according to claim 1.

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