JP2013114802A - Light-emitting element substrate and manufacturing method thereof, surface light-emitting element, luminaire, and backlight - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light-emitting element substrate and a manufacturing method therefor which, in addition to solving the problems associated with mass production capability and the ease of manufacture, improves the efficiency of light extraction of a surface light-emitting element using an OLED and also exhibits increased yield and heightened reliability, as well as provide a surface light-emitting element using the substrate and a luminaire and a backlight using the surface light-emitting element.SOLUTION: In a light-emitting element substrate used as a substrate for a surface light-emitting element consisting of a transparent electrode, an organic thin film layer and a cathode which are laminated one on another, there are provided a transparent support substrate and a high refraction index layer disposed between the support substrate and the transparent electrode, which consists of one or two or more layers having a higher refraction index than that of the support substrate. The high refraction index layer are composed to include a light scattering section which scatters light entering from the transparent electrode side and a flat section which abuts on the transparent electrode. The haze value of the high refraction index layer is made to be 5% or less, or the diameter of bubbles present in the high refraction index layer are made to be one tenth the thickness of the high refraction index layer.

Description

  The present invention relates to a light emitting element substrate and a manufacturing method thereof, a surface light emitting element, a lighting fixture, and a backlight.

  In recent years, flat panel displays have been actively developed. As a typical example of a surface light emitting element that is a light emitting element used in such a flat panel display, an organic electroluminescence element (OLED) can be given. An OLED is a light-emitting element that uses electroluminescence of a solid fluorescent substance, but has a laminated structure of materials having different refractive indexes, and therefore, due to the influence of reflection at the interface, the radiation efficiency of light to the outside ( There is a problem that the light extraction efficiency is low.

  When the light extraction efficiency is calculated by simple calculation, the ratio of the light that is confined in each layer and cannot be extracted to the outside and the ratio of the light that is radiated to the outside is approximately as guided light that is confined in the transparent electrode or organic thin film layer and cannot be extracted. 45%, which is about 35% of the waveguide light that is confined in the substrate and cannot be extracted, it can be seen that only about 20% of the emitted light can be extracted to the outside. Similar results are described in Non-Patent Document 1, for example.

  Thus, many examples have been proposed to solve the above-described problems by providing means for converting the light emission angle on the substrate of the OLED. Specifically, a diffraction grating structure is produced on a substrate to prevent reflection with respect to light of a specific wavelength, and a similar effect can be obtained by introducing a lens structure on the substrate surface to improve the extraction efficiency. What you expect. Although these techniques have a certain effect in improving the extraction efficiency, it is necessary to actively create a complicated fine structure, and thus it is difficult to apply them practically in the manufacturing process.

  On the other hand, for example, Patent Document 1 proposes to use a special glass base material having a refractive index comparable to that of the transparent conductive film to eliminate the thin-film guided light and improve the extraction efficiency. . When a structure such as a lens is provided on the light emission side opposite to the organic thin film layer of the substrate, the thin film guided light remains in the layer and cannot be extracted. There is an advantage in that it is possible to take out the thin-film guided light. However, in order to industrially mass-produce special high refractive index substrates as used in Patent Document 1, it is very expensive and difficult to put into practical use.

  As another method for reducing the thin-film guided light, a structure in which the refraction angle can be changed between the substrate and the transparent conductive film (ITO (Indium Tin Oxide), etc.) by a diffraction grating or a scattering structure is used. A method of forming and inserting is conceivable. In such a case, it is difficult to directly form a transparent electrode film so as to follow the structure on the substrate, so the surface of the base material is flattened using a material having a refractive index equivalent to that of the transparent electrode. Need to do.

  For example, Patent Document 2 proposes that an inorganic EL element is manufactured by using a spin-on-glass (SOG) material on a substrate having random unevenness as a substrate for an inorganic EL element, using a Spin On Glass (SOG) material. In Patent Document 3, a substrate having a surface roughness Ra = 0.01 to 0.6 μm is formed by depositing SiN having a high refractive index of 0.4 to 2 μm using a chemical vapor deposition (CVD) method. It has been proposed to produce an organic EL element as a substrate material, reduce thin-film guided light, and improve light extraction efficiency.

  Furthermore, as another method for reducing thin film guided light, for example, Patent Document 4 proposes forming a high refractive index glass layer containing a scattering component such as air between ITO and a substrate. ing.

  Patent Document 5 discloses a glass substrate for an organic EL element in which a transparent conductive film is formed on the surface, and an organic EL element is formed on the transparent conductive film. A glass plate having an uneven surface for scattering light from the organic EL element on the surface and a glass fired film having a higher refractive index than the glass plate and provided on the uneven surface of the glass plate The glass firing film describes a method in which the glass firing film gives the surface on which the transparent conductive film is formed by flattening the unevenness of the uneven surface of the glass plate.

JP 2009-238507 A Japanese Patent Laid-Open No. 10-241856 JP 2003-297572 A International Publication No. 2009/017035 JP 2010-198797 A

Advanced Material 6 page 491 (1994)

  However, when the method described in Patent Document 2 is used, an SOG material is used as a flattening material for flattening the unevenness. However, as a result of actual investigations by the present inventors, the SOG material is used. It was found that it was very difficult to obtain a film thickness of 1-2 μm or more without defects. That is, if the method of Patent Document 2 is used to form unevenness to such an extent that thin-film guided light can be reduced, flattening cannot be achieved. It has been found that the effect on reduction is hardly obtained. Originally, a flattening film for flattening irregularities needs to have a refractive index comparable to that of the electrode material on the upper part, but Patent Document 2 describes a refractive index of the flattening material. There is no detailed effect.

  In addition, when the method described in Patent Document 3 is used, the high refractive index material for planarization is SiN formed by using the CVD method. The above disadvantages are great.

  Furthermore, in the method described in Patent Document 4, scattering components such as bubbles and fillers are intentionally present in the high refractive index glass layer to cause the high refractive index glass layer itself to function as the scattering layer. If bubbles or fillers are present in contact with the electrodes, the surface of the high refractive index glass layer (substrate) will not be flat, and it will be difficult to form a homogeneous transparent conductive film. Patent Document 4 describes a method for intentionally preventing air bubbles from being present on the surface of a highly refractive glass layer. However, if this method is to be realized, manufacturing difficulties are expected. .

  Further, according to the study of the method described in Patent Document 5, the smoothness of the surface of the glass fired film is still low at the firing temperature of the glass paste in this method. No mention is made of bubbles that are generated during production and are expected to be inherent in the film. For this reason, it is difficult to form a homogeneous transparent conductive film on the glass fired film of Patent Document 5, and it is difficult to ensure the lifetime and reliability of the OLED.

  As described above, when the surface on which the transparent conductive film (transparent electrode) is formed (interface between the transparent conductive film and the substrate) is not flat, the yield of the manufactured OLED decreases or the life and reliability of the OLED are low. It will become.

  As described above, at present, no method has yet been proposed that can realize all of mass productivity, ease of manufacture, improvement of light extraction efficiency, and improvement of yield, lifetime, and reliability.

  Accordingly, the present invention has been made in view of the above-described present situation, and solves the above-described problems such as mass productivity and ease of manufacture, and improves the light extraction efficiency of a surface light emitting device using an OLED. To provide a substrate for a surface light emitting device that improves the yield and has a high lifetime and reliability, a method for manufacturing the same, a surface light emitting device using the substrate, and a lighting fixture and a backlight using the surface light emitting device. Objective.

  As a result of intensive studies to solve the above problems, the present inventor formed a glass layer having a light scattering function for increasing the extraction efficiency on the surface of a support substrate such as a glass substrate, and the glass layer was transparent. By using a glass paste composition containing a low melting point glass frit having a refractive index equal to or higher than the refractive index of the support substrate as a planarizing material for planarizing the interface with the electrode, according to Snell's law, It has been found that light that has been totally reflected and cannot be extracted from within the element can be extracted outside the element (in the air). Further, as a result of further studies, the inventor has improved the device yield and improved the lifetime and reliability. In the glass layer formed by the glass paste composition adjacent to the transparent electrode. It is necessary to positively remove bubbles and binders inherent in the glass paste, and it has been found that this can be achieved by baking the glass paste composition under vacuum or pressure, and the present invention is based on these findings. It came to complete.

  That is, according to an aspect of the present invention, there is provided a light-emitting element substrate used as a substrate of a surface light-emitting element in which a transparent electrode, an organic thin film layer, and a cathode are sequentially laminated, the transparent support substrate, and the support A high refractive index layer that is disposed between the substrate and the transparent electrode and has one or more layers having a refractive index greater than or equal to the refractive index of the support substrate, the high refractive index layer being the transparent A layer having a light scattering portion for scattering light incident from the electrode side and a flat surface in contact with the transparent electrode, and a haze value of a layer adjacent to the transparent electrode among the layers constituting the high refractive index layer is 5 % Or less is provided.

  According to another aspect of the present invention, there is provided a light emitting device substrate used as a substrate of a light emitting device in which a transparent electrode, an organic thin film layer, and a cathode are sequentially stacked, the transparent support substrate, and the support A high refractive index layer disposed between the substrate and the transparent electrode and having a refractive index greater than or equal to the refractive index of the support substrate, wherein the high refractive index layer scatters light incident from the transparent electrode side A layer having a light scattering portion to be formed and a flat surface in contact with the transparent electrode, and a diameter of a bubble existing in the high refractive index layer is a layer adjacent to the transparent electrode among layers constituting the high refractive index layer The ratio of the bubbles in the layer adjacent to the transparent electrode is the ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal cross section of the layer adjacent to the transparent electrode. 0.5% or less of the layer adjacent to the transparent electrode 0.5% or less in a proportion of the area of the vertical cross section of the bubble relative to the total area of the straight section, the light emitting element substrate is provided. In this light-emitting element substrate, it is preferable that the haze value of a layer adjacent to the transparent electrode among the layers constituting the high refractive index layer is 5% or less.

  In each of the light emitting element substrates, the interface between the support substrate and the high refractive index layer may be an uneven surface.

  In this case, it is preferable that the film thickness of the high refractive index layer is 30 times or more the average surface roughness Ra of the uneven surface.

  Moreover, it is preferable that the film thickness of the said high refractive index layer is 1.3 times or more of the maximum surface roughness Rz of the said uneven surface.

  The film thickness of the high refractive index layer is preferably 3 μm or more and 100 μm or less.

  Moreover, it is preferable that average surface roughness Ra of the said uneven | corrugated surface is 0.7 micrometer or more and 5 micrometers or less.

  Further, the uneven shape of the uneven surface may be a pyramid shape or a lens shape.

  The high refractive index layer may consist of only one layer.

  Alternatively, the high refractive index layer is adjacent to the support substrate and includes at least a light scattering layer having the light scattering portion, and a planarization layer adjacent to the transparent electrode and having the flat surface. It may consist of layers. At this time, the light scattering layer may contain a glass material and a scattering material having a refractive index different from that of the glass material.

  In addition, the light scattering layer that does not have an uneven surface at the interface between the support substrate and the high refractive index layer, the high refractive index layer is adjacent to the support substrate and has the light scattering portion, and the transparent electrode. The light scattering layer contains a glass material and a scattering material having a refractive index different from that of the glass material. May be.

  According to still another aspect of the present invention, there is provided a method for manufacturing a light-emitting element substrate as described above, wherein a glass frit having a refractive index higher than that of the support substrate, a solvent, and a resin are formed on the surface of the transparent support substrate. An application step of applying a glass paste composition containing, a drying step of drying the glass paste composition and volatilizing the solvent, and applying vacuum or pressure to the glass paste composition after the solvent has volatilized And a firing step of firing at a step, a method for producing a light-emitting element substrate is provided.

  Here, in the firing step, the glass paste composition may be fired under a vacuum of 0.3 Pa or less.

  Alternatively, in the firing step, the glass paste composition may be fired under a pressure of 110 kPa or more.

  In the method for manufacturing a light emitting element substrate, it is preferable that a glass transition temperature of the glass frit is 450 ° C. or lower.

  Moreover, it is preferable that the said drying process and the said baking process are implemented at the temperature of 500 degrees C or less.

  Moreover, before the said application | coating process, the surface roughening process which forms an uneven surface on the surface of the said support substrate may be further included. At this time, in the surface roughening step, the uneven surface may be formed by a sand blast method, a wet etching method, or a press method.

  The glass paste composition may further contain a scattering material having a refractive index different from that of the glass frit.

  According to still another aspect of the present invention, the above-described light emitting element substrate, a transparent electrode laminated on the light emitting element substrate, an organic thin film layer laminated on the transparent electrode, and the organic thin film layer A surface light emitting device is provided, comprising: a cathode laminated thereon.

  Moreover, according to another viewpoint of this invention, a lighting fixture provided with the said surface emitting element is provided.

  Moreover, according to another viewpoint of this invention, the backlight for display apparatuses provided with the said surface emitting element is provided.

  According to the present invention, a glass paste containing a low melting point glass frit having a refractive index equal to or higher than the refractive index of the support substrate as a planarizing material for flattening the interface with the transparent electrode of the high refractive index layer formed on the surface of the support substrate. By using the composition and firing the glass paste composition in a vacuum or under pressure, after solving the above problems such as mass productivity and ease of manufacture, the light emission of the surface light emitting device using the OLED It is possible to provide a substrate for a surface light emitting element, a manufacturing method thereof, and a surface light emitting element using the substrate, which improve the extraction efficiency, improve the yield, and have a high lifetime and reliability. Further, by using this surface light emitting element, it is possible to provide a high-performance lighting device or backlight having a long life and reliability.

It is explanatory drawing which shows the cross-sectional structure of a general OLED. It is explanatory drawing which shows the ratio of the light which is confined in each layer of a general OLED, and cannot be taken out, and the light radiated | emitted outside. It is explanatory drawing which shows the cross-sectional structure of the surface emitting element which concerns on the 1st Embodiment of this invention. It is a graph which shows the result of having calculated at a single interface how much light can be taken out in solid angle conversion, assuming that all the light beyond a critical angle can be taken out. It is explanatory drawing which shows the cross-sectional structure of the surface emitting element which concerns on the modification of the 1st Embodiment of this invention. It is explanatory drawing which shows an example of the manufacturing method of the surface emitting element which concerns on the same embodiment. It is explanatory drawing which shows an example of the formation method of the high refractive index layer which concerns on the embodiment. It is explanatory drawing which shows the cross-sectional structure of the surface emitting element which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows an example of the manufacturing method of the surface emitting element which concerns on the same embodiment. It is explanatory drawing which shows the cross-sectional structure of the surface emitting element which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows an example of the manufacturing method of the surface emitting element which concerns on the same embodiment. It is explanatory drawing which shows the cross-sectional structure of the surface emitting element which concerns on the 4th Embodiment of this invention. It is explanatory drawing which shows an example of the manufacturing method of the surface emitting element which concerns on the same embodiment. It is a graph which shows the example which compared the refractive index of the glass frit used for the high refractive index layer made as an experiment in the Example, and the refractive index of ITO used for the transparent electrode. It is a graph which shows the measurement result of the light extraction intensity | strength of the Example and comparative example of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[OLED issues]
Before describing a preferred embodiment of the present invention, as a premise thereof, a problem of a general OLED will be described.

(General OLED configuration)
First, a configuration of a general OLED will be described with reference to FIG. FIG. 1 is an explanatory diagram showing a cross-sectional configuration of a general OLED.

  As shown in FIG. 1, an OLED 10 includes an anode (transparent electrode) 12 made of a transparent conductive film such as ITO formed on a substrate 11 made of glass or the like by a sputtering method, a resistance heating vapor deposition method, or the like. Hole transport composed of N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (hereinafter abbreviated as NPD) formed on the anode 12 by the resistance heating vapor deposition method or the like. A layer 13, a light emitting layer 14 made of 8-hydroxyquinoline Al μmin μm (hereinafter abbreviated as Alq 3) formed on the hole transport layer 13 by a resistance heating vapor deposition method, and the like, and a resistance heating vapor deposition method on the light emitting layer 14. And a cathode 15 made of a metal film such as aluminum and the like. When a DC voltage or a DC current is applied with the anode 12 of the OLED 10 having the above configuration as a positive electrode and the cathode 15 as a negative electrode, holes are injected from the anode 12 into the light emitting layer 14 through the hole transport layer 13. Then, electrons are injected from the cathode 15 into the light emitting layer 14. In the light-emitting layer 14, recombination of holes and electrons occurs, and a light emission phenomenon occurs when excitons generated thereby shift from the excited state to the ground state.

  In such an OLED 10, light emitted from the phosphor in the light emitting layer 14 is normally emitted in all directions centering on the phosphor, and passes through the hole transport layer 13, the anode 12, and the substrate 11. Radiated into the air. Alternatively, the light is once reflected in the direction opposite to the light extraction direction (the direction of the substrate 11), reflected by the cathode 15, and radiated into the air via the light emitting layer 14, the hole transport layer 13, the anode 12, and the substrate 11. The However, when the light passes through the boundary surface of each medium, if the refractive index of the medium on the incident side is larger than the refractive index on the outgoing side, the angle at which the outgoing angle of the refracted wave becomes 90 °, that is, more than the critical angle. Light incident at a large angle cannot pass through the interface, is totally reflected, and light is not extracted into the air.

The relationship between the light refraction angle and the medium refractive index at the interface between different media generally follows Snell's law. According to Snell's law, when light travels from a medium 1 with a refractive index n _{1 to} a medium _{2 with} a refractive index n ₂ , n ₁ sin θ ₁ = n ₂ sin θ between the incident angle θ ₁ and the refractive angle θ _2. The relational expression ₂ holds. In this relational expression, when n ₁ > n ₂ holds, the incident angle θ ₁ = Arcsin (n ₂ / n ₁ ) at which θ ₂ = 90 ° is called a critical angle, and the incident angle is the critical angle. If larger than this, the light is totally reflected at the boundary surface between the medium 1 and the medium 2. Therefore, in an OLED that emits light isotropically, light emitted at an angle larger than this critical angle repeats total reflection at the interface, is confined inside the device, and is not emitted into the air.

  Here, the light extraction ratio of a general OLED as shown in FIG. 1 will be described with reference to FIG. FIG. 2 is an explanatory diagram showing the ratio of light that is confined in each layer of a general OLED and cannot be extracted and light emitted to the outside in a simple calculation using Snell's law. In the example shown in FIG. 2, it is assumed that the hole transport layer and the light emitting layer constituting the OLED have substantially the same refractive index, and n = 1.7 (in FIG. 2, they are collectively shown as an organic thin film layer. ), N = 2.0 when ITO was used as the transparent electrode, and n = 1.5 when a glass substrate was used as the substrate. As shown in FIG. 2, the ratio of guided light (thin film guided light) that is confined in a transparent electrode or an organic thin film layer and cannot be extracted is about 45%, and the ratio of substrate guided light that is confined in the substrate and cannot be extracted is about 35%. %, Only about 20% of the emitted light can be extracted to the outside.

  As described above, since the light extraction efficiency of the OLED is low, many examples for improving the light extraction efficiency have been proposed. However, in these examples, as described above, the light extraction efficiency is improved to some extent, but there is a problem in terms of mass productivity and ease of manufacture.

  Moreover, when producing surface emitting elements, such as OLED, high smoothness is calculated | required by the surface adjacent to the transparent electrode of a board | substrate. This is because many surface light-emitting elements are composed of thin films (several tens of nanometers to several micrometers), and if the surface of the substrate is uneven, current leakage occurs and the elements cannot be driven stably. Accordingly, if the surface of the substrate adjacent to the transparent electrode (interface between the transparent conductive film and the substrate) or the transparent electrode itself is not flat, the yield of the manufactured OLED may be reduced, or the lifetime and reliability of the OLED may be reduced. Resulting in. However, in the above-described example of improving the light extraction efficiency, the smoothness of the surface adjacent to the transparent electrode of the substrate as described above is not sufficiently considered.

  As described above, there is actually no technology related to OLED that can realize all of mass productivity, ease of manufacture, improvement of light extraction efficiency, and improvement of yield, lifetime, and reliability.

[Outline of the present invention]
Therefore, as a result of intensive studies on means that can solve the above problems, the present inventor has obtained the following two findings, and has completed the present invention based on these findings.

  The first finding is a means for improving the light extraction efficiency while ensuring mass productivity and ease of manufacture. This is because a glass layer having a light scattering function for increasing the extraction efficiency is formed on the surface of a support substrate such as a glass substrate, and the surface of the support substrate is used as a planarizing material for planarizing the interface between the glass layer and the transparent electrode. A glass paste composition containing a low melting point glass frit having a refractive index equal to or higher than the refractive index is used. As a result, according to Snell's law, light that is totally reflected at the interface between the layers and cannot be extracted from the element can be extracted outside the element (in the air).

  The second finding is a means for improving the yield of the element and increasing the lifetime and reliability of the element. This is because it is necessary to positively remove bubbles and binders that are adjacent to the transparent electrode and are inherent in the glass layer formed by the glass paste composition, in order to effectively remove the bubbles and binders. In other words, the glass paste composition may be fired under vacuum or under pressure. Thereby, since it can suppress that a big bubble exists in the interface part with a transparent electrode of a glass layer, the smoothness of the surface adjacent to the transparent electrode of a board | substrate can be improved markedly conventionally.

  Hereinafter, the present invention made based on the above two findings will be described in detail by taking four preferred embodiments as examples. Note that the OLED of the present invention is not limited to the following four embodiments, and may have other structures as long as it includes means obtained by the above-described two findings. It is natural.

[First Embodiment]
[Configuration of Surface Light Emitting Element 100]
First, the configuration of the surface light emitting device according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3 is an explanatory diagram showing a cross-sectional configuration of the surface light emitting device 100 according to the first embodiment of the present invention.

  As shown in FIG. 3, the surface light emitting device 100 according to the first embodiment of the present invention includes a support substrate 110, a high refractive index layer 120, a transparent electrode (transparent conductive film) 130, an organic thin film layer 140, The cathode 150 is mainly provided. Note that the light emitting element substrate according to the present embodiment includes a support substrate 110 and a high refractive index layer 120.

  The surface light emitting device 100 has a structure in which a concavo-convex surface 111 is formed on the surface of a support substrate 110 and the concavo-convex surface 111 is flattened by a high refractive index layer 120 (surface that contacts the transparent electrode 130). doing. In the surface light emitting device 100, the high refractive index layer 120 includes only one layer having a light scattering portion 121 that scatters light incident from the transparent electrode 130 side and a flat surface 123 in contact with the transparent electrode 130. . Hereinafter, each component of the surface light emitting element 100 will be described in detail.

(Supporting substrate 110)
The support substrate 110 is, for example, a substrate formed of a transparent material such as soda lime glass, non-alkali glass, high strain point glass (such as PD200), or transparent plastic, and on one surface thereof, An uneven surface 111 is provided. Examples of the transparent plastic for forming the support substrate 110 include insulative organic materials such as polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN). ), Polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), and the like. The uneven surface 111 is a surface having random unevenness that causes disturbance in the refraction angle of incident light when the light generated in the organic thin film layer 140 passes through the transparent electrode 130 and enters the support substrate 110. In the present invention, the high refractive index layer 120 is formed on the uneven surface 111 with a flattening material described later. However, the flattening material is a paste material made of glass frit, and it is necessary to melt the glass frit by firing. . Since this baking process is performed at a temperature of about 500 ° C., the support substrate 110 is preferably formed of a glass material having a higher melting point than a plastic material having a lower melting point.

  The degree of unevenness of the uneven surface 111 is not particularly limited, but is preferably 0.7 μm or more and 5 μm or less in terms of the average surface roughness Ra specified in JIS B 0601-2001. When Ra is smaller than 0.7 μm, the light extraction effect may not be sufficient. Moreover, when Ra exceeds 5 μm, the extraction efficiency tends to decrease. The reason is considered as follows. As in this embodiment, when light extraction is used to increase the extraction efficiency, the light is scattered within the surface light emitting device 100 by the light scattering portion 121 (the support substrate 110 where the uneven surface 111 is present). Each time it passes through a region near the interface with the refractive index layer 120, reflection is repeated many times, and as a result, light can be extracted outside the surface light emitting element 100. In consideration of such a mechanism, if Ra is large, the high refractive index layer 120 is inevitably thick in order to flatten. This is because if the thickness of the high refractive index layer 120 having a high refractive index is too thick, loss due to light absorption in the high refractive index layer 120 cannot be ignored. In this respect, the glass frit used as the material of the high refractive index layer 120 used in the present invention is made of a metal oxide and has an extremely small extinction coefficient k in the visible light region. The attenuation of is negligibly small.

  In general, when the surface roughness of a substrate is increased, when used in a display element such as a display, the light is scattered to the outside of each pixel (pixel) due to large light scattering, and blurring occurs. Therefore, although not preferred, a certain degree of unevenness (roughness) is required to increase the light extraction efficiency. When a board | substrate has a large unevenness | corrugation, a device is needed when using it for a display use. Therefore, by optimizing the unevenness of the substrate surface (setting value of Ra) for each application such as display use and illumination or backlight use, it is possible to satisfy each specification and extract light from the front. Become. The support substrate 110 according to the present embodiment assumes a lighting application, and forms the uneven surface 111 having a relatively large Ra.

  The average surface roughness Ra and the maximum roughness Rz described later in this embodiment can be easily measured using a contact-type surface roughness measuring instrument, a non-contact type optical roughness measuring instrument, or the like. Is possible.

  Here, when the uneven surface 111 as described above is provided on the surface of the support substrate 110, light incident on the uneven surface 111 is scattered, so the direction of the light traveling perpendicular to the support substrate 110 is the direction. The ratio of the light transmitted through the support substrate 110 without changing is reduced. Such a state may be expressed as the turbidity (haze value: Haze) of the substrate. Haze is a numerical value (percentage) of the ratio of the transmitted light component that is not perpendicular to the transmitted light that is incident perpendicular to the substrate (the support substrate 110 in this embodiment). A member having a high haze cannot be used for a portion that needs to improve external visibility, such as a window glass, but in order to increase the light extraction efficiency like the structure of the light emitting element substrate of the present embodiment, Thus, it is preferable that there are many components to scatter (non-perpendicular transmitted light components). From the above viewpoint, the haze of the support substrate 110 is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. Haze can be easily measured by a commercially available transmissometer with an integrating sphere or a haze meter.

(High refractive index layer 120)
The high refractive index layer 120 is disposed between the support substrate 110 and the transparent electrode 130 described above and has a refractive index equal to or higher than the refractive index of the support substrate 110 and scatters light incident from the transparent electrode 130 side. It has a light scattering portion 121 and a flat surface 123 in contact with the transparent electrode 130.

  Here, as described above, when a surface light emitting element such as an OLED is formed, high smoothness is required for the light emitting element substrate. Therefore, in this embodiment, in order to flatten the uneven surface 111 formed on the support substrate 110, a glass paste composition containing glass frit is used, and the uneven surface 111 formed on the surface of the support substrate 110 is used. In addition, the high refractive index layer 120 having the flat surface 123 on the side adjacent to the transparent electrode 130 is provided. As described above, various materials for flattening the unevenness of the substrate surface have been proposed, such as SOG material and CVD film. However, a film thickness that can flatten the unevenness having a large roughness is formed. There are many problems in practical use, such as being unable to perform the process, requiring a very expensive and sophisticated equipment for film formation, and taking time. According to the study by the present inventors, when an SOG material is used, the maximum film thickness that can be formed is at most about 1 to 2 μm, and even a SiN film formed using the CVD method can be practically formed. The film thickness is several μm. The structure (unevenness) for adjusting the refraction angle of the incident light to the substrate, such as light scattering and condensing, is a structure larger than the wavelength of the incident light (unevenness having a roughness larger than the wavelength of the incident light) If the SOG material or the CVD method is used, it is impossible to achieve flattening of the uneven surface.

  On the other hand, in the method using the glass frit of this embodiment, the glass frit is prepared by mixing a high boiling point solvent such as terpineol or butyl carbitol acetate with a thickening binder resin such as ethyl cellulose or acrylic resin. The uneven surface 111 can be easily flattened and the high refractive index layer 120 having a sufficient thickness can be formed simply by applying the glass paste to the support substrate 110, drying and baking. Is possible. The glass paste composition for forming the high refractive index layer 120 is a paste-like composition containing a glass frit, a solvent, and a resin. Hereinafter, each of the glass paste compositions according to the present embodiment will be described. The components will be described.

<Glass frit>
First, the glass frit used in the present embodiment has a thermal characteristic such that a transparent glass layer (high refractive index layer 120) can be formed at a temperature at which the support substrate 110 is not distorted or distorted. There is a need. A general glass substrate (for example, soda lime glass) used as the support substrate 110 is not preferable because a strain or distortion is generated when a temperature of 500 ° C. or higher is applied, and the support substrate 110 is warped. In order to form the high refractive index layer 120 at 500 ° C. or lower, the glass transition temperature (Tg) of the glass frit needs to be 450 ° C. or lower, preferably 400 ° C. or lower.

Further, if the linear expansion coefficient of the glass frit is different from the linear expansion coefficient of the material forming the support substrate 110, when the high refractive index layer 120 is formed, stress remains in the support substrate 110, causing cracks and the like. Become. Therefore, it is preferable that the linear expansion coefficient of the glass frit in the present embodiment is approximately the same as that of the material (for example, soda lime glass or non-alkali glass) that forms the support substrate 110. For example, in the case of soda lime glass, the linear expansion coefficient is about 85 × 10 ⁻⁷ / ° C., and therefore, a glass frit having a linear expansion coefficient of about (85 ± 10) × 10 ⁻⁷ / ° C. is preferable. According to the study by the present inventors, if the difference in linear expansion coefficient between the glass frit and the forming material of the support substrate 110 is larger than ± 10 × 10 ⁻⁷ , the film thickness formed by the glass frit is thin. It has been experimentally found that the high refractive index layer 120 may be broken such as cracks.

  The material forming the high refractive index layer 120, that is, the refractive index of the glass frit needs to have a refractive index higher than that of the support substrate 110. The refractive index of the glass frit is preferably about the same as that of the transparent electrode 130 (for example, formed of ITO). The refractive index of a substrate of a surface light emitting element such as a general OLED is about 1.5, and the refractive index of a transparent electrode (transparent conductive film) is about 2. If the refractive index of the high refractive index layer 120 is approximately the same as that of the support substrate 110, reflection at the interface with the transparent electrode 130 is the same as when the uneven surface 111 and the high refractive index layer 120 are absent, You can't hope to improve the extraction efficiency. Specifically, in the surface light emitting device 100 according to this embodiment, the refractive index of the high refractive index layer 120 is preferably about 1.7 to 2.5. Alternatively, the relationship between the refractive index nd1 of the glass frit for forming the high refractive index layer 120 (d represents 589 nm, which is a sodium D line) and the refractive index nd2 of the transparent electrode 130 (for example, ITO) Nd1 / nd2 ≧ 0.9 is preferable. The reason will be described below.

  As already described, there is a critical angle θ according to Snell's law at the interface between media having different refractive indexes n1 and n2, and this critical angle θ is expressed by θ = Arcsin (n2 / n1). For example, the critical angle of general glass (for example, nd = 1.5) and ITO (for example, nd = 2.0) is 48.6 ° from the above formula, and incident light with an angle less than this critical angle is It is deactivated by being guided through ITO or an organic thin film layer, that is, this incident light cannot be extracted. Here, FIG. 4 is a graph showing the result of calculating at a single interface how much light can be extracted in terms of solid angle, assuming that all light above the critical angle can be extracted. The extraction ratio shown on the vertical axis in FIG. 4 is a solid angle 2π of a solid angle (steradian: sr) = 2π (1-cos θ) of an incident angle θ (corresponding to all solid angles when all light can be extracted). The value (1-cos θ) divided by is expressed as a percentage.

  As is apparent from the calculation results shown in FIG. 4, it can be seen that when nd1 / nd2 ≧ 0.9, total reflection at the interface is sufficiently small and total reflection at the interface between the transparent conductive film and the substrate is reduced. . In order to make the influence of total reflection almost zero, it is preferable that nd1 / nd2 ≧ 1. More specifically, for example, when the transparent electrode 130 formed of ITO having a refractive index nd2 = 2.0 is used, the refractive index nd1 of the high refractive index layer 120 of the present embodiment is 1.8 or more. Preferably it is 2 or more.

Examples of the glass frit component having a low glass transition temperature and a high refractive index as described above are, for example, 1 selected from P ₂ O ₅ , SiO ₂ , B ₂ O ₃ , Ge ₂ O, and TeO ₂ as a network former. It contains seeds or two or more kinds of components, and as a high refractive index component, 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, Sb ₂ O ₃ can be used. High refractive index glass containing one or more components selected from two or more components can be used. Further, as the glass frit component in this embodiment, in addition to the above components, alkali metal oxides, alkaline earth metal oxides, fluorides, etc. are required for the refractive index in order to adjust the characteristics of the glass. You may use in the range which does not impair the physical property made. Specific examples of the glass frit component system include, 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 _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 System, P ₂ O ₅ —ZnO system, etc. Here, R ′ represents an alkali metal element, and R ″ represents an alkaline earth metal element. In addition, the component system mentioned above is only an example, and it is not limited to said example if it is a component system which satisfy | fills conditions, such as the glass transition temperature mentioned above and refractive index. The glass frit material as described above is not particularly limited as long as it has a high refractive index and a low melting point (450 ° C. or lower), but lead-free glass is preferable in view of environmental problems. 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, Sb 2 Among O ₃ , as an example in which the high refractive index layer 120 having a low melting point can be formed on the support substrate 110 having a relatively low heat resistance such as soda lime glass, a material containing Bi ₂ O ₃ can be preferably used. . As a preferable glass composition containing Bi ₂ O ₃ , for example, Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO, Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ , Bi ₂ O ₃ —B ₂ O ₃ —ZnO ₂ system, Bi ₂ O ₃ —B ₂ O ₃ —R ₂ O—Al ₂ O ₃ system (R is an alkali metal), and the like can be given.

<Solvent>
The solvent used in the glass paste composition of the present embodiment is not particularly limited as long as it is an organic solvent. However, considering the production process, if the drying rate is too fast, the organic solvent is dried during production, and solids are precipitated, which is not preferable. From such a point of view, the organic solvent used in the glass paste composition of the present embodiment is preferably a solvent having a boiling point of 150 ° C. or higher, more preferably 180 ° C. or higher. As such a solvent, for example, a terpene solvent (Terpineol etc.), carbitol solvents (butyl carbitol, butyl carbitol acetate) and the like can be used.

<Resin>
The resin used in the glass paste composition of the present embodiment is not particularly limited as long as it develops an appropriate viscosity for coating the paste, but it disappears at a temperature lower than the glass transition temperature of the glass frit. Preferred is a resin. This is because if the resin is not baked and removed at a temperature lower than the temperature at which the glass frit exhibits fluidity, the resin gasifies at the temperature at which the glass is baked, causing bubbles inside the glass. Specific examples that can be suitably used as such a resin include ethyl cellulose and nitrocellulose as cellulosic resins, and acrylic resin and methacrylic resin as acrylic resins.

<Other additives>
If necessary, the glass paste composition of the present embodiment may contain additives for the purpose of improving the dispersibility of the glass frit and the resin and adjusting the rheology. As such an additive, for example, adjustment of viscosity suitable for processes such as slit coating, polymers added for the purpose of improving dispersibility of glass frit, thickeners added for the purpose of rheology adjustment, Examples thereof include a dispersant added for the purpose of preparing a glass paste composition having good dispersibility. Examples of the polymer include acrylic polymers. Examples of the thickener include cellulose resins such as ethyl cellulose, polyoxyalkylene resins such as polyethylene glycol, and the like. Examples of the dispersant include dispersants such as polyvalent carboxylic acids and ammonium salts thereof. Examples of the polyvalent carboxylic acid include lower to higher aliphatic polyvalent carboxylic acids, and these may form an ammonium salt such as a tetrabutylammonium salt. Specifically, for example, the HIPLAAD series manufactured by Enomoto Kasei Co., Ltd., the Disperbyk series manufactured by Big Chemie, and the like can be mentioned. In addition, it is preferable that content of the above additives is 3 mass parts or less with respect to 100 mass parts of glass paste compositions, for example.

<Film thickness>
The thickness of the high refractive index layer 120 is not particularly limited as long as it is sufficient to flatten the uneven surface 111 of the support substrate 110. It is preferable that the thickness is 30 times or more and 40 times or less of the average roughness Ra. The absolute range of the film thickness of the high refractive index layer 120 is preferably about 3 μm or more and 100 μm or less. This is because the maximum height Rz of the uneven surface 111 formed by sandblasting or wet etching is approximately 10 to 20 times Ra as will be described later.

  From the same meaning as described above, the thickness of the high refractive index layer 120 is preferably 1.3 times or more the maximum roughness Rz (described in JIS B 0601-2001) of the uneven surface 111 of the support substrate 110. . This is because if it is less than 1.3 times Rz, the high refractive index layer 120 that provides sufficient reliability with respect to the driving stability described above cannot be obtained.

  As described above, it is impossible to easily form a flattened film having the above thickness with an SOG material (sol-gel material) or a vacuum process (CVD or the like). On the other hand, methods of obtaining a thick planarized film with an organic material such as a polymer are conceivable. However, these methods have sufficient heat resistance (300 ° C.) for forming a transparent conductive film (transparent electrode) such as ITO. In addition, as described above, the high refractive index layer 120 is required to have a high refractive index (preferably 2 or more), but such a refractive index is realized with an organic material. There can be no material that can. That is, unless the glass paste composition containing glass frit in the present embodiment is used, the high refractive index layer 120 having the above thickness cannot be easily formed.

  The film thickness of the high refractive index layer 120 can be confirmed by measuring the film thickness after firing. However, since the support substrate 110 has an uneven surface 111 (uneven structure), depending on the measurement position. Different film thicknesses. Therefore, the film thickness of the high refractive index layer 120 in this embodiment is the thickness from the deepest part of the uneven surface 111 to the uppermost part of the high refractive index layer 120, but the uneven surface 111 is randomly uneven. If it is a shape, it may be difficult to determine the deepest part even by analyzing the cross-sectional shape. In such a case, the film thickness is measured for 10 or more arbitrarily selected sites, There is no problem even if the maximum thickness portion is considered as the film thickness.

<Structure confirmation method, etc.>
Note that, when the uneven surface 111 is flattened, the above-described glass frit needs to be filled in the unevenness (the portion corresponding to the valley of the uneven surface 111) without any gap. Such structures of the support substrate 110 and the high refractive index layer 120 can be easily confirmed by observing the cross-sectional shape using a scanning electron microscope (SEM) or the like.

<Smoothness of the interface between the high refractive index layer 120 and the transparent electrode 130>
When producing the high refractive index layer 120 having the above-described configuration, by firing the glass paste composition described above under vacuum or pressure, bubbles are generated in the high refractive index layer 120 after firing. It can be remarkably suppressed. More specifically, the number of bubbles existing in the high refractive index layer 120 can be reduced and the size of the bubbles can be reduced by baking under the above-described vacuum or pressure. In this way, by suppressing the generation of bubbles in the high refractive index layer 120, the surface adjacent to the transparent electrode 130 of the high refractive index layer 120, that is, the interface between the high refractive index layer 120 and the transparent electrode 130 is smooth. The sex can be greatly improved. Since the smoothness of the interface between the high refractive index layer 120 and the transparent electrode 130 is improved, the manufacturing yield of the surface light emitting device 100 is improved and current leakage is suppressed. The lifetime and reliability of the device are also improved. The smoothness required for the interface between the high refractive index layer 120 and the transparent electrode 130 in this embodiment is Ra of the surface adjacent to the transparent electrode 130 of the high refractive index layer 120, preferably 30 nm or less, preferably 1 nm or less.

  Here, in the present embodiment, the above-described haze value (Haze) is used as one index of the degree of suppression of bubble generation in the high refractive index layer 120. That is, the haze value of the high refractive index layer 120 adjacent to the transparent electrode 130 in the light emitting element substrate for the surface light emitting element 100 according to the present embodiment is 5% or less. When the haze value of the high refractive index layer 120 exceeds 5%, the number of bubbles in the high refractive index layer 120 increases and the size of the bubbles increases, so that the high refractive index layer 120 and the transparent electrode 130 Sufficient smoothness of the interface cannot be secured.

  In addition, although the haze value of the high refractive index layer 120 in this embodiment can be measured with a commercially available transmittance meter with an integrating sphere or a haze meter, the haze value of the high refractive index layer 120 is a surface light emitting element. The haze value of the high refractive index layer 120 alone is used instead of the value of the entire light emitting element substrate of 100.

  In the present embodiment, a more direct index using the diameter of the bubbles and the ratio of the bubbles in the high refractive index layer 120 may be used as an index of the degree of suppression of bubble generation in the high refractive index layer 120. . In this case, the diameter of the bubbles present in the high refractive index layer 120 is 1/10 or less of the thickness of the high refractive index layer 120 adjacent to the transparent electrode 130, and preferably 1/100 or less. Further, the absolute value of the bubble diameter is preferably 5 μm or less, and more preferably 0.5 μm or less.

  Here, the diameter of the bubbles present in the high refractive index layer 120 is the equivalent circle diameter when the bubbles are assumed to be circles, and the field of view when the high refractive index layer 120 is observed using an optical microscope. It is an average value of the diameters of all the bubbles contained in the inside. The thickness of the high refractive index layer 120 is as described above.

  The ratio of the bubbles in the high refractive index layer 120 adjacent to the transparent electrode 130 is 0.5% or less in terms of the ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal cross section of the high refractive index layer 120, and The ratio of the area of the vertical cross section of the bubble to the total area of the vertical cross section of the high refractive index layer 120 is 0.5% or less. Preferably, the ratio of the bubbles in the high refractive index layer 120 is 0.1% or less as a ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal cross section of the high refractive index layer 120, and the high refractive index layer 120. The ratio of the area of the vertical cross section of the bubble to the total area of the vertical cross section is 0.1% or less.

  Here, the area of the horizontal (vertical) cross section of the bubble refers to the area of the horizontal (vertical cross section) when the bubble is assumed to be a sphere.

  When the diameter of the bubbles existing in the high refractive index layer 120 and the ratio of the bubbles in the high refractive index layer 120 exceed the above range, the bubbles in the high refractive index layer 120 are separated from the surface of the high refractive index layer 120. The probability of protruding toward the transparent electrode 130 is increased, and sufficient smoothness at the interface between the high refractive index layer 120 and the transparent electrode 130 cannot be ensured.

  On the other hand, if the diameter of the bubbles present in the high refractive index layer 120 and the ratio of the bubbles in the high refractive index layer 120 are both within the above range, the smoothness of the interface between the high refractive index layer 120 and the transparent electrode 130 is improved. It is preferable because it can be further improved.

<Uneven shape of uneven surface 111>
The uneven shape of the uneven surface 111 in the present embodiment may be the random shape described above, or may be a regular shape having a uniform structural unit such as a lens shape or a pyramid shape. . FIG. 5 is an explanatory diagram showing a cross-sectional configuration of a surface light emitting device 100 ′ according to a modification of the present embodiment.

  As shown in FIG. 5, unlike the surface light emitting device 100, the surface light emitting device 100 ′ has an uneven surface 111 formed on the surface of the support substrate 110 with a uniform structure such as a lens shape or a pyramid shape instead of a random shape. Has a unit. This is because when the surface light emitting device according to the present invention is applied to a display application, the uneven surface is not an irregular structure that causes a disorder in the refraction angle, but a lens structure as shown by the uneven surface 111 in FIG. A pyramid structure is preferable. In the surface light emitting device 100 described above, since the uneven surface 111 has a random structure, light generated in each light emitting layer may be mixed and color bleeding may occur. On the other hand, the light generated in the organic thin film layer 140 can be condensed because the concavo-convex surface 111 has a uniform structure unit as in the surface light emitting device 100 ′ according to the present modification. Therefore, unlike the surface light emitting device 100, there is no color blur, and the light extraction efficiency can be increased efficiently. There are no particular restrictions on the specific shape or size of such a lens structure or pyramid structure, which is sufficiently large for the wavelength range of the generated light and capable of exhibiting a light condensing effect, which is larger than the pixel size. What is necessary is just to have a small structural unit. The pixel size (pixel size) of a general display is about 100 to 600 μm, and each size of RGB is 1/3 of the size, so it is about 30 to 200 μm. Therefore, as a specific shape of the uneven surface 111 in this modification, a lens shape (substantially hemispherical shape) or a pyramid shape (substantially four) having a structural unit with a size (uneven height) of several μm to several tens μm. Pyramid shape).

  Here, FIG. 5 shows an example in which the shape of the concavo-convex surface 111 is a lens structure. However, even in the case of a pyramid structure, only the shape of each structural unit is different. This is the same as the structure.

  Further, the film thickness of the high refractive index layer 120 is not particularly limited as long as it is sufficient to flatten the uneven surface 111 of the support substrate 110. It is preferable that the height is not less than 1.3 times the maximum height of the 110 uneven surface 111. That is, if the uneven surface 111 has a lens structure and the structural unit of the lens is a hemispherical shape with a diameter of 10 μm, the maximum height of the uneven surface 111 of the support substrate 110 is 5 μm. The preferable thickness of 120 is 6.5 μm or more. If the lens structural unit is a hemispherical shape having a diameter of 80 μm, the preferable thickness of the high refractive index layer 120 is 52 μm or more.

  The other configuration of the surface light emitting element 100 ′ is the same as that of the surface light emitting element 100 described above, and thus detailed description thereof is omitted here.

(Transparent electrode 130)
The transparent electrode 130 is a layer that functions as an anode of the surface light emitting element 100, and has a conductivity, and a transparent material is used to extract light to the outside of the surface light emitting element 100. Specifically, as a material for forming the transparent electrode 130, a transparent oxide semiconductor, particularly ITO, IZO (Indium Zinc Oxide), ZnO, In ₂ O ₃ or the like having a high work function is preferably used.

(Organic thin film layer 140)
The organic thin film layer 140 includes at least a hole transport layer and a light emitting layer. The organic thin film layer 140 may further include a hole injection layer. When the organic thin film layer 140 includes both the hole transport layer and the hole injection layer, the hole injection layer is disposed closer to the transparent electrode 130 than the hole transport layer. The light emitting layer is disposed on the side farther from the transparent electrode 130 than the hole transport layer.

  As a hole transport material for forming the hole transport layer, for example, known materials such as α-NPD (NPB), TPD, TACP, and triphenyl tetramer can be used. Moreover, as a hole injection material which forms a hole injection layer, well-known materials, such as polyaniline, a polypyrrole, copper phthalocyanine (CuPc), PEDOT: PSS, can be used, for example.

  As an organic light emitting layer, 1 type (s) or 2 or more types can be included among a red light emitting layer, a green light emitting layer, and a blue light emitting layer.

  Examples of the material for forming the red light emitting layer include tetraphenylnaphthacene (rubrene), tris (1-phenylisoquinoline) iridium (III) (Ir (piq) 3), and bis (2-benzo [b] thiophene. 2-yl-pyridine) (acetylacetonate) iridium (III) (Ir (btp) 2 (acac)), tris (dibenzoylmethane) phenanthroline europium (III) (Eu (dbm) 3 (phen)), tris [4,4′-di-tert-butyl- (2,2 ′)-bipyridine] ruthenium (III) complex (Ru (dtb-bpy) 3 * 2 (PF6)), DCM1, DCM2, Eu (thenoyltrifluoro) Acetone) 3 (Eu (TTA) 3, butyl-6- (1,1,7,7-tetramethyldurori) Le-9-enyl) -4H- pyran) (DCJTB) can be used like, Besides, polyfluorene-based polymer, a polymeric light emitting material, such as polyvinyl-based polymer can be used.

  Examples of the material for forming the green light-emitting layer include Alq3, 3- (2-benzothiazolyl) -7- (diethylamino) coumarin (Coumarin6), 2,3,6,7-tetrahydro-1,1,7, 7, -Tetramethyl-1H, 5H, 11H-10- (2-benzothiazolyl) quinolidine- [9,9a, 1gh] coumarin (C545T), N, N′-dimethyl-quinacridone (DMQA), tris (2-phenyl) Pyridine) iridium (III) (Ir (ppy) 3) can be used, and in addition, polymer light-emitting substances such as polyfluorene-based polymers and polyvinyl-based polymers can also be used.

  Examples of the material for forming the blue light emitting layer include oxadiazole dimer dye (Bis-DAPOXP), spiro compounds (Spiro-DPVBi, Spiro-6P), triarylamine compounds, bis (styryl) amine (DPVBi, DSA), 4,4′-bis (9-ethyl-3-carbazovinylene) -1,1′-biphenyl (BCzVBi), perylene, 2,5,8,11-tetra-tert-butylperylene (TPBe), 9H -Carbazole-3,3 '-(1,4-phenylene-di-2,1-ethene-diyl) bis [9-ethyl- (9C)] (BCzVB), 4,4-bis [4- (di- p-tolylamino) styryl] biphenyl (DPAVBi), 4- (di-p-tolylamino) -4 ′-[(di-p-tolylamino) styri Ru] stilbene (DPAVB), 4,4′-bis [4- (diphenylamino) styryl] biphenyl (BDAVBi), bis (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) Iridium III (FIrPic) or the like can be used, and in addition, a polymer light-emitting substance such as a polyfluorene polymer or a polyvinyl polymer can be used.

Further, the organic thin film layer 140 may include an electron transport layer and an electron injection layer in order from the side closer to the cathode 150 than the light emitting layer. As an electron transport material for forming the electron transport layer, known materials such as an oxazole derivative (PBD, OXO-7), a triazole derivative, a boron derivative, a silole derivative, and Alq3 can be used. As the electron injecting material, for _example, be used LiF, Li 2 O, CaO, CsO, known materials such as CsF _2.

(Cathode 150)
Materials for forming the cathode 150 include metals, particularly metals having a small work function, such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and compounds thereof. Can be used.

[Method for Manufacturing Surface Light Emitting Element 100]
The configuration of the surface light emitting device 100 according to the present embodiment has been described in detail above. Subsequently, the method for manufacturing the surface light emitting device 100 according to the present embodiment having the above-described configuration with reference to FIGS. 6 and 7. Will be described in detail. FIG. 6 is an explanatory diagram illustrating an example of a method for manufacturing the surface light emitting device 100 according to the present embodiment. FIG. 7 is an explanatory diagram showing an example of a method for forming the high refractive index layer 120 according to the present embodiment.

  Here, the manufacturing method of the light emitting element substrate according to the present embodiment, which is the substrate of the surface light emitting element 100, includes a surface roughening process, a coating process, a drying process, and a baking process. The surface roughening step is a step of forming the uneven surface 111 on the surface of the support substrate 110. The coating step is a step of coating a glass paste composition containing a glass frit having a refractive index equal to or higher than that of the support substrate 110, a solvent, and a resin on the surface of the support substrate 110 on which the uneven surface 111 is formed. A drying process is a process of drying the glass paste composition apply | coated to the support substrate 110, and volatilizing a solvent. The baking step is a step of baking the glass paste composition after the solvent has been volatilized under vacuum or pressure to eliminate the resin and remove the resin and melt the glass frit to form the high refractive index layer 120 on the support substrate 110. is there. Hereinafter, a method for manufacturing the surface light emitting device 100 including these steps will be described.

(Surface roughening process)
As shown in FIG. 6, on the surface of the support substrate 110 such as soda lime glass or non-alkali glass (see FIG. 6A), by a method such as a sand blast method, a wet etching method (frost method) or a press method, Random uneven surfaces 111 are formed that cause disturbance in the refraction angle of incident light when light generated in the organic thin film layer 140 passes through the transparent electrode 130 and enters the support substrate 110 (FIG. 6B). See). The degree of unevenness of the uneven surface 111 formed at this time is not particularly limited as described above, but is preferably 0.7 μm or more and 5 μm or less in terms of average surface roughness Ra.

  Further, when the uneven surface 111 having a uniform structural unit as shown in FIG. 5 is formed, the uneven surface 111 on the surface of the support substrate 110 has a uniform shape such as a lens structure or a pyramid structure. It is formed so as to be uneven with a structural unit. Such a lens structure or pyramid structure can be formed using, for example, a mold thermal transfer method, a photolithography / wet etching method, laser processing, polishing with a grindstone, or the like.

(Preparation of glass paste composition)
Next, a glass paste composition containing the glass frit as described above, a solvent, and a resin is prepared. As a method for preparing this glass paste composition, glass frit, (binder) resin, and other components may be dissolved and mixed in a solvent and then kneaded with a roll mill or the like to produce a paste in which the glass frit is dispersed. The mixing ratio of the glass frit, the solvent and the resin may be, for example, about 70 to 80% by mass of the glass frit, 10 to 20% by mass of the solvent, and about 1 to 2% by mass of the resin. Note that, as described above, in consideration of the melting point of the support substrate 110, it is preferable to carry out a drying step and a baking step described later at a temperature of 500 ° C. or lower. The following is preferable.

(Coating process)
Next, as shown in FIG. 7, the prepared glass paste composition is coated (applied) on the surface of the uneven surface 111 of the support substrate 110 (see FIG. 7A). The method for applying the glass paste composition is not particularly limited, and for example, a known method such as bar coating, doctor blade, slit coating, or die coating can be used.

(Drying process)
Next, the support substrate 110 with the glass paste composition applied to the uneven surface 111 is transferred to a hot air dryer or the like to remove the solvent (see FIG. 7B). As described above, the drying temperature at this time is preferably 500 ° C. or lower so that the support substrate 110 does not melt. More preferably, it is 100 degreeC or more and 150 degrees C or less.

(Baking process)
After the drying step, the support substrate 110 from which the solvent has been removed is transferred to a baking furnace, and the binder resin is removed by burning at a temperature not lower than the glass transition temperature Tg and not higher than the softening temperature Ts of the glass frit. Is melted (see FIG. 7C). Furthermore, the high refractive index layer 120 is formed on the surface of the support substrate 110 by baking at a temperature not lower than the softening temperature Ts of the glass frit (preferably not higher than 500 ° C.) in a baking furnace (FIG. 7 ( d) and FIG. 6 (c)).

<Principle of vacuum firing and pressure firing>
Here, in this embodiment, the said baking process is performed under a vacuum or pressurization. Thereby, as described above, it is possible to significantly suppress the generation of bubbles in the high refractive index layer 120 after firing. Further, by suppressing the generation of bubbles in the high refractive index layer 120, the smoothness of the interface between the high refractive index layer 120 and the transparent electrode 130 is remarkably increased, so that the production yield of the surface light emitting device 100 is improved. In addition, the lifetime and reliability of the surface light emitting device 100 can be improved.

  Here, the principle which can suppress generation | occurrence | production of a bubble by vacuum baking and pressure baking is demonstrated. In the first place, the bubbles in the high refractive index layer 120 exist for the following reason. That is, air is mixed into the glass paste composition from the atmosphere, and air is present around the glass frit. The air remains even after firing, whereby bubbles are generated in the high refractive index layer 120. Thus, after baking the glass paste composition to form the high refractive index layer 120, it is extremely difficult to remove the bubbles generated in the layer. Therefore, as a result of the study by the present inventors, it is sufficient that air does not exist around the glass frit at the time when the glass frit is melted in the firing process. For this purpose, the firing process is performed under vacuum or under pressure. It was found that it should be. In order to prevent air from being present around the glass frit when the glass frit is melted, it is important that the glass frit is in a vacuum or a pressurized state before the glass frit is melted.

<Vacuum firing>
In the case of vacuum firing, since the surroundings of the glass frit at the time of firing are in a vacuum atmosphere, naturally there is almost no air around the glass frit. Therefore, even if the glass paste composition is fired in this state, almost no bubbles are generated in the fired high refractive index layer 120. In order to effectively suppress the generation of bubbles, it is preferable that the glass paste composition is fired under a vacuum of 0.3 Pa or less in the firing step.

<Pressure firing>
In the case of pressure firing, since the glass paste composition is compressed and the glass frit is aggregated during firing, there is almost no air around the glass frit. Therefore, even if the glass paste composition is fired in this state, almost no bubbles are generated in the fired high refractive index layer 120. In order to effectively suppress the generation of bubbles, it is preferable that the glass paste composition is fired under a pressure of 110 kPa or more in the firing step.

  As described above, the high refractive index layer 120 is obtained by coating (coating) the paste composition containing the glass frit described above, followed by drying and baking. If necessary, this operation is repeated a plurality of times. Repeatedly, a desired thickness can be obtained. In particular, when the necessary thickness of the high refractive index layer 120 exceeds 40 to 50 μm, it is preferable to repeat the coating and baking a plurality of times. As described above, in order to improve the light extraction efficiency, it is necessary to increase the maximum height of the unevenness of the support substrate 110. Therefore, in order to flatten such a large unevenness, the high refractive index layer 120 is used. It is necessary to increase the thickness. Therefore, when such large irregularities are formed, the undulations and irregularities on the surface of the support substrate 110 can be made smoother by applying and baking the glass paste composition a plurality of times.

(Formation of transparent electrode 130, organic thin film layer 140, and cathode 150)
Next, ITO, IZO, ZnO, In ₂ O ₃ or the like is formed on the support substrate 110 whose surface is planarized by the high refractive index layer 120 by using a method such as spin coating or sputtering, so that the transparent electrode 130 is formed. Further, after forming an organic thin film layer 140 including a hole transport layer and a light emitting layer by vapor-depositing a hole transport material or a light emitting material on the transparent electrode 130, Ag, Mg, Al is formed on the organic thin film layer 140. The surface light emitting device 100 including the organic thin film layer 140 can be manufactured by forming a cathode 150 by vapor-depositing a metal such as (see FIG. 6D). In addition, as a formation method of the organic thin film layer 140 or the cathode 150, vacuum deposition, a casting method (spin casting method, dipping method, etc.), an inkjet method, a printing method (letterpress printing, gravure printing, offset printing, screen printing, etc.), etc. These known methods can be used.

[Use of the surface light emitting device 100]
The light-emitting element substrate used for the surface light-emitting element 100 of the present embodiment has irregularities (surface roughness) that are equal to or greater than the wavelength order, and thereby scatters light incident on the element, and efficiently converts light of all wavelengths. It can be taken out well. Therefore, the surface light emitting device 100 can be suitably used as a white surface light emitting device or the like, and can be applied to a lighting fixture or a backlight for a display device that requires high efficiency.

[Second Embodiment]
[Configuration of Surface Light Emitting Element 200]
Next, the configuration of the surface light emitting device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory diagram showing a cross-sectional configuration of a surface light emitting device 200 according to the second embodiment of the present invention.

  As shown in FIG. 8, the surface light emitting device 200 according to the second embodiment of the present invention includes a support substrate 210, a high refractive index layer 220, a transparent electrode (transparent conductive film) 230, an organic thin film layer 240, The cathode 250 is mainly provided. Note that the light emitting element substrate according to the present embodiment includes a support substrate 210 and a high refractive index layer 220.

  In the surface light emitting device 200, an uneven surface 211 is formed on the surface of the support substrate 210, and the uneven surface 211 has a structure in which the surface (the surface in contact with the transparent electrode 230) is flattened by the high refractive index layer 220. doing. Further, the high refractive index layer 220 of the surface light emitting element 200 includes a light scattering layer 221 having a light scattering portion that scatters light incident from the transparent electrode 230 side adjacent to the support substrate 210, and a flat surface adjacent to the transparent electrode 230. It consists of two layers of the planarization layer 223 which has the surface 223a. As described above, the high refractive index layer 220 according to the present embodiment is disposed at the interface between the light scattering layer 221 focusing on the function of scattering light incident from the transparent electrode 230 side and the high refractive index layer 220 and the transparent electrode 230. The functions of the high refractive index layer 220 are separated into two layers, the planarization layer 223 that emphasizes the function of improving the yield by giving high smoothness, and each function can be realized to a higher degree. .

  Here, regarding the support substrate 210, the transparent electrode 230, the organic thin film layer 240, the cathode 250, and the uneven surface 211 of the uneven surface 211 according to the present embodiment, the support substrate 110 and the transparent electrode 130 according to the first embodiment described above. The organic thin film layer 140, the cathode 150, and the concave and convex surfaces 111 are similar in shape to the concave and convex surfaces, and thus detailed description thereof is omitted. Hereinafter, the configuration of the high refractive index layer 220 will be described in detail.

(High refractive index layer 220)
As described above, the high refractive index layer 220 has a two-layer structure of the light scattering layer 221 and the planarization layer 223. The high refractive index layer 220 according to the present embodiment is an intermediate layer (not shown) between the light scattering layer 221 and the planarization layer 223 as long as the functions of the light scattering layer 221 and the planarization layer 223 are not impaired. ) May be included.

<Light scattering layer 221>
The light scattering layer 221 is formed on the uneven surface 211 of the support substrate 210, and has a function of scattering light incident from the transparent electrode 230 side by the uneven shape of the uneven surface 211. This scattering function is the same as the scattering function in the high refractive index layer 120 of the first embodiment. The light scattering layer 221 can be formed using the glass paste composition described above, but the refractive index of the glass frit in this case may be equal to or higher than the refractive index of the support substrate 210. Specifically, It is preferable that it is 1.6 or more and 2.0 or less.

  Further, the light scattering layer 221 does not need to positively remove bubbles and the like. This is because a planarization layer 223 is provided between the light scattering layer 221 and the transparent electrode 230 to enhance the smoothness of the interface between the high refractive index layer 220 and the transparent electrode 230. Therefore, it is not necessary to perform the baking of the glass paste composition when forming the light scattering layer 221 particularly under vacuum or pressure.

<Planarization layer 223>
The planarization layer 223 has a flat surface 223a at the interface with the transparent electrode 230, and has a function of improving the manufacturing yield of the surface light emitting device 200 and improving the life and reliability of the surface light emitting device 200. Therefore, the planarization layer 223 needs to positively remove bubbles in the layer, and for this reason, the baking of the glass paste composition when forming the planarization layer 223 needs to be performed under vacuum or under pressure. There is.

  In addition, the refractive index of the glass frit in the glass paste composition for forming the planarizing layer 223 needs to be equal to or higher than the refractive index of the support substrate 210. If the refractive indexes of the light scattering layer 221 and the planarizing layer 223 are approximately the same as those of the support substrate 210, the reflection at the interface with the transparent electrode 230 is the same as when the uneven surface 211 and the high refractive index layer 220 are not provided. Therefore, improvement in light extraction efficiency cannot be desired. Furthermore, the refractive index of the glass frit for forming the planarizing layer 223 is preferably equal to or higher than the refractive index of the transparent electrode 230. Specifically, in the surface light emitting device 200 according to this embodiment, the planarization layer 223 preferably has a refractive index of about 1.7 to 2.5. Alternatively, the relationship between the refractive index nd1 of the glass frit for forming the planarization layer 223 (d represents 589 nm which is a D line of sodium) and the refractive index nd2 of the transparent electrode 230 (for example, ITO) is It is preferable that nd1 / nd2 ≧ 0.9. The reason is as described above with reference to FIG.

<Smoothness of the interface between the planarizing layer 223 and the transparent electrode 230>
When producing the planarization layer 223 having the above-described configuration, it is noticeable that bubbles are generated in the planarization layer 223 after firing by firing the glass paste composition described above under vacuum or pressure. Can be suppressed. More specifically, the number of bubbles existing in the planarization layer 223 can be reduced and the size of the bubbles can be reduced by the above-described baking under vacuum or pressure. In this way, by suppressing the generation of bubbles in the planarization layer 223, the smoothness of the surface adjacent to the transparent electrode 230 of the planarization layer 223, that is, the interface between the planarization layer 223 and the transparent electrode 230 is remarkably improved. Can be improved. Since the smoothness of the interface between the planarizing layer 223 and the transparent electrode 230 is improved, the manufacturing yield of the surface light emitting element 200 is improved and current leakage is suppressed. Lifetime and reliability are also improved. The smoothness required for the interface between the planarization layer 223 and the transparent electrode 230 in this embodiment is Ra of the surface adjacent to the transparent electrode 230 of the planarization layer 223, and is 30 nm or less, preferably 1 nm. There are:

  Here, in this embodiment, a haze value (Haze) is used as one index of the degree of suppression of bubble generation in the planarization layer 223, as in the first embodiment. That is, the haze value of the planarizing layer 223 adjacent to the transparent electrode 230 in the light emitting element substrate for the surface light emitting element 200 according to the present embodiment is 5% or less. When the haze value of the planarization layer 223 exceeds 5%, the number of bubbles in the planarization layer 223 increases and the size of the bubbles increases, so that the interface between the planarization layer 223 and the transparent electrode 230 is sufficient. Smoothness cannot be secured.

  In addition, although the haze value of the planarization layer 223 in this embodiment can be measured with a commercially available transmittance meter with an integrating sphere or a haze meter, as the haze value of the planarization layer 223, The haze value of the planarization layer 223 alone is used instead of the value of the entire light emitting element substrate.

  In the present embodiment, a more direct index using the diameter of the bubble and the ratio of the bubbles in the planarization layer 223 may be used as an index of the degree of suppression of the bubble generation in the planarization layer 223. In this case, the diameter of the bubbles present in the planarizing layer 223 is 1/10 or less of the thickness of the planarizing layer 223 adjacent to the transparent electrode 230, and preferably 1/100 or less. Further, the absolute value of the bubble diameter is preferably 5 μm or less, and more preferably 0.5 μm or less.

  Here, the diameter of the bubble present in the planarization layer 223 is a circle-equivalent diameter when the bubble is assumed to be a circle, and within the visual field when the planarization layer 223 is observed using an optical microscope. It is an average value of the diameters of all bubbles included.

  Further, the ratio of the bubbles in the planarization layer 223 adjacent to the transparent electrode 230 is 0.5% or less in terms of the ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal section of the planarization layer 223 and flat. The ratio of the area of the vertical cross section of the bubbles to the total area of the vertical cross section of the chemical layer 223 is 0.5% or less. Preferably, the ratio of the bubbles in the planarization layer 223 is 0.1% or less as a ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal section of the planarization layer 223, and the vertical cross section of the planarization layer 223. The ratio of the area of the vertical cross section of the bubble to the total area is 0.1% or less.

  Here, the area of the horizontal (vertical) cross section of the bubble refers to the area of the horizontal (vertical cross section) when the bubble is assumed to be a sphere.

  When the diameter of the bubbles existing in the planarization layer 223 and the ratio of the bubbles in the planarization layer 223 exceed the above range, the bubbles in the planarization layer 223 are moved from the surface of the planarization layer 223 to the transparent electrode 230 side. And the smoothness of the interface between the planarization layer 223 and the transparent electrode 230 cannot be ensured.

  On the other hand, when both the diameter of the bubbles present in the planarization layer 223 and the ratio of the bubbles in the planarization layer 223 are within the above range, the smoothness of the interface between the planarization layer 223 and the transparent electrode 230 is further improved. This is preferable.

  Since the other configuration relating to the high refractive index layer 220 is the same as that of the high refractive index layer 120 according to the first embodiment described above, detailed description thereof is omitted.

[Method for Manufacturing Surface Light Emitting Element 200]
The configuration of the surface light emitting device 200 according to the present embodiment has been described in detail above. Subsequently, the method for manufacturing the surface light emitting device 200 according to the present embodiment having the above-described configuration will be described in detail with reference to FIG. explain. FIG. 9 is an explanatory diagram showing an example of a method for manufacturing the surface light emitting device 200 according to the present embodiment.

  Here, the manufacturing method of the light emitting element substrate according to the present embodiment, which is the substrate of the surface light emitting element 200, includes a surface roughening process, a coating process, a drying process, and a baking process. The surface roughening step is a step of forming the uneven surface 211 on the surface of the support substrate 210. The coating step is a step of coating a glass paste composition containing a glass frit having a refractive index equal to or higher than that of the support substrate 210, a solvent, and a resin on the surface of the support substrate 210 on which the uneven surface 211 is formed. A drying process is a process of drying the glass paste composition apply | coated to the support substrate 210, and volatilizing a solvent. The baking step is a step of baking the glass paste composition after the solvent has been volatilized under vacuum or pressure to eliminate and remove the resin and melt the glass frit to form the high refractive index layer 220 on the support substrate 210. is there. Hereinafter, a method for manufacturing the surface light emitting device 200 including these steps will be described.

(Surface roughening process)
As shown in FIG. 9, on the surface of a support substrate 210 such as soda lime glass, non-alkali glass, high strain point glass (PD200) (see FIG. 9A), sand blast method, wet etching method (frost method) Alternatively, a random uneven surface 211 that causes a disturbance in the refraction angle of incident light when the light generated in the organic thin film layer 240 passes through the transparent electrode 230 and enters the support substrate 210 by a method such as a press method. It forms (refer FIG.9 (b)). More specifically, the surface roughening step can be performed by the same method as in the first embodiment.

(Preparation of glass paste composition)
Next, a glass paste composition containing the glass frit as described above, a solvent, and a resin is prepared. The method for preparing this glass paste composition is the same as in the first embodiment described above.

  Here, in this embodiment, since the high refractive index layer 220 has a two-layer structure of the light scattering layer 221 and the smoothing layer 223, the glass paste composition is also used for forming the light scattering layer 221. And those for forming the smoothing layer 223 are prepared. At this time, the same glass paste composition may be used for the light scattering layer 221 and the flattening layer 223, or different ones may be used. Moreover, as a glass frit contained in at least the glass paste composition for the planarizing layer 223, it is preferable to use a glass frit having a refractive index equal to or higher than that of the transparent electrode 230.

(Coating process, drying process, firing process)
Next, the glass paste composition prepared for the light scattering layer 221 is coated (applied) on the surface of the uneven surface 211 of the support substrate 210. The method for applying the glass paste composition is not particularly limited, and for example, a known method such as bar coating, doctor blade, slit coating, or die coating can be used.

  Next, the support substrate 210 having the uneven surface 211 coated with the glass paste composition is transferred to a hot air dryer or the like to remove the solvent. As described above, the drying temperature at this time is preferably a temperature of 500 ° C. or lower so that the support substrate 210 does not melt. More preferably, it is 100 degreeC or more and 150 degrees C or less.

  After the drying step, the support substrate 210 from which the solvent has been removed is transferred to a baking furnace, and the binder resin is removed by burning at a temperature not lower than the glass transition temperature Tg and not higher than the softening temperature Ts of the glass frit. To melt. Further, the light scattering layer 221 is formed on the surface of the support substrate 210 by baking at a temperature of the glass frit softening temperature Ts or higher (preferably 500 ° C. or lower) in a baking furnace (FIG. 9C). )).

  Further, the flattening layer 223 is formed on the surface of the light scattering layer 221 by repeating the same coating process, drying process and baking process as the formation of the light scattering layer 221 (see FIG. 9D). The firing step when forming the planarizing layer 223 is performed under vacuum or under pressure using the same method as the firing step when forming the high refractive index layer 120 according to the first embodiment. Thereby, it is possible to remarkably suppress the generation of bubbles in the planarization layer 223 after firing. And, by suppressing the generation of bubbles in the planarization layer 223, the smoothness of the interface between the planarization layer 223 and the transparent electrode 230 is remarkably increased, so that the production yield of the surface light emitting device 200 is improved, and The lifetime and reliability of the surface light emitting device 200 can be improved.

(Formation of transparent electrode 230, organic thin film layer 240, and cathode 250)
Next, ITO, IZO, ZnO, In ₂ O ₃ or the like is formed on the support substrate 210 whose surface is planarized by the high refractive index layer 220 (particularly, the planarization layer 223) by using a method such as spin coating or sputtering. To form a transparent electrode 230. Further, after forming an organic thin film layer 240 including a hole transport layer and a light emitting layer by vapor-depositing a hole transport material or a light emitting material on the transparent electrode 230, Ag, Mg, Al is formed on the organic thin film layer 240. The surface light emitting device 200 including the organic thin film layer 240 can be manufactured by forming a cathode 250 by vapor-depositing a metal such as (see FIG. 9E). In addition, as a formation method of the organic thin film layer 240 and the cathode 250, the method similar to 1st Embodiment can be used.

[Third Embodiment]
[Configuration of Surface Light Emitting Element 300]
Next, the configuration of the surface light emitting device according to the third embodiment of the present invention will be described with reference to FIG. FIG. 10 is an explanatory diagram showing a cross-sectional configuration of a surface light emitting device 300 according to the third embodiment of the present invention.

  As shown in FIG. 10, a surface light emitting device 300 according to the third embodiment of the present invention includes a support substrate 310, a high refractive index layer 320, a transparent electrode (transparent conductive film) 330, an organic thin film layer 340, The cathode 350 is mainly provided. Note that the light emitting element substrate according to the present embodiment includes a support substrate 310 and a high refractive index layer 320.

  In the surface light emitting device 300, an uneven surface 311 is formed on the surface of the support substrate 310, and the uneven surface 311 has a structure in which the surface (the surface in contact with the transparent electrode 330) is flattened by the high refractive index layer 320. doing. In addition, the high refractive index layer 320 of the surface light emitting device 300 includes a light scattering layer 321 having a light scattering portion that scatters light incident from the transparent electrode 330 side adjacent to the support substrate 310, and a flat surface adjacent to the transparent electrode 330. It consists of two layers of the planarization layer 323 which has the surface 323a. As described above, the high refractive index layer 320 according to the present embodiment is disposed at the interface between the light scattering layer 321 that emphasizes the function of scattering light incident from the transparent electrode 330 side, and the high refractive index layer 320 and the transparent electrode 330. The functions of the high refractive index layer 320 are separated into two layers, a planarization layer 323 that emphasizes the function of improving the yield by giving high smoothness, and each function can be realized to a higher degree. .

  Furthermore, in the surface light emitting device 300 according to the present embodiment, the light scattering layer 321 is made of a glass material (glass) in order to more effectively scatter the light incident on the light scattering layer 321 and further improve the light extraction efficiency. In addition to the frit, a scattering material 325 having a refractive index different from that of the glass material is contained.

  Here, regarding the support substrate 310, the transparent electrode 330, the organic thin film layer 340, the cathode 350, and the uneven shape of the uneven surface 311 according to the present embodiment, the support substrate 110 and the transparent electrode 130 according to the first embodiment described above. The organic thin film layer 140, the cathode 150, and the concave and convex surfaces 111 are similar in shape to the concave and convex surfaces, and thus detailed description thereof is omitted. Hereinafter, the configuration of the high refractive index layer 320 will be described in detail.

(High refractive index layer 320)
As described above, the high refractive index layer 320 has a two-layer structure of the light scattering layer 321 and the flattening layer 323, and the light scattering layer 321 has a refractive index different from that of the glass material in addition to the glass material. Further included is a scattering material 325 having a refractive index. That is, the high refractive index layer 320 according to the present embodiment is different from the high refractive index layer 220 according to the second embodiment only in that the scattering material 325 is further included. The high refractive index layer 320 according to this embodiment is an intermediate layer (not shown) between the light scattering layer 321 and the planarization layer 323 as long as the functions of the light scattering layer 321 and the planarization layer 323 are not impaired. ) May be included.

<Light scattering layer 321>
The light scattering layer 321 is formed on the uneven surface 311 of the support substrate 310 and has a function of scattering light incident from the transparent electrode 330 side by the uneven shape of the uneven surface 311. This scattering function is the same as the scattering function in the high refractive index layer 120 of the first embodiment. The light scattering layer 321 can be formed using the glass paste composition described above, but the refractive index of the glass frit in this case may be equal to or higher than the refractive index of the support substrate 310. Specifically, It is preferable that it is 1.6 or more and 2.0 or less.

  Further, the light scattering layer 321 does not need to positively remove bubbles and the like. This is because a planarization layer 323 is provided between the light scattering layer 321 and the transparent electrode 330 to improve the smoothness of the interface between the high refractive index layer 320 and the transparent electrode 330. Therefore, the baking of the glass paste composition when forming the light scattering layer 321 is not particularly required to be performed under vacuum or under pressure.

Further, the light scattering layer 321 contains a scattering material 325. The scattering material 325 is not particularly limited as long as it has a refractive index different from that of the glass frit used for forming the light scattering layer 321. For example, TiO ₂ , SiO ₂ , Al ₂ O ₃ , ZnO, ZnS _{, PbTiO 2, ZnTe, Pb 3} O 3, PbCrO 4, ZnCrO 4, Cr 2 O 3, ZrO 2, WO 3, SrTiO 3, Y 2 O 3, Eu 2 O 3, La 2 O 3, ZrSiO 4 , etc. Inorganic compounds can be used. These scattering materials 325 may be used alone or in combination of two or more.

  In addition, the scattering material 325 is preferably included in the glass paste composition for forming the light scattering layer 321 in an amount of 0.1% by volume to 74% by volume. More preferably, it is 1 volume% or more and 30 volume% or less. If the content of the scattering material 325 is less than 0.1% by volume, the effect of increasing light scattering is not sufficient, and if the content of the scattering material 325 exceeds 74% by volume (close-packed state), firing is performed. Since it becomes difficult to hold | maintain the shape of a highly refractive thin film later, it is unpreferable.

<Planarization layer 323>
The planarization layer 323 has a flat surface 323a at the interface with the transparent electrode 330, and has a function of improving the manufacturing yield of the surface light emitting device 300 and improving the life and reliability of the surface light emitting device 300. Therefore, the planarization layer 323 needs to positively remove bubbles in the layer, and for this reason, the baking of the glass paste composition when forming the planarization layer 323 needs to be performed under vacuum or under pressure. There is.

  The other configuration of the planarization layer 323 is the same as that of the planarization layer 223 according to the second embodiment described above. Further, since the other configuration relating to the high refractive index layer 320 is the same as that of the high refractive index layer 120 according to the first embodiment described above, detailed description thereof is omitted.

[Method for Manufacturing Surface Light Emitting Element 300]
The configuration of the surface light emitting device 300 according to the present embodiment has been described in detail above. Subsequently, with reference to FIG. 11, the method for manufacturing the surface light emitting device 300 according to the present embodiment having the above-described configuration will be described in detail. explain. FIG. 11 is an explanatory view showing an example of a method for manufacturing the surface light emitting device 300 according to the present embodiment.

  Here, the manufacturing method of the light emitting element substrate according to the present embodiment, which is the substrate of the surface light emitting element 300, includes a surface roughening process, a coating process, a drying process, and a baking process. The surface roughening step is a step of forming the uneven surface 311 on the surface of the support substrate 310. The coating step is a step of coating a glass paste composition containing a glass frit having a refractive index equal to or higher than that of the support substrate 310, a solvent, and a resin on the surface of the support substrate 310 on which the uneven surface 311 is formed. A drying process is a process of drying the glass paste composition apply | coated to the support substrate 310, and volatilizing a solvent. The baking step is a step of baking the glass paste composition after the solvent has been volatilized under vacuum or pressure to eliminate the resin and remove the resin and melt the glass frit to form the high refractive index layer 320 on the support substrate 310. is there. Hereinafter, a method for manufacturing the surface light emitting device 300 including these steps will be described.

(Surface roughening process)
As shown in FIG. 11, on the surface of a support substrate 310 such as soda lime glass or non-alkali glass (see FIG. 11A), by a method such as a sand blast method, a wet etching method (frost method) or a press method, Random uneven surfaces 311 are formed that cause disturbance in the refraction angle of incident light when the light generated in the organic thin film layer 340 passes through the transparent electrode 330 and enters the support substrate 310 (FIG. 11B). See). More specifically, the surface roughening step can be performed by the same method as in the first embodiment.

(Preparation of glass paste composition)
Next, a glass paste composition containing the glass frit as described above, a solvent, and a resin is prepared. The method for preparing this glass paste composition is basically the same as in the second embodiment described above.

  However, since the high refractive index layer 320 has a two-layer structure of the light scattering layer 321 and the smoothing layer 323, the glass paste composition is also used for forming the light scattering layer 321 and the smoothing layer. In this case, the glass paste composition for forming the light scattering layer 321 needs to contain the scattering material 325 described above. The kind and content of the scattering material 325 that can be used at this time are as described above. Therefore, in the present embodiment, unlike the second embodiment, the same glass paste composition for the light scattering layer 321 and the glass paste composition for the planarization layer 323 cannot be used. Moreover, as a glass frit contained in at least the glass paste composition for the planarizing layer 323, it is preferable to use a glass frit having a refractive index equal to or higher than that of the transparent electrode 330.

(Coating process, drying process, firing process)
Next, a glass paste composition containing the scattering material 325 prepared for the light scattering layer 321 is coated (applied) on the surface of the uneven surface 311 of the support substrate 310. The method for applying the glass paste composition is not particularly limited, and for example, a known method such as bar coating, doctor blade, slit coating, or die coating can be used.

  Next, the support substrate 310 having the uneven surface 311 coated with the glass paste composition is transferred to a hot air dryer or the like to remove the solvent. As described above, the drying temperature at this time is preferably 500 ° C. or lower so that the support substrate 310 does not melt. More preferably, it is 100 degreeC or more and 150 degrees C or less.

  After the drying step, the support substrate 310 from which the solvent has been removed is transferred to a firing furnace, and the binder resin is removed by burning at a temperature not lower than the glass transition temperature Tg and not higher than the softening temperature Ts of the glass frit. To melt. Further, the light scattering layer 321 is formed on the surface of the support substrate 310 by baking at a temperature not lower than the softening temperature Ts of the glass frit (preferably not higher than 500 ° C.) in a baking furnace (FIG. 11 (c). )).

  Furthermore, the same coating process, drying process, and baking process as the formation of the light scattering layer 321 are repeated to form a planarization layer 323 on the surface of the light scattering layer 321 (see FIG. 11D). The firing step when forming the planarizing layer 323 is performed under vacuum or under pressure using the same method as the firing step when forming the high refractive index layer 120 according to the first embodiment. Thereby, it is possible to remarkably suppress the generation of bubbles in the planarization layer 323 after firing. And, by suppressing the generation of bubbles in the planarization layer 323, the smoothness of the interface between the planarization layer 323 and the transparent electrode 330 is remarkably increased, so that the production yield of the surface light emitting device 300 is improved, and In addition, the life and reliability of the surface light emitting device 300 can be improved.

(Formation of transparent electrode 330, organic thin film layer 340, and cathode 350)
Next, ITO, IZO, ZnO, In ₂ O ₃ or the like is formed on the support substrate 310 whose surface is planarized by the high refractive index layer 320 (particularly, the planarization layer 323) by using a method such as spin coating or sputtering. To form a transparent electrode 330. Further, after an organic thin film layer 340 including a hole transport layer and a light emitting layer is formed on the transparent electrode 330 by vapor deposition of a hole transport material, a light emitting material, etc., Ag, Mg, Al is formed on the organic thin film layer 340. The cathode 350 is formed by vapor-depositing a metal such as the surface light emitting device 300 including the organic thin film layer 340 (see FIG. 11E). As a method for forming the organic thin film layer 340 and the cathode 350, the same method as in the first embodiment can be used.

[Fourth Embodiment]
[Configuration of Surface Light Emitting Element 400]
Next, the configuration of a surface light emitting device according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 12 is an explanatory diagram showing a cross-sectional configuration of a surface light emitting device 400 according to the fourth embodiment of the present invention.

  As shown in FIG. 12, a surface light emitting device 400 according to the fourth embodiment of the present invention includes a support substrate 410, a high refractive index layer 420, a transparent electrode (transparent conductive film) 430, an organic thin film layer 440, The cathode 450 is mainly provided. The light emitting element substrate according to this embodiment includes a support substrate 410 and a high refractive index layer 420.

  In the surface light emitting device 400, an uneven surface is not formed on the surface of the support substrate 410, and the high refractive index layer 420 is formed on a relatively flat surface. Further, the high refractive index layer 420 of the surface light emitting device 400 includes a light scattering layer 421 having a light scattering portion that scatters light incident from the transparent electrode 430 side adjacent to the support substrate 410, and a flat surface adjacent to the transparent electrode 430. It consists of two layers of the planarization layer 423 which has the surface 423a. As described above, the high refractive index layer 420 according to the present embodiment is disposed at the interface between the light scattering layer 421 that emphasizes the function of scattering light incident from the transparent electrode 430 side, and the high refractive index layer 420 and the transparent electrode 430. The functions of the high-refractive index layer 420 are separated into two layers, a planarization layer 423 that emphasizes the function of improving the yield by giving high smoothness, and each function can be realized to a higher degree. .

  In the surface light emitting device 400 according to the present embodiment, the light scattering layer 421 is different from the glass material in addition to the glass material (glass frit) in order to have a function of scattering the light incident on the light scattering layer 421. Contains a scattering material 425 having a refractive index.

  Here, since the transparent electrode 430, the organic thin film layer 440, and the cathode 450 according to the present embodiment are the same as the transparent electrode 130, the organic thin film layer 140, and the cathode 150 according to the first embodiment described above, these Detailed description is omitted. Hereinafter, the configuration of the support substrate 410 and the high refractive index layer 420 will be described in detail.

(Supporting substrate 410)
Unlike the cases of the first to third embodiments described above, the support substrate 410 does not have an uneven surface. Therefore, the light scattering function in the high refractive index layer 420 is not realized by the uneven surface of the support substrate, but the scattering material 425 having a refractive index different from that of the glass frit for forming the layer in the light scattering layer 421. It is realized by containing. The configuration of the support substrate 410 is the same as that of the support substrate 110 according to the first embodiment except that the surface does not have an uneven surface.

(High refractive index layer 420)
As described above, the high refractive index layer 420 has a two-layer structure of the light scattering layer 421 and the planarization layer 423, and the light scattering layer 421 has a refraction different from that of the glass material in addition to the glass material. Further included is a scattering material 425 having a refractive index. That is, the high refractive index layer 420 according to the present embodiment has the same configuration as the high refractive index layer 320 according to the third embodiment, although the surface shape of the support substrate on which the layer is formed is different. Yes. Note that the high refractive index layer 420 according to this embodiment is an intermediate layer (not shown) between the light scattering layer 421 and the planarization layer 423 unless the functions of the light scattering layer 421 and the planarization layer 423 are hindered. ) May be included.

<Light scattering layer 421>
The light scattering layer 421 is formed on the surface of the support substrate 410 and contains the scattering material 425. Since the scattering material 425 is dispersed and arranged in the light scattering layer 421, it has a function of scattering light incident from the transparent electrode 430 side. The light scattering layer 421 can be formed using the glass paste composition described above, and the refractive index of the glass frit in this case may be equal to or higher than the refractive index of the support substrate 410. Specifically, It is preferable that it is 1.4 or more and 2.0 or less.

  Further, the light scattering layer 421 does not need to positively remove bubbles and the like. This is because a flattening layer 423 is provided between the light scattering layer 421 and the transparent electrode 430 to improve the smoothness of the interface between the high refractive index layer 420 and the transparent electrode 430. Therefore, the baking of the glass paste composition when forming the light scattering layer 421 does not need to be performed particularly under vacuum or pressure.

  Further, the light scattering layer 421 contains a scattering material 425. The kind and content of the scattering material 425 are the same as those in the third embodiment.

<Planarization layer 423>
The planarization layer 423 has a flat surface 423 a at the interface with the transparent electrode 430, and has a function of improving the manufacturing yield of the surface light emitting device 400 and improving the life and reliability of the surface light emitting device 400. Accordingly, the planarization layer 423 needs to positively remove bubbles in the layer, and for this reason, the baking of the glass paste composition when forming the planarization layer 423 needs to be performed under vacuum or under pressure. There is.

  The other configuration of the planarization layer 423 is the same as that of the planarization layer 223 according to the second embodiment described above. Further, since the other configuration relating to the high refractive index layer 420 is the same as that of the high refractive index layer 120 according to the first embodiment described above, detailed description thereof is omitted.

[Method for Manufacturing Surface Light Emitting Element 400]
The configuration of the surface light emitting device 400 according to the present embodiment has been described in detail above. Subsequently, with reference to FIG. 13, the method for manufacturing the surface light emitting device 400 according to the present embodiment having the above-described configuration will be described in detail. explain. FIG. 13 is an explanatory diagram illustrating an example of a method for manufacturing the surface light emitting device 400 according to the present embodiment.

  Here, the manufacturing method of the light emitting element substrate according to the present embodiment, which is the substrate of the surface light emitting element 400, includes a coating process, a drying process, and a baking process. Unlike the above-described first to third embodiments, the surface roughening step is not included. The coating process is a process of coating a glass paste composition containing a glass frit having a refractive index equal to or higher than that of the support substrate 410, a solvent, and a resin on the surface of the relatively flat support substrate 410. A drying process is a process of drying the glass paste composition apply | coated to the support substrate 410, and volatilizing a solvent. The baking step is a step of baking the glass paste composition after the solvent has been volatilized under vacuum or pressure to eliminate the resin and remove the resin and melt the glass frit to form the high refractive index layer 420 on the support substrate 410. is there. Hereinafter, a method for manufacturing the surface light emitting device 400 including these steps will be described.

(Preparation of glass paste composition)
First, a glass paste composition containing the glass frit as described above, a solvent, and a resin is prepared. The method for preparing this glass paste composition is exactly the same as in the third embodiment described above.

(Coating process, drying process, firing process)
Next, a glass paste composition containing the scattering material 425 prepared for the light scattering layer 421 is coated (applied) on the surface of the support substrate 410 (see FIG. 13A). The method for applying the glass paste composition is not particularly limited, and for example, a known method such as bar coating, doctor blade, slit coating, or die coating can be used.

  Next, the support substrate 410 having the glass paste composition applied to the surface is transferred to a hot air dryer or the like to remove the solvent. As described above, the drying temperature at this time is preferably 500 ° C. or lower so that the support substrate 410 does not melt. More preferably, it is 100 degreeC or more and 150 degrees C or less.

  After the drying step, the support substrate 410 from which the solvent has been removed is transferred to a baking furnace, and the binder resin is removed by burning at a temperature not lower than the glass transition temperature Tg and not higher than the softening temperature Ts of the glass frit. To melt. Further, the light scattering layer 421 is formed on the surface of the support substrate 410 by baking at a temperature not lower than the softening temperature Ts of the glass frit (preferably not higher than 500 ° C.) in a baking furnace (FIG. 13B). )).

  Furthermore, the same coating process, drying process, and baking process as the formation of the light scattering layer 421 are repeated to form a planarization layer 423 on the surface of the light scattering layer 421 (see FIG. 13C). The firing step when forming the planarizing layer 423 is performed under vacuum or under pressure using the same method as the firing step when forming the high refractive index layer 120 according to the first embodiment. Thereby, it is possible to remarkably suppress the generation of bubbles in the planarizing layer 423 after firing. And, by suppressing the generation of bubbles in the planarization layer 423, the smoothness of the interface between the planarization layer 423 and the transparent electrode 430 is remarkably increased, so that the production yield of the surface light emitting device 400 is improved, and The life and reliability of the surface light emitting device 400 can be improved.

(Formation of transparent electrode 430, organic thin film layer 440, and cathode 450)
Next, ITO, IZO, ZnO, In ₂ O ₃ or the like is formed on the supporting substrate 410 whose surface is planarized by the high refractive index layer 420 (particularly, the planarizing layer 423) using a method such as spin coating or sputtering. To form a transparent electrode 430. Further, an organic thin film layer 440 including a hole transport layer and a light emitting layer is formed on the transparent electrode 430 by vapor deposition of a hole transport material or a light emitting material, and then Ag, Mg, Al is formed on the organic thin film layer 440. The cathode 450 is formed by vapor-depositing a metal such as the surface light-emitting element 400 including the organic thin film layer 440 (see FIG. 13D). As a method for forming the organic thin film layer 440 and the cathode 450, the same method as in the first embodiment can be used.

[Summary]
As described above, according to the surface light emitting devices 100, 200, 300, and 400 according to the first to fourth embodiments of the present invention, light that is totally reflected by Snell's law and cannot be extracted from the device. Since it can be extracted, the light extraction efficiency of a surface light emitting element such as an OLED can be greatly improved.

  In particular, in each of the above-described embodiments, an uneven structure that causes disorder in the refractive index is provided at the interface between the support substrate and the high refractive index layer, or the scattering material 425 is included in the high refractive index layer. By forming a flat surface at the interface with the transparent electrode with a material having a structure capable of scattering light and extracting the light to the front surface and having a refractive index equal to or higher than that of the transparent electrode, about 1.5-2. It was found that an improvement in light extraction efficiency of 0 times and a high yield can be obtained. In the method described in Patent Document 4, the high refractive index layer itself functions as a scattering layer by intentionally causing scattering components such as bubbles and fillers in the high refractive index glass. If bubbles or fillers are present in contact with the electrode, it is difficult to form a homogeneous transparent electrode, and it is impossible to ensure life and reliability. Patent Document 4 describes a method in which bubbles are not intentionally present on the surface, but manufacturing difficulties are expected. There is also a problem that optical light cannot be controlled due to the bubbles. This problem suggests that it cannot be applied in applications such as a display having a plurality of fine pixels.

  On the other hand, in each embodiment of the present invention, by eliminating bubbles and the like as much as possible, problems such as a decrease in yield and a decrease in lifetime and reliability, which are concerned by bubbles and the like, are solved. As a method for positively eliminating bubbles and the like that are factors that reduce the yield, lifetime, and reliability of the element, a step of firing under vacuum or pressure is employed.

  Further, in order to further flatten the interface with the transparent electrode flattened by the high refractive index layer, it is a general process for producing OLEDs, and the glass polishing process forms a transparent electrode. Preferably it is done before. In addition, when a polishing step is introduced, if there are bubbles or the like inside the high refractive index layer to be polished, the portion where the bubbles or the like exist is polished, resulting in a concave shape defect, a bright spot, dark spot It can be easily understood that problems related to reliability such as point and leak occur frequently.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

(Production of light-emitting element substrate)
First, a light emitting element substrate used as a substrate such as an OLED was manufactured. Specifically, a soda lime glass having a thickness of 0.7 mm and 50 × 50 mm is used as a support substrate, and the surface of the soda lime glass is sprayed with # 800 alumina powder under the condition of 0.5 KPa. A formed support substrate with unevenness (hereinafter referred to as “concave substrate”) was obtained. When the surface of the concavo-convex substrate was observed with a laser microscope VK9510 manufactured by Keyence, concavo-convex portions of Ra = 0.7 um were formed. When measured with a Toyo Seiki haze meter “Haze Guard II”, it was found that the uneven substrate had a transmittance of 82% and a haze value of 91%, and an uneven surface functioning as a light scattering portion was formed.

Apart from this, 150 g of Bi ₂ O ₃ —B ₂ O ₃ —ZnO glass frit (particle size distribution D50 = 1.6 μm) having a glass transition temperature Tg = 400 ° C., ₃ g of ethyl cellulose STD45 (manufactured by Dow Chemical Co.), terpineol 32 0.9 g and 14.1 g of butyl carbitol acetate were dissolved and mixed, and then kneaded with a three-roll mill to prepare a glass paste composition.

  The obtained glass paste composition was coated on the concavo-convex substrate and the concavo-convex substrate prepared above (soda lime glass substrate not subjected to sandblasting) using a doctor blade, and the solvent was removed with a hot air dryer at 120 ° C. After removal, transfer to a firing furnace, remove the binder resin by firing at 350 ° C. for 30 minutes, and then fire at 30 ° C. for 30 minutes to form a high refractive index layer, which is a transparent glass layer, on the surface of each substrate did.

  It was 30 micrometers when the film thickness of the high refractive index layer formed on the board | substrate without an unevenness | corrugation was measured with the stylus-type film thickness meter (DEKTAK) by ULVAC. It was found that a glass layer (high refractive index layer) that was colorless and transparent and had a smooth surface was formed. Ra of the substrate on which this high refractive index layer was formed was 30 nm or less.

  Further, when the high refractive index layer was formed on the substrate without unevenness, the total light transmittance of the substrate baked in the air (air baked) was 72.2%, and the haze value was 40.2% (Table 2). (1) Refer to Air).

  On the other hand, the total light transmittance of the substrate fired in vacuum (vacuum firing) when forming the high refractive index layer on the substrate without unevenness was 82.3%, and the haze value was 2.66% (Table 2). (2) See Vac.).

  Moreover, in order to further flatten the outermost surface of the vacuum-baked substrate, a substrate added with a polishing step was also produced.

  Next, 120 nm of ITO was formed on soda lime glass and the three types of glass substrates prepared above using an RF magnetron sputtering apparatus.

  Here, FIG. 14 shows an example in which the refractive index of the glass frit used in the above-produced high refractive index layer is compared with the refractive index of ITO used in the transparent electrode. As can be understood from FIG. 14, comparing the refractive index of the glass frit with the refractive index of ITO, it is shown that the refractive index of the glass frit is larger. From this result, it was suggested that it is possible to avoid a decrease in light extraction efficiency due to total reflection because the refractive index on the substrate side (high refractive index layer) is higher than that of the transparent electrode.

(Examination of firing conditions of glass paste composition)
Next, the optimum baking conditions for the glass paste composition were examined. The above-described uneven substrate was used as the support substrate, and the above-described glass paste composition was used as a light-emitting element substrate sample having a high refractive index layer formed on the support substrate. In this example, atmospheric firing (hereinafter sometimes referred to as “Air”) refers to a step of firing the glass paste composition under atmospheric pressure. Also, vacuum firing (hereinafter sometimes referred to as “Vac.”) Is a step of maintaining the state in which the inside of the firing furnace is decompressed to 0.3 Pa or less at a predetermined timing during firing of the glass paste composition. Indicates. Furthermore, pressure firing (hereinafter sometimes referred to as “Press”) is a step of maintaining a state in which the inside of the firing furnace is pressurized to 110 kPa or more at a predetermined timing during firing of the glass paste composition. Show.

  In this examination, the firing process was divided into two steps, Step A (step of eliminating the binder resin) and Step B (step of firing the glass frit), and each step was performed under the process conditions shown in Table 1. Table 1 shows temperature conditions for each step. (1) Atmospheric baking (Air), both steps are performed in the atmosphere. (2) Vacuum baking (Vac.) And (3) Pressure baking (Press ), Step A was performed in the atmosphere, and Step B was set as a vacuum condition and a pressure condition, respectively. The transmittance and haze value of the high refractive index layer formed on the support substrate by firing as described above were measured. The results are shown in Table 2.

As is clear from Table 2, it was shown that the haze value was drastically lowered by adding a step of baking under vacuum or pressure after baking of the binder resin. This is considered to be due to the fact that the bubbles existing inside the high refractive index layer are reduced (and further reduced). Further, it was confirmed that the transmittance was improved by about 10% as the haze value decreased. In Table 2, Ref. (Glass) is data on a glass substrate used as a support substrate shown for reference. Further, when the inside of the fired high refractive index layer (observation field of view 0.05 mm ² ) is observed using an optical microscope, the ratio of bubbles is 6.2 to 6.8% in the air fired sample, the vacuum fired sample It was 0.1 to 0.3%. From this result, it was shown that the ratio of bubbles was reduced to about 2 to 5% in the case of atmospheric baking in vacuum baking.

(Scattering effect due to uneven surface of support substrate)
Next, the result of examining the scattering effect by the uneven surface formed on the surface of the support substrate is shown below. The glass paste composition obtained as described above was coated on the substrate with unevenness and the substrate without unevenness, respectively, using a doctor blade, and after removing the solvent with a 120 ° C. hot air dryer, Each substrate is transferred to a baking furnace, baked at 350 ° C. for 20 minutes to remove the binder resin, and further baked at 500 ° C. for 30 minutes to form a high refractive index layer, which is a transparent glass layer, on the surface of each substrate. Formed.

  Furthermore, it was 25 micrometers when the film thickness of the glass layer formed on the board | substrate without an unevenness | corrugation was measured with the stylus-type film thickness meter (DEKTAK) by ULVAC. When observed with an optical microscope, the film prepared using the glass paste composition has some bubbles, but there is not enough to scatter light effectively. It was found that a layer was formed. The Ra of the substrate without unevenness on which this glass layer was formed was 30 nm or less.

  Further, the total light transmittance of the substrate in which the glass layer was formed on the substrate without unevenness was 79%, and the haze value was 10%. Furthermore, when the refractive index of the glass layer was measured with prism coupler MODEL2000 (manufactured by Metricon), the refractive index nd was 1.99.

  On the other hand, the total light transmittance of the substrate in which the glass layer was formed on the uneven substrate was 71%, the haze value was 90%, and Ra was 30 nm or less. Thus, although the scattering layer derived from the uneven surface exists in the substrate, a light emitting device substrate having a smooth surface could be produced.

  Next, 120 nm of ITO was formed on each of the soda lime glass and the two types of glass substrates prepared above using a DC magnetron sputtering apparatus. A substrate (A) using a substrate with a glass layer formed on a substrate with unevenness, a substrate (B) using a substrate with a glass layer formed on a substrate without unevenness, and a substrate using soda lime glass Let it be a substrate (C).

  Next, as a blue light-emitting material, LΜMOGENF650 manufactured by BASF was deposited on the substrates (A) to (C) by 200 nm using a resistance heating vapor deposition machine. Fluorescence intensity of the obtained three types of substrates with fluorescent film was measured using a fluorescence spectrophotometer (F7000, manufactured by Hitachi High-Technologies Corporation). When the luminescence in all directions collected by the integrating sphere was normalized (light extraction intensity) with the absorbed excitation light quantity, the results shown in Table 3 were obtained. FIG. 15 shows the results of measurement with a fluorescence spectrophotometer.

  In the example shown in Table 3 and FIG. 15, the EL element is not actually manufactured, but as is clear from Table 3 and FIG. 15, the light extraction efficiency is obtained when the substrate to which the present invention is applied is used. Was found to be significantly improved.

  Similarly, Table 4 shows the results of estimating the light extraction efficiency using a green phosphor, a red phosphor, and a white phosphor. The substrates used are as shown in Table 4. As is apparent from Table 4, it was found that when a light emitting element substrate to which the present invention was applied was used, it was possible to effectively improve the extraction efficiency for light of any wavelength.

(Relationship between Ra, Haze and extraction efficiency)
Next, Table 5 shows the results of fabricating the same substrate by changing Ra of the substrate with unevenness and measuring the light extraction efficiency. Table 5 shows the Ra and Haze values of the substrate with unevenness and the method of forming the unevenness. As is apparent from Table 5, when the degree of unevenness is small, such as Ra is 0.01 μm or 0.1 μm, the Haze value is also small, and the effect of improving the light extraction efficiency is little or almost no. On the other hand, for example, when a concavo-convex substrate having a large Ra of 0.7 μm or more was used, the Haze value was also large, and it was confirmed that sufficient light extraction efficiency was improved.

(Study on suitable film thickness)
Next, Table 6 shows the results of studies on the film thickness of the high refractive index glass layer formed on the substrate with unevenness. In order to obtain a light-emitting element substrate having a sufficiently smooth surface as a result of forming high-refractive-index glass layers with various thicknesses on an uneven substrate having various Ras, the thickness of the glass layer required according to Ra is I found it different. For example, when Ra = 0.7 μm, 20 μm or more is necessary. It can be seen that in order to obtain a completely flattened surface, a film thickness approximately 30 to 40 times Ra is required. This is because Rz (maximum height) 10 to 20 times the numerical value of Ra exists.

(Example when the uneven surface has a lens structure)
A hemispherical microlens array having a diameter of 30 μm was formed on a soda lime glass substrate using a thermal transfer method of a mold. Next, the glass paste composition described above was applied and dried so that the film thickness after firing was 25 μm, and a substrate having a high refractive index layer having a microlens structure inside was obtained. Furthermore, 120 nm of ITO was formed on this substrate using a DC magnetron sputtering apparatus (referred to as substrate (A)). Separately, a glass paste composition having a thickness of 25 μm formed on a soda lime glass substrate and then sputtered with 120 nm ITO (B), and a substrate with soda lime glass sputtered with 120 nm ITO (C) Was made. As a blue light-emitting material, LΜMOGENF650 manufactured by BASF was vapor-deposited to a thickness of 200 nm on each of the substrates (A) to (C) using a resistance heating vapor deposition machine. Fluorescence intensity was measured for the obtained three types of substrates with fluorescent film using a fluorescence spectrophotometer (F7000, manufactured by Hitachi High-Technologies Corporation). When the light emission in all directions collected by the integrating sphere was normalized by the absorbed light quantity absorbed, the results shown in Table 7 were obtained. The improvement of the light extraction efficiency was confirmed not only in the case of a random uneven surface, but also in the case where the microlens was included in the substrate.

(Example of Organic Thin Film Element (OLED): Example of First Embodiment)
In order to evaluate the OLED having the structure of the first embodiment of the present invention described above, the following substrates T1-1 to T1-6 were produced. The substrate T1-1 was prepared as a comparative substrate, and was a sample in which an indium tin oxide (ITO) film was directly formed on a glass substrate as a transparent electrode. For the substrate T1-2, a glass paste composition (nd = 1.98, composition: described later) having a refractive index close to the refractive index of the transparent electrode ITO with respect to a glass substrate having no concavo-convex structure is formed using a bar coating method. It is a sample in which a high refractive index layer is formed by air baking (Air) after coating. The substrate T1-3 is a glass paste composition (nd = 1.98, composition: Bi ₂ O ₃ —B ₂ O ₃ −) having a refractive index close to that of the transparent electrode ITO with respect to a glass substrate having no uneven structure. SiO ₂ —ZnO-based glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol, and butyl carbitol acetate were dissolved and mixed using a bar coating method, followed by vacuum firing (Vac.). This is a sample in which a high refractive index layer is formed. The substrate T1-4 was coated with the glass paste composition using a bar coating method on a glass substrate having a random concavo-convex structure formed on the surface using a sand blast method, and then fired in the air (Air) to obtain a high refractive index. It is the sample which formed the layer into a film. The substrate T1-5 was coated with the glass paste composition using a bar coating method on a glass substrate having a random concavo-convex structure formed on the surface using a sand blast method, and then subjected to vacuum baking (Vac.) For high refraction. It is the sample which formed the rate layer into a film. Further, the substrate T1-6 is a sample obtained by performing vacuum baking in the same manner as the substrate T1-5 and then polishing (Lap) the outermost surface of the substrate to further improve the smoothness of the substrate. Lap processing is effective in a vacuum-baked substrate. When bubbles exist in the high refractive index layer, defects such as a dent shape due to the bubbles existing on the surface appear by lap processing the surface of the high refractive index layer. Therefore, in order to further smooth the surface of the substrate by Lap processing, it is necessary to perform vacuum baking to eliminate bubbles existing in the high refractive index layer.

  In the method described in Patent Document 4, scattering components such as bubbles and fillers are intentionally present in the high refractive index layer, and the high refractive index layer itself functions as a scattering layer. It can also be seen from this study that the presence of bubbles or fillers in the part in contact with the surface makes it difficult to form a homogeneous transparent electrode, and it is impossible to ensure the life and reliability.

The substrates T1-1 to T1-6 produced as described above were leveled for 60 minutes in a place where the humidity was controlled to 50% after applying the glass paste composition, and then heated with a 120 ° C hot air dryer. And dried for 30 minutes. Furthermore, after depositing an ITO film on each substrate, UV / O ₃ cleaning treatment was performed after cleaning steps such as brush cleaning, ultrasonic cleaning, and degreasing. Subsequently, PEDOT / PSS as a hole injection layer, an interlayer layer (IL) as a hole transport layer, and a polyfluorene material as a light emitting layer (EML) were spin-coated. Thereafter, aluminum (Al) was vacuum deposited as a cathode at 70 nm. Finally, the sealing plate to which the calcium oxide-based desiccant was attached was attached to the OLED substrate using an ultraviolet curable resin, and the resin was cured by irradiating with ultraviolet rays to prepare an OLED sample. The current-voltage-luminance characteristics were measured for these OLED samples by combining a KEITKEYKEY source meter 2400 and a Photo Research Spectra ScanPR 600 luminance meter. As for the current-voltage characteristics, the same characteristics were obtained in any of the elements. From the result of the luminance-current density, when the light emitting element substrate (substrates T1-5, T1-6) of the first embodiment of the present invention is used, it is 1.8-2 compared to the case where other substrates are used. It was proved that a luminance of about 0.0 times was obtained. Table 8 shows the extraction efficiency and yield of the OLED samples produced using the substrates T1-1 to T1-6. In addition, the taking-out efficiency was shown by the relative evaluation which set the taking-out efficiency in the board | substrate T1-1 which has not formed the high refractive index layer to 1.

  As shown in Table 8, the yield is better when vacuum firing is performed than when air firing is performed, and when polished after firing, the yield is dramatically improved. Has been demonstrated. However, an improvement in the light extraction effect of a sample (in the case of using the substrate T1-2) that is considered to correspond to the element of Patent Document 4 prototyped in this study could not be found. It is considered that the reason why the light extraction effect is not obtained is that it is difficult to control the bubble size, the number of bubbles, and the position control of the bubbles, and that the light is scattered and the light is not extracted to the front surface of the substrate.

(Example of organic EL element (OLED): example of second embodiment)
In order to evaluate the OLED having the structure of the second embodiment of the present invention described above, the following substrates T2-1 to T2-3 were prepared. The substrate T2-1 was prepared as a comparative substrate, and was a sample in which an indium tin oxide (ITO) film was formed directly on a glass substrate as a transparent electrode. Substrate T2-2 is a glass paste composition having a refractive index close to the refractive index of transparent electrode ITO (nd = 1.98, composition) with respect to a glass substrate having a random concavo-convex structure formed on the surface using sandblasting. : Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol and butyl carbitol acetate dissolved and mixed) using a bar coat method In this sample, a high refractive index layer having a two-layer structure was formed by air-coating (Air) and then re-coating the glass paste composition thereon, followed by vacuum baking (Vac.). The substrate T2-3 was vacuum-baked (Vac.) After applying the glass paste composition using a bar coating method on a glass substrate having a random concavo-convex structure formed on the surface using a sand blast method, A sample in which a high refractive index layer having a two-layer structure was formed by re-coating the glass paste composition and vacuum firing (Vac.) Thereon.

Substrates T2-1 to T2-3 produced as described above were leveled for 60 minutes in a place where the humidity was controlled to 50% after applying the glass paste composition, and then heated with a 120 ° C hot air dryer. And dried for 30 minutes. Furthermore, after depositing an ITO film on each substrate, UV / O ₃ cleaning treatment was performed after cleaning steps such as brush cleaning, ultrasonic cleaning, and degreasing. Subsequently, PEDOT / PSS as a hole injection layer, an interlayer layer (IL) as a hole transport layer, and a polyfluorene material as a light emitting layer (EML) were spin-coated. Thereafter, aluminum (Al) was vacuum deposited as a cathode at 70 nm. Finally, the sealing plate to which the calcium oxide-based desiccant was attached was attached to the OLED substrate using an ultraviolet curable resin, and the resin was cured by irradiating with ultraviolet rays to prepare an OLED sample. The current-voltage-luminance characteristics were measured for these OLED samples by combining a KEITKEYKEY source meter 2400 and a Photo Research Spectra ScanPR 600 luminance meter. As for the current-voltage characteristics, the same characteristics were obtained in any of the elements. From the result of luminance-current density, when the light emitting element substrate (substrates T2-2, T2-3) of the second embodiment of the present invention is used, 1.9-2 compared to the case of using other substrates. It was proved that a luminance of about 0.0 times was obtained. Table 9 shows the extraction efficiency and yield of the OLED samples manufactured using the substrates T2-1 to T2-3. The take-out efficiency was shown by relative evaluation with the take-out efficiency in the substrate T2-1 not having a high refractive index layer being 1.

  As shown in Table 9, when either the substrate T2-2 or T2-3 was used, the extraction efficiency and the yield were improved.

(Example of organic EL element (OLED): example of third embodiment)
In order to evaluate the OLED having the structure of the third embodiment of the present invention described above, the following substrates T3-1 to T3-4 were prepared. The substrate T3-1 was prepared as a comparative substrate, and was a sample in which indium tin oxide (ITO) was formed directly on a glass substrate as a transparent electrode. Substrate T3-2 is a glass paste composition having a refractive index close to the refractive index of transparent electrode ITO (nd = 1.98, composition) with respect to a glass substrate having a random concavo-convex structure formed on the surface using a sandblast method. : Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol, and butyl carbitol acetate are dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ combination) using a bar coating method, followed by air firing (Air) to form a high refractive index layer having a single layer structure. Substrate T3-3 is a glass paste composition having a refractive index close to the refractive index of transparent electrode ITO (nd = 1.98, composition) with respect to a glass substrate having a random concavo-convex structure formed on the surface using a sandblast method. : Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol, and butyl carbitol acetate are dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ combination) using a bar coating method, followed by air firing (Air), and further a glass paste composition having a refractive index close to the refractive index of the transparent electrode ITO ( nd = 1.98, _{composition: Bi 2 O 3 -B 2 O} 3 -SiO 2 -ZnO based glass frit (Tg = 400 ℃), d Le cellulose STD45 (manufactured by Dow Chemical Co.), terpineol, a vacuum baking (Vac.) To sample deposited a high refractive index layer having a two-layer structure after recoated lysis mixture) of butyl carbitol acetate. Substrate T3-4 is a glass paste composition having a refractive index close to the refractive index of transparent electrode ITO (nd = 1.98, composition) with respect to a glass substrate having a random concavo-convex structure formed on the surface using sandblasting. : Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol, and butyl carbitol acetate are dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ combination) using a bar coating method, followed by vacuum baking (Vac.) And further having a refractive index close to that of the transparent electrode ITO. (nd = 1.98, _{composition: Bi 2 O 3 -B 2 O} 3 -SiO 2 -ZnO based glass frit (Tg = 400 ℃), Chill cellulose STD45 (manufactured by Dow Chemical Co.), terpineol, a vacuum baking (Vac.) To sample deposited a high refractive index layer having a two-layer structure after recoated lysis mixture) of butyl carbitol acetate.

The substrates T3-1 to T3-4 produced as described above were leveled for 60 minutes in a place where the humidity was controlled to 50% after applying the glass paste composition, and then heated with a 120 ° C hot air dryer. And dried for 30 minutes. Furthermore, after depositing an ITO film on each substrate, UV / O ₃ cleaning treatment was performed after cleaning steps such as brush cleaning, ultrasonic cleaning, and degreasing. Subsequently, PEDOT / PSS as a hole injection layer, an interlayer layer (IL) as a hole transport layer, and a polyfluorene material as a light emitting layer (EML) were spin-coated. Thereafter, aluminum (Al) was vacuum deposited as a cathode at 70 nm. Finally, the sealing plate to which the calcium oxide-based desiccant was attached was attached to the OLED substrate using an ultraviolet curable resin, and the resin was cured by irradiating with ultraviolet rays to prepare an OLED sample. The current-voltage-luminance characteristics were measured for these OLED samples by combining a KEITKEYKEY source meter 2400 and a Photo Research Spectra ScanPR 600 luminance meter. As for the current-voltage characteristics, the same characteristics were obtained in any of the elements. From the result of luminance-current density, when the light emitting element substrate (substrates T3-3, T3-4) of the third embodiment of the present invention is used, 1.9-2 compared to the case where other substrates are used. It was proved that a luminance of about 0.0 times was obtained. Table 10 shows the extraction efficiency and yield of the OLED samples produced using the substrates T3-1 to T3-4. The take-out efficiency was shown by relative evaluation with the take-out efficiency in the substrate T3-1 not having a high refractive index layer as 1.

  As shown in Table 10, when either the substrate T3-3 or T3-4 was used, the extraction efficiency and the yield were improved. On the other hand, when the substrate T3-2 was used, the interface between the high refractive index layer and the transparent electrode ITO was not completely flattened, and many defective portions were generated in the transparent electrode ITO. As a result, leakage current was confirmed. This leakage current locally deteriorates the OLED element and significantly reduces the reliability of the OLED element.

(Example of organic EL element (OLED): example of fourth embodiment)
In order to evaluate the OLED having the structure of the fourth embodiment of the present invention described above, the following substrates T4-1 to T4-4 were prepared. The substrate T4-1 was prepared as a comparative substrate, and was a sample in which an indium tin oxide (ITO) film was directly formed on a glass substrate as a transparent electrode. Substrate T4-2, to the glass substrate without concave-glass paste composition having a refractive index close to the refractive index of the transparent electrode ITO (nd = 1.98, _{composition: Bi 2 O 3 -B 2 O} 3 -SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol and butyl carbitol acetate dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ ) ) Is applied using a bar coating method, and then air-fired (Air) to form a single-layer high refractive index layer. Substrate T4-3, to the glass substrate without concave-glass paste composition having a refractive index close to the refractive index of the transparent electrode ITO (nd = 1.98, _{composition: Bi 2 O 3 -B 2 O} 3 -SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol and butyl carbitol acetate dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ ) ) Is applied using the bar coating method and then air-fired (Air), and further, a glass paste composition (nd = 1.98, composition: Bi ₂ ) having a refractive index close to that of the transparent electrode ITO. _{O 3 -B 2 O 3 -SiO 2} -ZnO based glass frit (Tg = 400 ℃), ethylcellulose STD45 (manufactured by Dow Chemical Co.) Terpineol, a vacuum baking (Vac.) To sample deposited a high refractive index layer having a two-layer structure after recoated lysis mixture) of butyl carbitol acetate. Substrate T4-4, to the glass substrate without concave-glass paste composition having a refractive index close to the refractive index of the transparent electrode ITO (nd = 1.98, _{composition: Bi 2 O 3 -B 2 O} 3 -SiO ₂ —ZnO glass frit (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol and butyl carbitol acetate dissolved and mixed with a scattering material (TiO ₂ , SiO ₂ , Al ₂ O ₃ ) ) Is applied using a bar coating method and then vacuum baked (Vac.), And a glass paste composition (nd = 1.98, composition: Bi) having a refractive index close to that of the transparent electrode ITO is further formed thereon. _{2 O 3 -B 2 O 3 -SiO} 2 -ZnO based glass frit (Tg = 400 ℃), ethylcellulose STD45 (Dow Chemical Co. Terpineol, a vacuum baking (Vac.) To sample deposited a high refractive index layer having a two-layer structure after recoated lysis mixture) of butyl carbitol acetate.

Substrates T4-1 to T4-4 produced as described above were leveled for 60 minutes in a place where the humidity was controlled to 50% after applying the glass paste composition, and then heated with a 120 ° C hot air dryer. And dried for 30 minutes. Furthermore, after depositing an ITO film on each substrate, UV / O ₃ cleaning treatment was performed after cleaning steps such as brush cleaning, ultrasonic cleaning, and degreasing. Subsequently, PEDOT / PSS as a hole injection layer, an interlayer layer (IL) as a hole transport layer, and a polyfluorene material as a light emitting layer (EML) were spin-coated. Thereafter, aluminum (Al) was vacuum deposited as a cathode at 70 nm. Finally, the sealing plate to which the calcium oxide-based desiccant was attached was attached to the OLED substrate using an ultraviolet curable resin, and the resin was cured by irradiating with ultraviolet rays to prepare an OLED sample. The current-voltage-luminance characteristics were measured for these OLED samples by combining a KEITKEYKEY source meter 2400 and a Photo Research Spectra ScanPR 600 luminance meter. As for the current-voltage characteristics, the same characteristics were obtained in any of the elements. From the result of luminance-current density, when the light emitting element substrate (substrates T4-3, T4-4) of the fourth embodiment of the present invention is used, 1.9-2 compared to the case of using other substrates. It was proved that a luminance of about 0.0 times was obtained. Table 11 shows the extraction efficiency and yield of the OLED samples produced using the substrates T4-1 to T4-4. In addition, the taking-out efficiency was shown by the relative evaluation which set the taking-out efficiency in the board | substrate T4-1 which has not formed the high refractive index layer to 1.

  As shown in Table 11, when either the substrate T4-3 or T4-4 was used, the extraction efficiency and the yield were improved. On the other hand, when the substrate T4-2 is used, it is equivalent to the method described in the above-mentioned Patent Document 4, but the interface between the high refractive index layer and the transparent electrode ITO cannot be completely flattened and the transparent electrode ITO is used. As a result of many defective parts, leakage current was confirmed. This leakage current locally deteriorates the OLED element and significantly reduces the reliability of the OLED element.

(Example of lighting equipment: Example of white lighting)
A glass paste composition having a refractive index close to the refractive index of the transparent electrode ITO (nd = 1.98, composition: Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —ZnO-based glass frit on a glass substrate having an uneven structure. (Tg = 400 ° C.), ethyl cellulose STD45 (manufactured by Dow Chemical Co., Ltd.), terpineol and butyl carbitol acetate dissolved and mixed) were applied using a bar coating method and then vacuum baked (Vac.) To form a high refractive index layer. A substrate (B) on which a high refractive index layer was formed by applying the glass paste composition to a glass substrate without a concavo-convex structure using a bar coating method and then vacuum baking (Vac.). Three types of substrates were prepared: a glass substrate (C) having no uneven structure. Next, an ITO film was formed on these three types of substrates (A) to (C), followed by UV / O3 cleaning treatment after cleaning steps such as brush cleaning, ultrasonic cleaning, and degreasing. Subsequently, PEDOT / PSS as a hole injection layer, an interlayer layer (IL) as a hole transport layer, and a polyfluorene material as a light emitting layer (EML) were spin-coated. As the light emitting layer, a material in which red, green, and blue light emitting materials were mixed at a ratio of 1: 1: 8 was used. Thereafter, aluminum (Al) was vacuum deposited as a cathode at 70 nm. Finally, the sealing plate with the calcium oxide-based desiccant attached is attached to the OLED substrate using an ultraviolet curable resin, and the resin is cured by irradiating with an ultraviolet ray. Each sample of Example (C) was produced. The current-voltage-total luminous flux characteristics were measured on these samples by combining a source meter 2400, a integrating sphere and an illuminometer, manufactured by KEITKEY Corporation. In any of the element samples, white light emission with CIE chromaticity (0.31, 0.33) was obtained. Table 12 shows the measurement results.

  As shown in Table 12, the total luminous flux of Example (A) was much larger than the total luminous fluxes of Comparative Examples (B) and (C). In Example (A), light emission was observed in an area larger than the actual area of 2 mm square of the element, and the effect of light scattering could be confirmed. Further, in the devices of Comparative Examples (B) and (C), the guided light from the end face of the substrate was confirmed, and it was found that the light was not extracted to the front. On the other hand, in the element of Example (A), since guided light was not confirmed, it is clear that the light extraction efficiency is greatly improved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

100, 200, 300, 400 Surface light emitting device 110, 210, 310, 410 Support substrate 111, 211, 311 Uneven surface 120, 220, 320, 420 High refractive index layer 221, 321, 421 Light scattering layer 223, 323, 423 Planarization layer 123, 223a, 323a, 423a Flat surface 325, 425 Scattering material 130, 230, 330, 430 Transparent electrode 140, 240, 340, 440 Organic thin film layer 150, 250, 350, 450 Cathode

Claims (24)

A light emitting device substrate used as a substrate of a surface light emitting device in which a transparent electrode, an organic thin film layer, and a cathode are sequentially laminated,
A transparent support substrate;
A high refractive index layer which is disposed between the support substrate and the transparent electrode and which is composed of one or more layers having a refractive index equal to or higher than the refractive index of the support substrate;
With
The high refractive index layer has a light scattering portion for scattering light incident from the transparent electrode side, and a flat surface in contact with the transparent electrode,
Among the layers constituting the high refractive index layer, the haze value of the layer adjacent to the transparent electrode is 5% or less. A light emitting device substrate used as a substrate of a light emitting device in which a transparent electrode, an organic thin film layer, and a cathode are sequentially laminated,
A transparent support substrate;
A high refractive index layer disposed between the support substrate and the transparent electrode and having a refractive index equal to or higher than the refractive index of the support substrate;
With
The high refractive index layer has a light scattering portion for scattering light incident from the transparent electrode side, and a flat surface in contact with the transparent electrode,
The diameter of the bubbles present in the high refractive index layer is 1/10 or less of the thickness of the layer adjacent to the transparent electrode among the layers constituting the high refractive index layer,
The ratio of the bubbles in the layer adjacent to the transparent electrode is 0.5% or less as a ratio of the area of the horizontal cross section of the bubbles to the total area of the horizontal cross section of the layer adjacent to the transparent electrode, and the transparent The ratio of the area of the said vertical cross section of the said bubble with respect to the total area of the vertical cross section of the layer adjacent to an electrode is 0.5% or less, The light emitting element substrate characterized by the above-mentioned.   The light emitting device substrate according to claim 2, wherein a haze value of a layer adjacent to the transparent electrode among the layers constituting the high refractive index layer is 5% or less.   The light emitting device substrate according to claim 1, wherein an interface between the support substrate and the high refractive index layer is an uneven surface.   The light-emitting element substrate according to claim 4, wherein a film thickness of the high refractive index layer is 30 times or more of an average surface roughness Ra of the uneven surface.   6. The light-emitting element substrate according to claim 4, wherein a film thickness of the high refractive index layer is 1.3 times or more of a maximum surface roughness Rz of the uneven surface.   7. The light-emitting element substrate according to claim 4, wherein a film thickness of the high refractive index layer is 3 μm or more and 100 μm or less.   8. The light emitting device substrate according to claim 4, wherein the uneven surface has an average surface roughness Ra of 0.7 μm or more and 5 μm or less.   The light-emitting element substrate according to any one of claims 4 to 8, wherein the uneven shape of the uneven surface is a pyramid shape or a lens shape.   The light emitting device substrate according to claim 4, wherein the high refractive index layer is composed of only one layer. The high refractive index layer is
A light scattering layer adjacent to the support substrate and having the light scattering portion;
A planarization layer adjacent to the transparent electrode and having the flat surface;
The light-emitting element substrate according to claim 4, comprising two or more layers including at least   The light-emitting element substrate according to claim 11, wherein the light scattering layer contains a glass material and a scattering material having a refractive index different from that of the glass material. The high refractive index layer is adjacent to the support substrate and has a light scattering portion;
A planarization layer adjacent to the transparent electrode and having the flat surface;
Consisting of two or more layers containing at least
The light scattering layer contains a glass material and a scattering material having a refractive index different from that of the glass material,
The light-emitting element substrate according to claim 1, wherein the light-emitting element substrate has no uneven surface at an interface between the support substrate and the high refractive index layer. It is a manufacturing method of the light emitting element substrate according to any one of claims 1 to 13,
An application step of applying a glass paste composition containing a glass frit having a refractive index equal to or higher than that of the support substrate, a solvent, and a resin to the surface of the transparent support substrate;
Drying the glass paste composition and evaporating the solvent; and
A baking step of baking the glass paste composition after the solvent is volatilized under vacuum or pressure;
A method for manufacturing a light-emitting element substrate, comprising:   The method for manufacturing a light-emitting element substrate according to claim 14, wherein, in the baking step, the glass paste composition is fired under a vacuum of 0.3 Pa or less.   The method for manufacturing a light-emitting element substrate according to claim 14, wherein in the baking step, the glass paste composition is fired under a pressure of 110 kPa or more.   The method of manufacturing a light emitting element substrate according to any one of claims 14 to 16, wherein a glass transition temperature of the glass frit is 450 ° C or lower.   The method of manufacturing a light emitting device substrate according to claim 17, wherein the drying step and the baking step are performed at a temperature of 500 ° C. or less.   The method for manufacturing a light-emitting element substrate according to any one of claims 14 to 18, further comprising a surface roughening step of forming an uneven surface on the surface of the support substrate before the coating step. .   The method for manufacturing a light-emitting element substrate according to claim 19, wherein in the surface roughening step, the uneven surface is formed by a sandblasting method, a wet etching method, or a pressing method.   21. The method of manufacturing a light-emitting element substrate according to claim 14, wherein the glass paste composition further contains a scattering material having a refractive index different from that of the glass frit. The light emitting element substrate according to any one of claims 1 to 13,
A transparent electrode laminated on the light emitting element substrate;
An organic thin film layer laminated on the transparent electrode;
A cathode laminated on the organic thin film layer;
A surface light emitting device comprising:   A lighting fixture comprising the surface light emitting device according to claim 22. A backlight comprising the surface light emitting device according to claim 22.