JP2013232279A - Sealing film and organic light-emitting diode using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing film combining a light extraction function and a moisture-absorbing function required for an organic light-emitting diode, or the like.SOLUTION: A sealing film 30 consists of an organic resin film 31 into which first particles 32 for light scattering, and second particles 33 for moisture absorption are dispersed. The first particles 32 have a refractive index larger than that of the organic resin film 31, and consist of a material capable of transmitting visible light (e.g. ZrO, BaTiO, TiO, ZnO, YO, AlO). The second particles 33 have properties to be combined with water, and consist of a material capable of transmitting visible light (e.g. alkaline earth metal oxide, alkali metal oxide, metal halogenide, metal sulfate, metal perchlorate).

Description

  The present invention relates to a sealing film, and more particularly to a technique effective when applied to a sealing film having a light extraction function and a sealing function necessary for an organic light emitting diode or the like.

  Organic light-emitting diodes (hereinafter abbreviated as OLEDs) are formed by injecting charge carriers (electrons and holes) into an organic molecular layer of a thin film and recombining the charge carriers in the organic molecular layer. It is an element that converts electricity into light.

  A semiconductor or an insulator is used for the organic molecular layer of the thin film, and the emission energy changes according to the type of molecule and its energy gap. Therefore, since the emission color can be controlled by appropriately selecting the molecules, a color light emitting element can be configured by using molecules showing red, green, and blue light emission constituting the three primary colors of light. For these reasons, research and development aimed at application of OLEDs, centering on display devices and lighting devices, are actively conducted all over the world.

  In the case of an OLED, charge carriers are injected into the organic molecular layer by electrons from the cathode and holes from the anode. In order to increase injection efficiency, the cathode (cathode) and the anode (anode) are different. Material is used. Typically, as an anode material, for example, a transparent metal oxide conductor having a large work function of about 5 eV such as indium tin oxide (ITO) or indium zinc oxide (IZO), An organic conductor such as PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)) is used. As the cathode material, a conductor made of an alkali metal, an alkaline earth metal, or a compound thereof having a small work function is used.

  The organic molecular layer of OLED is a layer responsible for light emission, but it is rarely used as a single layer, and in addition to the light emitting layer, a carrier transport layer, a carrier blocking layer, a carrier generation layer, etc. according to the type of carrier are appropriately used. Used. These layers are basically intended to improve luminous efficiency, and in many cases, organic substances are used.

  As described above, in the OLED, many parts directly related to light emission are composed of organic substances. In general, these organic substances are known to be unstable with respect to oxygen and moisture. Similarly, it is well known that alkali metals and alkaline earth metals and their compounds used for the cathode are also unstable with respect to moisture and oxygen. By reacting with moisture and oxygen, the organic molecules constituting the OLED deactivate their functions, and the light emitting function is lost. In addition, the cathode also changes to a different compound by reacting with moisture and oxygen, and loses its function as a charge carrier injection electrode.

For example, Non-Patent Document 1 describes the deactivation of light emission caused by cathode deterioration that occurs when an OLED is left in the atmosphere. Therefore, in order to avoid such an influence, the OLED element is usually sealed with a material having extremely low moisture and oxygen permeability. For example, Non-Patent Document 2 has a description of realizing a sealing film having a moisture permeability of 10 ⁻⁷ g / m ² · day with an organic / inorganic laminated structure and applying this sealing film to an OLED. .

  In the light emitted from the OLED, electrons and holes are recombined in the organic molecules of the light emitting layer, and emitted in all directions around the organic molecules. An OLED has a multilayer structure composed of an organic layer such as a carrier transport layer, an electrode, a sealing layer, etc., and each layer has a specific refractive index, so that emitted light depends on the incident angle to the interface of each layer. Reflected and refracted.

FIG. 1A is a diagram schematically showing how light is reflected and refracted at an interface between substances having different refractive indexes. If the refractive index interface through which light of the substance of the material and n ₂ n _1, generally, the light does not go straight at the interface, some is reflected, the remainder refracted transmits the interface.

In this case, _{n 1} sinθ 1 = _n 2 relationship sin [theta ₂ is established between the incident angle theta ₁ and refraction angle theta ₂ with respect to the normal of the interface. Therefore, when n ₁ > n ₂ , light incident at an incident angle larger than the critical angle θ _C satisfying sin θ _C = n ₂ / n ₁ = 1 is totally reflected at the interface.

FIG. 1B is a diagram schematically illustrating a case where light is transmitted through two interfaces. Since the incident angles θ _i1 and θ _i2 of light at the two interfaces are smaller than the critical angle θ _{C at} which total reflection occurs, light is transmitted from the layer having a refractive index of n _{1 to} the layer of n ₃ .

FIG. 1C is a diagram schematically showing how light that has passed through one interface undergoes total reflection at the next interface. Since the incident angle θ _{i1 at} the interface between the n ₁ layer and the n ₂ layer is smaller than the critical angle θ _C, the light transmitted through the interface is the interface between the refractive index n ₂ layer and the n ₃ layer. It is totally reflected. As long as the incident angle to the interface does not change due to scattering, the totally reflected light is confined in the layers of refractive index n ₁ and n ₂ and propagates in the layer and attenuates.

  Typical values of the refractive index of each layer constituting the OLED are 1.7 to 1.8 for each organic molecule layer and about 2.0 for the transparent electrode. When general glass having a refractive index of about 1.5 is used as the sealing material, the refractive index of the air layer outside the element is 1.0, so that light is transmitted from the organic molecular layer that is the light emitting layer to the air layer. Repeated reflection and refraction at multiple interfaces before coming out.

  FIG. 2 schematically shows this state. The light emitted from the light emitting point 21 in FIG. 2 is emitted in all directions around the light emitting point 21, and half of the light is reflected by the reflective electrode 11 on the substrate 10. In addition, the light emitted in the horizontal direction indicated by the path 23 propagates through the organic molecular layer 12 unless it is scattered, and is reflected, transmitted, scattered, and attenuated at the end, and finally disappears. 2 (light emitted in the direction indicated by paths 24, 25, 26, and 27) and light reflected by the surface of the reflective electrode 11 (in the direction indicated by path 22). The emitted light) is reflected and refracted at the interfaces of the organic molecular layer 12, the transparent electrode 13, and the transparent glass layer (sealing layer) 14, and part of the light reaches the air layer 15. Further, the remaining light is repeatedly reflected and refracted at the interface of each layer, and is confined in each layer and attenuates or disappears inside the OLED without going out to the air layer 15, or in the lateral direction of the element at the end of the OLED. To penetrate. In other words, the OLED element has a problem that only a part of the emitted light can be extracted to the outside when no device for extracting the light is used. For example, according to Non-Patent Document 3, in the case of the configuration shown in FIG. 2, only about 20% of the emitted light can be extracted outside.

  In order to solve the above-described problems, when applying OLED, a device for extracting emitted light is devised. For example, microlenses are densely arranged at the interface between the transparent glass layer 14 and the air layer 15 in FIG. 2 or the interface between the transparent electrode 13 and the transparent glass layer 14, and the amount of light extraction is changed by changing the direction of refraction at the interface. There is a method of increasing the number, a method of increasing the amount of light extracted by diffracting a micro lattice at the interface, a method of forming a photonic crystal at the interface, a method of utilizing light scattering in a film in which fine particles are dispersed, and the like. . Non-Patent Document 3 outlines examples of such devices.

  Thus, when applying OLED, the subject of preventing deterioration of a device by a water | moisture content or oxygen, and taking out easily the light which is easy to lose inside an element arises.

  Therefore, at present, as in Patent Document 1, for example, layers corresponding to the above problems are stacked to solve each problem. Further, as disclosed in Patent Document 2 and Patent Document 3, metal oxide particles and a hygroscopic substance are simultaneously dispersed in a binder or a sealant to provide a film that combines light extraction and light absorption utilizing light scattering. Things are also done.

  In Patent Document 4, a first reflective electrode, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and a second transparent electrode are formed on a glass substrate, and a refractive index of 2. 6. An organic light-emitting device in which light emitted from a light-emitting layer is efficiently extracted to the outside by forming a light extraction layer having an average refractive index of 1.4 composed of titania particles having an average particle diameter of 150 nm and silica sol is disclosed. Has been.

Special table 2008-538155 gazette JP 2006-286627 A JP 2007-184279 A JP 2010-0667464 A

Journal of Surface Science, Volume 25, Section 62 (2004) Proceedings of International Display Workshops 2010, Item 1593 (Proc. IDW'10, 1593 (2010).) Optical Materials, Vol. 32, Section 221 (2009) (Optical Materials 32, 221 (2005).)

  However, the method of Patent Document 1 that solves each problem by laminating layers corresponding to each problem has a problem of increasing the manufacturing cost such as an increase in the number of processes and an increase in members. Further, when an inorganic / organic laminated film as in Non-Patent Document 2 is used as the sealing film, there is a problem in that a large loss is caused in terms of light extraction due to a mismatch in refractive index in each layer of the laminated film. Occurs.

  Furthermore, the methods disclosed in Patent Documents 2 and 3 cannot always solve all the above-mentioned problems related to OLED. That is, the size of the metal oxide particles dispersed in the binder used in Patent Documents 2 and 3 is limited to an average of 100 nm or less in order to maintain the transparency of the film. However, a cured film of a dispersion composition obtained by dispersing such particles in a binder or the like has only a refractive action on visible light emitted from the OLED. This is because the particle size is small with respect to the wavelength of visible light, so that the scattering by the particle is almost negligible, and only the effect of changing the average refractive index of the binder and the like due to the mixing of the particle is the light. Because I can't feel it. For this reason, only the effect of adding a film with a large refractive index can be obtained as a light extraction function, and as a result, the difference in refractive index with the surrounding material changes, which causes a change in the amount of light confinement. Effect. In many cases, the average refractive index of the binder or the like is increased by mixing the metal oxide particles, and the difference in refractive index from the surrounding material is increased, so that many effects cannot be expected from the viewpoint of light extraction.

  An object of the present invention is to provide a sealing film having both a light extraction function and a moisture absorption function necessary for an organic light emitting diode or the like.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The sealing film of the present invention disperses the first particles in the organic film, imparts a light extraction function by light scattering of the first particles, and disperses the second particles made of a hygroscopic substance in the organic film. Thus, a sealing function of moisture and oxygen is given.

  The organic film used in the present invention is preferably transparent and has a refractive index comparable to that of the underlying material. Thereby, the light that has passed through the base and reached the interface with the sealing film can be taken into the organic film without being reflected or refracted by the interface.

  The organic film is preferably a resin that is cured by heat or light. In order to prevent damage to the OLED at the time of curing, it is desirable that the thermosetting can be cured at a low temperature for as short a time as possible, specifically at a temperature of about 80 to 100 ° C. In the case of photocuring, it is necessary not to damage the organic molecular layer of the OLED. Although UV light is generally used for photocuring of the resin, it is desirable to cure with long-wavelength UV light because short-wavelength UV light is easily damaged.

  The size of the first particles mixed in the organic film to cause light scattering needs to be a size that efficiently scatters light emitted from the OLED. For this reason, it is desirable that the average particle diameter of the first particles is about 1 to 10 times the wavelength of light. Specifically, the thickness is desirably 200 nm to 10 μm, and more desirably 400 nm to 2 μm.

  The material of the first particles only needs to be transparent and have a refractive index larger than that of the organic film. Since the refractive index of a general organic resin is about 1.3 to 1.7 at most, it may be 1.8 or more. Since transparent oxide particles with a high refractive index are occupied by metal oxides, a practical value is about 1.8 to 2.8.

  The shape of the first particle is preferably a spherical shape or a polyhedron close thereto. However, it is not always necessary to have a regular shape such as a cube, and it is sufficient that the characteristic length of the fine particles as a whole does not have large anisotropy, and the surface may be uneven.

  The concentration of the first particles in the organic film depends on the dispersibility of the particles in the organic film, but is generally preferably 2 to 50 wt%, preferably 5 to 30 wt%, and more preferably 10 to 25 wt%. is there.

  The thickness of the sealing film depends on the size and concentration of the dispersed particles and the viscosity of the composition constituting the organic film, but is 1 to 200 μm, more preferably 1 to 50 μm, and even more preferably 1 to 1 μm. It is about 10 μm.

  By forming the sealing film under these conditions, light that enters the sealing film and is reflected or totally reflected at the interface and stays in the sealing film can be efficiently extracted to the outside.

  Examples of the second particles dispersed in the organic film for moisture absorption include substances having hygroscopic properties such as alkaline earth metal oxides, alkali metal oxides, metal halides, metal sulfates, and metal perchlorates. Particles are used. Among these, alkaline earth metal oxides are preferable from the viewpoints of handling, cost, hygroscopicity and the like. In general, powder has a property of easily absorbing moisture regardless of the material. Desirably, the second particles mixed with the resin for moisture absorption do not absorb moisture as much as possible. Also from such a point, CaO is more preferable because an anhydride can be easily obtained.

  If the diameter of the second particle is too smaller than the wavelength of light, it has the effect of changing the average refractive index of the resin with respect to the light. Therefore, unless the organic film is taken into consideration, the diameter of the second particle is smaller than the wavelength of the light. Particles having an excessively large particle size (specifically, a particle size of less than about 200 nm) are not preferable. Particles having a particle size of less than 200 nm have a high surface area to volume ratio, and have an advantage of higher moisture absorption efficiency than those having a larger particle size when compared with the same weight. However, if the particle size is reduced, a treatment such as modification of the surface with organic molecules is required for dispersion, which is not preferable in terms of hygroscopicity. On the other hand, particles that are too large (200 μm or more in particle size) are not preferable because the ratio of the surface area to the volume decreases and the hygroscopic efficiency decreases. Therefore, the average particle diameter of the second particles is preferably about 200 nm to 200 μm. Furthermore, considering that the second particles for moisture absorption also have a light scattering function, it is preferable for controlling the optical function to have the same size as the first particles used for light scattering. It is.

For example, in addition to light scattering particles (first particles), CaO particles (second particles) are dispersed in the resin at a concentration of 20 wt% with respect to the weight of the organic resin, and the sealing film has a thickness of 10 μm. Consider the case of forming. Since the density of the resin is approximately ρ _P ˜1 g / cm ³ and the density of _CaO is ρ _CaO ˜3.35 g / cm ³ , when CaO completely absorbs moisture, 747.4 mg / m ² per unit area (41.5 mol) can be absorbed. Considering realistically, if about 10 wt% of the dispersed particles contribute to moisture absorption, 74.7 mg / m ² of water is absorbed.

For example, Proceedings of the International Society for Optical Engineering, Vol. 4105, Item 75 (2001) (Proc. SPIE 4105, 75 (2001).) Provides an estimate of the water vapor transmission rate allowed for OLED devices. Accordingly, OLED devices are required to have a water vapor ^{transmission rate} of <10 ⁻⁵ g / m ² · day. This document makes a trial calculation based on the amount of water necessary for deactivation of the cathode electrode used in the OLED. Therefore, in consideration of the fact that it is expected that a stricter standard than this estimation is actually required, the standard of moisture permeability required for the OLED is set to 10 ⁻⁶ g / m ² · day.

Laminating an organic film in which the first and second particles are dispersed, and an inorganic film having a water vapor permeability of, for example, 10 ⁻⁴ g / m ² · day and capable of transmitting visible light. Thus, a laminated sealing film that can satisfy the required specifications for approximately two years can be obtained. Further, the hygroscopicity can be further increased by increasing the thickness of the sealing film, increasing the concentration of particles to be dispersed, or lowering the moisture permeability of the inorganic film. In this way, by making the sealing film a laminated structure of an organic film and an inorganic film, it is possible to easily achieve high performance and long life of the sealing function and the addition of the light extraction function simultaneously. Can do.

Since fine particles cannot be dispersed in the inorganic film, it is necessary to select a refractive index considering light extraction when determining the composition of the inorganic film. The preferable refractive index of the inorganic film used in the present invention is about 1.5 to 2.2, and the density is about 2.2 to 3.3 g / cm ³ . Examples of such an inorganic film include SiO ₂ , SiN, and SiON. It is known that the film density of these films changes depending on the film forming method and film forming conditions, and the refractive index changes accordingly. For example, Japanese Patent Application Laid-Open No. 2003-262750 discloses that the refractive index changes depending on the amount of nitrogen gas supplied when forming the SiON film. Furthermore, since the SiON film can widely change the composition of the film from SiO ₂ to SiN, the control range of the refractive index can be expanded.

  The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

  It is possible to realize a sealing film having both a light extraction function necessary for an OLED and the like and a sealing function of moisture and oxygen.

(A) is a diagram schematically showing how light is reflected and refracted at an interface between substances having different refractive indexes, and (b) is a diagram schematically showing a case where light is transmitted through two interfaces; (C) is the figure which showed typically a mode that the light which passed through one interface received total reflection in the next interface. It is the figure which showed typically how the light light-emitted in the light emitting layer of OLED propagates the inside of OLED. It is sectional drawing which shows typically the sealing film which is Embodiment 1 of this invention. It is sectional drawing which shows typically the sealing film which is Embodiment 2 of this invention. It is sectional drawing which shows typically the structure of the top emission type OLED using the sealing film of this invention.

(Embodiment 1)
FIG. 3 is a cross-sectional view schematically showing a sealing film having a light extraction function and a sealing function, which is an embodiment of the present invention.

  As shown in FIG. 3, a sealing film 30 made of an organic resin film 31 in which first particles 32 for light scattering and second particles 33 for moisture absorption are dispersed is formed on the substrate 10. Has been. In addition, since the particle size of the 1st particle | grain 32 and the particle size of the 2nd particle | grain 32 have distribution, respectively, there exists dispersion | variation in a particle size centering on an average particle size.

  In the first embodiment, an epoxy resin is used for the organic resin film 31. First, in order to photocur the epoxy monomer, 5 parts by weight of an acid generator and 1 part by weight of a photosensitizer were mixed with 100 parts by weight of the epoxy monomer to obtain a composition.

  The epoxy monomer is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (3, 4-Epoxycyclohexylmethyl 3, 4-epoxycyclohexanecarboxylate), and the acid generator is diphenyliodonium hexafluorophosphate (Diphenyliodonium). Hexafluorophosphate) and 9,10-dibutoxyanthracene were used as photosensitizers, respectively. 25 wt% of the first particles 32 were mixed therewith, and the particles were dispersed by rotary stirring and ultrasonic treatment.

ZrO ₂ (average particle size 0.57 μm, 1 μm, and 2 μm), BaTiO ₂ (average particle size 400 nm, and 1 μm), and TiO ₂ (average particle size 2 μm) were used for the first particles 32, respectively. Note that no surface treatment of the first particles 32 is performed. Furthermore, as the second particles 33, anhydrous CaO particles (average particle size 3 μm) were mixed at 10 wt% with respect to the weight of the monomer composition and dispersed in the same manner. The above operation was performed in a dry nitrogen atmosphere to avoid moisture absorption.

The obtained mixture was formed on a glass substrate 10 by a spin coater (rotation speed: 5000 rpm), and then the film was cured using a UV-LED lamp. A UV-LED lamp having a center wavelength of 375 nm and an output of 12 mW / cm ² was used and irradiated for 60 seconds. These operations were also performed under a nitrogen atmosphere. In this way, a sealing film 30 having a thickness of about 10 μm was obtained. Next, this sealing film 30 was attached to the glass substrate side of the bottom emission type OLED element formed on the glass substrate via a refractive index adjusting liquid. When the amount of light emitted from the OLED when the sealing film 30 was attached to the glass substrate and when it was not attached was evaluated using an integrating sphere, the ratio of the amount of light when it was attached to the case where it was not attached is It became like Table 1.

  In the first embodiment, the photocurable alicyclic epoxy resin is used for the resin (organic resin film 31), but the present invention is not limited to this. A resin that is photocured without damaging the OLED by irradiating UV light for a short time, or a resin that is thermoset at a temperature of about 100 ° C. and having a transmittance of 90% or more may be used. Examples of such resins include epoxy resins, acrylic resins, methacrylic resins, and silicone resins. Epoxy resins are relatively resistant to light irradiation, have less degassing due to light irradiation, and have advantages such as widening the choice of curing method and curing conditions when including thermal curing. Acrylic resins and methacrylic resins have advantages such as high transmittance and a great number of curing options. Silicone-based resins have the advantage of extremely high transparency and extremely stability against light irradiation. There are other options such as vinyl resin, urethane resin, and cellulose resin.

The particles for light scattering (first particles 32) are not limited to the three types taken up in the first embodiment. It is only necessary to be transparent and stable and have a refractive index larger than that of the resin. Examples of such particles include ZnO _x , Y ₂ O ₃ , Al ₂ O _{3 and the} like. The size of the particles is not limited to those listed above. When the average particle size was 200 nm to 10 μm and the concentration range was as follows, the light extraction amount could be increased to at least about 1.3 times. If it was 400 nm-2 micrometers, it could be increased to at least about 1.5 times. The particle concentration is not limited to the above. When the particle concentration was 2 wt% to 50 wt% with respect to the weight of the resin, a light extraction amount of 1.3 times or more could be obtained. Further, the amount of light extraction can be increased approximately 1.4 times if it is 5 to 30 wt%, and approximately 1.5 times or more if it is 10 to 25 wt%. The particle type and the average particle size are not limited to a single type, and a plurality of types may be mixed.

Further, the particles for absorbing moisture (second particles 33) are not limited to those described above. Alkaline earth metal oxides other than CaO (for example, MgO, SrO, BaO), alkali metal oxides (for example, Li ₂ O, Na ₂ O, K ₂ O), metal halides (for example, CaCl ₂ , MgCl ₂ , SrCl ₂₎ , YCl ₂ , CuCl, CsF, TaF ₂ ), metal sulfides (for example, Li ₂ SO ₄ , Na ₂ SO ₄ , CaSO ₄ , MgSO ₄ ) and other hygroscopic substances may be used. Regarding the particle diameter, the first embodiment uses an object having an average particle diameter of 3 μm. However, there is no problem even if particles having a size of a fraction of 1 to 10 times the wavelength of light are used. It is sufficient that the particle diameter is at least within this range or distributed within this range. Further, a plurality of such particles may be included with respect to the type and particle size of the particles.

  Regarding the method for forming the sealing film 30, the spin coater is used in the first embodiment, but the present invention is not limited thereto.

(Embodiment 2)
The sealing film of the second embodiment is configured by a laminated film of an organic film and an inorganic film that have been provided with a light extraction function and a sealing function. FIG. 4 is a cross-sectional view schematically showing this configuration.

First, an inorganic film 41a made of SiON is formed on the glass substrate 10 by sputtering. The gas flow rate during film formation was adjusted, and the film was formed such that the ratio (O: N) of oxygen atoms (O) to nitrogen atoms (N) in the film was approximately 7: 3. At this time, the film density was 3 g / cm ² and the refractive index was 1.8. The film thickness was approximately 100 nm.

  Next, an organic resin film 31a in which light scattering particles (first particles) and moisture absorption particles (second particles) are dispersed on the inorganic film 41a in the same manner as in the first embodiment. A film was formed. This operation is repeated to obtain a laminated film in which a set of inorganic films 41a, 41b, and 41c and organic resin films 31a, 31b, and 31c is stacked in three layers. Finally, an inorganic film 41d was formed on the laminated film in the same manner to obtain a sealing film 40 having a laminated structure of an organic film and an inorganic film.

  The composition of the inorganic film is not limited to SiON. Decreasing the ratio of oxygen atoms (O) increases the density of the film and increases the barrier property, but has the disadvantage that coloring occurs. On the other hand, increasing the ratio of oxygen atoms (O) decreases the refractive index of the film and reduces the loss due to reflection at the interface between the organic film and the inorganic film, but decreases the density of the film and lowers the barrier properties.

  Moreover, each composition and film thickness of the inorganic films 41a, 41b, 41c, and 41d may be different in each layer. Accordingly, for example, by increasing the moisture permeability of the inorganic film on the side in contact with air, the life can be further extended. In this case, by reducing the refractive index of the other inorganic film and taking in more light incident from the light emitting layer side of the OLED into the sealing film 40, the high refractive index inorganic film in contact with the atmosphere It is possible to reduce reflection loss due to a large refractive index difference formed between the air layer. Furthermore, the number of inorganic films is not limited to four.

  Similarly, the composition of the organic resin films 31a, 31b and 31c need not be the same in all layers. For example, a high concentration of particles for scattering light (first particles) is set in a film closer to the light emitting layer side, and a high concentration of particles for absorbing moisture (second particles) is set in a layer closer to the air side. By setting to, the hygroscopicity can be enhanced without impairing the scattering function. Furthermore, the number of organic resin films is not limited to three.

  In the second embodiment, the inorganic film 41a is first formed on the substrate 10, but the organic resin film 31a may be formed first. When the inorganic film is formed first, there is an advantage that the inorganic film works as a barrier film to the base when forming the organic resin film.

(Embodiment 3)
FIG. 5 is a cross-sectional view schematically showing a configuration of a top emission type OLED using the sealing film 40 of the second embodiment. As shown in FIG. 5, the top emission type OLED has a configuration in which a reflective electrode 11, an organic molecular layer 12 including an organic light emitting layer, a transparent electrode 13, and a sealing film 40 are laminated on a substrate 10 in this order. The reflective electrode 11 constituting the cathode is made of a metal that reflects light such as silver (Ag) or Al (aluminum), and the transparent electrode 13 constituting the anode is made of ITO or IZO.

  The procedure for forming the OLED followed the method described in the second embodiment in Patent Document 4 (Japanese Patent Laid-Open No. 2010-0667464). Each layer constituting the OLED was formed in a vacuum apparatus in order to prevent damage. Next, the sealing film 40 is formed on the transparent electrode 13. However, in the second embodiment, the sealing film 40 is formed on the glass substrate. However, in the third embodiment, the sealing film 40 is formed on the transparent electrode 13. In this case, it is desirable that the first film formed on the transparent electrode 13 is an inorganic film, not an organic film. This is because damage to the underlayer (OLED) due to the liquid monomer when forming the organic film and UV light irradiated during curing can be prevented.

  When the sealing film 40 is formed on the OLED, the transparent electrode 13 functions as a temporary sealing film, so that the subsequent formation of the organic film can be performed quickly in the atmosphere. However, in this case, in order to prevent moisture in the atmosphere from being adsorbed on the surface of each film or moisture absorption of each film, it is desirable to carry out under a dry inert gas. Further, it is desirable to move between the load lock chamber of the vacuum apparatus and the dry inert gas environment without being exposed to the atmosphere even when transporting between the vacuum layer and the dry inert gas environment.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The sealing film of the present invention can be used in various fields as a functional film having not only a sealing film of OLED but also a light extraction function and a sealing function of moisture and oxygen.

  The present invention can be used for a sealing film having a light extraction function and a sealing function necessary for an OLED or the like.

10 Substrate 11 Reflecting electrode 12 Organic molecular layer 13 Transparent electrode 14 Transparent glass layer (sealing layer)
15 Air layer 21 Light emitting points 22 to 27 Path 30 Sealing film 31, 31a to 31c Organic resin film 32 First particle 33 Second particle 40 Sealing film 41a to 41d Inorganic film

Claims (18)

A sealing film in which first and second particles are dispersed in an organic film,
The first particles are made of a substance having a refractive index larger than that of the organic film and capable of transmitting visible light.
The sealing film, wherein the second particles are made of a substance that has a property of combining with water and can transmit visible light.   The sealing film according to claim 1, wherein the organic film is made of a resin that is cured by heat or light.   The organic film is made of one or more substances selected from the group consisting of epoxy resins, acrylic resins, methacrylic resins, silicone resins, vinyl resins, urethane resins, and cellulose resins. The sealing film according to claim 1.   The sealing film according to claim 1, wherein an average particle diameter of the first particles is 200 nm to 10 μm.   The sealing film according to claim 4, wherein the average particle diameter of the first particles is 400 nm to 2 μm.   The sealing film according to claim 1, wherein the concentration of the first particles in the organic film is 2 to 50 wt%.   The sealing film according to claim 6, wherein the concentration of the first particles in the organic film is 10 to 25 wt%.   The sealing film according to claim 1, wherein the refractive index of the first particles is 1.8 to 2.8. The first particle is made of one or more kinds of substances selected from the group consisting of ZrO ₂ , BaTiO ₂ , TiO ₂ , ZnO _x , Y ₂ O ₃ , and Al ₂ O _3. The sealing film as described.   The second particles are made of one or more substances selected from the group consisting of alkaline earth metal oxides, alkali metal oxides, metal halides, metal sulfates, and metal perchlorates. The sealing film according to claim 1.   The sealing film according to claim 1, wherein the second particles have an average particle diameter of 200 nm to 200 μm.   The sealing film according to claim 1, wherein the organic film and an inorganic film capable of transmitting visible light are laminated.   The sealing film according to claim 12, wherein the inorganic film has a refractive index of 1.5 to 2.2. The sealing film according to claim 12, wherein the density of the inorganic film is 2.2 to 3.3 g / cm ³ . The sealing film according to claim 12, wherein the inorganic film is made of one or more kinds of materials selected from the group consisting of SiO ₂ , SiN, and SiON. A substrate,
A reflective electrode formed on the substrate;
An organic molecular layer formed on the reflective electrode and including at least an organic light emitting layer;
A transparent electrode formed on the organic molecular layer;
A sealing film formed on the transparent electrode;
An organic light emitting diode comprising:
The sealing film is
A single layer organic film in which the first and second particles are dispersed;
The first particles are made of a substance having a refractive index larger than that of the organic film and capable of transmitting visible light.
2. The organic light emitting diode according to claim 1, wherein the second particle is made of a substance having a property of combining with water and capable of transmitting visible light. The first particles are made of one or more substances selected from the group consisting of ZrO ₂ , BaTiO ₂ , TiO ₂ , ZnO _x , Y ₂ O ₃ , Al ₂ O ₃ ,
The second particles are made of one or more substances selected from the group consisting of alkaline earth metal oxides, alkali metal oxides, metal halides, metal sulfates, and metal perchlorates. The organic light emitting diode according to claim 16.   The organic light emitting diode according to claim 16, wherein the sealing film has a laminated structure of the organic film and an inorganic film capable of transmitting visible light.