JP2009037800A - Light-emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element incorporating a function of controlling direction independency of light-extraction intensity, without giving rise to increase of an occupancy space of the element. <P>SOLUTION: The light-emitting element has a light-extraction side of a light-emitting part sealed by multilayer sealing films having at least one organic layer. It contains at least one refractive index adjustment layer in lamination of the multilayer sealing films for adjusting a refraction index of the multilayer sealing films. In the manufacturing method of the light-emitting element with a light-extraction side of a light-emitting part sealed by multilayer sealing films having at least one organic layer, at least one refraction index adjustment layer is formed in the lamination of the multilayer sealing films for adjusting a refraction index of the multilayer sealing films. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device typified by an organic EL device (organic electroluminescence device) and a method for producing the same, and more specifically, the refractive index of a multilayer sealing film for sealing a light emitting layer can be adjusted. The present invention relates to a light-emitting element that improves light extraction efficiency and a method for manufacturing the same.

  In light emitting elements such as organic EL elements and light emitting diode display elements, a light emitting layer sandwiched between an anode and a cathode is laminated on a substrate, and a multilayer sealing film is laminated so as to cover the light emitting layer. In a conventional light emitting device, a glass substrate is used as a substrate. However, in order to meet the demands of lightening the device, improving impact resistance, increasing the area of the device, and increasing the efficiency of manufacturing, a plastic substrate is used. It has begun to be used (for example, Patent Document 1).

  The plastic substrate is flexible and can be easily obtained in a large area, and the cutting work for dividing the light emitting layer into units after the lamination is facilitated. However, the plastic substrate has higher gas and liquid permeability than the glass substrate. Display materials such as the organic EL light-emitting layer encapsulated by the substrate and the upper multilayer sealing film are easily oxidized and easily deteriorated by contact with water. Therefore, when using a plastic substrate, a lower sealing film having a high barrier property against gas and liquid is laminated on the substrate, and then a light emitting layer is laminated on the lower multilayer sealing film, and the laminated light emitting layer An upper multilayer sealing film is laminated so as to cover the surface.

  The lower sealing film is usually formed with the same configuration and the same material as the upper multilayer sealing film. These lower multilayer sealing film and upper multilayer sealing film usually have at least one inorganic layer and at least one organic layer. The number of stacked layers is determined as necessary. Basically, inorganic layers and organic layers are alternately stacked.

  Light extraction from the light emitting element may be performed from the substrate side, from the upper multilayer sealing film side, or from both the substrate side and the upper multilayer sealing film side. The type of light emitting element that extracts light from the substrate side is called a bottom emission type light emitting element, and the type of light emitting element that extracts light from the upper multilayer sealing film side is called a top emission type light emitting element. This light emitting element is called a dual emission type light emitting element. In these types of light emitting elements, the common thing to say is that the multilayer sealing film on the light extraction side needs to be transparent or translucent, and the light extraction efficiency is affected by its physical characteristics. It is. Therefore, in the conventional light emitting device, the multilayer sealing film on the light extraction side is made of a flat layer that is as transparent as possible.

Special table 2003-53745 gazette

  In the conventional light emitting element, it may be necessary to control the direction dependency of the light extraction intensity depending on the application of the various lighting devices, various display devices, and various electronic devices. In such a case, various optical elements such as a scattering sheet are provided on the entire light extraction surface of the light emitting element. However, the installation of these additional optical elements necessitates an occupied space for the various devices on which the light emitting elements are mounted, and this tends to become a bottleneck in downsizing the devices, so improvement is required. Yes.

  The present invention has been made in view of the above-described conventional circumstances, and the problem is that a light-emitting element incorporating a function for controlling the direction dependency of the light extraction intensity is accompanied by an increase in the occupied space of the element. There is no provision. Here, the control of the direction dependency of the light extraction intensity in the light emitting element means the control of the viewing angle on the light emitting surface of the light emitting element or the improvement of the light extraction efficiency in front of the light emitting element.

  In order to solve the above-described problems, a light emitting device according to the present invention is a light emitting device in which a light extraction side of a light emitting unit is sealed with a multilayer sealing film having at least one organic layer. It is characterized by including at least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film in the lamination.

  The method for manufacturing a light emitting device according to the present invention is a method for manufacturing a light emitting device in which a light extraction side of a light emitting part is sealed with a multilayer sealing film having at least one organic layer, the multilayer sealing film At least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film is formed during the lamination of the multilayer sealing film.

  The said structure WHEREIN: It is preferable to form the said refractive index adjustment layer by containing the particulate compound which has a refractive index different from the base material.

  In the above configuration, the multilayer sealing film is formed of at least one first film and at least one second film, and the refractive index adjusting layer is formed from the at least one first film and at least one second film. You may form between these films.

  Further, in the above configuration, the multilayer sealing film is formed of at least one first film and at least one second film, and the refractive index adjusting layer is formed on the at least one first film in the particulate form. You may form by making a compound contain.

  Moreover, in the said structure, it is preferable to use an acrylic polymer as a base material of the said refractive index adjustment layer.

  In the above structure, the first film is preferably an organic layer, the second film is preferably an inorganic layer, and the organic film is preferably formed from an acrylic polymer.

  In the above configuration, a hollow structure may be used as the particulate compound. Moreover, you may use at least 1 sort (s) chosen from the group which consists of a silica, a polystyrene, and a fluorine substituted polystyrene as this granular compound.

  The present invention is particularly useful when the target light-emitting element is an organic EL light-emitting element.

  The light emitting device according to the present invention is transparent from the front, but becomes opaque when viewed from an oblique direction, and the front luminance of the light emitting device is improved. Such an effect can be achieved by forming at least one refractive index adjusting layer in the multilayer sealing film on the light extraction side. Since this refractive index adjusting layer is formed by containing a particulate compound having a refractive index different from that of the base material, it can be easily formed as one layer in the multilayer sealing film. As the base material of the refractive index adjustment layer, the organic layer forming the multilayer sealing film may be used as it is, or an organic compound that forms a new layer may be used. Is easy. In addition, in the case of using an optical film which is a conventional means, an advanced attaching step and an optical film member are required. In the manufacturing method of the present invention, the refractive index adjustment layer is formed by a normal sealing film formation. Since the process can be performed during the process, a light-emitting element with a simple process and excellent light extraction efficiency can be easily manufactured.

  Therefore, according to the light emitting element and the manufacturing method thereof according to the present invention, it is possible to provide a light emitting element with improved light extraction efficiency without increasing the space occupied by the light emitting element.

Below, the light emitting element concerning this invention and its manufacturing method are demonstrated in more detail.
As described above, the light emitting device according to the present invention is the light emitting device according to the present invention, wherein the light extraction side of the light emitting part is sealed by the multilayer sealing film having at least one organic layer. It is characterized by including at least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film in the lamination of the sealing films.

  The method for manufacturing a light emitting device according to the present invention is a method for manufacturing a light emitting device in which a light extraction side of a light emitting part is sealed with a multilayer sealing film having at least one organic layer, the multilayer sealing film At least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film is formed during the lamination of the multilayer sealing film.

  Since the refractive index adjusting layer is formed by containing a particulate compound having a refractive index different from that of the base material, it can be easily formed as one layer in the multilayer sealing film. As the base material of the refractive index adjusting layer, the organic layer forming the multilayer sealing film may be used as it is, or an organic compound for newly forming a layer may be used.

  The refractive index adjusting layer contains a particulate compound having a refractive index different from that of the base material in the base material. This particulate compound is preferably uniformly dispersed and scatters the light traveling outward from the light emitting part by each transparent particle, so that the direction dependency of the extracted light intensity can be controlled. The base material of the refractive index adjusting layer is configured using a material similar to or similar to the constituent material of the organic layer forming the multilayer sealing film.

  By adjusting the particle size of the particulate compound used in the refractive index adjusting layer, the refractive index value can be controlled. Also, the refractive index can be controlled by the amount of the particulate compound used. The amount of the particulate compound added is preferably adjusted within a range of 0.01 to 50% by mass with respect to the total amount of the refractive index adjusting layer. If it is less than 0.01% by mass, the desired refractive index control is not performed, and if it exceeds 50% by mass, the film strength of the refractive index adjusting layer may be deteriorated. Further, the average particle diameter of the particulate compound is not uniquely determined by the target degree of refractive index control and the amount added, but is preferably adjusted in the range of 0.05 μm to 1 μm.

  Moreover, it is preferable that the particulate compound mixed in the organic layer which is a base material of the refractive index adjusting layer is uniformly dispersed in the layer. In addition, the particulate compound mixed in the organic layer may be dispersed only in the layer so as not to disturb the interface of the organic layer, or it is dispersed so as to protrude from the interface to the outside of the layer and to form irregularities in the interface. Also good. Since the refractive index is further adjusted by forming irregularities at the interface of the organic layer, it is preferable from the viewpoint that the controllability of the total refractive index can be improved.

  In the present invention, since the refractive index adjusting layer is formed in the multilayer sealing layer, it can be formed in the lower multilayer sealing layer or can be formed in the upper multilayer sealing film. Therefore, the light-emitting element which is the subject of the present invention can be applied to a top emission type light emitting element, a bottom emission type light emitting element, and a dual emission type light emitting element.

  Hereinafter, the structure of the multilayer sealing film constituting the light emitting device of the present invention, the constituent materials thereof, and the constituent materials of the refractive index adjusting layer will be described in detail.

In the present invention, the lower multilayer sealing film formed on the substrate may be directly laminated on the substrate, or may be laminated via some intermediate layer. As such an intermediate layer, for example, a lyophilic layer for making the substrate surface lyophilic can be considered. Such a direct or indirect stacking relationship is the same in the stacking relationship of the lower multilayer sealing film-the light emitting layer-the upper multilayer sealing film in the light emitting device of the present invention. That is, the light emitting part may be directly laminated on the lower multilayer sealing film, or indirectly laminated. Similarly, the upper multilayer sealing film formed on the light emitting layer may be directly laminated on the light emitting layer or indirectly laminated. For example, when an example of a laminated structure in an organic EL element is given, flexible substrate / (organic / inorganic) lower multilayer sealing film / anode (for example, ITO) / hole injection layer (for example, MoO ₃ film / poly (3, 4) Ethylenedioxythiophene / polystyrene sulfonic acid film) / polymer organic light emitting material layer / electron injection layer (for example, Ba film) / cathode layer (for example, Al film) / (organic / inorganic) upper multilayer sealing film) ).

  The thickness of the organic layer and the inorganic layer constituting the lower and upper multilayer sealing films is preferably in the range of 50 to 10 μm. When the thickness is less than 50 mm, it is difficult to maintain the mechanical properties of the film well. When the thickness exceeds 10 μm, the entire film thickness is increased. In an organic EL element or the like, the light extraction efficiency from the light emitting layer is affected. In some cases.

(Constituent material of lower and upper multilayer sealing films)
As the inorganic layer constituting the lower and upper multilayer sealing films, materials such as silicon oxide (SiO ₂ ), silicon nitride (SiN), silicon oxynitride (SiON), and aluminum oxide (Al ₂ O ₃ ) are preferably used. Used. As a method for forming the inorganic film, a known thin film forming method such as a sputtering method or a plasma CVD method can be used. In addition, in the multilayer sealing film used for this invention, the layer which consists of inorganic films is called an inorganic layer.

  On the other hand, as the organic layer constituting the lower and upper multilayer sealing films, mainly, an organic monomer having a (meth) acryl group having good adhesion with the inorganic layer material, that is, a (meth) acrylic compound is polymerized. The acrylic polymer formed is preferably used. In the multilayer sealing film used in the present invention, a layer made of an organic film is referred to as an organic layer.

  The (meth) acrylic compound is formed into a coating film by a known coating film forming method such as a solution coating method or a spray coating method, and light energy (chemical rays such as electron beam, plasma beam, ultraviolet ray) is applied to the coating film. It polymerizes by irradiating or applying thermal energy to obtain an acrylic polymer. At this time, in the present invention, a solid structure is formed on one side of the organic layer simultaneously with the complete curing of the organic layer by the semi-curing means or the coating film forming means on the lyophobic surface for at least one organic layer.

  The (meth) acrylic compound is not particularly limited as long as it is a compound containing one or more (meth) acrylic groups in the molecule. When there is one (meth) acryl group, higher adhesion to the inorganic layer can be obtained. When the number is two or three, the crosslink density is high, and the film strength of the organic layer is higher.

  Examples of the (meth) acrylic compound include compounds having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) ) Acrylates, compounds having amino groups such as diethylaminoethyl (meth) acrylate, (meth) acrylic acid, 2- (meth) acryloisooxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, etc. It has a cyclic skeleton such as a compound having a carboxyl group, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclohexyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate ( Acrylate), isoamyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol ( Acrylic monofunctional compounds such as (meth) acrylate, diethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol (meth) acrylate, 1,9-nonanediol di (meth) ) Acrylate, triethylene di (meth) acrylate, PEG # 200 di (meth) acrylate, PEG # 400 di (meth) acrylate, PEG # 600 di (meth) acrylate, neo Bifunctional (meth) acrylic compounds such as bifunctional urethane (meth) acrylates, such as bifunctional epoxy (meth) acrylates, bifunctional acrylic (meth) acrylates, etc., such as ntil di (meth) acrylate and dimethylol tricyclodecane di (meth) acrylate Can be mentioned. Examples of the compound having three or more (meth) acrylic acids include dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, trimethylolpropane triacrylate, and trimethylol. An acrylic polyfunctional monomer such as propanetetraacrylate, (meth) acryl polyfunctional epoxy acrylate, (meth) acryl polyfunctional urethane acrylate, and the like can be used.

(Particulate compound used for refractive index adjustment layer)
As described above, the refractive index adjustment layer may be formed by uniformly adding a particulate compound to the material monomer when forming the organic layer constituting the multilayer sealing layer. . In that case, the organic layer of a multilayer sealing layer is used together as a refractive index adjustment layer. Alternatively, a refractive index adjustment layer may be newly interposed between the layers constituting the multilayer sealing layer. In this case, a refractive index adjustment layer is newly formed in the same manner as in the case of forming the organic layer.

  The particulate compound used for the refractive index adjusting layer may be organic particles, inorganic particles, or a mixture thereof. These particulate compounds may have a large refractive index or a small refractive index relative to the refractive index of the organic compound used as a base material of the refractive index adjusting layer. It is appropriately selected depending on the target degree of control of the refractive index. As a combination of the refractive index of the base material and the particulate compound, a combination of an inorganic material having a high refractive index and an organic material having a low refractive index, a combination of an organic material having a high refractive index and an organic material having a low refractive index, or , And a mixture of several types of these materials. The difference in refractive index here is preferably a difference of 0.05 or more, more preferably a difference of 0.1 or more, from the viewpoint of effectively causing light scattering.

  The size of the particulate compound is preferably about the same as the wavelength of light, from the viewpoint of effectively inducing uniform light scattering, and is preferably 0.05 μm to 1 μm, more preferably 0.00. 1 μm to 0.8 μm.

  Here, examples of the particulate compound having a small particle diameter include metal oxides such as titanium oxide and aluminum oxide, metal composite oxide fine particles, high refractive index fine particles such as organic titanium compounds, acrylic acid esters, and methacrylic esters. Low refractive index fine particle materials such as spherical hollow fine particles, porous fine particles, multi-layered fine particles such as core / shell structures, fluororesin fine particles and hollow glass fine particles obtained by polymerizing monomers mainly with acid esters and styrene Can be used.

  As described above, the addition amount of the particulate compound is adjusted within the range of 0.01% by mass to 50% by mass, but retains the mechanical strength of the refractive index adjustment layer and aggregates fine particles. From the viewpoint of preventing, the amount added is preferably 20% by mass or less, and more preferably 10% by mass or less.

(Other additives)
As described above, the refractive index adjusting layer (organic layer) tends to decrease the mechanical strength by adding the particulate compound. Therefore, in order to improve the strength of the layer and the adhesion to the adjacent layer, DPHA ( Additives such as polyfunctional acrylates such as dipentaerythritol hexaacrylate: hexafunctional acrylate), fluorine-substituted products thereof, polyfunctional epoxy compounds, and silane coupling agents may be used.

  The sealing film used in the present invention may have an adhesion improving layer. The adhesion improving layer includes a material that enhances the adhesion, and examples of the material that enhances the adhesion include a crosslinked polymer compound and a silane coupling agent.

  The cross-linked polymer compound is obtained by cross-linking a monomer compound (polymerizable compound) having a polymerizable substituent by application of heat energy or light energy and the action of a thermal polymerization initiator or photopolymerization initiator. Is mentioned. A polymerizable substituent (sometimes referred to as a crosslinking group) refers to a substituent that can form a compound by forming a bond between two or more molecules by causing a polymerization reaction. Examples of such a crosslinking group include a vinyl group, an acetylene group, a butenyl group, an acrylic group, an acrylate group, an acrylamide group, a methacryl group, a methacrylate group, a methacrylamide group, a vinyl ether group, a vinylamino group, a silanol group, and a small ring ( For example, a group having a cyclopropyl group, a cyclobutyl group, an epoxy group, an oxetane group, a diketene group, an episulfide group, or the like, a lactone group, a lactam group, or a group containing a siloxane derivative.

  In addition to the above groups, combinations of groups capable of forming an ester bond or an amide bond can also be used. For example, a combination of an ester group and an amino group, an ester group and a hydroxyl group, or the like.

  Moreover, the material which shows physical adsorptivity to an interface like a silane coupling agent is also mentioned.

  Among the above materials, a monomer having a (meth) acrylate group is particularly preferable. Specific examples of the monofunctional monomer having a (meth) acrylate group include 2-ethylhexyl carbitol acrylate and 2-hydroxyethyl acrylate. Specific examples of the bifunctional monomer having a (meth) acrylate group include 1,6-hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and triethylene glycol. Examples include di (meth) acrylate and 3-methylpentanediol di (meth) acrylate. Specific examples of other polyfunctional monomers having a (meth) acrylate group include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipentaerythritol penta (meth). Examples thereof include acrylate, dipentaerythritol hexa (meth) acrylate, and trispentaerythritol octa (meth) acrylate. Among them, a polyfunctional monomer having two or more functions, preferably five or more functions, and more preferably eight or more functions is excellent in curability and adhesion, and is preferably used. Here, the “number of functionalities” means the “number of crosslinking groups” described above. That is, the functional group of the polyfunctional monomer means a crosslinking group that the monomer has.

  In addition, about the crosslinking agent used for the said superposition | polymerization, it describes in the 17th-56th pages of a photopolymer handbook (Industry Research Society publication, 1989), for example.

  Moreover, when the above-mentioned material has a fluorine atom, the water repellent effect also acts and the barrier property of the sealing film can be improved.

  The light emitting device and the method for manufacturing the light emitting device according to the present invention having the above-described configuration are particularly useful when the light emitting device is an organic EL device. Also in such an organic EL element, the configuration of the multilayer sealing film described in detail above is the same. Therefore, other main components such as a substrate and a light emitting layer in the organic EL element to which the present invention can be suitably applied will be described in detail below.

(substrate)
The substrate used for the organic EL element may be any substrate that does not change when the electrode is formed and the organic layer is formed. For example, glass, plastic, polymer film, silicon substrate, or a laminate of these is used. It is done.

(Electrode and light emitting layer)
As a basic structure of the organic EL element, at least one light emitting layer is provided between an electrode composed of a pair of an anode (first electrode) and a cathode (second electrode) in which at least the cathode is transparent or translucent with light transmission. Have For the light emitting layer, a low molecular weight and / or high molecular weight organic light emitting material is used.

  In the organic EL element, examples of components around the light emitting layer include those provided between the cathode and the light emitting layer and those provided between the anode and the light emitting layer as layers other than the cathode, the anode, and the light emitting layer. Examples of the material provided between the cathode and the light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer.

  The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode, and the electron transport layer is a layer having a function of improving electron injection from the electron injection layer or the electron transport layer closer to the cathode. is there. When the electron injection layer or the electron transport layer has a function of blocking hole transport, these layers may be referred to as a hole blocking layer. Having the function of blocking hole transport makes it possible, for example, to produce an element that allows only hole current to flow, and confirm the blocking effect by reducing the current value.

  Examples of what is provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer.

  The hole injection layer is a layer having a function of improving the hole injection efficiency from the cathode, and the hole transport layer improves the hole injection from the hole injection layer or the hole transport layer closer to the anode. This is a functional layer. When the hole injection layer or the hole transport layer has a function of blocking electron transport, these layers may be referred to as an electron block layer. Having the function of blocking electron transport makes it possible, for example, to manufacture an element that allows only electron current to flow, and confirm the blocking effect by reducing the current value.

Various combinations around the light emitting layer as described above include a structure in which a hole transport layer is provided between the anode and the light emitting layer, a structure in which an electron transport layer is provided between the cathode and the light emitting layer, and a cathode and light emission. Examples include a configuration in which an electron transport layer is provided between the layers and a hole transport layer is provided between the anode and the light emitting layer. For example, the following structures a) to d) are specifically exemplified.
a) Anode / light emitting layer / cathode b) Anode / hole transport layer / light emitting layer / cathode c) Anode / light emitting layer / electron transport layer / cathode d) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (Here, / indicates that each layer is laminated adjacently. The same shall apply hereinafter.)

  Here, as described above, the light emitting layer is a layer having a function of emitting light, the hole transporting layer is a layer having a function of transporting holes, and the electron transporting layer has a function of transporting electrons. It is a layer which has. The electron transport layer and the hole transport layer are collectively referred to as a charge transport layer. Two or more light emitting layers, hole transport layers, and electron transport layers may be used independently. Further, among the charge transport layers provided adjacent to the electrodes, those having a function of improving the charge injection efficiency from the electrodes and having the effect of lowering the driving voltage of the element are particularly charge injection layers (hole injection layers). , An electron injection layer).

  Furthermore, in order to improve the adhesion with the electrode or the improvement of charge injection from the electrode, the charge injection layer or the insulating layer having a thickness of 2 nm or less may be provided adjacent to the electrode, and the adhesion at the interface may be increased. In order to improve or prevent mixing, a thin buffer layer may be inserted at the interface between the charge transport layer and the light emitting layer. The order and number of layers to be laminated, and the thickness of each layer can be appropriately used in consideration of light emission efficiency and element lifetime.

Moreover, as an organic EL element provided with a charge injection layer (electron injection layer, hole injection layer), an organic EL element provided with a charge injection layer adjacent to the cathode, and a charge injection layer provided adjacent to the anode. An organic EL element is mentioned. For example, the following structures e) to p) are specifically mentioned.
e) Anode / charge injection layer / light emitting layer / cathode f) Anode / light emitting layer / charge injection layer / cathode g) Anode / charge injection layer / light emitting layer / charge injection layer / cathode h) Anode / charge injection layer / hole Transport layer / light emitting layer / cathode i) anode / hole transport layer / light emitting layer / charge injection layer / cathode j) anode / charge injection layer / hole transport layer / light emitting layer / charge injection layer / cathode k) anode / charge Injection layer / light emitting layer / charge transport layer / cathode l) anode / light emitting layer / electron transport layer / charge injection layer / cathode m) anode / charge injection layer / light emitting layer / electron transport layer / charge injection layer / cathode n) anode / Charge injection layer / hole transport layer / light emitting layer / charge transport layer / cathode o) anode / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode p) anode / charge injection layer / hole transport Layer / light emitting layer / electron transport layer / charge injection layer / cathode

(anode)
For the anode, for example, as a transparent electrode or a semitransparent electrode, a metal oxide, metal sulfide or metal thin film with high electrical conductivity can be used, and a high transmittance can be suitably used. Are appropriately selected and used. Specifically, indium oxide, zinc oxide, tin oxide, and a composite film made of conductive glass made of indium / tin / oxide (ITO), indium / zinc / oxide, etc. (NESA) Etc.), gold, platinum, silver, copper and the like are used, and ITO, indium / zinc / oxide, and tin oxide are preferable. Examples of the production method include a vacuum deposition method, a sputtering method, an ion plating method, a plating method, and the like. Further, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the anode.

  The film thickness of the anode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm. is there.

(Hole injection layer)
As described above, the hole injection layer can be provided between the anode and the hole transport layer or between the anode and the light emitting layer. Materials for forming the hole injection layer include phenylamine, starburst amine, phthalocyanine, vanadium oxide, molybdenum oxide, ruthenium oxide, aluminum oxide and other oxides, amorphous carbon, polyaniline, polythiophene derivatives, etc. It is done.

(Hole transport layer)
Materials constituting the hole transport layer include polyvinyl carbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine. Derivatives, polyaniline or derivatives thereof, polythiophene or derivatives thereof, polyarylamine or derivatives thereof, polypyrrole or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof, etc. Is exemplified.

  Among these, as a hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in a side chain or a main chain, polyaniline or a derivative thereof, Polymeric hole transport materials such as polythiophene or derivatives thereof, polyarylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and more preferred Is polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in a side chain or a main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

(Light emitting layer)
In the present invention, the light emitting layer is an organic light emitting layer, and usually has organic substances (low molecular compounds and high molecular compounds) that mainly emit fluorescence or phosphorescence. Further, a dopant material may be further included. Examples of the material for forming the light emitting layer that can be used in the present invention include the following.

(Light-emitting layer forming material 1: dye-based material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

(Light emitting layer forming material 2: metal complex material)
Examples of the metal complex material include metal complexes that emit light from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyls. Zinc complex, porphyrin zinc complex, europium complex, etc., which has Al, Zn, Be or the like as the central metal or rare earth metal such as Tb, Eu, or Dy, and the ligand is oxadiazole, thiadiazole, phenylpyridine, phenylbenzo Examples thereof include metal complexes having an imidazole or quinoline structure.

(Light-emitting layer forming material 3: polymer material)
Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized chromophores and metal complex light emitting materials. Etc.

  Examples of the material that emits blue light among the light emitting layer forming materials include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

  Examples of the light emitting layer forming material that emits green light include quinacridone derivatives, coumarin derivatives, polymers thereof, polyparaphenylene vinylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

  Examples of the material that emits red light among the light emitting layer forming materials include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

(Light-emitting layer forming material 4: dopant material)
A dopant can be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like.

(Electron transport layer)
As the material for forming the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthraquinodi. Examples include methane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, and the like. The

  Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferable.

(Electron injection layer)
As described above, the electron injection layer is provided between the electron transport layer and the cathode, or between the light emitting layer and the cathode. Depending on the type of the light emitting layer, the electron injection layer is an electron injection layer having a single layer structure of Ca layer, or a metal of group IA and IIA of the periodic table excluding Ca and having a work function of 1. It is possible to provide an electron injection layer having a laminated structure of a Ca layer and a layer formed of one or more of 5-3.0 eV metal and oxides, halides and carbonates of the metal. . Examples of metals of Group IA of the periodic table having a work function of 1.5 to 3.0 eV or oxides, halides, and carbonates thereof include lithium, lithium fluoride, sodium oxide, lithium oxide, lithium carbonate, and the like. Can be mentioned. Examples of metals of Group IIA of the periodic table excluding Ca having a work function of 1.5 to 3.0 eV or oxides, halides and carbonates thereof include strontium, magnesium oxide, magnesium fluoride, fluorine Strontium fluoride, barium fluoride, strontium oxide, magnesium carbonate and the like.

(cathode)
For the cathode, as transparent or semi-transparent electrode, metal, graphite or graphite intercalation compound, inorganic semiconductor such as ZnO (zinc oxide), ITO (indium tin oxide), IZO (indium zinc zinc oxide), etc. And conductive oxides such as strontium oxide and barium oxide. Examples of the metal include alkali metals such as lithium, sodium, potassium, rubidium and cesium; alkaline earth metals such as beryllium, magnesium, calcium, strontium and barium, gold, silver, platinum, copper, manganese, titanium, cobalt, Transition metals such as nickel and tungsten; tin, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium; and alloys of two or more thereof. Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, and the like. The cathode may have a laminated structure of two or more layers. Examples of this include a laminated structure of the above metals, metal oxides, fluorides, alloys thereof, and metals such as aluminum, silver, and chromium.

  Examples of the present invention will be described below. The following examples are preferred examples for explaining the present invention, and do not limit the present invention.

  In addition, a following example is an illustration in case a light emitting element is an organic EL element. In this organic EL element, as described above, the electrode element is most simply composed of only an anode and a cathode, and these may be laminated on both sides of the light emitting layer to form a light emitting part. In addition to the anode and cathode, other electrode elements such as hole injection layer, hole transport layer, electron transport layer, and electron injection layer are combined in various ways and stacked on the light emitting layer to form a light emitting part. May be. In the following examples, the electrode elements formed on both sides of the light emitting layer are simply described, but it is obvious that the present invention can be similarly applied to any configuration of electrode elements stacked on the light emitting layer. is there. That is, after various combinations of electrode elements are laminated on the light emitting layer, a multilayer sealing film is laminated thereon. In the present invention, the light emitting layer is sealed with the multilayer sealing film means the above-described configuration.

Example 1
(Method for producing organic EL element)
A glass substrate on which ITO with a thickness of about 150 nm formed by sputtering is patterned is washed with an organic solvent, an alkaline detergent, and ultrapure water, and then dried on a UV-O ₃ apparatus (Technovision Co., Ltd.). The UV-O ₃ treatment (lyophilic treatment) is performed using a product name “Model 312 UV-O ₃ Cleaning System” manufactured by the company.

  A suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (trade name “Bytron P TP AI 4083” manufactured by HC Starck B-Tech Co., Ltd.) is filtered through a 0.5 μm filter on the ITO side of the substrate. Then, the suspension is formed into a film with a thickness of 70 nm by spin coating, and dried on the hot plate at 200 ° C. for 10 minutes in the air.

  Next, a 1.5% by mass solution of a polymer organic light-emitting material (trade name “Lumation GP1300” manufactured by Cymation Co., Ltd.) is prepared using a solvent in which xylene and anisole are mixed 1: 1. This solution is deposited to a thickness of 80 nm on a substrate on which “Bytron P” has been deposited, using spin coating.

The light emitting layer in the extraction electrode part and the sealing area part is removed, introduced into a vacuum chamber, and transferred to a heating chamber (hereinafter, the process in vacuum or nitrogen is performed, and the element in the process is exposed to the atmosphere. Absent.). Next, heating is performed at a temperature of about 100 ° C. for 60 minutes in a vacuum (degree of vacuum is 1 × 10 ⁻⁴ Pa or less).

  Thereafter, the substrate is transferred to the vapor deposition chamber, aligned with the cathode mask, and vapor deposited so that the cathode is formed on the light emitting portion and the extraction electrode portion. For the cathode, Ba metal is heated by resistance heating, the deposition rate is about 2 mm / sec, and the film thickness is 50 mm. Vapor deposition.

(Formation of organic / inorganic sealing film)
After the device is created, the substrate is transferred to a film sealing device (trade name “Guardian 200” manufactured by VITEX, USA) without being exposed to the atmosphere from the vapor deposition chamber. Align and set the mask on the substrate. Next, the substrate is moved to the inorganic film formation chamber, and aluminum oxide which is the first inorganic layer is formed by sputtering. Argon gas and oxygen gas are introduced using an Al metal target having a purity of 5N, and an aluminum oxide film is formed on the substrate. A transparent and flat aluminum oxide film having a thickness of about 60 nm is obtained.

  After forming the first inorganic layer, the inorganic layer mask is removed, replaced with an organic layer mask, and transferred to the organic film forming chamber. Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name “CR”) having an average particle size of 0.25 μm as an organic monomer material (made by VITEX, trade name “Vitex Barix Resin System monomer material (Vitex 701)”). -50 ") 3% by mass added is introduced into the vaporizer, the organic monomer is vaporized, the vapor of the organic monomer material mixed with the refractive index adjusting material is ejected from the slit nozzle, and the substrate is placed on the nozzle The monomer is attached to the substrate so that the film has a uniform thickness by passing at a constant speed. Next, the substrate to which the monomer is attached is irradiated with UV light to crosslink and cure the monomer, thereby forming a first organic layer. The obtained film is a transparent and flat film, and the film thickness is about 1.3 μm.

  After forming the first organic layer, the substrate is moved to the inorganic film formation chamber, and argon and oxygen are introduced, and the second inorganic layer, aluminum oxide, is formed by sputtering. A transparent and flat aluminum oxide film having a thickness of about 40 nm is formed. A transparent and flat aluminum oxide film having a thickness of about 40 nm is formed. After the second inorganic layer is formed, the second organic layer is formed in the same manner as the first organic layer, and after the second organic layer is formed, the third inorganic layer is formed in the same manner as the second inorganic layer. Form a layer. Similarly, a third organic layer and a fourth inorganic layer are formed to obtain a multilayer sealing film.

  In the configuration of the multilayer sealing film of the above embodiment, the first inorganic layer and the second inorganic layer correspond to the first film and the second film defined in the present invention, respectively. Similarly, the relationship between the second inorganic layer and the third inorganic layer also corresponds to the first film and the second film defined in the present invention, respectively, and further, the third inorganic layer and the fourth inorganic layer The relationship with the layers also corresponds to the first film and the second film defined in the present invention, respectively. Then, a refractive index adjusting layer (a first organic layer, a second organic layer, and a third organic layer) is formed between the respective inorganic layers.

(Comparative Example 1)
An organic EL element is obtained in the same manner as in Example 1 except that the refractive index adjusting material (titanium oxide fine particles) is not added to the organic monomer material forming the organic layer in Example 1.

(Light extraction efficiency improvement test)
The organic EL element produced in Example 1 and Comparative Example 1 was introduced into an integrating sphere (trade name “Organic EL Luminescence Characteristic Evaluation Device” manufactured by Optel), and the total luminous flux at the same current density of 1 mA / cm ^2. By comparing these, it can be confirmed that the light extraction efficiency of the organic EL element of the example is improved as compared with the organic EL element of the comparative example.

  As described above, the light-emitting device according to the present invention is a light-emitting device in which the light extraction side of the light-emitting portion is sealed with a multilayer sealing film having at least one organic layer. It includes at least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film. A method for manufacturing a light emitting device according to the present invention is a method for manufacturing a light emitting device in which a light extraction side of a light emitting part is sealed with a multilayer sealing film having at least one organic layer, the multilayer sealing film At least one refractive index adjusting layer for adjusting the refractive index of the multilayer sealing film is formed during the lamination of the multilayer sealing film.

  The light emitting device according to the present invention is transparent from the front, but becomes opaque when viewed from an oblique direction, and the front luminance of the light emitting device is improved. The formation of the refractive index adjusting layer in the light emitting device can be performed during the normal sealing film forming process by the manufacturing method of the present invention, and thus the process is simple and the light emitting device excellent in light extraction efficiency can be easily obtained. Can be manufactured.

  As described above, according to the light emitting device and the method for manufacturing the same according to the present invention, it is possible to provide a light emitting device with improved light extraction efficiency at a low cost without increasing the space occupied by the light emitting device. The present invention having such characteristics is particularly suitable for improving light extraction efficiency in an organic EL element.

Claims (24)

In the light emitting device in which the light extraction side of the light emitting part is sealed by the multilayer sealing film having at least one organic layer,
A light emitting device comprising at least one refractive index adjusting layer for adjusting a refractive index of the multilayer sealing film in the stack of the multilayer sealing films.   The light emitting device according to claim 1, wherein the refractive index adjusting layer contains a particulate compound having a refractive index different from that of the base material.   The light emitting device according to claim 1, wherein the multilayer sealing film has at least one first film and at least one second film.   The light emitting device according to claim 3, wherein the refractive index adjustment layer is formed between the at least one first film and the at least one second film.   4. The light emitting device according to claim 3, wherein the refractive index adjusting layer is the at least one first film containing the particulate compound.   The light emitting device according to claim 1, wherein the base material of the refractive index adjusting layer is an acrylic polymer.   The light-emitting element according to claim 3, wherein the first film is an organic film.   The light emitting device according to any one of claims 1 to 7, wherein the particulate compound has a hollow structure.   The light emitting device according to any one of claims 1 to 8, wherein the granular compound is composed of at least one selected from the group consisting of silica, polystyrene, and fluorine-substituted polystyrene.   The light emitting device according to claim 7, wherein the organic film is made of an acrylic polymer.   The light emitting device according to any one of claims 3 to 10, wherein the second film is an inorganic film.   It is an organic EL element, The light emitting element of any one of Claims 1-11 characterized by the above-mentioned. A method for manufacturing a light emitting device, wherein a light extraction side of a light emitting part is sealed with a multilayer sealing film having at least one organic layer,
A method for manufacturing a light-emitting element, comprising forming at least one refractive index adjusting layer for adjusting a refractive index of the multilayer sealing film during the stacking of the multilayer sealing films.   The method of manufacturing a light emitting element according to claim 13, wherein the refractive index adjusting layer is formed by including a particulate compound having a refractive index different from that of the base material.   15. The method for manufacturing a light-emitting element according to claim 13, wherein the multilayer sealing film is formed of at least one first film and at least one second film.   The method of manufacturing a light emitting device according to claim 15, wherein the refractive index adjustment layer is formed between the at least one first film and the at least one second film.   The method of manufacturing a light emitting element according to claim 15, wherein the refractive index adjusting layer is formed by causing the at least one first film to contain the particulate compound.   The method for manufacturing a light-emitting element according to claim 13, wherein an acrylic polymer is used as a base material of the refractive index adjustment layer.   The method for manufacturing a light-emitting element according to claim 15, wherein the first film is an organic film.   The method for manufacturing a light-emitting element according to any one of claims 13 to 19, wherein a hollow structure is used as the particulate compound.   21. The method for producing a light-emitting element according to claim 13, wherein at least one selected from the group consisting of silica, polystyrene, and fluorine-substituted polystyrene is used as the granular compound.   The method for manufacturing a light-emitting element according to any one of claims 19 to 21, wherein the organic film is formed of an acrylic polymer.   The method for manufacturing a light-emitting element according to any one of claims 15 to 22, wherein the second film is an inorganic film.   The method for producing a light-emitting element according to any one of claims 13 to 23, wherein the light-emitting element is an organic EL element.