JP2007114266A - Optical element, method of manufacturing optical element, and organic electroluminescence element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which has high precision and high performance, is light in weight, and has satisfactory productivity, to provide a method of manufacturing the optical element, and to provide an organic electroluminescence element having the same structure with the optical element. <P>SOLUTION: The optical element has a glass layer formed of a pattern of periodic structures which are arrayed with a fine constant periodic interval corresponding to wavelength of light made incident on a resin substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element, a method for manufacturing the optical element, and an organic electroluminescence element.

  As the development of the information and communications industry accelerates, organic electroluminescence elements are attracting attention as next-generation display elements, while display elements having high performance are required.

  Organic EL elements emit light from the materials that make up the screen. Therefore, unlike LCD products, no backlight is required, so power consumption is kept low, and the panel thickness is further reduced by the amount of backlight space. Therefore, application to portable devices is expected. In addition, since a large area can be easily formed and a desired color can be obtained by selecting a light emitting material, application research has been actively conducted because of its promising use as a large area full color display element.

  The basic structure of the organic electroluminescence element is a structure in which a transparent electrode, an organic compound light emitting layer composed of one or more layers, and an electrode are laminated on a transparent substrate. In the organic electroluminescence device having such a structure, holes emitted from the transparent electrode and electrons injected from the electrode recombine in the light emitting layer to emit light by itself. The emitted light is reflected directly or by an electrode formed of aluminum or the like and exits from the organic electroluminescence element from the transparent electrode side.

  However, the amount of light that can exit from the transparent substrate is very small, and it is generally known that only about 15% to 20% of the light generated in the light emitting layer can be extracted. Yes. This is because the light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the organic electroluminescence element. It is considered that light undergoes total reflection with the transparent substrate, the light is guided through the transparent substrate or the light emitting layer, and as a result, the light escapes in the lateral direction of the element. Various methods have been studied as a technique for improving such a low light extraction efficiency. For example, it is disclosed that a diffraction grating is formed at a position where total reflection at an element interface is suppressed (for example, Patent Document 1). reference).

  The method of improving the light extraction efficiency by providing the diffraction grating described above is a diffraction having a fine concavo-convex shape with a periodic structure pattern arranged at a minute constant periodic interval such as the wavelength of light generated from the light emitting layer. The grating utilizes the property that the direction of light can be changed to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction or second-order diffraction. That is, of the light generated from the light emitting layer, light that cannot be emitted outside due to total reflection between layers is diffracted by introducing a diffraction grating into the transparent substrate, and is conventionally confined by total reflection. Trying to extract the light out.

  Some of such diffraction gratings form, for example, a concavo-convex shape directly on a glass substrate. As a specific method for forming an uneven shape, for example, a resist pattern is formed on a glass substrate by a known photolithography technique (resist application, exposure, development), and then wet etching using hydrofluoric acid is performed. There is a method of manufacturing.

As another method for forming a diffraction grating, a method using an SOG (Spin on glass) solution is disclosed (for example, see Patent Document 2). In this method, an SOG solution is applied onto a glass substrate by a spin coating method, then a heat treatment at 300 ° C. to 400 ° C. is performed to form a silicon oxide film, and then a well-known photolithography technique (resist application, exposure) is performed as described above. , Development) and wet etching using a 15: 1 solution of BOE (Buffered Oxide Etchant).
Japanese Patent Laid-Open No. 11-283951 JP 2000-180617 A

  However, in the invention of Patent Document 1, as a method for providing a diffraction grating for an emission wavelength range of 350 nm to 800 nm of an organic electroluminescence element, a method using an i-line resist and an i-line stepper is specifically described. It is only a method of directly forming a diffraction grating with a minute constant period pattern in the range of 0.4 μm to 1 μm formed by performing a lithography process on a glass substrate, and a diffraction grating having an equivalent minute constant period is made of resin. There is no description regarding the method of providing the substrate.

  In addition, in the invention of Patent Document 2, as a method of providing the disclosed diffraction grating, in order to make SOG coated on a glass substrate into a glass layer mainly composed of hard silicon oxide, 300 ° C. to 400 ° C. Therefore, there is a problem that it cannot be used for a resin substrate having low heat resistance instead of a glass substrate.

  In addition, organic electroluminescence elements as next-generation display elements have a high degree of freedom in shape so as to be applied to portable devices, and there is a need for an increase in area for application to large-area full-color display elements. In response to these needs, instead of a glass substrate that is heavy, fragile and difficult to increase in area, it has a high degree of freedom in shape and can be provided in a roll state as a substrate material with a large area. There is a strong expectation for a resin substrate that has the advantages of being able to cope with the increase in productivity and having good productivity.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optical element with high accuracy, high functionality, light weight and good productivity, a method for manufacturing the optical element, and the optical element. An organic electroluminescence element having the same structure as an optical element is provided.

  The above object can be achieved by any of the following means.

  (1) An optical element having a glass layer on which a pattern of a periodic structure arranged at minute constant periodic intervals corresponding to the wavelength of light incident on a resin substrate is formed.

  (2) The optical element according to (1), wherein the glass layer is a glass layer made of room temperature curable SOG.

(3) forming a room temperature curing SOG layer on the resin substrate;
Curing the room temperature curable SOG layer to a glass layer;
(2) forming a pattern of a periodic structure arranged at a minute fixed periodic interval corresponding to the wavelength of incident light on the glass layer by photolithography and etching. Of manufacturing the optical element.

(4) forming a room temperature curing type SOG layer on the surface of the mold having the inverted coincidence shape of the pattern of the periodic structure arranged at minute constant periodic intervals corresponding to the wavelength of the incident light;
Overlaying a resin substrate on the surface of the room temperature curable SOG layer;
A step of curing the room temperature curable SOG layer in a state where the room temperature curable SOG layer and the resin substrate are overlapped to form a glass layer;
The method for producing an optical element according to (2), further comprising a step of peeling the glass layer adhered to the resin substrate from the mold.

(5) forming a room temperature curing SOG layer on the resin substrate;
Pressing a mold having a reversal coincidence shape of a periodic structure pattern arranged at minute constant periodic intervals corresponding to the wavelength of light incident on the room temperature curable SOG layer;
Curing the room temperature curable SOG layer with the mold pressed against the room temperature curable SOG layer to form a glass layer;
The method for producing an optical element according to (2), further comprising a step of peeling the mold from the glass layer.

(6) In an organic electroluminescence device in which at least a transparent electrode layer, an organic light emitting layer, and an electrode layer are sequentially laminated on a transparent substrate.
A glass having a periodic structure pattern in which the transparent substrate is arranged on the surface of the transparent substrate on the side where the transparent electrode layer is provided, and is arranged at minute constant periodic intervals corresponding to the wavelength of incident light. An organic electroluminescent element, which is a resin substrate having a layer.

  (7) The organic electroluminescent element according to (6), wherein the glass layer is a glass layer made of room temperature curable SOG.

  (8) The organic electroluminescence element according to (6) or (7), wherein the pattern of the periodic structure is a diffraction grating having a two-dimensional period.

  According to the first aspect of the present invention, in the optical element of the present invention, since the substrate is a resin, it is lightweight and can be easily processed into a shape, and can form a fine structure with high accuracy. The layer has a pattern of a periodic structure arranged at a minute constant periodic interval corresponding to the wavelength of incident light, and can make it possible to efficiently change the course of incident light. For example, it can have a function like a diffraction grating. Therefore, it is possible to provide an optical element with high accuracy, high function, light weight, and high productivity.

  According to the third to fifth aspects of the present invention, a minute fixed period having a function capable of changing the path of incident light on a resin substrate that is lightweight and easy to process. Patterns of periodic structures arranged at intervals can be formed on the glass layer with high accuracy. Therefore, it is possible to provide a method for manufacturing an optical element having high functionality, high performance, light weight, and high productivity.

  According to the sixth aspect of the present invention, in the organic electroluminescence element of the present invention, since the substrate is a resin, it is lightweight and easy to process the shape, and a fine structure can be formed with high accuracy. The glass layer that can be formed has a pattern of a periodic structure arranged at a minute constant periodic interval corresponding to the wavelength of incident light, and it is possible to efficiently change the course of incident light. Can have functions that can. The pattern of the periodic structure arranged at the above-described minute constant periodic intervals can be used as a diffraction grating capable of improving the light extraction efficiency in the organic electroluminescence element. Therefore, it is possible to provide an organic electroluminescence device having high functionality, high performance, light weight and good productivity. Moreover, since the surface on which the organic light emitting layer on the resin substrate is laminated is a glass layer, the heat resistance of this surface is improved. Therefore, since the influence of the deformation or alteration of the resin substrate due to heat at the time of forming the transparent electrode layer, the organic light emitting layer, and the electrode layer is reduced, it is possible to provide a high-quality and high-reliability organic electroluminescence element. .

  FIG. 1 schematically shows a cross-sectional structure of an organic EL element having a diffraction grating as an example of the embodiment of the present invention.

  The structure of an organic electroluminescence element (hereinafter referred to as an organic EL element) is a structure in which one or more organic light emitting layers (hereinafter referred to as light emitting layers) are laminated between electrodes. Anode / light emitting layer / cathode structure, anode / hole injection layer / light emitting layer / electron injection layer / cathode structure, anode / hole injection layer / light emitting layer / cathode structure, anode / light emitting layer / electron Examples include an injection layer / cathode structure. Here, the hole injection layer and the electron injection layer are provided between the electrode and the light emitting layer as necessary for lowering the driving voltage and improving the light emission luminance.

  The structure shown in FIG. 1 is the anode / light-emitting layer / electron injection layer / cathode of the above example, where 1 is a transparent substrate that forms an organic EL element, and 2 has a periodic structure pattern that forms a diffraction grating. A glass layer, 3 is a transparent electrode (anode), 4 is a light emitting layer, 5 is an electron injection layer, and 6 is an electrode (cathode). The light emitting layer 4 includes a hole transport layer 4a and an electron transport layer 4b. In this case, light is emitted from the electron transport layer 4b. Hereinafter, the organic EL element having the structure shown in FIG. 1 will be described in detail.

  The transparent substrate 1 used for the organic EL element is a resin transparent substrate having a high degree of freedom in shape. By using a resin substrate as the transparent substrate 1, the substrate on which the organic EL element is formed can be lighter and more productive than a glass substrate. Hereinafter, the resin substrate is denoted by reference numeral 1.

  As the resin substrate 1, for example, a substrate made of a thermoplastic resin such as polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone (PES), polyetherketone, or polypropylene can be used. Also, a thermosetting resin substrate that is made better in terms of heat resistance and surface flatness than thermoplastic resins, and that is made with careful attention to surface flatness by precision molding using a casting polymerization method (for example, acrylic thermosetting) (Reactive resin substrate) can also be used (Japanese Patent Laid-Open No. 9-129376). The resin substrate 1 according to the present invention is not particularly limited to the above-mentioned substrates, and is appropriately selected from well-known resin films, sheets, or rolls with good productivity when necessary in large quantities. That's fine.

  Next, a description will be given of forming a diffraction grating on the resin substrate 1 using a room temperature curable SOG as a material. The room temperature curable SOG is an SOG that is cured in a temperature range from room temperature (a temperature that is not specially heated or cooled) to 200 ° C. or less to form a glass layer (film) mainly composed of silicon oxide. As this room temperature curable SOG, for example, there is Siragusital (trade name, Micro Technology Laboratory Co., Ltd.). Hereinafter, the room temperature curable SOG is simply referred to as SOG.

  First, as shown in FIG. 2, a glass layer 22 is formed by applying SOG onto a resin substrate 21 by spin coating and curing at room temperature (FIG. 2A). Thereafter, a photoresist 23 is applied onto the glass layer 22 which is a well-known photolithography process by the same spin coat method and cured, and a pattern for forming a diffraction grating is exposed and developed on the photoresist 23, thereby developing a resist pattern. 23a is formed (FIG. 2C). Next, the glass layer 22 is etched using a known etching method (either dry etching method or wet etching method) using the resist pattern 23a as a mask, and then the resist pattern is removed (FIG. 2D). . By doing so, a glass layer 22 a having a diffraction grating is formed on the resin substrate 21.

  Here, the thickness of the SOG applied to the resin substrate 21 is from the viewpoint of processing and processing such as optical function, transmittance, stress, and viscosity of the SOG due to the periodic structure pattern provided on the glass layer formed by SOG. What is necessary is just to decide suitably. For example, in the case of the diffraction grating as in the present embodiment, it may be about 1 μm, and may be about 100 μm depending on the viscosity of SOG.

  As a method other than the above method for forming a glass layer having a diffraction grating on a resin substrate, the following method may be used. For example, a reversal coincidence shape of a mold that is molded into SOG using silicon as a base material is formed using a known photolithography technique (resist coating, exposure, development) and etching technique, and this is used as a silicon mother mold. An electroforming process using, for example, nickel is performed on the silicon mother die to form a nickel electroforming mold, which can be used as a molding die. Using this mold, for example, a diffraction grating can be formed by the following method.

  (1) As shown in FIG. 3, SOG 32 is applied on the resin substrate 31 by using a spin coating method (FIG. 3A). The resin substrate 1 having the glass layer 2 on which the diffraction grating is formed is separated from the die 33 after press molding (FIG. 3C) with the molding die 33 obtained by the above method and curing. Mold (FIG. 3D). This method is also called a nanoimprint method.

  (2) As shown in FIG. 4, SOG is applied to the molding die 43 obtained by the above method using a spin coating method (FIG. 4B). After the resin substrate 41 is placed thereon and cured (FIG. 4D), the resin substrate 41 having the glass layer 42a on which the diffraction grating is formed is released from the mold 43 (FIG. 4E). This method is also called a cast method.

  In addition, you may provide a mold release process to the metal mold | die used above. Examples of the release treatment include a fluorine resin coating and a release plating coating.

  Here, the curing temperature for curing the glass layer 2 is preferably set to a temperature that does not affect the resin substrate 1 such as deformation or alteration within a range from room temperature to 200 ° C. or less.

  In addition, it is desirable that the formed diffraction grating has a two-dimensional period in which irregularities are formed into a pattern of a periodic structure in which irregularities are arranged at a constant period interval. This is because the light emitted from the light emitting layer 4 is randomly generated in all directions, so by making a diffraction grating having a two-dimensional period, the light traveling in all directions is diffracted, and the light extraction efficiency is reduced to a one-dimensional period. This is because it can be made larger than the diffraction grating it has. Specific examples of the arrangement of the diffraction grating include a cylindrical lattice arrangement, a square lattice arrangement, a triangular lattice arrangement, and a honeycomb (hexagonal) lattice arrangement in which the arrangement is repeated two-dimensionally. Also, for example, a cylindrical hole lattice arrangement which is a reversal coincidence shape of the cylindrical lattice arrangement may be used.

  FIG. 6 shows an example of a diffraction grating having a two-dimensional period. 6A schematically shows a diffraction grating formed on the glass layer 62a on the surface of the resin substrate 61, and FIG. 6B schematically shows a cross section taken along line XX in FIG. 6A. is there. In this diffraction grating, a circle 65 having a diameter d has a two-dimensional periodic grating arrangement with a period p. Here, the circle 65 in FIG. 6 is a hole, but may be a protrusion.

  In the pattern of the periodic structure forming the above diffraction grating, for example, a minute constant periodic interval expressed by a distance from the deepest part of the concave to the deepest part of the next concave or from the top of the convex to the top of the next convex, concave or The convex size (the size is the diameter of the hole in the case of a cylindrical hole, for example) and the depth from the deepest part of the concave to the highest part of the convex is the emission wavelength that is targeted for improvement in light extraction efficiency It may be determined appropriately with reference to the refractive index, diffraction order, etc. of the medium serving as the optical path. The minute constant periodic interval is generally in the range of 0.1 μm to 4 μm, although it depends on the wavelength of incident light.

Here, since the emission wavelength of the organic EL element has a width in the spectrum, the center wavelength (λ ₀ ) shown below may be used as a representative value for convenience. The concept of the center wavelength (λ ₀ ) is not limited to the light emission wavelength of the organic EL element, but may be applied to light having a spectrum with a wide width.

The center wavelength (λ ₀ ) is defined by the following formula (1).

However,
I (λ): emission intensity at a certain wavelength λ1: lower limit wavelength λ2 of light wavelength range determined to use a diffraction grating (optical element): determined to use a diffraction grating (optical element) This is the upper limit wavelength of the wavelength range of light.

  As described above, by using the resin substrate 1 having the glass layer 2 on which the diffraction grating is formed as the substrate on which the organic EL element A is formed, the light extraction efficiency is improved, and the organic material has high functionality, high performance, light weight, and good productivity. An EL element can be manufactured.

  In general, on the surface of the resin substrate, an inorganic material, an organic material film, or a hybrid film of both having a function of suppressing the intrusion of a substance that causes deterioration of the organic EL element such as moisture or oxygen is formed as a barrier layer. The material that can be used as the barrier layer may be any material that has a function of suppressing the intrusion of substances that cause deterioration of the organic EL element such as moisture and oxygen as described above. For example, silicon oxide, silicon dioxide, silicon nitride Etc. can be used. Therefore, by providing the glass layer 2 on the resin substrate 1, the glass layer 2 can serve as a barrier layer, and it is unnecessary to provide a separate barrier layer.

  In addition, the structure of having the glass layer 2 on which the diffraction grating is formed on the resin substrate 1 is not a substrate on which the organic EL element is formed, but is a highly functional optical having a fine shape like a diffraction grating. It can be used in an element or other display substrate. Examples of the fine shape include a binarized diffraction grating as an example of the present embodiment, a zone plate, a scattering shape, and the like, and a cross-sectional shape of only two steps of a flat portion and a convex portion. Instead of binarization, it may be formed in multiple steps on the stairs. Further, an antireflection shape in which a plurality of conical shapes as shown in FIG.

  After the diffraction grating is formed on the glass layer 2 provided on the resin substrate 1 as described above, the transparent electrode 3 and subsequent layers are sequentially stacked to obtain the organic EL element A. This will be described below.

The material of the transparent electrode 3 is preferably an electrode material having a high work function. Specific examples thereof include indium tin oxide (ITO), tin oxide (SnO ₂ ), indium oxide / zinc oxide based amorphous transparent. Examples thereof include transparent conductive materials such as a conductive film (IZO: Indium Zinc Oxide, manufactured by Idemitsu Kosan Co., Ltd.) (registered trademark). In order to form a thin film using these transparent conductive materials (also referred to as film formation), generally, a method such as vapor deposition or sputtering is used.

  Although the thickness (also referred to as film thickness) of the transparent electrode 3 of the present embodiment depends on the material, for example, in the case of an ITO film, it is usually 10 from the tip of the convex portion of the concavo-convex surface by the diffraction grating serving as the foundation of the ITO film. A range of ˜1000 nm, preferably a range of 10 to 250 nm is selected. Further, after the transparent conductive film is formed, the surface thereof is flattened by polishing or the like as necessary.

  After the formation of the transparent electrode 3, a hole transport layer 4 a and an electron transport layer 4 b are sequentially formed as the light emitting layer 4.

  The hole transport layer 4a is made of a material having a function of transporting holes (hereinafter referred to as a hole transport material), and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer.

  The hole transport material is not particularly limited, and is conventionally used as a charge injection / transport material for holes in photoconductive materials, and used for the hole injection layer and hole transport layer of organic EL devices. Any known one can be selected and used. The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic.

  Specifically, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives Hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, aromatic tertiary amine compounds, styrylamine compounds, or conductive polymer oligomers, particularly thiophene oligomers.

  Of these, porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds are preferred, and aromatic tertiary amine compounds are particularly preferred.

  Representative examples of the aromatic tertiary amine compound and styrylamine compound include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N ′. -Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; Bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p- Tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, '-Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) biphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino -(2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, as well as those described in US Pat. No. 5,061,569 Having four condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which three triphenylamine units described in No. 88 are linked in a starburst type In addition, inorganic semiconductors such as p-type-Si and p-type-SiC can also be used as the hole transport material.

  The hole transport layer 4a can be formed by depositing the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.

  Although there is no restriction | limiting in particular about the film thickness of the positive hole transport layer 4a, Usually, it selects in 5 nm-5 micrometers. The hole transport layer 4a may have a single layer structure composed of one or more of the above materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  The electron transport layer 104b is made of a material having a function of transporting electrons (hereinafter referred to as an electron transport material), and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer.

  Conventionally, the following materials are known as an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side. Moreover, the electron transport layer 4b should just have the function to transmit the electron inject | poured from the cathode to a light emitting layer, and can select arbitrary things from a conventionally well-known compound, and can also use it as an electron transport material. it can.

  Examples of the electron transport material include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. In addition, in this oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material.

Further, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (hereinafter abbreviated as Alq ₃ ), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo- 8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc and the like, and the central metal of these metal complexes is In, Metal complexes replaced with Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material.

  In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material.

  Further, a distyrylpyrazine derivative conventionally used as a material for the light emitting layer 4 can also be used as an electron transport material, and inorganic semiconductors such as n-type-Si and n-type-SiC can be used as well as a hole transport layer. It can be used as an electron transport material.

  The electron transport layer 4b can be formed by forming a film of the above compound by a known method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.

  Although there is no restriction | limiting in particular about the film thickness of the electron carrying layer 4b, Usually, it selects in 5 nm-5 micrometers. The electron transport layer 4b may have a single layer structure composed of one or more of these electron transport materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

  Details of the material of the electron injection layer 5 are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Examples include a metal buffer layer represented by an alkali metal compound buffer layer represented by lithium fluoride, an alkaline earth metal compound buffer layer represented by magnesium fluoride, and an oxide buffer layer represented by aluminum oxide.

  Any of the above electron injection layers is desirably a very thin film, and although depending on the material, the film thickness is preferably in the range of 0.1 nm to 5 μm.

  The cathode 6 is preferably a material having a small work function for the purpose of injecting electrons into the electron transport layer or the light emitting layer. The cathode material is not particularly limited, and specifically, indium, aluminum, magnesium, magnesium-indium alloy, magnesium-aluminum alloy, aluminum-scandium-lithium alloy, magnesium-silver alloy and the like can be used.

  The formation method of the electron injection layer 5 and the cathode 6 is not specifically limited, What is necessary is just to select suitably from a well-known method, for example, it can form by vacuum evaporation method sputtering method etc.

  A desired organic EL element can be obtained by providing the cathode 6. The produced organic EL element is preferably sealed with a known protective film (passivation film).

  Organic EL device having a laminated structure of resin substrate / glass layer (including light extraction structure) / transparent electrode / light emitting layer / electron injection layer / electrode, and provided with a periodic structure pattern arranged at regular intervals on the glass layer Was made. This will be specifically described below.

Example 1
In Example 1, a glass layer formed by directly applying SOG to a transparent resin substrate 21 and curing SOG becomes a diffraction grating by using a known photolithography technique (resist application, exposure, development) and etching technique. The organic EL element uses a resin substrate 21 on which a periodic structure pattern is formed. This organic EL element will be described below according to the steps shown in FIG.

  As the resin substrate 21, polycarbonate (PC) (n = 1.58) having a size of 30 mm × 30 mm and a thickness of 0.4 mm, which is a resin substrate, was used. A glass layer 22 was formed by applying sylagcital (trade name), which is a room temperature curable SOG, on a resin film by spin coating to a thickness of 300 nm and allowing it to stand at room temperature for about 24 hours to cure (FIG. 2A). At this time, the applied siragital (trade name) was diluted with a ratio of siragital (main agent and catalyst) and isopropyl alcohol (IPA) of 100: 20, and the spin coat rotation speed during application was 6000 rpm. Next, a photoresist 23 is applied onto the glass layer 22 by a spin coating method (FIG. 2B), and exposure is performed using a mask having a two-dimensional periodic interval of 300 nm and a diameter of 200 nm. The resist pattern 23a was provided by developing (FIG.2 (c)). Next, the diffraction grating is a cylindrical hole pattern having a depth of 200 nm on the surface of the glass layer by etching the glass layer 22 provided with the above resist pattern using a known dry etching method and then removing the resist. Was formed (FIG. 2D).

  The shape of the diffraction grating produced here is the most light extraction efficiency with respect to the center wavelength of 520 nm obtained from the formula (2) from the emission spectrum example shown in FIG. 5 which the light emitted from the light emitting layer produced below has. The shape was good.

  On the glass layer 22a having the above diffraction grating, an ITO film as a transparent electrode 24 is formed by a known sputtering method so that the thickness from the convex upper part of the glass layer surface is 150 nm, and then the surface is polished. Then, this surface was set to have an average surface roughness Ra ≦ 2 nm (FIG. 2E).

  As described below, a hole transport layer, an electron transport layer, then an electron injection layer 26, and finally a cathode 27 are sequentially deposited on the transparent electrode 24 by a known vacuum deposition. The film was formed using the method.

Specifically, the light-emitting layer 25 includes NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl) as a hole transport layer at 55 nm and Alq ₃ (Tris) as an electron transport layer. 60 nm of (8-quinolinol) aluminum) and 1 nm of LiF (lithium fluoride) as the electron injection layer 26 were sequentially formed. Finally, a desired organic EL element was completed by depositing 200 nm of Al (aluminum) as the cathode 27. The produced organic EL element was sealed with a known protective film (passivation film).

(Example 2)
Example 2 was obtained by directly applying SOG to a resin substrate, pressing the SOG applied with a separately prepared mold having a periodic structure pattern, curing the SOG to form a glass layer, and then releasing the mold. The organic EL element uses a resin substrate having a glass layer on which a periodic structure pattern to be a diffraction grating is formed. This organic EL element will be described below according to the steps shown in FIG.

  As the resin substrate 31, polycarbonate (PC) (n = 1.58) having a thickness of 0.4 mm, which is the same resin substrate as in Example 1, was used. In order to form a separately prepared diffraction grating on a resin substrate 31 after diluting Siragusital (trade name), which is a room temperature curable SOG 32, in the same manner as in Example 1 and applying it by spin coating (FIG. 3A). After the SOG 32 is cured by maintaining the state of pressing with a pressure of 40 kPa in a mold having a concave and convex shape (described below) 33 for 3 hours (FIG. 3C), the mold 33 is released. Molded (FIG. 3 (d)).

  After the transparent electrode of Example 1 on the glass layer 32a on which the diffraction grating is formed on the resin substrate 31, the same material and the same method are used to include the transparent electrode, the light emitting layer, the electron injection layer, and the cathode (whichever Is also not shown), and a desired organic EL element was completed. The produced organic EL element was sealed with a known protective film (passivation film).

  Here, the mold 33 for molding the SOG 32 will be described. First, using a silicon substrate as a base material, a reversal coincidence shape of a mold for molding SOG was formed using a known photolithography technique (resist application, exposure, development) and etching technique, and this was used as a silicon matrix. The shape formed as the silicon matrix was a cylindrical hole pattern with a two-dimensional constant periodic interval of 300 nm, a diameter of 200 nm, and a depth of 200 nm. The silicon matrix was subjected to nickel electroforming, and then the electroforming was released from the silicon matrix to produce a nickel electromold. This nickel electroforming mold becomes a mold 33 having a cylindrical projection pattern with a two-dimensional constant periodic interval of 300 nm, a diameter of 200 nm, and a height of 200 nm. Therefore, the shape of the diffraction grating formed on the glass layer using this mold 33 can be made substantially the same as that of the first embodiment. A fluororesin film was provided on the mold surface as a mold release treatment.

(Example 3)
In Example 3, SOG is directly applied on a mold equivalent to Example 2 prepared separately, a transparent resin substrate is stacked thereon, SOG is cured to form a glass layer, and then released. Thus, an organic EL element using a resin substrate having a glass layer having a periodic structure pattern to be a diffraction grating is obtained. This organic EL element will be described below according to the steps shown in FIG.

  The same nickel electroforming mold produced in Example 2 is produced. On this mold 43, SOG 42 was applied by spin coating so that the thickness from the top of the mold unevenness was about 300 nm (FIG. 4B). After the polycarbonate (PC) having the same thickness of 0.4 mm as in Example 1 was overlaid on the SOG 42 (FIG. 4D), the state was maintained for 3 hours to cure the SOG 42, The mold was released from the mold 43 (FIG. 4E).

  After the formation of the transparent electrode of Example 1 on the glass layer 42a on which the diffraction grating is formed on the resin substrate 41, the light emitting layer, the electron injection layer, and the cathode including the transparent electrode using the same material and the same method are used. A desired organic EL element was completed by laminating (none of which is shown). The produced organic EL element was sealed with a known protective film (passivation film).

(Comparative Example 1)
Unlike Example 1, without using a diffraction grating with a glass layer, polycarbonate (PC) (n = 1.58) having exactly the same thickness of 0.4 mm as in Example 1 was used as a resin substrate and the same material and the same method were used. Then, an organic EL element as Comparative Example 1 was completed by laminating a transparent electrode, a light emitting layer, an electron injection layer, and a cathode. The produced organic EL element was sealed with a known protective film (passivation film) in the same manner as in Examples 1 to 3.

(Evaluation results)
The organic EL element on the resin substrate having the glass layer having the diffraction grating according to Examples 1 to 3 and the organic EL element manufactured on the resin substrate not having the diffraction grating according to Comparative Example 1 are operated under the same conditions, and 500 lx. As a result of visual observation under illumination light, when the brightness of Examples 1 to 3 and Comparative Example 1 were compared, the organic EL elements of Examples 1 to 3 were clearly brighter than the organic EL element of Comparative Example 1. Was recognized. From this, it was confirmed that the diffraction grating formed on the glass layer on the resin substrate was functioning sufficiently.

It is a figure which shows typically the cross section of the structure of the organic EL element with the diffraction grating of an example of embodiment. It is a figure explaining an example of the process of producing an organic EL element. It is a figure explaining an example of the process of producing an organic EL element. It is a figure explaining an example of the process of producing an organic EL element. It is a figure explaining a center wavelength from the example of the emission spectrum of the organic EL element in Example 1. FIG. It is a figure which shows the outline of an example of a diffraction grating as an example of a fine shape. It is a figure which shows the outline of an example of an antireflection shape as an example of a fine shape.

Explanation of symbols

1, 21, 31, 41, 61 Resin substrate 2, 22a, 32a, 42a, 62a Fine glass layer 3, 24 Transparent electrode 4, 25 Light emitting layer 5, 26 Electron injection layer 6, 27 Cathode 22, 32, 42 SOG
23 resist 23a resist pattern 33, 43 mold

Claims (8)

An optical element having a glass layer on which a pattern of a periodic structure arranged at minute constant periodic intervals corresponding to the wavelength of light incident on a resin substrate is formed. The optical element according to claim 1, wherein the glass layer is a glass layer made of room-temperature curable SOG. Forming a room temperature curable SOG layer on a resin substrate;
Curing the room temperature curable SOG layer to a glass layer;
3. The method of forming a periodic structure pattern arranged at a minute constant periodic interval corresponding to the wavelength of incident light on the glass layer by photolithography processing and etching processing. Of manufacturing the optical element. Forming a room temperature curing SOG layer on the surface of a mold having a reversal coincidence shape of a periodic structure pattern arranged at a minute constant periodic interval corresponding to the wavelength of incident light;
Overlaying a resin substrate on the surface of the room temperature curable SOG layer;
A step of curing the room temperature curable SOG layer in a state where the room temperature curable SOG layer and the resin substrate are overlapped to form a glass layer;
The method for producing an optical element according to claim 2, further comprising a step of peeling the glass layer adhered to the resin substrate from the mold. Forming a room temperature curable SOG layer on a resin substrate;
Pressing a mold having a reversal coincidence shape of a periodic structure pattern arranged at minute constant periodic intervals corresponding to the wavelength of light incident on the room temperature curable SOG layer;
Curing the room temperature curable SOG layer with the mold pressed against the room temperature curable SOG layer to form a glass layer;
The method for producing an optical element according to claim 2, further comprising a step of peeling the mold from the glass layer. In an organic electroluminescence device in which at least a transparent electrode layer, an organic light emitting layer and an electrode layer are sequentially laminated on a transparent substrate,
A glass having a periodic structure pattern in which the transparent substrate is arranged on the surface of the transparent substrate on the side where the transparent electrode layer is provided, and is arranged at minute constant periodic intervals corresponding to the wavelength of incident light. An organic electroluminescence element, which is a resin substrate having a layer. The organic electroluminescence device according to claim 6, wherein the glass layer is a glass layer made of room temperature curing SOG. The organic electroluminescence device according to claim 6 or 7, wherein the pattern of the periodic structure is a diffraction grating having a two-dimensional period.

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