JP2007265987A - Light emitting element, light emitting device, manufacturing method of light emitting device, and sheet-like sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the light extraction efficiency of a light emitting element such as an electroluminescent element. <P>SOLUTION: From the side of a substrate 101, a first electrode 103, a light emitting layer 104, and a second electrode 105 are sequentially stacked. The first electrode 103 is a reflective electrode. The second electrode 105 is an electrode which transmits visible light, and light emitted from the light emitting layer 104 is extracted from the second electrode 105. In contact with the surface of the second electrode 105, many fine particles 106 are provided. The fine particles 106 have refractive indices which are equal to or higher than that of the second electrode 105. Since light which passes through the second electrode 105 is scattered and refracted by the fine particles 106, the amount of light which is totally reflected at an interface between the second electrode 105 and gas 110 is reduced, and light extraction efficiency is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting element and a light emitting device having the light emitting element. Further, the present invention relates to a method for sealing a light emitting element and a member used for sealing.

  Improvements in flat panel displays such as liquid crystal panels have progressed, and higher quality images, lower power consumption, and longer life have been achieved. In putting an electroluminescence panel (hereinafter referred to as an EL panel) that uses an electroluminescence element (hereinafter referred to as an EL element) into a pixel into practical use, it is brighter and brighter with lower power consumption in order to take advantage of the features of a self-luminous panel. Realization of display is required. For this purpose, power efficiency is being improved by improving current luminance characteristics of materials used in EL elements. However, the above-described method has a limit in improving power efficiency.

  The efficiency of extracting light emitted from the light emitting layer of the EL element to the outside (light extraction efficiency) is only about 20%. The reason for the low light extraction efficiency is that total reflection occurs when the light emitted from the light emitting layer passes through the interface of the films having different refractive indexes, and the totally reflected light is absorbed and attenuated inside the EL element. It is because it radiates | emits from the side surface of a light emitting element, for example, the end surface of a glass substrate.

Patent Document 1 describes an EL element in which the light extraction efficiency is improved by reducing the total reflection amount. In Patent Document 1, by providing a film in which particles are dispersed on a transparent conductive film, light passing through the film is scattered by the particles, and light incident on the interface between the transparent conductive film and the low refractive index film is critical. The proportion of light incident at an angle exceeding the angle is reduced.
JP 2004-303724 A

  The structure of the EL panel is classified into a bottom emission structure (bottom surface light emitting structure) and a top emission structure (top surface light emitting structure) depending on the difference in the light extraction direction. In the bottom emission structure, light is extracted after passing through the substrate provided with the EL element, and in the top emission structure, light is extracted from above the EL element. Note that the terms “bottom emission structure” and “top emission structure” are often used for the structure of an organic EL panel. In this specification, a light emitting element or a light emitting device is used in the light extraction direction regardless of the type of the light emitting element. It will be used to distinguish the structure of

  Since the light emission area of the EL element is less limited in the top emission structure than in the bottom emission structure, the aperture ratio of the active matrix EL panel can be increased by adopting the top emission structure. Therefore, in an active matrix EL panel, the top emission structure is more advantageous for lower power consumption and higher image quality.

  An object of the present invention is to reduce the amount of light totally reflected by the light emitting layer by means different from that of Patent Document 1, improve the light extraction efficiency of the light emitting element, and reduce power consumption.

  The light-emitting element of the present invention includes at least a light-emitting layer between a first electrode and a second electrode facing each other and between the first electrode and the second electrode. The first electrode, the light emitting layer, and the second electrode are stacked in this order, and light emitted from the light emitting layer is extracted from the second electrode.

  The first electrode of the light-emitting element is an electrode that can reflect light from the light-emitting layer. The second electrode is an electrode that can transmit light from the light emitting layer.

  In addition, the light-emitting element of the present invention only needs to have at least one light-emitting layer between the first electrode and the second electrode. A plurality of light emitting layers may be provided between the electrodes. For example, when an organic EL element is formed as a light emitting element, each layer such as an electron injection layer, an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer is appropriately formed in addition to the light emitting layer. The light emitting element having such a configuration is also included in the category of the present invention. In the case where an inorganic EL element is formed as the light-emitting element, an insulating layer can be provided between one or both of the light-emitting layer and the first electrode and between the light-emitting layer and the second electrode.

  The light emitting element of the present invention is provided with a plurality of fine particles in contact with the surface of the second electrode from which light is extracted, and the refractive index of the fine particles is equal to or higher than the refractive index of the second electrode. It is characterized by being.

  The refractive index of the second electrode means the refractive index of the single layer film when the second electrode is a single layer film. In the case of a multilayer film, it means the refractive index of the film closest to the light extraction side, that is, the refractive index of the film having fine particles on the surface.

  In the present invention, the shape of the second electrode surface is changed by providing a plurality of fine particles having a predetermined refractive index. That is, the second electrode is an electrode having a plurality of convex portions on the surface. By providing fine particles on the surface, the critical angle of the light passing through the surface of the second electrode becomes diversified, and light that is totally reflected and cannot be extracted by the conventional EL element can pass therethrough. The amount of light totally passing through the second electrode is reduced, and the light extraction efficiency can be improved.

  In order to prevent total reflection from occurring at the interface between the fine particles and the second electrode, the refractive index of the fine particles is equal to or higher than the refractive index of the second electrode.

  A protective film made of a transparent conductive film or an insulating film can be provided in contact with the surface of the second electrode on which the fine particles are provided. In order to prevent total reflection at the interface between the protective film and the second electrode, the refractive index of the protective film is the same as or higher than that of the second electrode.

  In another light-emitting element of the present invention, a protective film is provided in contact with the surface of the second electrode, and a plurality of fine particles are provided in contact with the surface on the light extraction side of the protective film. Further, in order not to cause total reflection at the interface between the protective film and the second electrode, the refractive index of the protective film is equal to or higher than that of the second electrode, and the refractive index of the fine particles is the refractive index of the protective film. Another feature is that it is equal to or higher than the rate.

  Here, the refractive index of the protective film means the refractive index of the single layer film when the protective film is a single layer film, and when the protective film is a multilayer film, a film closest to the light extraction side, that is, a fine particle is provided. It refers to the refractive index of the film being used.

  Similarly to the case where the fine particles are provided on the surface of the second electrode, the light emitting element of the present invention is also provided with fine particles having a predetermined refractive index on the surface of the protective film from which light is extracted. The shape is changed. As a result, the amount of total reflection of light that has passed through the protective film is reduced, so that the light extraction efficiency of the light emitting element is improved.

  According to the present invention, when the light emitted from the light emitting layer is extracted from the second electrode or the protective film, the amount of light totally reflected is reduced, so that the light extraction efficiency is improved. Improvement in light extraction efficiency can reduce power consumption of the light-emitting element and the light-emitting device using the light-emitting element. In particular, by adopting a top emission structure, the effect of reducing power consumption can be made more remarkable.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different ways. It will be readily understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the invention. The present invention is not construed as being limited to the description of this embodiment mode.

  Moreover, it is possible to combine each embodiment suitably, without deviating from the meaning of this invention. In different embodiments, since common elements have been described with the same reference numerals, the description may be omitted.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of a light-emitting device including the light-emitting element of this embodiment. A lower structure 102 of a light emitting element is provided on the substrate 101, and three light emitting elements are provided on the lower structure 102.

  In the light-emitting element, the first electrode 103, the light-emitting layer 104, and the second electrode 105 are stacked in this order from the substrate 101 side. A plurality of fine particles 106 are provided in contact with the surface of the second electrode 105 from the second electrode side. Note that the second electrode 105 of the light-emitting element is provided integrally with the three elements. The partition wall 107 is provided to separate elements and is formed of an insulating material. The partition 107 separates the first electrode 103 and the light-emitting layer 104 for each element.

  A sealing substrate 109 is fixed to the substrate 101 by a sealing material 108 provided so as to surround the periphery of the substrate 101, and the light emitting element is sealed. In this embodiment, a gas 110 is filled in a space hermetically sealed by the substrate 101, the sealing material 108, and the substrate 109. The gas 110 is preferably an inert gas such as nitrogen or argon.

  The substrate 101 only needs to be a light-emitting element or a support base for the substrate 102, and a quartz substrate, a semiconductor substrate, a glass substrate, a plastic substrate, a flexible plastic film, or the like can be used. Further, since light is not extracted from the substrate 101 side, it is not necessary to be transparent, and it may be colored or opaque.

  As the sealing substrate 109, a substrate having high transmittance with respect to visible light is used in order to extract light from the light-emitting element. For example, a quartz substrate, a glass substrate, a plastic substrate, a flexible plastic film, or the like can be used. A color filter may be provided on the sealing substrate 109 to improve the color purity of light emission, or the light emission color of the light-emitting element may be converted. Further, although the flat substrate 109 is used, the shape is not limited to this, and it is sufficient that sealing can be performed. For example, a cap-like thing such as a sealing can can be used.

  The lower structure 102 can function as a support for supporting the light emitting element. The substructure 102 may not need to be provided. In the case where an active matrix pixel is provided in the light emitting device, the lower structure 102 includes, for example, an element such as a transistor or a capacitor for controlling the luminance or light emission timing of the light emitting element, an interlayer insulating film, a wiring, or the like. A circuit containing is formed.

  A first electrode 103 is formed on the lower structure 102. The first electrode 103 has a function of reflecting light emitted from the light-emitting layer and functions as a cathode. The first electrode is formed of a reflective conductive film made of metal or alloy. As this metal film, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu) Palladium (Pd), aluminum (Al), silver (Ag), and the like. Examples of the alloy film include an alloy of magnesium and silver, an alloy of aluminum and lithium, and the like. A film for forming the first electrode 103 can be formed by a sputtering method, an evaporation method, or the like.

  The first electrode 103 may be formed of a multilayer film in which a transparent conductive film is stacked on the metal film or alloy film, or a multilayer film in which the metal film or alloy film is sandwiched between two transparent conductive films. it can. Further, a multilayer film made of transparent conductive films having different refractive indexes can be used for the first electrode 103. The reflectance can be improved by using multiple interference of light.

  After the first electrode 103 is formed, a partition wall 107 is formed. The partition wall 107 is formed by forming an insulating film on the surface of the lower structure 102 and etching an area where a light emitting element is formed in the insulating film to form an opening. The partition wall 107 is made of an organic material such as an acrylic resin, a siloxane resin, a polyimide resin, or an epoxy resin, an inorganic material such as silicon oxide, silicon oxide containing nitrogen, silicon nitride containing oxygen, or an inorganic material and an organic film material. It may be formed using both. The organic material film such as acrylic is formed, for example, by applying a raw material solution and baking it. The inorganic material film is formed by a CVD method or a sputtering method.

  A light emitting layer 104 is formed over the first electrode 103 by vapor deposition or the like. The light emitting layer 104 is a layer containing a light emitting substance. A known material can be used for the light-emitting layer 104, and either a low molecular material or a high molecular material can be used. Note that as a material for forming the light-emitting layer 104, not only an organic compound but also an organic compound mixed with an inorganic compound or an inorganic compound can be used. The light-emitting layer 104 can be manufactured by, for example, a vapor deposition method using a metal mask, a droplet discharge method (typically, an ink jet method) without using a metal mask, a spin coating method, a dip coating method, a printing method, or the like. Depending on the material of the light emitting layer, a dry method or a wet method is selected.

  A second electrode 105 is formed over the light-emitting layer 104. The second electrode 105 functions as an anode and can transmit light emitted from the light-emitting layer 104. Light generated in the light-emitting layer 104 is extracted directly or after being reflected by the first electrode 103 and extracted from the second electrode 105.

  The second electrode 105 is typically made of a transparent conductive film. In particular, in the case where the light-emitting element is an organic EL element, a material with low visible light transmittance such as metal is extremely thin on the first electrode 103 side for adjusting the work function, and the thickness is 1 nm to 50 nm, preferably 5 nm to A conductive film in which a transparent conductive film is stacked thereon can also be used. In this case, the extremely thin film is made of gold (Au), platinum, (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co ), Copper (Cu), palladium (Pd), silver (Ag), or the like. These thin films can be formed using, for example, a sputtering method or a vapor deposition method.

  The material of the transparent conductive film used for the second electrode 105 is a material having high transmittance with respect to light in the visible light region (400 to 800 nm), and is typically a metal oxide. For example, there are oxides of elements selected from zinc (Zn), indium (In), and tin (Sn), and compounds obtained by adding a dopant to these oxides. Examples of the zinc oxide dopant include elements such as Al, Ga, B, In, and Si, and oxides of elements selected from these elements. Note that zinc oxides containing these dopants are called AZO, GZO, BZO, and IZO, respectively. Examples of the indium oxide dopant include Sn and Ti. Indium oxide to which Sn is added is called ITO (Indium Tin Oxide). Examples of tin oxide dopants include Sb and F. Furthermore, as the transparent conductive film, a compound in which two kinds of oxides selected from the above-described zinc oxide, indium oxide, tin oxide, and oxides containing a dopant can be used.

  Next, fine particles 106 are dispersed on the surface of the second electrode 105 by a dry method or a wet method in the same manner as the spacer distribution of the liquid crystal panel. The dry method is a method in which the fine particles 106 are naturally dropped by the action of air current or static electricity. The wet method is a method of spraying a mixture in which fine particles 106 are mixed in a solvent. When the mixture containing the fine particles 106 is sprayed by the wet method, if the solvent that evaporates before the fine particles 106 reach the substrate 101 is not used, the mixture containing the fine particles 106 is sprayed and then the light emitting layer 104 is affected. The solvent is evaporated by heating to an extent (less than 100 ° C.).

  As another wet method in which the fine particles 106 are provided on the surface of the second electrode 105, a mixture of the fine particles 106 and a volatile solvent such as alcohol is applied to the surface of the second electrode 105, and the solvent A method of volatilizing can also be used. Examples of the application method include a casting method, a spin coating method, a spray method, an ink jet method, a printing method, and a dropping method.

  The solvent of the mixture in which the fine particles are mixed is selected depending on the material of the fine particles 106 such as water, alcohol such as ethanol or isopropanol (IPA).

  The fine particles 106 are made of a material having a refractive index higher than or equal to that of the second electrode 105. In the present embodiment, the refractive index of the second electrode 105 is the refractive index of the transparent conductive film used for the second electrode 105.

  In order to seal the light emitting element, a substrate 109 provided with an uncured sealing material 108 around is prepared. The uncured sealing material 108 is provided around the substrate 109 in a predetermined shape by a printing method, a dispenser method, or the like. The sealant 108 can also be provided on the substrate 101 side after the fine particles 106 are dispersed on the second electrode 105.

  For the sealing material 108, a photo-curing resin or a thermosetting resin using UV light such as an epoxy resin or an acrylic resin can be used. Since the material of the light emitting layer 104 is easily decomposed by heating, a photocurable resin is optimal for the sealant 108. If it is a thermosetting resin, a resin having a curing temperature of 100 ° C. or lower is preferable.

  The substrate 101 and the substrate 109 on which the fine particles 106 are dispersed are overlapped, and the two substrates 101 and 109 are bonded to each other. Before the substrate 101 and the substrate 109 are overlapped, the uncured sealing material 108 is slightly cured by heat treatment or light irradiation. In a state where the substrate 101 and the substrate 109 are overlapped, the uncured sealing material 108 is irradiated with UV light to be completely cured, and the substrate 101 and the substrate 109 are fixed. At this time, pressure is applied to the substrate 101 and the substrate 109 as necessary. In addition, in this specification, uncured means the state which is not hardened | cured completely. Of course, when a thermosetting resin is used for the sealant 108, heat treatment is performed. In addition, as a series of work environments in which the substrate 101 and the substrate 109 are overlapped and the sealing material 108 is completely cured, it is desirable that the atmosphere does not contain moisture and oxygen as much as possible. For example, a nitrogen atmosphere may be used. In addition, this atmosphere can be reduced to atmospheric pressure or slightly lower than atmospheric pressure. In the manufacturing process of a light emitting device having a solid-sealed structure, which will be described later, it is desirable to reduce the pressure to some extent from atmospheric pressure.

  By curing the sealing material 108, the space between the substrate 101 and the substrate 109 is hermetically sealed and filled with the gas 110.

  After sealing the substrate 101 with the substrate 109, the substrate 109 is divided into an arbitrary size to obtain a light emitting device of an arbitrary size.

  This embodiment is characterized in that the shape of the surface of the second electrode 105 is changed by providing a plurality of fine particles 106 on the surface of the second electrode 105 on the light extraction side. The surface of the second electrode 105 has a plurality of convex portions due to the plurality of fine particles 106, and the critical angle of light incident on the interface between the second electrode 105 and the gas 110 varies from place to place. That is, in this case, light having an incident angle that has been totally reflected is normally not totally reflected but is refracted and scattered by the fine particles 106 and can pass through the second electrode 105. Thus, by providing the fine particles 106 in contact with the surface of the second electrode 105, the amount of light totally reflected at the interface between the second electrode 105 and the gas 110 is reduced, and the light extraction efficiency is improved.

  Note that Patent Document 1 describes that light extraction efficiency is improved by providing a particle-containing transparent electrode layer 3 ′ in which fine particles are dispersed on the transparent electrode layer 3 (FIG. 2 and its description). reference). That is, in Patent Document 1, light is scattered by the fine particles in the particle-containing transparent electrode layer 3 ′ to change the light angle to an angle that does not totally reflect, thereby improving the extraction efficiency. It does not change the condition (critical angle) of total reflection of light extracted from the electrode layer 3. On the other hand, the invention proposed in this specification improves the light extraction efficiency by changing the shape of the interface between the second electrode 105 and the gas 110 to change the total reflection condition of the interface itself. The invention proposed in the book is completely different from Patent Document 1 in essential principle.

The material of the fine particles 106 may be either an organic material or an inorganic material. Tin oxide (SnO ₂ ), zinc oxide (ZnO), ITO, etc., oxides including oxides and dopants listed as the transparent conductive film material of the second electrode 105, strontium oxide (Sr ₃ O ₂ ), oxidation Examples thereof include metal oxides such as aluminum (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), yttrium oxide (Y ₂ O ₃ ), and cerium oxide (CeO ₂ , CeO ₂ Ce ₂ O ₃ ). Various ferroelectric materials can be used. For example, there are oxide ferroelectric materials such as barium titanate (BaTiO ₃ ), KNbO ₃ , and LiNbO ₃ . Further, silicon oxide, silicon nitride, silicon nitride oxide (SiN _x O _y , 0 <x <4/3, 0 <y <2, 0 <3x + 2y ≦ 4), zirconia, DLC (diamond-like carbon), carbon nanotube, etc. Inorganic materials can be used.

  The size (particle size) of the fine particles 106 needs to be a size with which the above-described effect can be obtained, and is 2 nm or more, more preferably 20 nm or more. Further, the size of the fine particles 106 preferably does not exceed the wavelength in the visible light region, and the upper limit is set to 800 nm. Considering the optical design of the light emitting element, it is preferable to set the upper limit to 100 nm.

  The shape of the fine particles 106 is preferably a shape that effectively collects or scatters light. For example, a columnar shape, a polyhedral shape, a polygonal pyramid shape such as a triangular pyramid, a conical shape, a concave lens shape, a convex lens shape, a kamaboko shape, a prism Shape, sphere, hemisphere and the like.

  A large number of fine particles 106 are provided on the surface of the second electrode 105, but all the fine particles 106 need not have the same material, size, and shape, and may be different from each other.

  The light-emitting element of the present invention is not limited to the structure shown in FIG. 1 or the like, and any structure having at least one light-emitting layer between two electrodes may be used. Light-emitting elements using electroluminescence are distinguished depending on whether the light-emitting material contained in the light-emitting layer is an organic compound or an inorganic compound. In general, the former is called an organic EL element and the latter is called an inorganic EL element. It is.

  For example, when the organic EL device is a light emitting device, functional layers such as an electron injection layer, an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer can be freely combined in addition to the light emitting layer. May be. A plurality of light emitting layers may be provided between the electrodes.

  In addition, an inorganic EL element can be formed as a light-emitting element. Inorganic EL elements are classified into a dispersion-type inorganic EL element and a thin-film inorganic EL element depending on the element structure. The former has a light-emitting layer in which particles of a light-emitting material are dispersed in a binder, and the latter has a light-emitting layer made of a thin film of the light-emitting material. It is common in the point that requires. Two mechanisms of light emission are accepted. One is a donor-acceptor recombination mechanism that utilizes a donor level and an acceptor level. The other is a localization mechanism that utilizes inner-shell electronic transitions of metal ions. In general, a dispersion-type inorganic EL often has a donor-acceptor recombination mechanism, and a thin-film inorganic EL element often has a localized mechanism.

  The inorganic EL element emits light by applying a voltage between a pair of electrode layers sandwiching the light emitting layer, and can operate in either direct current drive or alternating current drive.

(Embodiment 2)
The present embodiment will be described with reference to FIG. In Embodiment 1, the gas-tight space between the substrate 101 and the substrate 109 is filled with gas. However, the light-emitting device of this embodiment fills this space with a liquid-phase material, and the liquid-phase material is filled with the gas-phase material. Solids formed by curing are filled. As described above, a sealing structure of a light emitting device in which a solid is provided between substrates is called a solid sealing structure, and may be used to distinguish from a structure filled with gas. This terminology will also be used throughout this specification to distinguish it from gas-filled structures.

  A substrate 101 in which fine particles 106 are dispersed on the surface of the second electrode 105 is prepared by the process described in Embodiment 1 (FIG. 2A).

  Next, as in the first embodiment, an uncured sealing material 108 is provided around the substrate 101 in a predetermined shape by a printing method, a dispenser method, or the like (FIG. 2B).

  In this embodiment, the filler 201 is provided in the space between the substrate 101 and the substrate 109 that is hermetically sealed by the sealing material 108. As a material of the filler 201, a UV light curable resin such as an epoxy resin or an acrylic resin, a visible light curable resin, or a thermosetting resin is used. When the material of the light emitting layer 104 is an organic material, a UV light curable resin or a visible light curable resin is preferable in consideration of the low heat resistance of the organic material. When a thermosetting resin is used, a resin having a curing temperature of 100 ° C. or lower is selected. After the sealing material 108 is provided, an uncured (liquid phase) filler 201 is dropped into a region surrounded by the sealing material 108 (FIG. 2C).

  Next, the substrate 109 is overlaid on the substrate 101 on which the uncured sealing material 108 and the filler 201 are prepared. While applying pressure to the substrate 101 and the substrate 109, the uncured sealing material 108 and the filler 201 are irradiated with light or heated to be cured, and the substrate 109 is fixed to the substrate 101. The cured filler 201 is provided in contact with the surface of the second substrate and the surface of the second electrode 105 to fix the substrate 109 to the substrate 101. Further, the fine particles 106 are fixed to the surface of the second electrode 105 by the filler 201. After the sealing material 108 and the filler 201 are cured, the substrate 109 is divided to form a light emitting device having an arbitrary size (FIG. 2D).

(Embodiment 3)
This embodiment will be described with reference to FIG. The present embodiment also shows a light emitting device having a solid sealing structure as in the second embodiment.

  Through the process described in Embodiment Mode 1, a substrate 101 in which a light-emitting element including the first electrode 103, the light-emitting layer 104, and the second electrode 105 is formed over the lower structure 102 is prepared. Then, before spraying the fine particles, the sealing material 108 is provided around the substrate 101 as shown in the first embodiment (FIG. 3A).

  An uncured (liquid phase) filler 302 in which the fine particles 106 are dispersed is prepared. The material of the filler 302 is the same as that of the filler 201 of the second embodiment. An uncured filler 302 in which the fine particles 106 are dispersed is dropped into a region surrounded by the sealing material 108 (FIG. 3B). Note that before the uncured filler 302 is dropped, the uncured sealing material 108 is slightly cured in advance by UV light irradiation treatment or heat treatment.

  The substrate 109 is overlaid on the substrate 101, and the substrate 101 and the substrate 109 are attached to each other. Then, the substrate 101 is allowed to stand so that as many particles 106 in the filler 302 as possible can come into contact with the surface of the second electrode 105. Thereafter, the sealing material 108 and the filling material 302 are completely cured by irradiation with UV light or heating to obtain a light emitting device having a solid sealing structure (FIG. 3C). Note that the sealant 108 and the filler 302 are completely cured while applying pressure to the substrate 101 and the substrate 109 as necessary.

  In this embodiment, in order to provide the fine particles 106 on the surface of the second electrode 105, the fine particles 106 are dispersed in the material of the filler 302 and dropped onto the surface of the second electrode 105. In the light emitting device of the present embodiment, the fine particles 106 are also dispersed in the filler 302, and this point distinguishes the present embodiment from the second embodiment.

(Embodiment 4)
This embodiment is shown in FIG. The present embodiment is a light emitting device having a solid sealing structure. In Embodiment 3, a filler in which fine particles are dispersed is dropped onto the substrate side on which the light emitting element is provided. On the other hand, in this embodiment, it is dropped on the other sealing substrate.

  A sealing material 108 is provided around the substrate 109 in a predetermined shape by a printing method, a dispenser method, or the like (FIG. 4A).

  An uncured (liquid phase) filler 312 in which fine particles 106 are dispersed is prepared. The material of the filler 312 is the same as that of the filler 201 of the second embodiment. An uncured filler 312 in which the fine particles 106 are dispersed is dropped into a region surrounded by the sealing material 108 (FIG. 4B). Note that the uncured sealing material 108 is slightly cured in advance before the uncured filler 312 is dropped.

  Through the process described in Embodiment Mode 1, a substrate 101 in which a light-emitting element including the first electrode 103, the light-emitting layer 104, and the second electrode 105 is formed over the lower structure 102 is prepared. The substrate 101 is overlaid on the substrate 109 (FIG. 4C).

  The substrate 101 is overlaid on the substrate 109, and the substrate 101 and the substrate 109 are attached to each other. Thereafter, the top and bottom are replaced, and the substrate 101 side is turned down. Then, the substrate 101 is allowed to stand to precipitate the fine particles 106 in the filler 312. Thereafter, the sealing material 108 and the filling material 312 are completely cured by irradiation with UV light or heating to obtain a light emitting device having a solid sealing structure (FIG. 4D).

  In addition, in the solid sealing structure in which the sealing material is provided in the periphery as shown in the embodiments 2 to 4, the cured filler may not be provided in the entire region surrounded by the sealing material, and is cured. It is only necessary to cover at least the region where the light emitting element is provided over the substrate 101 (the region where the light emitting layer 104 and the second electrode 105 are provided).

(Embodiment 5)
This embodiment is shown in FIG. The present embodiment is a light emitting device having a solid sealing structure. In Embodiments 2 to 4, a solid sealing structure provided with a solid obtained by curing a liquid phase material is shown. In the present embodiment, a solid sealing structure using a solid obtained by curing a sheet-like (also referred to as film-like) sealing material provided on a film substrate is shown.

  As described in Embodiment 1, the substrate 101 in which the fine particles 106 are dispersed on the surface of the second electrode 105 is prepared (FIG. 5A).

  In order to fix the substrate 109 to the substrate 101, a sheet-like sealing material 501 is prepared. The uncured sheet-shaped sealing material 501 is a sheet-shaped sealing material made of a resin material having an adhesive function. As the resin material, UV light curable resin, visible light curable resin, or thermosetting resin can be used. In order to protect the adhesive surface, both surfaces are covered with a film substrate 502. The film base material 502 on one surface of the sealing material 501 is peeled off, and the surface is overlapped with the surface of the substrate 101 (FIG. 5B).

  Next, the film substrate on the other side is peeled off. Thereafter, the substrate 109 is overlaid on the substrate 101. The sheet-like sealing material 501 is cured by applying UV light or heating while applying pressure to the substrate 101 and the substrate 109, and the substrate 109 is fixed to the substrate 101. Further, the fine particles 106 are firmly fixed to the second electrode 105 by the cured sealing material 501. (FIG. 5C).

  By using the sheet-like sealing material 501 in this manner, the effects of fixing the substrate 109 to the substrate 101, forming a solid-sealed light emitting device, and fixing the fine particles 106 can be obtained. .

  In the step shown in FIG. 5B, the sheet-like sealing material 501 can be provided not on the substrate 101 but on the sealing substrate 109 side. In this case, instead of spraying the fine particles 106 on the surface of the second electrode, the fine particles 106 can be sprayed on the surface of the sealing material 501 provided on the substrate 109.

(Embodiment 6)
This embodiment is shown in FIG. As in the fifth embodiment, the present embodiment is a light emitting device having a solid sealing structure using a sheet-like sealing material.

  An uncured sheet-shaped sealing material 511 is prepared. The uncured sheet-like sealing material 511 is a resin layer having an adhesive function, and both surfaces thereof are covered with the film base material 512. As the resin layer constituting the sheet-like sealing material 511, a UV light curable resin, a visible light curable resin, or a thermosetting resin is used. (Fig. 6 (a))

  The film substrate 512 on one side is peeled off, and fine particles 106 are provided on that side. By using a printing method such as a dry method or a wet method as described in Embodiment Mode 1 or a gravure printing method, the fine particles 106 are provided on one surface of the sealant 511, and a sheet shape with the fine particles 106 is provided. A sealing material 511 is prepared (FIG. 6B).

  As described in Embodiment Mode 1, a substrate 101 on which a light emitting element is formed is prepared. A sheet-like sealing material 511 with fine particles 106 is disposed on the surface of the substrate 101. At this time, the surface of the sealing material 511 having the fine particles 106 is brought into contact with the second electrode 105 (FIG. 6C).

  The other film base 512 is peeled off from the sealing material 511, and the substrate 109 is overlaid on the surface. The sheet-like sealing material 511 is cured by applying UV light or heating while applying pressure to the substrate 101 and the substrate 109, and the substrate 109 is fixed to the substrate 101 (FIG. 6D).

  The substrate 109 and the substrate 101 can be stacked after the sealing material 511 with the fine particles 106 is provided on the surface of the substrate 109. Also at this time, the sealing material 511 is arranged so that the surface side on which the fine particles 106 are not scattered becomes the substrate 109 side.

  The sheet-like sealing material 511 with the fine particles 106 shown in FIG. 6B is that the substrate 109 is fixed to the substrate 101, a light emitting device having a solid sealing structure is formed, and the fine particles 106 are fixed. In addition to the effect, the light extraction efficiency of the light emitting element is improved. As described above, the sheet-like sealing material with fine particles is very useful as a member of a light-emitting device that extracts light from the light-emitting element from above the light-emitting element.

  Note that when a light emitting device having a solid sealing structure is formed using a sheet-like sealing material as shown in Embodiments 5 and 6, the sheet-like sealing material does not cover the entire surface of the substrate 101 or the substrate 109. Good. The sheet-like sealing material may cover at least a region where the light emitting element is provided over the substrate 101 (a region where the light emitting layer 104 and the second electrode 105 are provided).

(Embodiment 7)
This embodiment will be described with reference to FIGS. In this embodiment, a light emitting device including a light emitting element in which fine particles are sandwiched between a second electrode and a transparent conductive film is exemplified.

  As described in Embodiment Mode 1, the substrate 101 in which the fine particles 106 are dispersed on the surface of the second electrode 105 is prepared.

  The surface of the second electrode 105 provided with the fine particles 106 is made of a transparent conductive film. A protective film 601 is further formed on the transparent conductive film. As a result, the fine particles 106 are sandwiched between the transparent conductive film on the surface of the second electrode 105 and the protective film 601. Thereby, the fine particles 106 are more firmly fixed to the surface of the second electrode than in the configuration without the protective film 601. (Fig. 7)

  As the material of the protective film 601, a material having the same or higher refractive index than that of the transparent conductive film forming the surface of the second electrode 105 is selected. This is for suppressing total reflection at the interface between the second electrode 105 and the protective film 601. Specifically, the material of the transparent conductive film described in Embodiment 1 can be selected.

  For example, the protective film 601 is formed using the transparent conductive film described in Embodiment 1. These transparent conductive films can be formed by sputtering or vapor deposition.

In addition to the transparent conductive film, the protective film 601 includes silicon oxide (SiO _y , 0 <y ≦ 2), silicon nitride (SiN _x , 0 <x ≦ 4/3), silicon nitride oxide (SiN _x O _y). 0 <x <4/3, 0 <y <2, 0 <3x + 2y ≦ 4), DLC, aluminum nitride, or the like can be used. These films can be formed by CVD, sputtering, or vapor deposition. For example, when the refractive index of the protective film 601 is formed by plasma CVD, silicon oxide, silicon nitride, silicon nitride oxide, or the like is adjusted by adjusting the ratio and type of source gas, the processing temperature, and the like. This can be done by adjusting the relative dielectric constant.

  By using the same transparent conductive film as the surface of the second electrode 105 as the protective film 601, and making the refractive indexes of the second electrode 105 and the protective film 601 the same, the optical design of the light emitting device is facilitated. When a silicon nitride film having a lower water permeability than the transparent conductive film or a silicon nitride oxide film having a nitrogen composition ratio higher than oxygen is used for the protective film 601, it is advantageous in terms of suppressing deterioration of the light-emitting element due to moisture. is there.

  When the refractive index of the protective film 601 is the same as that of the second electrode, unevenness due to the fine particles 106 is generated on the surface of the protective film 601 in order to suppress total reflection of light passing through the protective film 601. For example, this object can be achieved by increasing the size of the fine particles 106. On the other hand, in the case where the refractive index of the protective film 601 is larger than the refractive index of the second electrode 105, the surface of the protective film 601 does not have to be uneven due to the fine particles 106.

  As described in Embodiments 1, 2, and 5, the substrate 109 is fixed to the substrate 101, and the light emitting element is sealed. The light-emitting device which performed the sealing process of Embodiment 1, 2, 5 is shown to Fig.8 (a)-(c). 8A corresponds to the first embodiment, FIG. 8B corresponds to the second embodiment, and FIG. 8C corresponds to the fifth embodiment.

(Embodiment 8)
This embodiment will be described with reference to FIGS. In this embodiment, a light-emitting device including a light-emitting element in which a protective film is provided over the second electrode is shown.

  A substrate 101 on which a light-emitting element including the first electrode 103, the light-emitting layer 104, and the second electrode 105 is formed is prepared by the process described in Embodiment Mode 1. Then, a protective film 611 is formed in contact with the surface of the second electrode 105. Then, fine particles 106 are provided on the protective film 611. In order to provide the fine particles 106, as in the first embodiment, the fine particles 106 may be dispersed by a dry method or a wet method.

As the protective film 611, a film having a high visible light transmittance is used. Specifically, silicon oxide (SiO _y , 0 <y ≦ 2), silicon nitride (SiN _x , 0 <x ≦ 4/3), Silicon nitride oxide (SiN _x O _y , 0 <x <4/3, 0 <y <2, 0 <3x + 2y ≦ 4), DLC, aluminum nitride, or the like can be used. The protective film 611 is formed according to the material of the protective film 611 such as a vapor deposition method, a sputtering method, a plasma CVD method, or a coating method in which a film is formed from a raw material solution in which a raw material is dissolved in a solvent.

  In order not to cause total reflection at the interface between the second electrode 105 and the protective film 611, the material of the protective film 611 has a refractive index that is the same as or higher than that of the second electrode 105. It is preferred to select the material. In order to adjust the refractive index of the protective film 611, for example, when silicon oxide, silicon nitride, silicon nitride oxide, or the like is formed by a plasma CVD method, the ratio and type of source gas, the processing temperature, and the like are adjusted and deposited. This can be done by adjusting the relative dielectric constant of the film.

  For the fine particles 106, a material having a refractive index equal to or larger than that of the second electrode 105 is selected so as not to cause total reflection at the interface between the second electrode 105 and the protective film 611. Is preferred.

  Next, as described in the first, second, and fifth embodiments, the substrate 109 is fixed to the substrate 101. Further, as described in Embodiment 6, sealing can be performed with a sheet-like sealing material with fine particles 106. The light-emitting device which performed the sealing process of Embodiment 1, 2, 5 and 6 is shown to Fig.10 (a)-(c). 10A corresponds to the first embodiment, FIG. 10B corresponds to the second embodiment, and FIG. 10C corresponds to the fifth and sixth embodiments.

  Further, instead of spraying the fine particles 106, as shown in the third and fourth embodiments, a method of dropping an uncured filler in which fine particles are dispersed can be employed. A light-emitting device manufactured by employing the methods of Embodiments 3 and 4 is shown in FIG.

  The light emitting element of this embodiment can also improve the light extraction efficiency from the light emitting element based on the same principle as that described in Embodiment 1. That is, since the shape of the surface of the protective film 611 is changed by providing a plurality of fine particles 106 on the surface of the protective film 611 on the light extraction side, the total reflection at the interface between the second electrode 105 and the fine particles 106 is usually performed. Even light having an incident angle to be guided can be refracted and scattered by the protective film 611 without being totally reflected and pass through the fine particles 106. Thus, by providing a plurality of fine particles in contact with the surface of the protective film 611, the amount of light totally reflected at the interface between the second electrode 105 and the protective film 611 is reduced, and light extraction efficiency is improved.

(Embodiment 9)
This embodiment will be described with reference to FIG. In FIG. 1, the case where the fine particles 106 are polyhedral and have different shapes and sizes is illustrated. Depending on the shape of the fine particles, the action of the lens or prism becomes significant. For example, as shown in FIG. 12A, the shape of the fine particles 701 is a sphere. By allowing the spherical fine particles 701 to pass through, the light that has passed through the second electrode 105 can be collected. In the case of solid sealing, the spherical fine particles 701 are fixed in a state of being pressed against the surface of the second electrode 105 by the pressure applied when the substrate 101 and the substrate 109 are fixed.

  Further, as shown in FIG. 12B, the shape of the fine particles 702 may be a triangular pyramid or a triangular prism, and the fine particles 702 may have a prism function. Since light is scattered by passing through the fine particles 702, the viewing angle can be widened. Further, the light passing through the second electrode 105 can be condensed by passing through the spherical fine particles 701.

  In addition, as shown in FIG. 12C, spherical fine particles 701 and triangular pyramid or triangular fine particles 702 may be provided together.

  12A to 12C, the fine particles 701 and 702 are not uniform in size, but may be the same size. Further, in FIGS. 12A to 12C, the structure of the second embodiment is adopted as the structure of the light emitting device as an example, but it is needless to say that the structures of other embodiments can be adopted.

(Embodiment 10)
This embodiment will be described with reference to FIGS. In this embodiment, an example in which an active matrix EL panel having a display function is used as a light-emitting device will be described.

  FIG. 13 is a schematic view of the active matrix EL panel as viewed from the front. A sealing substrate 801 is fixed to the substrate 800 with a sealant 802. The space between the substrate 800 and the substrate 801 is made airtight. In this embodiment, the EL panel sealing structure is a solid sealing structure, and this space is filled with a filler made of resin.

  The substrate 800 is provided with a pixel portion 803, a writing gate signal line driver circuit portion 804, an erasing gate signal line driver circuit portion 805, and a source signal line driver circuit portion 806. The drive circuit units 804 to 806 are each connected to an FPC (flexible printed circuit) 807 that is an external input terminal via a wiring group. The source signal line driver circuit unit 806, the write gate signal line driver circuit unit 804, and the erase gate signal line driver circuit unit 805 respectively receive a video signal, a clock signal, a start signal, and a reset signal from the FPC 807. Receive etc. A printed wiring board (PWB) 808 is attached to the FPC 807.

  Transistors in the pixel portion 803 and the driver circuit portions 804 to 806 are formed of thin film transistors (TFTs). Note that the driver circuit portions 804 to 806 are not necessarily provided on the same substrate 800 as the pixel portion 803 as described above. For example, an IC chip mounted on an FPC on which a wiring pattern is formed ( TCP) or the like may be used and provided outside the substrate. A part of each of the driving circuits 804 to 806 may be provided on the substrate 800 and a part may be provided outside the substrate 800.

  FIG. 14 is a diagram illustrating a circuit for operating one pixel. The pixel portion 803 has a plurality of pixels arranged in a plane. One pixel includes a first transistor 811, a second transistor 812, and a light emitting element 813. Further, a source signal line 814 and a current supply line 815 extending in the column direction, and a gate signal line 816 extending in the row direction are provided. The light-emitting element 813 is an EL element having a top emission structure, and light is extracted from the substrate 801 side.

  Each of the first transistor 811 and the second transistor 812 is a three-terminal element including a gate electrode, a drain region, and a source region, and has a channel region between the drain region and the source region. Here, since the source region and the drain region vary depending on the structure and operating conditions of the transistor, it is difficult to limit which is the source region or the drain region. Therefore, in this specification, the three terminals of the transistor are referred to as a gate electrode, a first electrode, and a second electrode.

  In the writing gate signal line driver circuit portion 804, the gate signal line 816 is electrically connected to the writing gate signal line driver circuit 819 through the switch 818. By controlling the switch 818, the gate signal line 816 is selected to be electrically connected to or disconnected from the writing gate signal line driver circuit 819.

  In the erase gate signal line driver circuit portion 805, the gate signal line 816 is electrically connected to the erase gate signal line driver circuit 821 through the switch 820. By controlling the switch 820, the gate signal line 816 is selected to be electrically connected to or disconnected from the erasing gate signal line driver circuit 821.

  In the source signal line driver circuit portion 806, the source signal line 814 is electrically connected to either the source signal line driver circuit 823 or the power source 824 by the switch 822.

  In the first transistor 811, the gate electrode is electrically connected to the gate signal line 816, the first electrode is electrically connected to the source signal line 814, and the second electrode is electrically connected to the gate electrode of the second transistor 812. Connected.

  As described above, the second transistor 812 has the gate electrode electrically connected to the second electrode of the first transistor, the first electrode electrically connected to the current supply line 815, and the second electrode serving as the light emitting element. 813 is electrically connected to the first electrode. The second electrode of the light emitting element 813 has a constant potential.

  The structure of the pixel of this embodiment will be described with reference to FIG. In this embodiment, since the EL panel has a solid sealing structure, an airtight space between the substrate 800 and the sealing substrate 801 is filled with a filler 830 made of resin. A lower structure 831 and a light emitting element 813 are formed on the substrate 800. As the lower structure 831, the first transistor 811 and the second transistor 812 illustrated in FIG. 14 are formed over the base film 832. The lower structure 831 can function as a support for the light-emitting element. An interlayer insulating film 833 is formed over the first transistor 811 and the second transistor 812, and a light-emitting element 813 and a partition wall 834 made of an insulating material are formed over the interlayer insulating film 833.

  The first transistor 811 and the second transistor 812 are top-gate thin film transistors in which a gate electrode is provided on the side opposite to the substrate with a semiconductor layer in which a channel formation region is formed as a center. The thin film transistor structure of the first and second transistors 811 and 812 is not particularly limited, and may be, for example, a bottom gate type. In the case of a bottom gate, the semiconductor layer forming a channel may be formed with a protective film (channel protection type), or the semiconductor layer forming the channel may be partially concave ( Channel etch type).

  In addition, the semiconductor layer in which the channel formation regions of the first and second transistors 811 and 812 are formed may be either a crystalline semiconductor or an amorphous semiconductor.

  Specific examples of the crystalline semiconductor of the semiconductor layer include those made of single crystal or polycrystalline silicon, silicon germanium, or the like. These may be formed by laser crystallization, or may be formed by crystallization by a solid phase growth method using nickel or the like, for example.

  In the case where the semiconductor layer is formed using an amorphous semiconductor, for example, amorphous silicon, all of the N-channel thin film transistors included in the pixel portion 803 are preferably included. Other than that, the pixel portion 803 may be formed of one of an N-channel transistor and a P-channel transistor, or may be formed of both transistors.

  The transistors used in the driver circuit portions 804 to 806 are similar to the first and second transistors 811 and 812 in the pixel portion 803. The driver circuit portions 804 to 806 can be entirely constituted by thin film transistors, or part of the circuit can be constituted by thin film transistors and the rest can be constituted by IC chips in accordance with the performance of the transistors. In addition, all of the transistors in the driver circuit portions 804 to 806 may be configured by any one of N-channel and P-channel transistors, or may be configured by both transistors.

  In FIG. 15, the light-emitting element 813 includes a light-emitting layer 837 between a first electrode 835 and a second electrode 836. A first electrode 835, a light emitting layer 837, and a second electrode 836 are stacked in this order over the interlayer insulating film 833. The first electrode 835 is a reflective electrode and functions as a cathode. The second electrode 836 is a light-transmitting electrode and functions as an anode. Light emitted from the light-emitting layer 837 is extracted from the second electrode 836.

  The first electrode 835 is connected to the second electrode of the transistor 812 through a contact hole provided in the interlayer insulating film 833.

  A plurality of fine particles 838 are provided in contact with the surface of the second electrode 836. The fine particles reduce the amount of total reflection of light incident on the interface between the second electrode 836 and the filler 830, so that the light extraction efficiency of the light-emitting element 813 can be improved.

  In this embodiment, although the solid sealing structure shown in Embodiment 2 is applied as the EL panel sealing structure, it is needless to say that the sealing structures of other embodiments can be applied.

  A method for driving the EL panel of this embodiment will be described with reference to FIG. FIG. 16 is a diagram for explaining the operation of a frame over time. In FIG. 16, the horizontal direction represents the passage of time, and the vertical direction represents the number of scanning stages of the gate signal line.

  When image display is performed using the EL panel of this embodiment, the screen rewriting operation and the display operation are repeatedly performed during the display period. The number of rewrites is not particularly limited, but is preferably at least about 60 times per second so that a person viewing the image does not feel flicker. Here, a period during which one screen (one frame) is rewritten and displayed is referred to as one frame period.

As shown in FIG. 16, one frame is time-divided into four subframes 841, 842, 843, and 844 including a writing period 841a, 842a, 843a, and 844a and a holding period 841b, 842b, 843b, and 844b. . A light emitting element to which a signal for emitting light is given is in a light emitting state in the holding period. The ratio of the length of the holding period in each subframe is as follows: first subframe 841: second subframe 842: third subframe 843: fourth subframe 844 = 2 ³ : 2 ² : 2 ¹ : 2 ⁰ = 8: 4: 2: 1. As a result, 4-bit gradation can be expressed. However, the number of bits and the number of gradations are not limited to those described here. For example, eight subframes may be provided so that 8-bit gradation can be performed.

  An operation in one frame will be described. First, in the subframe 841, write operations are performed in order from the first row to the last row. Therefore, the start time of the writing period differs depending on the row. From the row in which the writing period 841a is completed, the holding period 841b is shifted in order. In the holding period, the light-emitting element to which a signal for emitting light is given is in a light-emitting state. Further, the processing proceeds to the next subframe 842 in order from the row in which the holding period 841b ends, and the writing operation is performed in order from the first row to the last row as in the case of the subframe 841.

  The above operation is repeated, and the holding period 844b of the subframe 844 is ended. When the operation in the subframe 844 is completed, the process proceeds to the next frame. Thus, the accumulated time of the light emission in each subframe is the light emission time of each light emitting element in one frame. Various display colors having different brightness and chromaticity can be formed by changing the light emission time for each light emitting element and combining them in various ways within one pixel.

  When it is desired to forcibly end the holding period in the row that has already been written and shifted to the holding period before the writing up to the last row is finished as in the subframe 844, the erasing period is after the holding period 844b. It is preferable to provide 844c and control so that the light emission is forcibly stopped. Then, the row that is forcibly set to the non-light emitting state is kept in the non-light emitting state for a certain period (this period is referred to as a non-light emitting period 844d). Then, as soon as the writing period of the last row ends, the next (or frame) writing period starts from the first row. Accordingly, it is possible to prevent the writing period of the subframe 844 from overlapping with the writing period of the next subframe.

  In this embodiment, the subframes 841 to 844 are arranged in order from the longest holding period. However, the subframes 841 to 844 are not necessarily arranged as in this embodiment, and may be arranged in order from the shortest holding period, for example. Alternatively, a long holding period and a short holding period may be arranged at random. In addition, the subframe may be further divided into a plurality of frames. That is, the gate signal line may be scanned a plurality of times during the period when the same video signal is applied.

  The operation of the circuit shown in FIG. 14 in the writing period and the erasing period will be described. First, the operation in the writing period will be described. In the writing period, the gate signal line 816 in the n-th row (n is a natural number) is electrically connected to the writing gate signal line driving circuit 819 by the switch 818. On the other hand, the switch 820 is disconnected from the erasing gate signal line driving circuit 821.

  The source signal line 814 is electrically connected to the source signal line driver circuit 823 through the switch 822. Here, a signal is input to the gate of the first transistor 811 connected to the gate signal line 816 in the n-th row (n is a natural number), and the first transistor 811 is turned on. At this time, video signals are simultaneously input to the source signal lines 814 from the first column to the last column. Note that the video signals input from the source signal lines 814 in each column are independent from each other.

  The video signal input from the source signal line 814 is input to the gate electrode of the second transistor 812 through the first transistor 811 connected to each source signal line 814. Then, depending on the current value, the light emitting element 813 determines light emission or non-light emission. For example, in the case where the second transistor 812 is a P-channel transistor, the light emitting element 813 emits light when a Low Level signal is input to the gate electrode of the second transistor 812. On the other hand, in the case where the second transistor 812 is an n-channel transistor, a high level signal is input to the gate electrode of the second transistor 812 so that a current flows through the light-emitting element 813 and the light-emitting element 813 emits light. .

  Next, the operation in the erasing period will be described. In the erasing period, the gate signal line 816 in the n-th row (n is a natural number) is electrically connected to the erasing gate signal line driving circuit 821 through the switch 820. On the other hand, the write gate signal line drive circuit 819 and the switch 818 are not connected. The source signal line 814 is electrically connected to the power source 824 by the switch 822. A signal is input to the gate of the first transistor 811 connected to the gate signal line 816 in the n-th row, and the first transistor 811 is turned on. At this time, the erase signal is simultaneously input to the source signal lines 814 from the first column to the last column.

  The erase signal input from the source signal line 814 is input to the gate electrode of the second transistor 812 through the first transistor 811 connected to each source signal line 814. A signal input to the second transistor 812 blocks current supply from the current supply line 815 to the light-emitting element 813, and the light-emitting element 813 is forcibly turned off. For example, in the case where the second transistor 812 is a p-channel transistor, the light-emitting element 813 does not emit light when a high level signal is input to the gate electrode of the second transistor 812. On the other hand, in the case where the second transistor 812 is an n-channel transistor, a light level signal is input to the gate electrode of the second transistor 812 so that the light-emitting element 813 does not emit light.

  In the erasing period, for the nth row (n is a natural number), a signal for erasing is input by the operation as described above. However, as described above, the nth row may be an erasing period and the other row (mth row (m is a natural number)) may be a writing period. In such a case, it is necessary to input a signal for erasure to the n-th row and a signal for writing to the m-th row using the source signal line 814 of the same column. It is preferable to operate as described above.

  The gate signal line 816 and the erasing gate signal line driver circuit 821 are immediately disconnected after the light emitting element 813 in the nth row does not emit light by the operation in the erasing period described above. The switch 822 is switched to connect the source signal line 814 and the source signal line driver circuit 823. Then, the gate signal line 816 and the write gate signal line driver circuit 819 are connected by the switch 818. Then, a signal is selectively input from the writing gate signal line driver circuit 819 to the gate signal line 816 in the m-th row, the first transistor 811 is turned on, and the source signal line driver circuit 823 receives one column. A signal for writing is input to the source signal line 814 from the first to the last column. By this signal, the m-th row light emitting element emits light or does not emit light.

  Immediately after the writing period for the m-th row is completed as described above, the erasing period for the (n + 1) -th row is started. Therefore, the switch 818 disconnects the gate signal line 816 and the write gate signal line drive circuit 819 and connects the erase gate signal line drive circuit 821 with the switch 820. In addition, the source signal line 814 is connected to the power source 824 by switching the switch 822. A signal is input from the erasing gate signal line driver circuit 821 to the gate signal line 816 of the (n + 1) th row to turn on the first transistor 811 and an erasing signal is input from the power source 824. Thereafter, similarly, the erasing period and the writing period may be repeated until the erasing period of the last row is operated.

(Embodiment 11)
The light-emitting elements to the light-emitting devices described in Embodiments 1 to 8 can achieve low power consumption by improving light extraction efficiency. Therefore, by mounting these light-emitting devices as a display portion, vivid and bright display with low power consumption can be achieved.

  The light-emitting devices of Embodiments 1 to 9 can be suitably used for display units of battery-driven electronic devices, large-screen display devices, and display units of electronic devices. For example, the sound of a television device (television, television receiver), digital camera, digital video camera, mobile phone device (mobile phone), PDA or other portable information terminal, portable game machine, monitor, computer, car audio, etc. Examples thereof include an image reproducing device provided with a recording medium such as a reproducing device and a home game machine. A specific example will be described with reference to FIG. The light-emitting device used for the display portion may have either an active matrix type or a passive type structure.

  A light-emitting device is used for the display portion 911 of the portable information terminal device illustrated in FIG.

  A light-emitting device is used for the finder 914 of the digital video camera shown in FIG. 17B and the display portion 913 for displaying the captured video.

  A light-emitting device can be applied to the display portion 915 of the cellular phone illustrated in FIG.

  The light-emitting device of the above embodiment is used for the display portion 916 of the portable television device illustrated in FIG.

  The light-emitting device of the above embodiment can be applied to the display portion 917 of a notebook or laptop computer shown in FIG.

  The light-emitting device of the present invention can be applied to the display portion 918 of the television device illustrated in FIG. Note that there are television devices such as a small-sized device mounted on a portable terminal such as the cellular phone shown in FIG. 17D, a medium-sized device that can be carried, and a large-sized device (for example, 40 inches or more). However, the light-emitting device of the above embodiment can be applied to the display portions of television devices having various screen sizes.

Embodiment 12
In this embodiment, a mode in which the light emitting device is applied to a planar lighting device will be described. The light-emitting devices of Embodiments 1 to 9 can be used as a planar lighting device in addition to the display unit. For example, when a liquid crystal panel is used for the display unit of the electronic device exemplified in the above embodiment, the light emitting device of the above embodiment can be mounted as a backlight of the liquid crystal panel. When used as a lighting device, a passive light emitting device is preferable.

  FIG. 18 illustrates an example of a liquid crystal display device using the light-emitting device as a backlight. The liquid crystal display device illustrated in FIG. 18 includes a housing 921, a liquid crystal layer 922, a backlight 923, and a housing 924, and the liquid crystal layer 922 is connected to a driver IC 925. The backlight 923 uses the light-emitting device of the present invention, and a current is supplied from a terminal 926.

  In addition, the liquid crystal display device including the backlight according to the present embodiment can be used as a display unit of various electronic devices as described in the eleventh embodiment.

  By using the light emitting device to which the present invention is applied as a backlight of a liquid crystal display device, a bright backlight with low power consumption can be obtained. In addition, the light-emitting device to which the present invention is applied is a surface-emitting illumination device and can have a large area, so that the backlight can have a large area and a liquid crystal display device can have a large area. Further, since the light emitting device is thin and has low power consumption, the display device can be thinned and the power consumption can be reduced.

Sectional drawing of light-emitting device (Embodiment 1) Sectional drawing of light-emitting device (Embodiment 2) Sectional drawing of light-emitting device (Embodiment 3) Sectional drawing of light-emitting device (Embodiment 4) Sectional drawing of light-emitting device (Embodiment 5) Sectional drawing of light-emitting device (Embodiment 6) Sectional drawing of light-emitting device (Embodiment 7) Sectional drawing of light-emitting device (Embodiment 7) Sectional drawing of light-emitting device (Embodiment 8) Sectional drawing of light-emitting device (Embodiment 8) Sectional drawing of light-emitting device (Embodiment 8) Sectional drawing of light-emitting device (Embodiment 9) Top view of light emitting device (Embodiment 10) FIG. 10 illustrates a pixel circuit of a light-emitting device (Embodiment 10). Sectional drawing of pixel of light-emitting device (Embodiment 10) FIG. 10 illustrates a driving method of a light emitting device (Embodiment 10). FIG. 11 illustrates an embodiment in which a light-emitting device is applied to an electronic device (Embodiment 11). FIG. 12 illustrates a mode in which the light-emitting device is applied to a planar lighting device (Embodiment 12).

Explanation of symbols

101 Substrate 102 Substructure 103 First Electrode 104 Light-Emitting Layer 105 Second Electrode 106 Fine Particle 107 Partition 108 Sealing Material 109 Substrate (For Sealing)
110 gas

Claims (37)

A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked;
A plurality of fine particles in contact with the upper surface of the second electrode;
Have
The light emitted from the light emitting layer is extracted through the upper surface of the second electrode provided with the fine particles,
The light emitting element, wherein the fine particles have a refractive index equal to or higher than a refractive index of the second electrode. A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked;
A plurality of fine particles in contact with the upper surface of the second electrode;
A protective film covering the upper surface of the second electrode provided with the fine particles;
Have
The light emitted from the light emitting layer is extracted through the upper surface of the second electrode provided with the fine particles,
The refractive index of the fine particles is equal to or higher than the refractive index of the second electrode,
The light-emitting element, wherein the protective film has a refractive index equal to or higher than a refractive index of the second electrode. A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked;
A protective film in contact with the upper surface of the second electrode;
A plurality of fine particles in contact with the upper surface of the protective film;
Have
Light emitted from the light emitting layer is extracted through the upper surface of the second electrode;
The refractive index of the protective film is equal to or higher than that of the second electrode,
The light emitting device, wherein the fine particles have a refractive index equal to or higher than a refractive index of the protective film. A first substrate;
A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked on the first substrate;
A plurality of fine particles in contact with the upper surface of the second electrode;
A second substrate facing the first substrate;
Between the first substrate and the second substrate, the first electrode, the light emitting layer, and the second electrode are sealed between the first substrate and the second substrate. A provided sealing material;
Have
The light emitted from the light emitting layer is extracted from the second substrate through the upper surface of the second electrode provided with the fine particles,
The light-emitting device, wherein the fine particles have a refractive index equal to or higher than a refractive index of the second electrode. A protective film formed in contact with the upper surface of the second electrode provided with the fine particles,
The light emitting device according to claim 4, wherein the protective film has a refractive index equal to or higher than that of the second electrode.   6. The light emitting device according to claim 4, wherein a space between the first substrate and the second substrate that is hermetically sealed by the sealing material is filled with a gas. A solid is provided in an area surrounded by the sealing material;
The light emitting device according to claim 4, wherein the solid covers at least a region where the light emitting layer is provided and is in contact with the second electrode. A solid is provided in an area surrounded by the sealing material;
The light emitting device according to claim 5, wherein the solid covers at least a region where the light emitting layer is provided and is in contact with the protective film.   The light emitting device according to claim 7 or 8, wherein the fine particles are dispersed inside the solid.   The light emitting device according to claim 7, wherein the solid is made of a resin. A first substrate;
A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked on the first substrate;
A plurality of fine particles in contact with the upper surface of the second electrode;
A second substrate facing the first substrate;
A sheet-like sealing material for fixing the second substrate to the first substrate;
Have
The sheet-shaped sealing material covers at least a region where the light emitting layer is provided and is in contact with the second electrode,
The light emitted from the light emitting layer is extracted from the second substrate through the upper surface of the second electrode provided with the fine particles,
The light-emitting device, wherein the fine particles have a refractive index equal to or higher than a refractive index of the second electrode. A first substrate;
A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked on the first substrate;
A plurality of fine particles in contact with the upper surface of the second electrode;
A protective film formed in contact with the upper surface of the second electrode provided with the fine particles;
A second substrate facing the first substrate;
A sheet-like sealing material for fixing the second substrate to the first substrate;
Have
The sheet-like sealing material covers at least a region where the light emitting layer is provided, and is in contact with the protective film,
The light emitted from the light emitting layer is extracted from the second substrate through the upper surface of the second electrode provided with the fine particles,
The refractive index of the protective film is equal to or higher than that of the second electrode,
The light-emitting device, wherein the fine particles have a refractive index equal to or higher than a refractive index of the second electrode. A first substrate;
A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked on the first substrate;
A protective film in contact with the upper surface of the second electrode;
A plurality of fine particles in contact with the upper surface of the protective film;
A second substrate facing the first substrate;
A sealing material provided between the first substrate and the second substrate for sealing the first electrode, the light emitting layer, and the second electrode;
Have
The light emitted from the light emitting layer is extracted from the second substrate through the upper surface of the second electrode provided with the fine particles,
The refractive index of the protective film is equal to or higher than that of the second electrode,
The light emitting device according to claim 1, wherein a refractive index of the fine particles is equal to or higher than a refractive index of the protective film.   The light emitting device according to claim 13, wherein a space between the first substrate and the second substrate that is airtight by the sealant is filled with a gas. A solid is provided in a region surrounded by the sealing material, the solid covers at least a region in which the light emitting layer is provided, and a solid is provided in contact with the protective film and the second substrate. The light-emitting device according to claim 13.   The light emitting device according to claim 15, wherein the solid is made of a resin.   The light emitting device according to claim 15 or 16, wherein the fine particles are dispersed inside the solid. A first substrate;
A first electrode, a light emitting layer, and a second electrode, which are sequentially stacked on the first substrate;
A protective film in contact with the upper surface of the second electrode;
A plurality of fine particles in contact with the upper surface of the protective film;
A second substrate facing the first substrate;
A sheet-like sealing material for fixing the second substrate to the first substrate;
Have
The sheet-like sealing material covers at least a region where the light emitting layer is provided, and is in contact with the protective film,
The light emitted from the light emitting layer is extracted from the second substrate through the upper surface of the second electrode provided with the fine particles,
The refractive index of the protective film is equal to or higher than that of the second electrode,
The light emitting device according to claim 1, wherein a refractive index of the fine particles is equal to or higher than a refractive index of the protective film. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A plurality of fine particles having a refractive index equal to or higher than that of the second electrode in contact with the upper surface of the second electrode;
A manufacturing method of a light-emitting device, wherein a sealant is provided around the first substrate or the second substrate, and the second substrate is fixed to the first substrate. A first substrate is formed by laminating a first electrode, a light emitting layer, and a second electrode in this order,
A plurality of fine particles having a refractive index equal to or higher than that of the second electrode in contact with the upper surface of the second electrode;
An uncured sealing material is provided around the first substrate,
Providing a liquid phase filler in a region surrounded by the uncured sealing material on the first substrate;
A second substrate overlaid on the first substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
An uncured sealing material is provided around the first substrate,
Preparing a liquid phase filler in which a plurality of fine particles having a refractive index equal to or higher than that of the second electrode are dispersed;
Providing the liquid phase filler in a region surrounded by the uncured sealing material on the first substrate;
A second substrate overlaid on the first substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
An uncured sealing material is provided around the second substrate,
Preparing a liquid phase filler in which a plurality of fine particles having a refractive index equal to or higher than that of the second electrode are dispersed;
Providing the liquid phase filler in a region surrounded by the uncured sealing material on the second substrate;
Overlaying the first substrate on the second substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A plurality of fine particles having a refractive index equal to or higher than that of the second electrode in contact with the upper surface of the second electrode;
The first substrate and the second substrate are stacked with an uncured sheet-shaped sealing material interposed therebetween,
A method for manufacturing a light-emitting device, wherein the uncured sheet-shaped sealing material is cured to fix the second substrate to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
Preparing an uncured sheet-like sealing material provided with a plurality of fine particles having a refractive index equal to or higher than that of the second electrode in contact with one upper surface;
With the surface on which the fine particles are provided facing the first substrate, the uncured sheet-shaped sealing material is sandwiched between the first substrate and the second substrate,
A method for manufacturing a light-emitting device, wherein the uncured sheet-shaped sealing material is cured to fix the second substrate to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A protective film is provided in contact with the upper surface of the second electrode,
In contact with the upper surface of the protective film, a plurality of fine particles having a refractive index equal to or higher than that of the protective film is provided,
A method for manufacturing a light-emitting device, wherein the second substrate is fixed to the first substrate with a sealant provided around the first substrate or the second substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A protective film is provided in contact with the upper surface of the second electrode,
In contact with the upper surface of the protective film, a plurality of fine particles having a refractive index equal to or higher than that of the protective film is provided,
An uncured sealing material is provided around the first substrate,
A liquid phase filler is provided in a region surrounded by the sealing material on the first substrate,
A second substrate overlaid on the first substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
An uncured sealing material is provided around the first substrate,
A protective film having a refractive index equal to or higher than that of the second electrode is provided in contact with the upper surface of the second electrode;
Preparing a liquid phase filler in which a plurality of fine particles having a refractive index equal to or higher than that of the protective film are dispersed;
Providing the liquid phase filler in a region surrounded by the sealing material on the first substrate;
A second substrate overlaid on the first substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A protective film having a refractive index equal to or higher than that of the second electrode is provided in contact with the upper surface of the second electrode;
An uncured sealing material is provided around the second substrate,
Preparing a liquid phase filler in which a plurality of fine particles having a refractive index equal to or higher than that of the protective film are dispersed;
Providing the liquid phase filler in a region surrounded by the uncured sealing material on the second substrate;
Overlaying the first substrate on the second substrate;
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid phase filler are cured, and the second substrate is fixed to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A protective film having a refractive index equal to or higher than that of the second electrode is provided in contact with the upper surface of the second electrode;
A plurality of fine particles having a refractive index equal to or higher than that of the protective film are provided in contact with the upper surface of the protective film,
The first substrate and the second substrate are stacked with an uncured sheet-shaped sealing material interposed therebetween,
A method for manufacturing a light-emitting device, wherein the uncured sheet-shaped sealing material is cured to fix the second substrate to the first substrate. On the first substrate, a first electrode, a light emitting layer, and a second electrode that transmits light from the light emitting layer are stacked in this order,
A protective film is provided in contact with the upper surface of the second electrode,
Prepare an uncured sheet-like sealing material provided with a plurality of fine particles having a refractive index equal to or higher than that of the protective film in contact with one upper surface,
With the surface on which the fine particles are provided facing the first substrate, the uncured sheet-shaped sealing material is sandwiched between the first substrate and the second substrate,
A method for manufacturing a light-emitting device, wherein the uncured sheet-shaped sealing material is cured to fix the second substrate to the first substrate. A device according to any one of claims 26 to 28.
A method for manufacturing a light-emitting device, wherein the uncured sealing material and the liquid-phase filler are cured in an atmosphere at a pressure lower than atmospheric pressure. In claim 29 or claim 30,
A method for manufacturing a light emitting device, comprising: curing the uncured sheet-shaped sealing material in an atmosphere having a pressure lower than atmospheric pressure. A film substrate;
A resin layer having an adhesive function on the film substrate;
A sheet-like sealing material comprising a plurality of fine particles in contact with the upper surface of the resin layer. In any one of Claims 1 thru | or 3,
The plurality of fine particles include at least one fine particle having a different size. In any one of Claims 4-18,
The light-emitting device, wherein the plurality of fine particles include at least one fine particle having a different size. In any one of claims 19 to 32,
The method for manufacturing a light-emitting device, wherein the plurality of fine particles include at least one fine particle having a different size. In claim 33,
The sheet-like sealing material, wherein the plurality of fine particles include at least one fine particle having a different size.

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