WO2014084220A1 - Organic electroluminescent element, and image display device and lighting device provided with same - Google Patents
Organic electroluminescent element, and image display device and lighting device provided with same Download PDFInfo
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- WO2014084220A1 WO2014084220A1 PCT/JP2013/081820 JP2013081820W WO2014084220A1 WO 2014084220 A1 WO2014084220 A1 WO 2014084220A1 JP 2013081820 W JP2013081820 W JP 2013081820W WO 2014084220 A1 WO2014084220 A1 WO 2014084220A1
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Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/22—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/10—Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
- H05B33/28—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode of translucent electrodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/875—Arrangements for extracting light from the devices
- H10K59/879—Arrangements for extracting light from the devices comprising refractive means, e.g. lenses
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/805—Electrodes
- H10K59/8051—Anodes
- H10K59/80515—Anodes characterised by their shape
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/805—Electrodes
- H10K59/8052—Cathodes
- H10K59/80521—Cathodes characterised by their shape
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/80—Constructional details
- H10K59/875—Arrangements for extracting light from the devices
- H10K59/878—Arrangements for extracting light from the devices comprising reflective means
Definitions
- the present invention relates to an organic EL element, and an image display device and an illumination device including the organic EL element.
- Organic EL elements have features such as a wide viewing angle, high-speed response, and clear self-luminous display. They are thin, lightweight, and have low power consumption. As expected. Organic EL elements are classified into a bottom emission type in which light is extracted from the support substrate side and a top emission type in which light is extracted from the opposite side of the support substrate, depending on the direction in which the light generated in the organic light emitting layer is extracted. .
- a bottom emission type organic EL device out of light emitted from the light emitting layer, light incident perpendicularly to the transparent substrate passes through the transparent substrate and is extracted outside the device.
- a small incident angle incident light and incident light
- the critical angle at the interface between the transparent substrate for example, glass (refractive index: 1.52)
- air refracted at the interface and extracted outside the device.
- these lights are called external mode lights.
- the light incident on the interface between the transparent substrate and air at an incident angle larger than the critical angle is totally reflected at the interface and is not taken out of the device, and finally Can be absorbed by the material.
- this light is referred to as substrate mode light, and the loss due to this is referred to as substrate loss.
- the light incident on the interface between the substrate and the cathode at an incident angle greater than the critical angle is also totally reflected at the interface and is not extracted outside the device, but is finally absorbed by the material. sell.
- an anode made of a transparent conductive oxide (for example, indium tin oxide (ITO (refractive index: 1.82)) and a transparent substrate (for example, glass (refractive index: 1) .52)
- ITO indium tin oxide
- a transparent substrate for example, glass (refractive index: 1) .52)
- waveguide mode light This loss is called waveguide loss.
- the light extraction efficiency of the organic EL element is generally limited to about 20% (for example, Patent Document 1). That is, about 80% of the light emitted from the light emitting layer is lost, and it is a big problem to reduce these losses and improve the light extraction efficiency.
- the extraction of the substrate mode light can be dealt with by providing a light diffusion sheet or the like on the transparent substrate (for example, Patent Document 2).
- Patent Document 2 research on the reduction and extraction of guided mode light and SPP mode light, particularly reduction and extraction of SPP mode light, has just started.
- Patent Document 3 discloses a configuration in which a high refractive index layer having a higher refractive index than that of an organic light emitting layer or a transparent electrode is inserted in the vicinity of the organic light emitting layer.
- Patent Document 2 discloses a configuration in which the refractive index of the organic light emitting layer and the transparent electrode is equivalently lowered by dispersing fine particles having a refractive index lower than that of the organic light emitting layer and the transparent electrode in the organic light emitting layer and the transparent electrode. ing.
- Patent Documents 4 and 5 disclose a configuration in which holes (cavities) are formed in an anode layer and a dielectric layer that are sequentially formed on a substrate. Light incident on the side surface of the cavity (interface extending perpendicular to the substrate) is refracted toward the substrate at this interface. By this effect, the ratio of light that causes total reflection can be reduced by changing the incident angle of the waveguide mode light to a shallow angle.
- Patent Documents 6 to 9 As a method for extracting the SPP mode light trapped on the metal surface, a configuration in which a periodic uneven structure is formed on the surface of the cathode is known (Patent Documents 6 to 9).
- a configuration is also known in which a diffractive lens is provided on the opposite side of the light emitting layer of the cathode (Patent Document 10).
- the present invention has been made in view of the above circumstances, and an object thereof is to provide an organic EL element in which SPP mode light is effectively extracted to improve light extraction efficiency, and an image display device and an illumination device including the organic EL element. To do.
- the inventors first extract SPP mode light as guided mode light and then take out the guided mode light to the outside of the device. Therefore, an effective structure for improving the light extraction efficiency was intensively studied based on simulations. Since it is difficult to directly measure the light extraction efficiency, we examined it based on simulation.
- the two-step light extraction mechanism is a reflective electrode side structure having a plurality of radiation starting points arranged periodically to enable generation of SPP mode light and extraction of the generated SPP mode light into an organic layer;
- the light transmission electrode side structure is provided with a plurality of diffraction lenses to extract the light extracted into the organic layer to the outside.
- the radiation starting point portion of the reflective electrode side structure is a portion that becomes a starting point from which the SPP mode light trapped on the metal surface is re-radiated.
- Each of the plurality of diffractive lenses provided in the light transmission electrode side structure of the present invention has a configuration in which a plurality of bands are arranged at equal intervals, or a plurality of bands so that the intervals are narrowed from the center of the lens toward the periphery. Is provided.
- the belt portions are arranged so as to be parallel to each other in a line extending in one direction in the plane.
- the belt portions are annular and arranged concentrically with each other.
- One lens is composed of two types of belt portions, a high refractive index belt portion and a low refractive index belt portion, and the refractive indexes of adjacent belt portions are different from each other. That is, the refractive index of the belt portion is configured to be “high, low, high, low ...” or “low, high, low, high ...” in order from the lens center.
- This diffractive lens has a function of condensing light emitted from the radiation starting point as a whole at a focal point in the normal direction of the substrate surface (a plane parallel to the light emitting surface). Therefore, the guided mode light incident on the diffractive lens is condensed in the normal direction of the substrate surface for each diffractive lens and is incident on the substrate surface or the like.
- the waveguide mode light changes to an angle at which the incident angle to the substrate (angle with respect to the normal of the substrate surface) is small. Therefore, the light extraction efficiency can be improved by increasing the light that can avoid total reflection at the interface between the substrate and air.
- the position of the focal point may be at a finite distance from the diffractive lens, or may be at infinity (a diffracted light becomes a plane wave propagating in the normal direction).
- an organic EL element comprising a light transmissive electrode, an organic layer including a light emitting layer made of an organic EL material, and a reflective electrode in order, and the reflective electrode is periodically formed on the surface of the organic layer.
- a plurality of radiating origin portions arranged, comprising a plurality of diffractive lenses on the opposite side of the organic layer from the reflective electrode, and the radiating origin portions overlapping the diffractive lenses in plan view An organic EL element characterized by being arranged in the above.
- a substrate is provided on the opposite side of the light transmissive electrode from the organic layer, and is configured to extract light from the substrate side to the outside.
- the light transmissive electrode is an anode
- the reflective electrode is The organic EL element according to (1), wherein the organic EL element is a cathode and includes the plurality of diffraction lenses between an outer surface of the substrate and the organic layer.
- the diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point portion in plan view, according to any one of (1) to (4), The organic EL element of description.
- an organic EL element in which SPP mode light and waveguide mode light are effectively extracted to improve light extraction efficiency, and an image display device and an illumination device including the organic EL element.
- FIG. 1 It is a schematic diagram in case the phase of the ring zone part of a diffraction lens and the ring zone part of a light transmissive electrode is reverse (reverse phase), (a) is a cross-sectional schematic diagram, (b) A plane schematic diagram. It is a cross-sectional schematic diagram for demonstrating an example of the organic EL element which concerns on other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating an example of the organic EL element which concerns on other embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating an example of the image display apparatus provided with the organic EL element of this invention. It is a cross-sectional schematic diagram for demonstrating an example of the illuminating device provided with the organic EL element of this invention.
- the structure of an organic EL element to which the present invention is applied, an image display apparatus and an illumination apparatus including the organic EL element will be described with reference to the drawings.
- the portions that become the features may be shown in an enlarged manner for convenience, and the dimensional ratios and the like of the respective components are not always the same as the actual ones.
- the materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these, and can be appropriately modified and implemented without changing the gist thereof.
- the configuration of the bottom emission type will be described.
- the organic EL element according to the present invention may be a top emission type.
- FIG. 1 is a schematic cross-sectional view for explaining an example of an organic EL element according to an embodiment of the present invention.
- FIG. 2 is a schematic plan view of a diffractive lens provided in the organic EL element of FIG.
- An organic EL element 10 according to an embodiment of the present invention includes an anode (light transmission electrode) 2, an organic layer 3 including a light emitting layer made of an organic EL material, and a cathode (reflection electrode) 4 on a substrate 1. It is the organic EL element 10 which comprises in order.
- the cathode 4 has a plurality of radiation starting points 4a periodically disposed on the surface 4A on the organic layer side.
- a plurality of diffractive lenses 5 are provided between the substrate 1 and the organic layer 3, and the radiation starting point portion 4 a is disposed at a position overlapping the diffractive lenses 5 in plan view.
- the diffractive lens only needs to be on the opposite side of the organic layer 3 from the cathode 4, and may be arranged at any position between the outer surface of the substrate 1 and the organic layer 3.
- the present embodiment is configured to be disposed between the substrate 1 and the organic layer 3 and particularly in the anode 2.
- the diffractive lens 5 is disposed in the anode 2 and has a plurality of annular portions 5a made of a concentric dielectric.
- the anode 2 has a plurality of concentric annular zone portions 2a arranged alternately with the annular zone portions 5a.
- either one of the annular zone 2a of the anode 2 or the annular zone 5a of the diffractive lens 5 includes not only an annular zone having a ring shape but also a central portion of a concentric circle and a circular center portion. Shall be.
- the anode 2 has a ring zone portion 2 a which is a circular center portion.
- the organic layer 3 has a layered portion 3 a disposed between the anode 2 and the cathode 4. Furthermore, the organic layer 3 has a part (in the example of FIG.
- a convex part 3b) corresponding to the shape of the radiation starting point part 4a a convex part 3b corresponding to the shape of the radiation starting point part 4a.
- the portion 3b corresponding to the shape of the radiation starting point portion 4a is a concave shape (recessed portion) formed on the surface of the reflective electrode on the organic layer side as shown in FIG. It becomes a convex shape, or a concave shape if the radiation starting point 4a is a convex shape.
- the diffractive lens 5 is provided so that the center thereof is disposed on the center line C1 of the radiation starting point portion 4a in plan view.
- the substrate 1 is a light-transmitting substrate and usually needs to be transparent to visible light.
- transparent to visible light means that it is only necessary to transmit visible light having a wavelength emitted from the light emitting layer, and does not need to be transparent over the entire visible light region.
- a smooth substrate having a transmittance in visible light of 400 to 700 nm of 50% or more is preferable.
- glass plates and polymer plates examples include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.
- the polymer plate examples include polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyether sulfide, polysulfone, and PEN (polyethylene naphthalate).
- the transmittance is preferably 50% or more and more preferably 70% or more with respect to the wavelength at which light emission has the maximum intensity.
- the substrate 1 is disposed on the side opposite to the organic layer 3 when viewed from the cathode 4.
- the substrate 1 can be made of an opaque material in addition to the same as described above. Specifically, for example, Cu, Ag, Au, Pt, W, Ti, Ta, Nb, Al alone, an alloy containing these elements, or a metal material such as stainless steel, Si, SiC, AlN, GaN, Nonmetallic materials such as GaAs and sapphire, and other substrate materials usually used in top emission type organic EL elements can be used.
- a material having high thermal conductivity is preferably used for the substrate.
- the anode 2 is an electrode for applying a voltage to the cathode 4 and injecting holes from the anode 2 into the light emitting layer. It is preferable to use a material made of a metal, an alloy, a conductive compound, or a mixture thereof having a high work function. Further, it is preferable to use a material having a work function of 4 eV or more and 6 eV or less so that the difference from the HOMO (Highest ⁇ Occupied Molecular Orbital) level of the organic layer in contact with the anode does not become excessive.
- HOMO Highest ⁇ Occupied Molecular Orbital
- the material of the anode 2 is not particularly limited as long as it is a translucent and conductive material.
- transparent inorganic oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, zinc oxide, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonic acid) ), Conductive polymers such as polyaniline, and conductive polymers doped with any acceptor, and transparent carbon materials such as carbon nanotubes and graphene.
- the anode 2 can be formed on the substrate 1 by, for example, a sputtering method, a vacuum deposition method, a coating method, or the like.
- the diffractive lens 5 includes a plurality of annular portions 5 a made of a concentric dielectric, and is made of a material having a refractive index different from that of the anode 2.
- the refractive index of the diffractive lens 5 is preferably lower than the refractive index of the anode 2.
- the material of the diffractive lens 5 is not particularly limited as long as it is a light-transmitting material having a refractive index lower than that of the anode 2.
- the material of the anode 2 is indium tin oxide (ITO (refractive index 1.82)), for example, spin-on glass (SOG (refractive index 1.25)), magnesium fluoride (MgF 2 (refractive index 1.38). )), Metal fluorides such as polytetrafluoroethylene (PTFE (refractive index 1.35)), silicon dioxide (SiO 2 (refractive index 1.45)), various low melting glass, various Examples include porous substances.
- the thickness of the diffractive lens 5 is not limited, but is, for example, 10 to 2000 nm, and preferably 50 to 1000 nm.
- the cathode 4 has a plurality of radiation starting points 4a periodically arranged on the surface 4A on the organic layer side.
- the radiation starting point portion 4a is preferably arranged at a position overlapping the diffraction lens 5 in plan view.
- the cathode 4 is an electrode for injecting electrons into the light emitting layer. It is preferable to use a material made of a metal, an alloy, a conductive compound, or a mixture thereof having a low work function, and the work function is 1.9 eV or more so that the difference from the LUMO (Lowest Unoccupied Molecular Orbital) level does not become excessive. It is preferable to use a voltage of 5 eV or less. Examples of such materials include simple substances such as Au, Ag, Cu, Zn, Al, Mg, alkali metals and alkaline earth metals, alloys of Au and Ag, alloys of Ag and Cu, and alloys such as brass. It is done.
- the cathode 4 may have a laminated structure of two or more layers.
- the thickness of the cathode 4 is not limited, but is, for example, 30 nm to 1 ⁇ m, and preferably 50 to 500 nm. If the thickness of the cathode 4 is less than 30 nm, the sheet resistance increases and the driving voltage rises. If the thickness of the cathode 4 is greater than 1 ⁇ m, heat and radiation damage during film formation and mechanical damage due to film stress accumulate in the electrode and the organic layer.
- the radiation starting point portion 4a has a concave shape, but is not limited thereto, and may be a convex shape or an uneven shape. Each shape of the radiation starting point portion 4a when viewed in a plan view may be any of a line-shaped unevenness, a dot-shaped unevenness (unevenness that is discretely arranged), and the like.
- One radiation starting point portion 4a (unit structure of the radiation starting point portion) may be composed of one concavo-convex structure or a plurality of concavo-convex structures.
- One radiation starting point is preferably smaller than the size of the diffractive lens in plan view.
- the distance (pitch) between the center lines of the adjacent radiation starting point portions 4a is preferably 10 ⁇ m or less at which SPP mode light can propagate. By setting such a pitch, before the SPP mode light is dissipated as heat, the SPP mode light can be scattered by the radiation starting point portion 4a and re-radiated as propagating light. It is preferable that the diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point in plan view. In this case, the pitch of the radiation starting point portion 4a is the same as the pitch of the diffraction lens 5.
- the organic layer 3 may include a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like in addition to a light emitting layer (organic light emitting layer) made of an organic EL material.
- the hole injection layer is a layer that assists hole injection from the anode 2 to the organic layer 3.
- Such a hole injection layer is preferably a material that injects holes into the light emitting layer with lower electric field strength.
- the material for forming the hole injection layer is not particularly limited as long as it can perform the above functions, and any material can be selected from known materials.
- the hole transport layer is a layer that transports holes to the light emitting region, and has a high hole mobility and a small ionization energy of usually 5.5 eV or less.
- the material to be formed as such a hole transport layer is not particularly limited as long as it has the above function, and any material can be selected and used from known materials.
- the electron injection layer is a layer that assists electron injection from the cathode 4 to the organic layer 3.
- Such an electron injection layer is preferably a material that injects electrons into the organic layer 3 with lower electric field strength.
- the material to be formed is not particularly limited as long as it can perform the above functions, and any material can be selected and used from known materials.
- the electron transport layer is a layer that transports electrons to the light emitting region and has a high electron mobility. The material for forming such an electron transport layer is not particularly limited as long as it can perform the above function, and any material can be selected and used from known materials.
- the organic layer 3 may be formed by a dry process such as an evaporation method or a transfer method, or may be formed by a wet process such as a spin coating method, a spray coating method, a die coating method, or a gravure printing method.
- the thickness of the organic layer 3 is not limited, but is, for example, 50 to 2000 nm, and preferably 100 to 1000 nm. If the thickness of the organic layer 3 is less than 50 nm, quenching other than SPP coupling by metal, such as reduction of internal QE due to punch-through current or lossy surface coupling, occurs. When the thickness of the organic layer 3 is greater than 1000 nm, the drive voltage increases.
- the light (arrow A1) traveling to the cathode 4 side is captured by the surface 4A of the cathode 4 and becomes SPP mode light.
- the SPP mode light moves along the surface 4A (arrow A2) and is emitted from the radiation starting point 4a1 (4a), and becomes a spherical wave or a cylindrical wave centered on the radiation starting point.
- the light extracted as the spherical wave or cylindrical wave passes through the organic layer 3 and the like (arrows B1, B2, B3) and is extracted out of the substrate.
- the light B1 is light that travels perpendicularly to the substrate toward the substrate, and the organic layer 3 and the anode 2 At this interface and the interface between the anode 2 and the substrate 1, the light passes through the dielectric layer 7 and the substrate 1 without being refracted, and is taken out to the outside.
- the light B2 and the light B3 are diffracted by the diffractive lens 5 so as to be condensed at the focal point on the center line C1 (see FIG. 1) of the radiation starting point portion 4a1 (4a).
- the incident angle on the substrate 1 is changed to a small angle due to diffraction by the diffraction lens 5.
- the light is incident at an angle greater than the critical angle at the interface between the substrate (eg, glass) and air, total reflection occurs.
- the incident angle on the substrate 1 is changed to a small angle by the diffraction by the diffractive lens 5, the light that can avoid total reflection at the interface between the substrate and air is increased, and the light extraction efficiency is improved. That is, by having a configuration including the diffractive lens 5, light extraction efficiency is improved.
- the organic EL device of the present invention even if the light emitted from the light emitting layer included in the organic layer is captured as SPP mode light on the cathode surface, the SPP mode light is emitted at the radiation starting point on the cathode surface. Can be taken out. Further, the light extracted from the cathode surface can be refracted in the front direction of the substrate by the diffraction lens 5 to increase the amount of light extracted in the front direction of the substrate.
- FIG. 4 shows a schematic plan view of an example in which the degree of density of the annular zone differs depending on the interval of the annular zone of the diffractive lens.
- (A) is a rough case (large interval)
- (c) is a dense case (small interval)
- (b) is an intermediate case.
- FIG. 5A and 5B show a cross-sectional schematic view and FIG. 5B a schematic plan view when the phase of the annular zone 5a of the diffractive lens 5 and the annular zone 2a of the anode 2 are reversed (reverse phase).
- the case of the opposite phase is a case where the positions of the annular portion 5a and the annular portion 2a are interchanged in FIG.
- the annular zone 5 a of the diffractive lens 5 occupies the circular central portion of the diffractive lens 5.
- the center of the annular zone 5 a of the diffractive lens 5 occupying the center of the circle is arranged on the center line of the radiation starting point 4 a of the cathode 4.
- the case of FIG. 1 is called “in-phase”.
- the annular zone 2 a of the anode 2 occupies the circular center portion, and the center of the annular zone 2 a of the anode 2 occupying the circular center portion is the radiation origin portion of the cathode 4. 4a is arranged on the center line.
- the “center of the annular zone 5a of the diffractive lens 5 occupying the circular center” is also the “annular zone 2a of the anode 2 occupying the circular central portion in the case of“ in phase ”.
- “Center of” is also “center of diffraction lens”.
- the width (interval) of the annular zone 5a is formed so as to decrease from the center of the diffractive lens 5 to the periphery. It is preferable.
- the annular zone 5a By forming the annular zone 5a in this way, the light incident on the outer periphery of the diffractive lens is bent more greatly (for example, the incident light beam B3 than B2 in FIG. 3), and the lens has a condensing function.
- the radiation starting point and the diffractive lens arranged at the overlapping position are close to each other (for example, when the radiation starting point 4a and the diffractive lens 5 are close to each other through only the organic layer 3 as shown in FIG.
- the diffraction lens of the organic EL element of the present invention may be provided at any position as long as it is on the opposite side of the organic layer from the cathode.
- the diffractive lens is provided in the anode.
- the diffractive lens may be provided in another layer or component such as in the organic layer or in the substrate, or may be provided in the interface between the layers.
- a configuration provided on the outer surface of the substrate may be employed.
- an organic EL element according to another embodiment of the present invention shown in FIG. 6 is an example of a configuration in which a diffraction lens 15 is provided between the substrate 1 and the anode 2.
- the diffractive lens 15 is formed such that dielectric ring zones 15a having a high refractive index and dielectric ring zones 15b having a low refractive index are alternately arranged.
- An anti-phase configuration in which the refractive index of the dielectric annular zone 15a is low and the refractive index of the annular zone 15b is higher than that may be used.
- the organic EL element according to still another embodiment of the present invention shown in FIG. 7 is an example of a configuration in which the diffraction lens 25 is provided on the outer surface 1A of the substrate 1.
- the diffractive lens 25 is formed such that dielectric ring zones 25a having a high refractive index and dielectric ring zones 25b having a low refractive index are alternately arranged.
- An antiphase configuration may be employed in which the refractive index of the dielectric annular zone 25a is low and the refractive index of the annular zone 25b is higher than that.
- FIG. 8 is a diagram illustrating an example of an image display device including the organic EL element.
- the image display device 100 shown in FIG. 8 is a so-called passive matrix image display device.
- an anode wiring 104, an anode auxiliary wiring 106, a cathode wiring 108, an insulating film 110, a cathode partition 112, a sealing plate 116, and a sealing material 118 are provided.
- a plurality of anode wirings 104 are formed on the substrate 1 of the organic EL element 10.
- the anode wirings 104 are arranged in parallel at a constant interval.
- the anode wiring 104 is made of a transparent conductive film, and for example, ITO (Indium Tin Oxide) can be used.
- the thickness of the anode wiring 104 can be set to 100 nm to 150 nm, for example.
- An anode auxiliary wiring 106 is formed on the end of each anode wiring 104.
- the anode auxiliary wiring 106 is electrically connected to the anode wiring 104. With this configuration, the anode auxiliary wiring 106 functions as a terminal for connecting to the external wiring on the end side of the substrate 1.
- the anode auxiliary wiring 106 is made of a metal film having a thickness of 500 nm to 600 nm, for example.
- a plurality of cathode wirings 108 are provided on the organic EL element 10.
- the plurality of cathode wirings 108 are arranged so as to be parallel to each other and orthogonal to the anode wiring 104.
- Al or an Al alloy can be used for the cathode wiring 108.
- the thickness of the cathode wiring 108 is, for example, 100 nm to 150 nm.
- a cathode auxiliary wiring (not shown) is provided at the end of the cathode wiring 108, similarly to the anode auxiliary wiring 106 for the anode wiring 104, and is electrically connected to the cathode wiring 108. Therefore, a current can flow between the cathode wiring 108 and the cathode auxiliary wiring.
- the organic EL element 10 is located between the anode wiring 104 and the cathode wiring 108 in the opening 120. In this case, the anode 2 of the organic EL element 10 is in contact with the anode wiring 104 and the cathode 4 is in contact with the cathode wiring 108.
- the thickness of the organic EL element 10 can be set to, for example, 150 nm to 200 nm.
- a plurality of cathode partition walls 112 are formed on the insulating film 110 along a direction perpendicular to the anode wiring 104.
- the cathode partition 112 plays a role for spatially separating the plurality of cathode wirings 108 so that the wirings of the cathode wirings 108 do not conduct with each other. Accordingly, the cathode wiring 108 is disposed between the adjacent cathode partition walls 112.
- the size of the cathode partition 112 for example, the one having a height of 2 ⁇ m to 3 ⁇ m and a width of 10 ⁇ m can be used.
- the substrate 1 is bonded through a sealing plate 116 and a sealing material 118. Thereby, the space in which the organic EL element 10 is provided can be sealed, and the organic EL element 10 can be prevented from being deteriorated by moisture in the air.
- a sealing plate 116 for example, a glass substrate having a thickness of 0.7 mm to 1.1 mm can be used.
- a current can be supplied to the organic EL element 10 via the anode auxiliary wiring 106 and the cathode auxiliary wiring (not shown) by a driving device (not shown) to cause the light emitting layer to emit light. Then, light can be emitted from the substrate 1 through the substrate 1.
- An image can be displayed on the image display device 100 by controlling the light emission and non-light emission of the organic EL element 10 corresponding to the above-described pixel by the control device.
- FIG. 9 is a diagram illustrating an example of an illumination device including the organic EL element 10 described above.
- the lighting device 200 shown in FIG. 9 includes the organic EL element 10 described above, and a terminal 202 that is installed adjacent to the substrate 1 (see FIG. 1) of the organic EL element 10 and connected to the anode 2 (see FIG. 1).
- the terminal 203 is connected to the cathode 4 (see FIG. 1), and the lighting circuit 201 is connected to the terminal 202 and the terminal 203 to drive the organic EL element 10.
- the lighting circuit 201 has a DC power supply (not shown) and a control circuit (not shown) inside, and supplies a current between the anode layer 2 and the cathode 4 of the organic EL element 10 through the terminal 202 and the terminal 203. Then, the organic EL element 10 is driven, the light emitting layer emits light, light is emitted from the substrate 1 through the support substrate 101, and is used as illumination light.
- the light emitting layer may be made of a light emitting material that emits white light, and each of the organic EL elements 10 using light emitting materials that emit green light (G), blue light (B), and red light (R). A plurality of them may be provided so that the combined light is white.
- the manufacturing method of the organic EL element of this invention is demonstrated.
- a method for manufacturing the organic EL element shown in FIG. 1 will be described.
- the method for forming the anode 2 is not particularly limited, and for example, a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, a CVD method, or the like can be used.
- the surface treatment includes high-frequency plasma treatment, sputtering treatment, corona treatment, UV ozone irradiation treatment, ultraviolet irradiation treatment, oxygen plasma treatment, and the like.
- anode buffer layer (not shown) instead of or in addition to the surface treatment of the surface treatment of the anode 2.
- anode buffer layer is applied by a wet process, spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating
- the film can be formed using a coating method such as a spray method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, or an inkjet printing method.
- the anode buffer layer When the anode buffer layer is produced by a dry process, the anode buffer layer can be formed by using a plasma treatment or the like exemplified in Japanese Patent Application Laid-Open No. 2006-303412.
- a method of forming a film of a single metal, a metal oxide, a metal nitride, or the like can be given.
- an electron beam evaporation method, a sputtering method, a chemical reaction method, a coating method, a vacuum evaporation method, or the like can be used.
- a method using photolithography as described in Patent Document 10 can be used to form the annular zone 2 a of the anode 2.
- a positive resist solution is applied onto the anode 2, and the excess resist solution is removed by spin coating or the like to form a resist layer.
- the resist layer has a predetermined corresponding to the annular zone 2a.
- the pattern is exposed.
- the resist layer in the exposed pattern portion is removed using a developer.
- the surface of the anode 2 is exposed corresponding to the exposed pattern portion.
- the exposed portion of the anode 2 is removed by etching to form the annular portion 2a.
- etching method either dry etching or wet etching can be used.
- the shape of the annular zone 2a can be controlled by combining isotropic etching and anisotropic etching.
- dry etching reactive ion etching (RIE: Reactive Ion Etching) using inductively coupled plasma or capacitively coupled plasma can be used.
- RIE reactive ion etching
- wet etching a solution of a metal salt such as an iron chloride aqueous solution or a method of immersing in an acid such as dilute hydrochloric acid or dilute sulfuric acid can be used.
- a ring zone portion 5 a made of a dielectric is formed to form a diffraction lens 5.
- the diffractive lens 5 is configured to fill between adjacent ring zones 2a.
- the formation of the diffractive lens 5 is not limited to the formation of the anode 2.
- a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, a CVD method, or the like can be used.
- an organic layer 3 including a light emitting layer made of an organic EL material is formed on the anode 2 and the diffraction lens 5.
- polishing or etching for flattening may be appropriately performed.
- a conventionally known method can be used and is not limited. For example, a method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method can be used.
- a concavo-convex structure is formed on the surface of the organic layer 3 so as to have a convex portion 3b at a position corresponding to the radiation starting point portion 4a of the cathode 4 to be formed later.
- a method using photolithography can be used for forming the unevenness. To do this, first, a positive resist solution is applied on the organic layer 3, and the excess resist solution is removed by spin coating or the like to form a resist layer.
- the resist layer has a predetermined corresponding to the radiation starting point part 4a.
- the pattern is exposed.
- the resist layer 11a in the exposed pattern portion is removed using a developer. As a result, the surface of the organic layer 3 is exposed corresponding to the exposed pattern portion.
- the exposed portion of the organic layer 3 is removed by etching to form a convex portion 3b.
- etching either dry etching or wet etching can be used.
- the shape of the convex portion 3b can be controlled by combining isotropic etching and anisotropic etching.
- dry etching reactive ion etching (RIE: Reactive Ion Etching) using inductively coupled plasma or capacitively coupled plasma, ashing treatment using oxygen plasma, or the like can be used.
- RIE reactive ion etching
- wet etching there can be used a method of immersing in various organic solvents in addition to dilute hydrochloric acid and dilute sulfuric acid.
- a concavo-convex structure including the convex portions 3 b corresponding to the radiation starting point portions 4 a can be formed on the surface of the organic layer 3 corresponding to the pattern. Since photolithography has alignment accuracy up to about 1 ⁇ m, it can be formed such that the radiation starting point of the cathode and the diffraction lens overlap in plan view.
- a cathode material is vapor-deposited on the organic layer 3, and the cathode 4 having the radiation starting point portion 4a is formed by following the uneven structure of the organic layer 3.
- a diffractive lens is formed by alternately forming two types of dielectric layers on a substrate 1 by a known film forming technique using a photolithography technique. 15 can be formed. About another structure, it can form by the method similar to the above-mentioned manufacturing method.
- the organic EL element shown in FIG. 7 for example, a known film forming technique is used in which two types of dielectric layers are alternately formed on the outer surface of the substrate by using a photolithography technique.
- the diffractive lens 25 can be formed by forming a film. About another structure, it can form by the method similar to the above-mentioned manufacturing method.
- FIGS. 10 and 11 show a finite difference time domain (FDTD: FDTD) in the case of an embodiment including a diffractive lens in the anode as shown in FIG. 1 as an example in order to confirm the effect of the organic EL element of the present invention.
- the result of computer simulation calculation using the light intensity of light into the substrate with respect to the total radiation intensity as the light extraction efficiency using the Finite Difference Time Domain Method) method is shown.
- the FDTD method is an analysis method for tracking the time change of the electromagnetic field at each point in space by differentiating Maxwell's equation describing the time change of the electromagnetic field spatially and temporally.
- the model of the diffraction lens used in the simulation has the same width of the annular zone and the density of the annular zone is rough.
- a simulation of a bottom emission type organic EL element is performed, but the top emission type organic EL element also differs only in the direction of light extraction, and exhibits the effects of the present invention.
- “cathode concavity and convexity + diffraction lens (coarse)” indicates that the cathode radiation starting point portion and the diffraction lens (diameter L (see FIG. 2) is 3.08 ⁇ m) are the same as those described above. This is the case of the configuration of “phase”.
- the diffractive lens includes four ring zones having a width of 440 nm (the number includes both 2a and 5a, and the central portion is also counted as one ring zone. The same applies to the following. .) This is the case.
- the “cathode concavity and convexity + diffractive lens (intermediate)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.63 ⁇ m) are in the above-mentioned “in phase”. It is. In this case, the diffractive lens has six ring zones having a width of 330 nm.
- the “cathode concavity and convexity + diffraction lens (multiple)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.3 ⁇ m) are in the above “in phase” It is.
- the diffractive lens has eight ring zones with a width of 220 nm.
- “reverse phase” indicates that the emission starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.08 ⁇ m) are the above-mentioned “cathode unevenness + diffraction lens (coarse)”.
- the diffractive lens has four ring zones having a width of 440 nm.
- diffractive lens only indicates a case where a diffractive lens having the same configuration as “cathode unevenness + diffractive lens (rough)” is included, but the cathode does not have a radiation starting point portion. These are listed as comparative examples.
- standard indicates a case in which a layered cathode without an emission starting portion, an organic layer, and an anode are laminated in order and does not have a diffractive lens (solid structure). It is what I put.
- FIG. 12 is a cross-sectional view showing a model structure of the organic EL element of the embodiment used in the simulation.
- the structure is the same as in FIG.
- the substrate 1 is made of glass, and a refractive index of 1.5 is used.
- the anode 2 is made of ITO, the refractive index is 1.82 + 0.009i at 550 nm, and other wavelengths are extrapolated by the Lorentz model.
- the diffractive lens 5 is made of SOG, and a refractive index of 1.25 is used. As the refractive index of the organic layer 3, 1.72 was used.
- the cathode 4 is made of aluminum (Al), the refractive index is 0.649 + 4.32i at 550 nm, and the other wavelengths are extrapolated by the Drude model. Thereafter, unless otherwise noted, the above values are used for the refractive indexes of glass, organic layer, and aluminum, respectively.
- the layer thicknesses of the anode 2 (or the diffractive lens 5), the layered portion 3a of the organic layer 3, and the cathode 4 were 150 nm, 150 nm, and 150 nm, respectively.
- the diffractive lenses 5 are arranged in a hexagonal fine shape in plan view so that there is no gap between adjacent diffractive lenses.
- the radiation starting point 4a is arranged at a position overlapping all the diffraction lenses 5, and the center of the diffraction lens 5 is arranged on the center line of the radiation starting point 4a in plan view.
- the depth of the recess was 100 nm and the diameter was 100 nm.
- the light extraction efficiency with a wavelength of 540 nm or less is greatly reduced in the “standard” configuration.
- the “diffractive lens only” configuration has low light extraction efficiency over the entire wavelength range.
- the “cathode unevenness + diffractive lens (rough)” configuration, the “cathode unevenness + diffraction lens (intermediate)” configuration, and the “cathode unevenness + diffraction lens (multiple)” configuration which are embodiments of the present invention
- the light extraction efficiency is higher in the entire wavelength range than in the case of the “diffractive lens only” configuration.
- the light extraction efficiency for wavelengths below 540 nm is improved compared to the “standard” configuration.
- the “cathode concavity and convexity + diffraction lens (multiple)” configuration improved light extraction efficiency by +10 several percent to 2 times or more over the entire wavelength range as compared with the “diffractive lens only” configuration.
- the “standard” configuration it is similar in the range of 570 nm to 620 nm, but is significantly superior in other wavelength ranges.
- an improvement of about + 30% to 10 times was observed at 450 nm to 550 nm, and an improvement of + 10% or more was observed at 700 nm to 750 nm.
- the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration.
- the roughness of the annular zone of the diffractive lens increases, that is, the “cathode uneven + diffractive lens (multiple)” configuration, the “cathode uneven + diffractive lens (middle)” configuration, and the “cathode uneven + diffractive lens (rough)” configuration.
- the degree of improvement decreases.
- the “reverse phase” configuration improves the light extraction efficiency over the “diffractive lens only” configuration in the wavelength range of 450 nm to 670 nm, and improves over the “standard” configuration in the wavelength range of 540 nm or less.
- the “cathode unevenness + diffractive lens (multiple)” configuration shows an improvement in light extraction efficiency of + 10% or more in the entire wavelength range as compared with the “diffractive lens only” configuration. It was. Improvements were seen in the wavelength range of 500 nm to 680 nm compared to the “standard” configuration. The “diffractive lens only” configuration had lower light extraction efficiency over the entire wavelength range than the “standard” configuration. Thus, it has been found that the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration. This effect is theoretically difficult to predict and can only be known after simulation.
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Abstract
An organic electroluminescent element (10) is provided with, in order, on a substrate (1), anodes (2), an organic layer (3) that includes a light-emitting layer comprising an organic electroluminescent material, and a cathode (4). The cathode (4) has a plurality of emission starting point sections (4a) periodically disposed on a surface (4A) on the organic layer side. A plurality of diffractive lenses (5) is provided between the substrate (1) and the organic layer (3). The emission starting point sections (4a) are characterized by being disposed in positions that overlap with the diffractive lenses (5) in a plan view.
Description
本発明は、有機ＥＬ素子並びにそれを備えた画像表示装置及び照明装置に関するものである。本願は、２０１２年１１月２７日に、日本に出願された特願２０１２－２５９１５０に基づき優先権を主張し、その内容をここに援用する。
The present invention relates to an organic EL element, and an image display device and an illumination device including the organic EL element. This application claims priority based on Japanese Patent Application No. 2012-259150 filed in Japan on November 27, 2012, the contents of which are incorporated herein by reference.
有機ＥＬ素子は、広視野角、高速応答、鮮明な自発光表示等の特徴を有し、薄型軽量で低消費電力であること等の理由から、次世代の照明装置や画像表示装置等の柱として期待されている。
有機ＥＬ素子は、有機発光層で発生した光が取り出される向きに応じて、支持基板側から光が取り出されるボトムエミッション型と、支持基板の反対側から光が取り出されるトップエミッション型とに分けられる。 Organic EL elements have features such as a wide viewing angle, high-speed response, and clear self-luminous display. They are thin, lightweight, and have low power consumption. As expected.
Organic EL elements are classified into a bottom emission type in which light is extracted from the support substrate side and a top emission type in which light is extracted from the opposite side of the support substrate, depending on the direction in which the light generated in the organic light emitting layer is extracted. .
有機ＥＬ素子は、有機発光層で発生した光が取り出される向きに応じて、支持基板側から光が取り出されるボトムエミッション型と、支持基板の反対側から光が取り出されるトップエミッション型とに分けられる。 Organic EL elements have features such as a wide viewing angle, high-speed response, and clear self-luminous display. They are thin, lightweight, and have low power consumption. As expected.
Organic EL elements are classified into a bottom emission type in which light is extracted from the support substrate side and a top emission type in which light is extracted from the opposite side of the support substrate, depending on the direction in which the light generated in the organic light emitting layer is extracted. .
例えば、ボトムエミッション型の有機ＥＬ素子において、発光層で発光した光のうち、透明基板に垂直に入射した光は透明基板を透過して素子の外部に取り出される。発光層で発光した光のうち、透明基板（例えば、ガラス（屈折率：１．５２））と空気（屈折率：１．０）との界面に臨界角以下の小さい入射角（入射光線と入射する界面の法線がなす角度）で入射した光は、その界面で屈折して素子の外部に取り出される。本明細書では、これらの光を外部モード（External Mode）光という。
これに対して、発光層で発光した光のうち、透明基板と空気との界面に臨界角より大きい入射角で入射した光はその界面で全反射されて素子の外部に取り出されず、最終的に材料に吸収されうる。本明細書では、この光を基板モード（Substrate Mode）光といい、これによる損失を基板損失という。
発光層で発光した光のうち、基板と陰極との間の界面に臨界角より大きい入射角で入射した光もその界面で全反射されて素子の外部に取り出されず、最終的に材料に吸収されうる。基板と陰極との間の界面としては、例えば、透明導電性酸化物からなる陽極（例えば、酸化インジウム錫（ＩＴＯ（屈折率：１．８２））と透明基板（例えば、ガラス（屈折率：１．５２））との界面や陽極と陰極間に配置する高屈折率層と低屈折率層との界面等が挙げられる。本明細書では、この光を導波モード（Waveguide Mode）光といい、これによる損失を導波損失という。
発光層で発光した光のうち、金属陰極等の金属媒質表面に入射して金属陰極の自由電子振動と結合し、表面プラズモンポラリトン（SPP；Surface Plasmon Polariton）として金属陰極の表面に捕捉された光も素子の外部に取り出されず、最終的に材料に吸収されうる。本明細書では、この光をSPPモード光といい、これによる損失をプラズモン損失という。 For example, in a bottom emission type organic EL device, out of light emitted from the light emitting layer, light incident perpendicularly to the transparent substrate passes through the transparent substrate and is extracted outside the device. Of the light emitted from the light-emitting layer, a small incident angle (incident light and incident light) below the critical angle at the interface between the transparent substrate (for example, glass (refractive index: 1.52)) and air (refractive index: 1.0) The light incident at an angle formed by the normal of the interface is refracted at the interface and extracted outside the device. In this specification, these lights are called external mode lights.
On the other hand, of the light emitted from the light emitting layer, the light incident on the interface between the transparent substrate and air at an incident angle larger than the critical angle is totally reflected at the interface and is not taken out of the device, and finally Can be absorbed by the material. In this specification, this light is referred to as substrate mode light, and the loss due to this is referred to as substrate loss.
Of the light emitted from the light-emitting layer, light incident on the interface between the substrate and the cathode at an incident angle greater than the critical angle is also totally reflected at the interface and is not extracted outside the device, but is finally absorbed by the material. sell. As the interface between the substrate and the cathode, for example, an anode made of a transparent conductive oxide (for example, indium tin oxide (ITO (refractive index: 1.82)) and a transparent substrate (for example, glass (refractive index: 1) .52)), the interface between the high refractive index layer and the low refractive index layer disposed between the anode and the cathode, etc. In this specification, this light is referred to as waveguide mode light. This loss is called waveguide loss.
Light emitted from the light-emitting layer is incident on the surface of a metal medium such as a metal cathode and is coupled with free electron vibration of the metal cathode, and is captured on the surface of the metal cathode as a surface plasmon polariton (SPP). Can not be taken out of the device and can be finally absorbed by the material. In this specification, this light is referred to as SPP mode light, and the resulting loss is referred to as plasmon loss.
これに対して、発光層で発光した光のうち、透明基板と空気との界面に臨界角より大きい入射角で入射した光はその界面で全反射されて素子の外部に取り出されず、最終的に材料に吸収されうる。本明細書では、この光を基板モード（Substrate Mode）光といい、これによる損失を基板損失という。
発光層で発光した光のうち、基板と陰極との間の界面に臨界角より大きい入射角で入射した光もその界面で全反射されて素子の外部に取り出されず、最終的に材料に吸収されうる。基板と陰極との間の界面としては、例えば、透明導電性酸化物からなる陽極（例えば、酸化インジウム錫（ＩＴＯ（屈折率：１．８２））と透明基板（例えば、ガラス（屈折率：１．５２））との界面や陽極と陰極間に配置する高屈折率層と低屈折率層との界面等が挙げられる。本明細書では、この光を導波モード（Waveguide Mode）光といい、これによる損失を導波損失という。
発光層で発光した光のうち、金属陰極等の金属媒質表面に入射して金属陰極の自由電子振動と結合し、表面プラズモンポラリトン（SPP；Surface Plasmon Polariton）として金属陰極の表面に捕捉された光も素子の外部に取り出されず、最終的に材料に吸収されうる。本明細書では、この光をSPPモード光といい、これによる損失をプラズモン損失という。 For example, in a bottom emission type organic EL device, out of light emitted from the light emitting layer, light incident perpendicularly to the transparent substrate passes through the transparent substrate and is extracted outside the device. Of the light emitted from the light-emitting layer, a small incident angle (incident light and incident light) below the critical angle at the interface between the transparent substrate (for example, glass (refractive index: 1.52)) and air (refractive index: 1.0) The light incident at an angle formed by the normal of the interface is refracted at the interface and extracted outside the device. In this specification, these lights are called external mode lights.
On the other hand, of the light emitted from the light emitting layer, the light incident on the interface between the transparent substrate and air at an incident angle larger than the critical angle is totally reflected at the interface and is not taken out of the device, and finally Can be absorbed by the material. In this specification, this light is referred to as substrate mode light, and the loss due to this is referred to as substrate loss.
Of the light emitted from the light-emitting layer, light incident on the interface between the substrate and the cathode at an incident angle greater than the critical angle is also totally reflected at the interface and is not extracted outside the device, but is finally absorbed by the material. sell. As the interface between the substrate and the cathode, for example, an anode made of a transparent conductive oxide (for example, indium tin oxide (ITO (refractive index: 1.82)) and a transparent substrate (for example, glass (refractive index: 1) .52)), the interface between the high refractive index layer and the low refractive index layer disposed between the anode and the cathode, etc. In this specification, this light is referred to as waveguide mode light. This loss is called waveguide loss.
Light emitted from the light-emitting layer is incident on the surface of a metal medium such as a metal cathode and is coupled with free electron vibration of the metal cathode, and is captured on the surface of the metal cathode as a surface plasmon polariton (SPP). Can not be taken out of the device and can be finally absorbed by the material. In this specification, this light is referred to as SPP mode light, and the resulting loss is referred to as plasmon loss.
有機EL素子の光取り出し効率（発光層で発光した光に対して素子の外部に取り出される光の割合）は一般に２０％程度に留まっている（例えば、特許文献１）。すなわち、発光層で発光した光のうち、約８０％が損失となっており、これらの損失を低減して光の取り出し効率を向上させることが大きな課題となっている。
ここで、基板モード光の取り出しについては透明基板上に光拡散シートなどを設けることで対処できる（例えば、特許文献２）。しかし、導波モード光及びSPPモード光の低減や取り出し、特にSPPモード光の低減や取り出しについては研究が緒に就いたばかりといえる。 The light extraction efficiency of the organic EL element (ratio of the light extracted outside the element with respect to the light emitted from the light emitting layer) is generally limited to about 20% (for example, Patent Document 1). That is, about 80% of the light emitted from the light emitting layer is lost, and it is a big problem to reduce these losses and improve the light extraction efficiency.
Here, the extraction of the substrate mode light can be dealt with by providing a light diffusion sheet or the like on the transparent substrate (for example, Patent Document 2). However, research on the reduction and extraction of guided mode light and SPP mode light, particularly reduction and extraction of SPP mode light, has just started.
ここで、基板モード光の取り出しについては透明基板上に光拡散シートなどを設けることで対処できる（例えば、特許文献２）。しかし、導波モード光及びSPPモード光の低減や取り出し、特にSPPモード光の低減や取り出しについては研究が緒に就いたばかりといえる。 The light extraction efficiency of the organic EL element (ratio of the light extracted outside the element with respect to the light emitted from the light emitting layer) is generally limited to about 20% (for example, Patent Document 1). That is, about 80% of the light emitted from the light emitting layer is lost, and it is a big problem to reduce these losses and improve the light extraction efficiency.
Here, the extraction of the substrate mode light can be dealt with by providing a light diffusion sheet or the like on the transparent substrate (for example, Patent Document 2). However, research on the reduction and extraction of guided mode light and SPP mode light, particularly reduction and extraction of SPP mode light, has just started.
導波モード光は、光が高屈折率材料から低屈折率材料に入射する際に全反射が起きることにより生じる。そのため、導波モード光を低減するには全反射を起きにくくする、あるいは、全反射を生じる光の割合を低減することによって導波モード光を低減する方策が知られている。
特許文献３には、有機発光層の近傍に有機発光層や透明電極よりも屈折率の高い高屈折率層を挿入する構成が開示されている。特許文献２には、有機発光層及び透明電極に有機発光層及び透明電極よりも低屈折率の微粒子を分散させることで、等価的に有機発光層及び透明電極の屈折率を下げる構成が開示されている。 The guided mode light is generated when total reflection occurs when light enters the low refractive index material from the high refractive index material. Therefore, in order to reduce the guided mode light, there are known measures for reducing the guided mode light by making the total reflection less likely to occur or by reducing the ratio of the light causing the total reflection.
Patent Document 3 discloses a configuration in which a high refractive index layer having a higher refractive index than that of an organic light emitting layer or a transparent electrode is inserted in the vicinity of the organic light emitting layer. Patent Document 2 discloses a configuration in which the refractive index of the organic light emitting layer and the transparent electrode is equivalently lowered by dispersing fine particles having a refractive index lower than that of the organic light emitting layer and the transparent electrode in the organic light emitting layer and the transparent electrode. ing.
特許文献３には、有機発光層の近傍に有機発光層や透明電極よりも屈折率の高い高屈折率層を挿入する構成が開示されている。特許文献２には、有機発光層及び透明電極に有機発光層及び透明電極よりも低屈折率の微粒子を分散させることで、等価的に有機発光層及び透明電極の屈折率を下げる構成が開示されている。 The guided mode light is generated when total reflection occurs when light enters the low refractive index material from the high refractive index material. Therefore, in order to reduce the guided mode light, there are known measures for reducing the guided mode light by making the total reflection less likely to occur or by reducing the ratio of the light causing the total reflection.
特許文献４及び特許文献５には、基板上に順に形成された陽極層及び誘電体層に孔（キャビティ）を有する構成が開示されている。このキャビティの側面（基板に対して垂直に延びる界面）に入射する光は、この界面において基板側に屈折する。この効果により、導波モード光の入射角を浅い角度に変えることで全反射を生じる光の割合を低減することができる。
Patent Documents 4 and 5 disclose a configuration in which holes (cavities) are formed in an anode layer and a dielectric layer that are sequentially formed on a substrate. Light incident on the side surface of the cavity (interface extending perpendicular to the substrate) is refracted toward the substrate at this interface. By this effect, the ratio of light that causes total reflection can be reduced by changing the incident angle of the waveguide mode light to a shallow angle.
一方、金属の表面に捕捉されたSPPモード光を取り出す方法として、陰極の表面に周期的な凹凸構造を形成する構成が知られている（特許文献６～９）。
On the other hand, as a method for extracting the SPP mode light trapped on the metal surface, a configuration in which a periodic uneven structure is formed on the surface of the cathode is known (Patent Documents 6 to 9).
陰極の発光層の反対側に、回折レンズを備える構成も知られている（特許文献１０）。
A configuration is also known in which a diffractive lens is provided on the opposite side of the light emitting layer of the cathode (Patent Document 10).
しかしながら、SPPモード光を有機層中まで取り出しても、その光を素子の外部に取り出すことができなければ、光取り出し効率を向上させることができない。
However, even if the SPP mode light is extracted into the organic layer, the light extraction efficiency cannot be improved unless the light can be extracted outside the device.
本発明は、上記事情に鑑みなされたものであり、SPPモード光を効果的に取り出して光取り出し効率が向上した有機ＥＬ素子並びにそれを備えた画像表示装置及び照明装置を提供することを目的とする。
The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic EL element in which SPP mode light is effectively extracted to improve light extraction efficiency, and an image display device and an illumination device including the organic EL element. To do.
本発明者らは、まず、SPPモード光を導波モード光として取り出し、その次に、その導波モード光を素子の外部に取り出すという２ステップの光取り出し機構を想定して多数の構造の中から、シミュレーションに基づいて光取り出し効率を向上させる有効な構造を鋭意検討した。
光取り出し効率を直接計測することは困難であるため、シミュレーションに基づいて検討を行った。 The inventors first extract SPP mode light as guided mode light and then take out the guided mode light to the outside of the device. Therefore, an effective structure for improving the light extraction efficiency was intensively studied based on simulations.
Since it is difficult to directly measure the light extraction efficiency, we examined it based on simulation.
光取り出し効率を直接計測することは困難であるため、シミュレーションに基づいて検討を行った。 The inventors first extract SPP mode light as guided mode light and then take out the guided mode light to the outside of the device. Therefore, an effective structure for improving the light extraction efficiency was intensively studied based on simulations.
Since it is difficult to directly measure the light extraction efficiency, we examined it based on simulation.
２ステップの光取り出し機構は、SPPモード光を生成し、生成されたSPPモード光を有機層内に取り出すことを可能にする周期的に配置する複数の放射起点部を備えた反射電極側構造と、その有機層内に取り出した光を外部に取り出すために複数の回折レンズを備えた光透過電極側構造とからなる。
The two-step light extraction mechanism is a reflective electrode side structure having a plurality of radiation starting points arranged periodically to enable generation of SPP mode light and extraction of the generated SPP mode light into an organic layer; The light transmission electrode side structure is provided with a plurality of diffraction lenses to extract the light extracted into the organic layer to the outside.
本発明の構成の概要を説明する。
まず、反射電極側構造について以下に説明する。
反射電極側構造の放射起点部とは、金属表面に捕捉されたSPPモード光が再放射する起点になる部分である。
平坦な金属表面に生成されるSPPモード光の角振動数をω、波数ベクトルの大きさをｋｓｐとすると、この分散関係は、金属の誘電率の実部εｍと、金属表面に接触する誘電体の誘電率εｄによって決まる。近似的には、次式（１）によって与えられる（ｃは入射光の速さ）。
An outline of the configuration of the present invention will be described.
First, the reflective electrode side structure will be described below.
The radiation starting point portion of the reflective electrode side structure is a portion that becomes a starting point from which the SPP mode light trapped on the metal surface is re-radiated.
When the angular frequency of SPP mode light generated on a flat metal surface is ω and the magnitude of the wave vector is k sp , this dispersion relation is in contact with the real part ε m of the dielectric constant of the metal and the metal surface. It depends on the dielectric constant ε d of the dielectric. Approximately, it is given by the following equation (1) (c is the speed of incident light).
まず、反射電極側構造について以下に説明する。
反射電極側構造の放射起点部とは、金属表面に捕捉されたSPPモード光が再放射する起点になる部分である。
平坦な金属表面に生成されるSPPモード光の角振動数をω、波数ベクトルの大きさをｋｓｐとすると、この分散関係は、金属の誘電率の実部εｍと、金属表面に接触する誘電体の誘電率εｄによって決まる。近似的には、次式（１）によって与えられる（ｃは入射光の速さ）。
First, the reflective electrode side structure will be described below.
The radiation starting point portion of the reflective electrode side structure is a portion that becomes a starting point from which the SPP mode light trapped on the metal surface is re-radiated.
When the angular frequency of SPP mode light generated on a flat metal surface is ω and the magnitude of the wave vector is k sp , this dispersion relation is in contact with the real part ε m of the dielectric constant of the metal and the metal surface. It depends on the dielectric constant ε d of the dielectric. Approximately, it is given by the following equation (1) (c is the speed of incident light).
通常の有機ＥＬ素子において、陰極等に用いられる金属材料においてはεｍ＜０である。そのため、ＳＰＰモード光の波数ｋｓｐは常に誘電体中の伝播光の波数（ω／ｃ）√εｍより大きい。したがって、反射電極表面が平坦であって凹（凸）構造を有さない場合には、SPPモード光は有機層中に取り出されることなく熱損失となってしまう。しかし、凹（凸）構造を設けると、この凹（凸）構造を中心として有機層中に光が再放射される。
すなわち、反射電極側構造のこの凹（凸）構造は放射起点部として機能する。 In a normal organic EL element, ε m <0 in a metal material used for a cathode or the like. Therefore, the wave number k sp of the SPP mode light is always larger than the wave number (ω / c) √ε m of propagating light in the dielectric. Therefore, when the surface of the reflective electrode is flat and does not have a concave (convex) structure, the SPP mode light is not taken out into the organic layer, and heat loss occurs. However, when a concave (convex) structure is provided, light is re-emitted into the organic layer around the concave (convex) structure.
That is, this concave (convex) structure of the reflective electrode side structure functions as a radiation starting point.
すなわち、反射電極側構造のこの凹（凸）構造は放射起点部として機能する。 In a normal organic EL element, ε m <0 in a metal material used for a cathode or the like. Therefore, the wave number k sp of the SPP mode light is always larger than the wave number (ω / c) √ε m of propagating light in the dielectric. Therefore, when the surface of the reflective electrode is flat and does not have a concave (convex) structure, the SPP mode light is not taken out into the organic layer, and heat loss occurs. However, when a concave (convex) structure is provided, light is re-emitted into the organic layer around the concave (convex) structure.
That is, this concave (convex) structure of the reflective electrode side structure functions as a radiation starting point.
次に、光透過電極側構造について以下に説明する。
本発明の光透過電極側構造が備える複数の回折レンズはそれぞれ、等しい間隔で複数の帯部が配置される構成、または、レンズの中心から周辺に向かって間隔が狭くなるように複数の帯部が配置される構成を備える。レンズが１次元の場合、帯部は面内の一方向に延伸したライン状で互いに平行となるように配置されている。レンズが２次元の場合、帯部は環状で互いに同心円状に配置されている。１つのレンズ内は、高屈折率の帯部と低屈折率の帯部の２種の帯部からなり、隣接する帯部の屈折率は互いに異なる。すなわち、帯部の屈折率は、レンズ中心から順に「高低高低…」または「低高低高…」となるように構成される。この回折レンズは、レンズ全体として、放射起点から放射された光を基板面（発光面に平行な平面）の法線方向にある焦点に集光する作用を有する。従って、回折レンズに入射した導波モード光は回折レンズごとに基板面の法線方向に集光されて基板面等に入射することになる。この集光作用により、導波モード光は基板への入射角（基板面の法線に対する角度）が小さい角度に変わる。そのため、基板と空気との界面等での全反射を避けられる光を増大して光取り出し効率を向上させることができる。ここで、上記焦点の位置は回折レンズから有限の距離にあってもよいし、無限遠（回折光が法線方向に伝播する平面波となる）にあってもよい。 Next, the light transmission electrode side structure will be described below.
Each of the plurality of diffractive lenses provided in the light transmission electrode side structure of the present invention has a configuration in which a plurality of bands are arranged at equal intervals, or a plurality of bands so that the intervals are narrowed from the center of the lens toward the periphery. Is provided. When the lens is one-dimensional, the belt portions are arranged so as to be parallel to each other in a line extending in one direction in the plane. When the lens is two-dimensional, the belt portions are annular and arranged concentrically with each other. One lens is composed of two types of belt portions, a high refractive index belt portion and a low refractive index belt portion, and the refractive indexes of adjacent belt portions are different from each other. That is, the refractive index of the belt portion is configured to be “high, low, high, low ...” or “low, high, low, high ...” in order from the lens center. This diffractive lens has a function of condensing light emitted from the radiation starting point as a whole at a focal point in the normal direction of the substrate surface (a plane parallel to the light emitting surface). Therefore, the guided mode light incident on the diffractive lens is condensed in the normal direction of the substrate surface for each diffractive lens and is incident on the substrate surface or the like. By this condensing action, the waveguide mode light changes to an angle at which the incident angle to the substrate (angle with respect to the normal of the substrate surface) is small. Therefore, the light extraction efficiency can be improved by increasing the light that can avoid total reflection at the interface between the substrate and air. Here, the position of the focal point may be at a finite distance from the diffractive lens, or may be at infinity (a diffracted light becomes a plane wave propagating in the normal direction).
本発明の光透過電極側構造が備える複数の回折レンズはそれぞれ、等しい間隔で複数の帯部が配置される構成、または、レンズの中心から周辺に向かって間隔が狭くなるように複数の帯部が配置される構成を備える。レンズが１次元の場合、帯部は面内の一方向に延伸したライン状で互いに平行となるように配置されている。レンズが２次元の場合、帯部は環状で互いに同心円状に配置されている。１つのレンズ内は、高屈折率の帯部と低屈折率の帯部の２種の帯部からなり、隣接する帯部の屈折率は互いに異なる。すなわち、帯部の屈折率は、レンズ中心から順に「高低高低…」または「低高低高…」となるように構成される。この回折レンズは、レンズ全体として、放射起点から放射された光を基板面（発光面に平行な平面）の法線方向にある焦点に集光する作用を有する。従って、回折レンズに入射した導波モード光は回折レンズごとに基板面の法線方向に集光されて基板面等に入射することになる。この集光作用により、導波モード光は基板への入射角（基板面の法線に対する角度）が小さい角度に変わる。そのため、基板と空気との界面等での全反射を避けられる光を増大して光取り出し効率を向上させることができる。ここで、上記焦点の位置は回折レンズから有限の距離にあってもよいし、無限遠（回折光が法線方向に伝播する平面波となる）にあってもよい。 Next, the light transmission electrode side structure will be described below.
Each of the plurality of diffractive lenses provided in the light transmission electrode side structure of the present invention has a configuration in which a plurality of bands are arranged at equal intervals, or a plurality of bands so that the intervals are narrowed from the center of the lens toward the periphery. Is provided. When the lens is one-dimensional, the belt portions are arranged so as to be parallel to each other in a line extending in one direction in the plane. When the lens is two-dimensional, the belt portions are annular and arranged concentrically with each other. One lens is composed of two types of belt portions, a high refractive index belt portion and a low refractive index belt portion, and the refractive indexes of adjacent belt portions are different from each other. That is, the refractive index of the belt portion is configured to be “high, low, high, low ...” or “low, high, low, high ...” in order from the lens center. This diffractive lens has a function of condensing light emitted from the radiation starting point as a whole at a focal point in the normal direction of the substrate surface (a plane parallel to the light emitting surface). Therefore, the guided mode light incident on the diffractive lens is condensed in the normal direction of the substrate surface for each diffractive lens and is incident on the substrate surface or the like. By this condensing action, the waveguide mode light changes to an angle at which the incident angle to the substrate (angle with respect to the normal of the substrate surface) is small. Therefore, the light extraction efficiency can be improved by increasing the light that can avoid total reflection at the interface between the substrate and air. Here, the position of the focal point may be at a finite distance from the diffractive lens, or may be at infinity (a diffracted light becomes a plane wave propagating in the normal direction).
本発明者らは、シミュレーションにより、放射起点部を有する反射電極側構造と、導波モード光を透明基板の法線方向に集光させる回折レンズを備えた光透過電極側構造とを組み合わせることにより、かかる反射電極側構造及び光透過電極側構造の単独の光取り出し効率の向上効果からは予測できないほどの顕著な効果を奏することを見い出し、本発明を完成させた。
The inventors of the present invention, by simulation, combine a reflection electrode side structure having a radiation starting point portion and a light transmission electrode side structure having a diffraction lens for condensing guided mode light in the normal direction of the transparent substrate. The present invention has been completed by finding that the reflective electrode side structure and the light transmissive electrode side structure have a remarkable effect that cannot be predicted from the effect of improving the light extraction efficiency alone.
上記の目的を達成するために、本発明は以下の構成を採用した。
（１）光透過電極と、有機ＥＬ材料からなる発光層を含む有機層と、反射電極とを順に具備する有機ＥＬ素子であって、前記反射電極は、その有機層側の表面に周期的に配置される複数の放射起点部を有するものであり、前記有機層の反射電極とは反対側に複数の回折レンズを備えてなり、前記放射起点部は、平面視して前記回折レンズに重なる位置に配置されることを特徴とする有機ＥＬ素子。
（２）前記光透過電極の前記有機層とは反対側に基板を有し、前記基板側から外部に光を取り出すように構成されており、前記光透過電極が陽極であり、前記反射電極が陰極であり、前記複数の回折レンズを前記基板の外表面から前記有機層との間に備えることを特徴とする（１）に記載の有機ＥＬ素子。
（３）前記回折レンズが前記光透過電極内に配置されることを特徴とする（１）又は２のいずれかに記載の有機ＥＬ素子。
（４）前記回折レンズは、同心円状の誘電体からなる輪帯部を複数有してなることを特徴とする（１）～（３）のいずれか一項に記載の有機ＥＬ素子。
（５）前記回折レンズは、その中心が平面視して前記放射起点部の中心線上に配置されるように設けられていることを特徴とする（１）～（４）のいずれか一項に記載の有機ＥＬ素子。
（６）前記放射起点部は、前記反射電極の前記有機層側の表面に形成された凹部であることを特徴とする（１）～（５）のいずれか一項に記載の有機ＥＬ素子。
（７）（１）～（６）のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする画像表示装置。
（８）（１）～（６）のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする照明装置。 In order to achieve the above object, the present invention employs the following configuration.
(1) An organic EL element comprising a light transmissive electrode, an organic layer including a light emitting layer made of an organic EL material, and a reflective electrode in order, and the reflective electrode is periodically formed on the surface of the organic layer. A plurality of radiating origin portions arranged, comprising a plurality of diffractive lenses on the opposite side of the organic layer from the reflective electrode, and the radiating origin portions overlapping the diffractive lenses in plan view An organic EL element characterized by being arranged in the above.
(2) A substrate is provided on the opposite side of the light transmissive electrode from the organic layer, and is configured to extract light from the substrate side to the outside. The light transmissive electrode is an anode, and the reflective electrode is The organic EL element according to (1), wherein the organic EL element is a cathode and includes the plurality of diffraction lenses between an outer surface of the substrate and the organic layer.
(3) The organic EL element according to (1) or 2, wherein the diffractive lens is disposed in the light transmitting electrode.
(4) The organic EL element according to any one of (1) to (3), wherein the diffractive lens includes a plurality of annular portions made of concentric dielectrics.
(5) The diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point portion in plan view, according to any one of (1) to (4), The organic EL element of description.
(6) The organic EL element according to any one of (1) to (5), wherein the radiation starting point portion is a concave portion formed on a surface of the reflective electrode on the organic layer side.
(7) An image display device comprising the organic EL element according to any one of (1) to (6).
(8) A lighting device comprising the organic EL element according to any one of (1) to (6).
（１）光透過電極と、有機ＥＬ材料からなる発光層を含む有機層と、反射電極とを順に具備する有機ＥＬ素子であって、前記反射電極は、その有機層側の表面に周期的に配置される複数の放射起点部を有するものであり、前記有機層の反射電極とは反対側に複数の回折レンズを備えてなり、前記放射起点部は、平面視して前記回折レンズに重なる位置に配置されることを特徴とする有機ＥＬ素子。
（２）前記光透過電極の前記有機層とは反対側に基板を有し、前記基板側から外部に光を取り出すように構成されており、前記光透過電極が陽極であり、前記反射電極が陰極であり、前記複数の回折レンズを前記基板の外表面から前記有機層との間に備えることを特徴とする（１）に記載の有機ＥＬ素子。
（３）前記回折レンズが前記光透過電極内に配置されることを特徴とする（１）又は２のいずれかに記載の有機ＥＬ素子。
（４）前記回折レンズは、同心円状の誘電体からなる輪帯部を複数有してなることを特徴とする（１）～（３）のいずれか一項に記載の有機ＥＬ素子。
（５）前記回折レンズは、その中心が平面視して前記放射起点部の中心線上に配置されるように設けられていることを特徴とする（１）～（４）のいずれか一項に記載の有機ＥＬ素子。
（６）前記放射起点部は、前記反射電極の前記有機層側の表面に形成された凹部であることを特徴とする（１）～（５）のいずれか一項に記載の有機ＥＬ素子。
（７）（１）～（６）のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする画像表示装置。
（８）（１）～（６）のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする照明装置。 In order to achieve the above object, the present invention employs the following configuration.
(1) An organic EL element comprising a light transmissive electrode, an organic layer including a light emitting layer made of an organic EL material, and a reflective electrode in order, and the reflective electrode is periodically formed on the surface of the organic layer. A plurality of radiating origin portions arranged, comprising a plurality of diffractive lenses on the opposite side of the organic layer from the reflective electrode, and the radiating origin portions overlapping the diffractive lenses in plan view An organic EL element characterized by being arranged in the above.
(2) A substrate is provided on the opposite side of the light transmissive electrode from the organic layer, and is configured to extract light from the substrate side to the outside. The light transmissive electrode is an anode, and the reflective electrode is The organic EL element according to (1), wherein the organic EL element is a cathode and includes the plurality of diffraction lenses between an outer surface of the substrate and the organic layer.
(3) The organic EL element according to (1) or 2, wherein the diffractive lens is disposed in the light transmitting electrode.
(4) The organic EL element according to any one of (1) to (3), wherein the diffractive lens includes a plurality of annular portions made of concentric dielectrics.
(5) The diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point portion in plan view, according to any one of (1) to (4), The organic EL element of description.
(6) The organic EL element according to any one of (1) to (5), wherein the radiation starting point portion is a concave portion formed on a surface of the reflective electrode on the organic layer side.
(7) An image display device comprising the organic EL element according to any one of (1) to (6).
(8) A lighting device comprising the organic EL element according to any one of (1) to (6).
本発明によれば、SPPモード光及び導波モード光を効果的に取り出して光取り出し効率が向上した有機ＥＬ素子並びにそれを備えた画像表示装置及び照明装置を提供できる。
According to the present invention, it is possible to provide an organic EL element in which SPP mode light and waveguide mode light are effectively extracted to improve light extraction efficiency, and an image display device and an illumination device including the organic EL element.
以下、本発明を適用した有機ＥＬ素子並びにそれを備えた画像表示装置及び照明装置について、図面を用いてその構成を説明する。以下の説明で用いる図面は、特徴をわかりやすくするために便宜上特徴となる部分を拡大して示している場合があり、各構成要素の寸法比率などは実際と同じであるとは限らない。以下の説明において例示される材料、寸法等は一例であって、本発明はそれらに限定されるものではなく、その要旨を変更しない範囲で適宜変更して実施することが可能である。
以下の実施形態では全て、ボトムエミッション型の場合の構成について説明する。しかし、本発明に係る有機ＥＬ素子はトップエミッション型でも構わない。以下の実施形態では、光透過電極を陽極、反射電極を陰極としているが、光透過電極を陰極、反射電極を陽極とした構成でも構わない。
以下の説明において例示される回折レンズの形状は、上記帯部が環状となる、２次元形状としている。しかし、本発明はこれに限定されるものではない。上記帯部が面内の一方向に延伸したライン状である１次元形状の回折レンズも使用することも可能である。 Hereinafter, the structure of an organic EL element to which the present invention is applied, an image display apparatus and an illumination apparatus including the organic EL element will be described with reference to the drawings. In the drawings used in the following description, in order to make the features easier to understand, the portions that become the features may be shown in an enlarged manner for convenience, and the dimensional ratios and the like of the respective components are not always the same as the actual ones. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these, and can be appropriately modified and implemented without changing the gist thereof.
In the following embodiments, the configuration of the bottom emission type will be described. However, the organic EL element according to the present invention may be a top emission type. In the following embodiments, the light transmission electrode is an anode and the reflection electrode is a cathode. However, the light transmission electrode may be a cathode and the reflection electrode may be an anode.
The shape of the diffractive lens exemplified in the following description is a two-dimensional shape in which the band is annular. However, the present invention is not limited to this. It is also possible to use a one-dimensional diffractive lens having a line shape in which the band portion extends in one direction in the plane.
以下の実施形態では全て、ボトムエミッション型の場合の構成について説明する。しかし、本発明に係る有機ＥＬ素子はトップエミッション型でも構わない。以下の実施形態では、光透過電極を陽極、反射電極を陰極としているが、光透過電極を陰極、反射電極を陽極とした構成でも構わない。
以下の説明において例示される回折レンズの形状は、上記帯部が環状となる、２次元形状としている。しかし、本発明はこれに限定されるものではない。上記帯部が面内の一方向に延伸したライン状である１次元形状の回折レンズも使用することも可能である。 Hereinafter, the structure of an organic EL element to which the present invention is applied, an image display apparatus and an illumination apparatus including the organic EL element will be described with reference to the drawings. In the drawings used in the following description, in order to make the features easier to understand, the portions that become the features may be shown in an enlarged manner for convenience, and the dimensional ratios and the like of the respective components are not always the same as the actual ones. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these, and can be appropriately modified and implemented without changing the gist thereof.
In the following embodiments, the configuration of the bottom emission type will be described. However, the organic EL element according to the present invention may be a top emission type. In the following embodiments, the light transmission electrode is an anode and the reflection electrode is a cathode. However, the light transmission electrode may be a cathode and the reflection electrode may be an anode.
The shape of the diffractive lens exemplified in the following description is a two-dimensional shape in which the band is annular. However, the present invention is not limited to this. It is also possible to use a one-dimensional diffractive lens having a line shape in which the band portion extends in one direction in the plane.
（有機ＥＬ素子）
図１は、本発明の一実施形態に係る有機ＥＬ素子の一例を説明するための断面模式図である。図２は、図１の有機ＥＬ素子が備える回折レンズの平面模式図である。
本発明の一実施形態に係る有機ＥＬ素子１０は、基板１上に、陽極（光透過電極）２と、有機ＥＬ材料からなる発光層を含む有機層３と、陰極（反射電極）４とを順に具備する有機ＥＬ素子１０である。この陰極４は、その有機層側の表面４Ａに周期的に配置される複数の放射起点部４ａを有する。この基板１と有機層３との間には、複数の回折レンズ５を備えてなり、放射起点部４ａは平面視して回折レンズ５に重なる位置に配置される。回折レンズは有機層３の陰極４とは反対側にあればよく、基板１の外表面から有機層３との間のいずれの位置に配置される構成でもよい。本実施形態は基板１と有機層３との間であって、特に陽極２内に配置される構成である。
図１に示す例では、回折レンズ５は陽極２内に配置され、同心円状の誘電体からなる輪帯部５ａを複数有してなる。陽極２は、この輪帯部５ａと交互に配置される同心円状の輪帯部２ａを複数有してなる。ここで、陽極２の輪帯部２ａまたは回折レンズ５の輪帯部５ａのいずれか一方は、輪状の形状を有する輪帯部だけでなく、同心円の中心部分であって円形の中心部も含むものとする。図１では、陽極２が円形の中心部である輪帯部２ａを有する場合である。
図１に示す例では、有機層３は、陽極２と陰極４との間に配置される層状部３ａを有する。さらに有機層３は、放射起点部４ａの形状に対応する部分（図１の例では、凸部３ｂ）を有する。有機層３のうち、放射起点部４ａの形状に対応する部分３ｂは、図１のように放射起点部４ａが反射電極の有機層側の表面に形成された凹形状（凹部）であれば、凸形状になるし、放射起点部４ａが凸形状であれば、凹形状になる。
図１に示す例では、回折レンズ５は、その中心が平面視して放射起点部４ａの中心線Ｃ１上に配置されるように設けられている。 (Organic EL device)
FIG. 1 is a schematic cross-sectional view for explaining an example of an organic EL element according to an embodiment of the present invention. FIG. 2 is a schematic plan view of a diffractive lens provided in the organic EL element of FIG.
Anorganic EL element 10 according to an embodiment of the present invention includes an anode (light transmission electrode) 2, an organic layer 3 including a light emitting layer made of an organic EL material, and a cathode (reflection electrode) 4 on a substrate 1. It is the organic EL element 10 which comprises in order. The cathode 4 has a plurality of radiation starting points 4a periodically disposed on the surface 4A on the organic layer side. A plurality of diffractive lenses 5 are provided between the substrate 1 and the organic layer 3, and the radiation starting point portion 4 a is disposed at a position overlapping the diffractive lenses 5 in plan view. The diffractive lens only needs to be on the opposite side of the organic layer 3 from the cathode 4, and may be arranged at any position between the outer surface of the substrate 1 and the organic layer 3. The present embodiment is configured to be disposed between the substrate 1 and the organic layer 3 and particularly in the anode 2.
In the example shown in FIG. 1, thediffractive lens 5 is disposed in the anode 2 and has a plurality of annular portions 5a made of a concentric dielectric. The anode 2 has a plurality of concentric annular zone portions 2a arranged alternately with the annular zone portions 5a. Here, either one of the annular zone 2a of the anode 2 or the annular zone 5a of the diffractive lens 5 includes not only an annular zone having a ring shape but also a central portion of a concentric circle and a circular center portion. Shall be. In FIG. 1, the anode 2 has a ring zone portion 2 a which is a circular center portion.
In the example shown in FIG. 1, theorganic layer 3 has a layered portion 3 a disposed between the anode 2 and the cathode 4. Furthermore, the organic layer 3 has a part (in the example of FIG. 1, a convex part 3b) corresponding to the shape of the radiation starting point part 4a. In the organic layer 3, the portion 3b corresponding to the shape of the radiation starting point portion 4a is a concave shape (recessed portion) formed on the surface of the reflective electrode on the organic layer side as shown in FIG. It becomes a convex shape, or a concave shape if the radiation starting point 4a is a convex shape.
In the example shown in FIG. 1, thediffractive lens 5 is provided so that the center thereof is disposed on the center line C1 of the radiation starting point portion 4a in plan view.
図１は、本発明の一実施形態に係る有機ＥＬ素子の一例を説明するための断面模式図である。図２は、図１の有機ＥＬ素子が備える回折レンズの平面模式図である。
本発明の一実施形態に係る有機ＥＬ素子１０は、基板１上に、陽極（光透過電極）２と、有機ＥＬ材料からなる発光層を含む有機層３と、陰極（反射電極）４とを順に具備する有機ＥＬ素子１０である。この陰極４は、その有機層側の表面４Ａに周期的に配置される複数の放射起点部４ａを有する。この基板１と有機層３との間には、複数の回折レンズ５を備えてなり、放射起点部４ａは平面視して回折レンズ５に重なる位置に配置される。回折レンズは有機層３の陰極４とは反対側にあればよく、基板１の外表面から有機層３との間のいずれの位置に配置される構成でもよい。本実施形態は基板１と有機層３との間であって、特に陽極２内に配置される構成である。
図１に示す例では、回折レンズ５は陽極２内に配置され、同心円状の誘電体からなる輪帯部５ａを複数有してなる。陽極２は、この輪帯部５ａと交互に配置される同心円状の輪帯部２ａを複数有してなる。ここで、陽極２の輪帯部２ａまたは回折レンズ５の輪帯部５ａのいずれか一方は、輪状の形状を有する輪帯部だけでなく、同心円の中心部分であって円形の中心部も含むものとする。図１では、陽極２が円形の中心部である輪帯部２ａを有する場合である。
図１に示す例では、有機層３は、陽極２と陰極４との間に配置される層状部３ａを有する。さらに有機層３は、放射起点部４ａの形状に対応する部分（図１の例では、凸部３ｂ）を有する。有機層３のうち、放射起点部４ａの形状に対応する部分３ｂは、図１のように放射起点部４ａが反射電極の有機層側の表面に形成された凹形状（凹部）であれば、凸形状になるし、放射起点部４ａが凸形状であれば、凹形状になる。
図１に示す例では、回折レンズ５は、その中心が平面視して放射起点部４ａの中心線Ｃ１上に配置されるように設けられている。 (Organic EL device)
FIG. 1 is a schematic cross-sectional view for explaining an example of an organic EL element according to an embodiment of the present invention. FIG. 2 is a schematic plan view of a diffractive lens provided in the organic EL element of FIG.
An
In the example shown in FIG. 1, the
In the example shown in FIG. 1, the
In the example shown in FIG. 1, the
ボトムエミッション型の有機ＥＬ素子の場合、基板１は透光性の基板であり、通常、可視光に対して透明であることが必要である。ここで、「可視光に対し透明である」とは、発光層から発する波長の可視光を透過することができればよいという意味であり、可視光領域全域にわたり透明である必要はない。４００～７００ｎｍの可視光における透過率が５０％以上で、平滑な基板が好ましい。
In the case of a bottom emission type organic EL element, the substrate 1 is a light-transmitting substrate and usually needs to be transparent to visible light. Here, “transparent to visible light” means that it is only necessary to transmit visible light having a wavelength emitted from the light emitting layer, and does not need to be transparent over the entire visible light region. A smooth substrate having a transmittance in visible light of 400 to 700 nm of 50% or more is preferable.
具体的には、ガラス板、ポリマー板等が挙げられる。ガラス板としては、特にソーダ石灰ガラス、バリウム・ストロンチウム含有ガラス、鉛ガラス、アルミノケイ酸ガラス、ホウケイ酸ガラス、バリウムホウケイ酸ガラス、石英等が挙げられる。またポリマー板としては、ポリカーボネート、ポリメチルメタクリレート、ポリエチレンテレフタレート、ポリエーテルサルファイド、ポリサルフォン、PEN（ポリエチレンナフタレート）等を挙げることができる。
Specific examples include glass plates and polymer plates. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyether sulfide, polysulfone, and PEN (polyethylene naphthalate).
発光光が可視光でない場合は、少なくとも発光波長領域に対して、可視光の場合と同様に透明であることが必要である。透過率としては、発光が最大強度となる波長に対し、５０％以上であることが好ましく、７０％以上であることが更に好ましい。
When the emitted light is not visible light, it is necessary to be transparent at least for the emission wavelength region as in the case of visible light. The transmittance is preferably 50% or more and more preferably 70% or more with respect to the wavelength at which light emission has the maximum intensity.
トップエミッション型素子の場合、基板１は、陰極４からみて有機層３とは反対側に配置される。トップエミッション型の場合には、基板１は、上記記載と同様なものの他に、不透明な材料も使用できる。具体的には、例えばＣｕ、Ａｇ、Ａｕ、Ｐｔ、Ｗ，Ｔｉ、Ｔａ、Ｎｂ、Ａｌの単体、またはこれらの元素を含んだ合金、あるいはステンレスなどの金属材料、Ｓｉ、ＳｉＣ、ＡｌＮ、ＧａＮ、ＧａＡｓ、サファイアなどの非金属材料、その他のトップエミッション型の有機ＥＬ素子で通常用いられる基板材料を用いることができる。素子の発光に伴い生じる熱を逃がすため、熱伝導率の高い材料を基板に用いることが好ましい。
In the case of a top emission type device, the substrate 1 is disposed on the side opposite to the organic layer 3 when viewed from the cathode 4. In the case of the top emission type, the substrate 1 can be made of an opaque material in addition to the same as described above. Specifically, for example, Cu, Ag, Au, Pt, W, Ti, Ta, Nb, Al alone, an alloy containing these elements, or a metal material such as stainless steel, Si, SiC, AlN, GaN, Nonmetallic materials such as GaAs and sapphire, and other substrate materials usually used in top emission type organic EL elements can be used. In order to release heat generated by light emission of the element, a material having high thermal conductivity is preferably used for the substrate.
基板１の厚さは、要求される機械的強度にもよるため、限定するものではない。好ましくは、０．０１ｍｍ～１０ｍｍ、より好ましくは０．０５ｍｍ～２ｍｍである。
The thickness of the substrate 1 is not limited because it depends on the required mechanical strength. The thickness is preferably 0.01 mm to 10 mm, more preferably 0.05 mm to 2 mm.
陽極２は、複数の同心円状の輪帯部２ａを備えている。この輪帯部２ａの間には、回折レンズ５を構成する同心円状の誘電体からなる輪帯部５ａが配置されている。
The anode 2 is provided with a plurality of concentric ring zones 2a. Between the annular zones 2a, annular zones 5a made of concentric dielectrics constituting the diffractive lens 5 are arranged.
陽極２は陰極４との間で電圧を印加し、陽極２より発光層に正孔を注入するための電極である。仕事関数の大きい金属、合金、導電性化合物、あるいはこれらの混合物からなる材料を用いることが好ましい。また陽極に接する有機層のＨＯＭＯ（Highest Occupied Molecular Orbital）準位との差が過大にならないように仕事関数が４ｅＶ以上６ｅＶ以下のものを用いるのが好ましい。
The anode 2 is an electrode for applying a voltage to the cathode 4 and injecting holes from the anode 2 into the light emitting layer. It is preferable to use a material made of a metal, an alloy, a conductive compound, or a mixture thereof having a high work function. Further, it is preferable to use a material having a work function of 4 eV or more and 6 eV or less so that the difference from the HOMO (Highest 陽極 Occupied Molecular Orbital) level of the organic layer in contact with the anode does not become excessive.
陽極２の材料としては透光性でかつ導電性の材料であれば特に制限はない。例えば、酸化インジウム錫（ＩＴＯ）、酸化インジウム亜鉛（ＩＺＯ）、酸化錫、酸化亜鉛などの透明無機酸化物、ＰＥＤＯＴ：ＰＳＳ（ポリ（３，４－エチレンジオキシチオフェン）－ポリ（スチレンスルホン酸））、ポリアニリンなどの導電性高分子および任意のアクセプタなどでドープした導電性高分子、カーボンナノチューブ、グラフェンなどの透明カーボン材料を挙げることができる。ここにおいて、陽極２は、基板１上に例えば、スパッタ法、真空蒸着法、塗布法などによって形成することができる。
The material of the anode 2 is not particularly limited as long as it is a translucent and conductive material. For example, transparent inorganic oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, zinc oxide, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonic acid) ), Conductive polymers such as polyaniline, and conductive polymers doped with any acceptor, and transparent carbon materials such as carbon nanotubes and graphene. Here, the anode 2 can be formed on the substrate 1 by, for example, a sputtering method, a vacuum deposition method, a coating method, or the like.
陽極２の厚さは限定するものではないが、例えば１０～２０００ｎｍであり、好ましくは５０～１０００ｎｍである。陽極２の厚さが１０ｎｍより薄いと輪帯部５ａの体積を大きくしにくくなり、有機層３まで取り出された光の回折・集光がされにくくなる。陽極２の厚さが２０００ｎｍより厚いと有機層３の平坦度を保てなくなると共に、陽極の透過率が低下するからである。
The thickness of the anode 2 is not limited, but is, for example, 10 to 2000 nm, preferably 50 to 1000 nm. If the thickness of the anode 2 is less than 10 nm, it becomes difficult to increase the volume of the annular zone 5a, and it becomes difficult to diffract and collect the light extracted to the organic layer 3. This is because when the thickness of the anode 2 is greater than 2000 nm, the flatness of the organic layer 3 cannot be maintained and the transmittance of the anode is lowered.
回折レンズ５は、同心円状の誘電体からなる輪帯部５ａを複数備えてなり、陽極２の屈折率と異なる屈折率を有する材料からなる。回折レンズ５の屈折率は陽極２の屈折率より低いことが好ましい。
回折レンズ５の屈折率が陽極２より低い場合、回折レンズ５の材料としては、透光性でかつ陽極２の屈折率より低い屈折率を有する材料であれば特に制限はない。陽極２の材料が酸化インジウム錫（ＩＴＯ（屈折率１．８２））である場合は、例えば、スピンオングラス（ＳＯＧ（屈折率１．２５））、フッ化マグネシウム（ＭｇＦ２（屈折率１．３８））等の金属フッ化物、ポリテトラフルオロエチレン（ＰＴＦＥ（屈折率１．３５））等の有機フッ素化合物、二酸化ケイ素（ＳｉＯ２（屈折率１．４５））、各種の低融点ガラス、各種の多孔性物質等が挙げられる。
回折レンズ５の厚さは限定するものではないが、例えば１０～２０００ｎｍであり、好ましくは５０～１０００ｎｍである。回折レンズ５の厚さが１０ｎｍより薄いと有機層に対する輪帯部５ａの体積が小さくなり、有機層３に取り出された光が回折・集光されにくくなる。回折レンズ５の厚さが２０００ｎｍより厚いと有機層３の平坦度を保ちにくくなる。 Thediffractive lens 5 includes a plurality of annular portions 5 a made of a concentric dielectric, and is made of a material having a refractive index different from that of the anode 2. The refractive index of the diffractive lens 5 is preferably lower than the refractive index of the anode 2.
When the refractive index of thediffractive lens 5 is lower than that of the anode 2, the material of the diffractive lens 5 is not particularly limited as long as it is a light-transmitting material having a refractive index lower than that of the anode 2. When the material of the anode 2 is indium tin oxide (ITO (refractive index 1.82)), for example, spin-on glass (SOG (refractive index 1.25)), magnesium fluoride (MgF 2 (refractive index 1.38). )), Metal fluorides such as polytetrafluoroethylene (PTFE (refractive index 1.35)), silicon dioxide (SiO 2 (refractive index 1.45)), various low melting glass, various Examples include porous substances.
The thickness of thediffractive lens 5 is not limited, but is, for example, 10 to 2000 nm, and preferably 50 to 1000 nm. If the thickness of the diffractive lens 5 is less than 10 nm, the volume of the annular zone 5a with respect to the organic layer becomes small, and the light extracted to the organic layer 3 becomes difficult to be diffracted and condensed. If the thickness of the diffractive lens 5 is greater than 2000 nm, it is difficult to maintain the flatness of the organic layer 3.
回折レンズ５の屈折率が陽極２より低い場合、回折レンズ５の材料としては、透光性でかつ陽極２の屈折率より低い屈折率を有する材料であれば特に制限はない。陽極２の材料が酸化インジウム錫（ＩＴＯ（屈折率１．８２））である場合は、例えば、スピンオングラス（ＳＯＧ（屈折率１．２５））、フッ化マグネシウム（ＭｇＦ２（屈折率１．３８））等の金属フッ化物、ポリテトラフルオロエチレン（ＰＴＦＥ（屈折率１．３５））等の有機フッ素化合物、二酸化ケイ素（ＳｉＯ２（屈折率１．４５））、各種の低融点ガラス、各種の多孔性物質等が挙げられる。
回折レンズ５の厚さは限定するものではないが、例えば１０～２０００ｎｍであり、好ましくは５０～１０００ｎｍである。回折レンズ５の厚さが１０ｎｍより薄いと有機層に対する輪帯部５ａの体積が小さくなり、有機層３に取り出された光が回折・集光されにくくなる。回折レンズ５の厚さが２０００ｎｍより厚いと有機層３の平坦度を保ちにくくなる。 The
When the refractive index of the
The thickness of the
陰極４は、その有機層側の表面４Ａに周期的に配置する複数の放射起点部４ａを有する。その放射起点部４ａは、平面視して回折レンズ５に重なる位置に配置されることが好ましい。
The cathode 4 has a plurality of radiation starting points 4a periodically arranged on the surface 4A on the organic layer side. The radiation starting point portion 4a is preferably arranged at a position overlapping the diffraction lens 5 in plan view.
陰極４は、発光層に電子を注入するための電極である。仕事関数の小さい金属、合金、導電性化合物、あるいはこれらの混合物からなる材料を用いることが好ましく、ＬＵＭＯ(Lowest Unoccupied Molecular Orbital)準位との差が過大にならないように仕事関数が１．９ｅＶ以上５ｅＶ以下のものを用いるのが好ましい。かかる材料としては例えば、Ａｕ、Ａｇ、Ｃｕ、Ｚｎ、Ａｌ、Ｍｇ、アルカリ金属、アルカリ土類金属等の単体や、ＡｕとＡｇとの合金、ＡｇとＣｕとの合金、真鍮等の合金が挙げられる。陰極４は、２層以上の積層構造であってもよい。
陰極４の厚さ（放射起点部４ａを含めた厚さ）は限定するものではないが、例えば３０ｎｍ～１μｍであり、好ましくは５０～５００ｎｍである。陰極４の厚さが３０ｎｍより薄いとシート抵抗が増加して、駆動電圧が上昇する。陰極４の厚さが１μｍより厚いと製膜時の熱や放射線ダメージ、膜応力による機械的ダメージが電極や有機層に蓄積してしまう。 Thecathode 4 is an electrode for injecting electrons into the light emitting layer. It is preferable to use a material made of a metal, an alloy, a conductive compound, or a mixture thereof having a low work function, and the work function is 1.9 eV or more so that the difference from the LUMO (Lowest Unoccupied Molecular Orbital) level does not become excessive. It is preferable to use a voltage of 5 eV or less. Examples of such materials include simple substances such as Au, Ag, Cu, Zn, Al, Mg, alkali metals and alkaline earth metals, alloys of Au and Ag, alloys of Ag and Cu, and alloys such as brass. It is done. The cathode 4 may have a laminated structure of two or more layers.
The thickness of the cathode 4 (thickness including the radiationstarting point portion 4a) is not limited, but is, for example, 30 nm to 1 μm, and preferably 50 to 500 nm. If the thickness of the cathode 4 is less than 30 nm, the sheet resistance increases and the driving voltage rises. If the thickness of the cathode 4 is greater than 1 μm, heat and radiation damage during film formation and mechanical damage due to film stress accumulate in the electrode and the organic layer.
陰極４の厚さ（放射起点部４ａを含めた厚さ）は限定するものではないが、例えば３０ｎｍ～１μｍであり、好ましくは５０～５００ｎｍである。陰極４の厚さが３０ｎｍより薄いとシート抵抗が増加して、駆動電圧が上昇する。陰極４の厚さが１μｍより厚いと製膜時の熱や放射線ダメージ、膜応力による機械的ダメージが電極や有機層に蓄積してしまう。 The
The thickness of the cathode 4 (thickness including the radiation
放射起点部４ａは凹形状を有するものであるが、これに限らず、凸形状、凹凸形状のいずれでもよい。平面視したときの放射起点部の４ａの一つ一つの形状は、ライン状の凹凸、ドット状の凹凸（離散配置する凹凸）等のいずれでもよい。
一つの放射起点部４ａ（放射起点部の単位構造）は、１個の凹凸構造からなるものでも、複数の凹凸構造からなるものでもよい。一つの放射起点部は平面視して回折レンズのサイズより小さいことが好ましい。
隣接する放射起点部４ａの中心線間の距離（ピッチ）は、SPPモード光が伝播できる１０μｍ以下であることが好ましい。このようなピッチとすることで、ＳＰＰモード光が熱として散逸する前に、放射起点部４ａによってＳＰＰモード光を散乱させ、伝播光として再放射させることが可能となる。
回折レンズは、その中心が平面視して前記放射起点部の中心線上に配置されるように設けられていることが好ましい。この場合、放射起点部４ａのピッチは、回折レンズ５のピッチと同じである。 The radiationstarting point portion 4a has a concave shape, but is not limited thereto, and may be a convex shape or an uneven shape. Each shape of the radiation starting point portion 4a when viewed in a plan view may be any of a line-shaped unevenness, a dot-shaped unevenness (unevenness that is discretely arranged), and the like.
One radiationstarting point portion 4a (unit structure of the radiation starting point portion) may be composed of one concavo-convex structure or a plurality of concavo-convex structures. One radiation starting point is preferably smaller than the size of the diffractive lens in plan view.
The distance (pitch) between the center lines of the adjacent radiationstarting point portions 4a is preferably 10 μm or less at which SPP mode light can propagate. By setting such a pitch, before the SPP mode light is dissipated as heat, the SPP mode light can be scattered by the radiation starting point portion 4a and re-radiated as propagating light.
It is preferable that the diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point in plan view. In this case, the pitch of the radiationstarting point portion 4a is the same as the pitch of the diffraction lens 5.
一つの放射起点部４ａ（放射起点部の単位構造）は、１個の凹凸構造からなるものでも、複数の凹凸構造からなるものでもよい。一つの放射起点部は平面視して回折レンズのサイズより小さいことが好ましい。
隣接する放射起点部４ａの中心線間の距離（ピッチ）は、SPPモード光が伝播できる１０μｍ以下であることが好ましい。このようなピッチとすることで、ＳＰＰモード光が熱として散逸する前に、放射起点部４ａによってＳＰＰモード光を散乱させ、伝播光として再放射させることが可能となる。
回折レンズは、その中心が平面視して前記放射起点部の中心線上に配置されるように設けられていることが好ましい。この場合、放射起点部４ａのピッチは、回折レンズ５のピッチと同じである。 The radiation
One radiation
The distance (pitch) between the center lines of the adjacent radiation
It is preferable that the diffractive lens is provided so that the center thereof is disposed on the center line of the radiation starting point in plan view. In this case, the pitch of the radiation
有機層３は、陽極２及び回折レンズ５と陰極４との間に配置される層状部３ａと、放射起点部４ａの形状に対応する部分（図１の例では、凸部３ｂ）とを有するものである。
The organic layer 3 has a layered portion 3a disposed between the anode 2 and the diffractive lens 5 and the cathode 4, and a portion corresponding to the shape of the radiation starting point portion 4a (in the example of FIG. 1, a convex portion 3b). Is.
発光層の材料としては、有機ＥＬ素子用の材料として知られる任意の材料を用いることができる。
有機層３は、有機ＥＬ材料からなる発光層（有機発光層）の他、正孔注入層、正孔輸送層、電子注入層、電子輸送層等を備えてもよい。 As a material of the light emitting layer, any material known as a material for an organic EL element can be used.
Theorganic layer 3 may include a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like in addition to a light emitting layer (organic light emitting layer) made of an organic EL material.
有機層３は、有機ＥＬ材料からなる発光層（有機発光層）の他、正孔注入層、正孔輸送層、電子注入層、電子輸送層等を備えてもよい。 As a material of the light emitting layer, any material known as a material for an organic EL element can be used.
The
正孔注入層は陽極２から有機層３への正孔注入を助ける層である。このような正孔注入層としてはより低い電界強度で正孔を発光層に注入する材料が好ましい。正孔注入層を、形成する材料としては、上記の機能を担えるものであれば特に制限はなく、公知のものの中から任意のものを選択して用いることができる。正孔輸送層は発光領域まで正孔を輸送する層であって、正孔移動度が大きく、イオン化エネルギーが通常５．５ｅＶ以下と小さい。このような正孔輸送層として形成する材料は、上記の機能を備えるものであれば特に制限はなく、公知のものの中から任意のものを選択して用いることができる。
The hole injection layer is a layer that assists hole injection from the anode 2 to the organic layer 3. Such a hole injection layer is preferably a material that injects holes into the light emitting layer with lower electric field strength. The material for forming the hole injection layer is not particularly limited as long as it can perform the above functions, and any material can be selected from known materials. The hole transport layer is a layer that transports holes to the light emitting region, and has a high hole mobility and a small ionization energy of usually 5.5 eV or less. The material to be formed as such a hole transport layer is not particularly limited as long as it has the above function, and any material can be selected and used from known materials.
電子注入層は陰極４から有機層３への電子注入を助ける層である。このような電子注入層としてはより低い電界強度で電子を有機層３に注入する材料が好ましい。形成する材料としては、上記の機能を担えるものであれば特に制限はなく、公知のものの中から任意のものを選択して用いることができる。電子輸送層は発光領域まで電子を輸送する層であって、電子移動度が大きい。このような電子輸送層として形成する材料は、上記の機能を担えるものであれば特に制限はなく、公知のものの中から任意のものを選択して用いることができる。
The electron injection layer is a layer that assists electron injection from the cathode 4 to the organic layer 3. Such an electron injection layer is preferably a material that injects electrons into the organic layer 3 with lower electric field strength. The material to be formed is not particularly limited as long as it can perform the above functions, and any material can be selected and used from known materials. The electron transport layer is a layer that transports electrons to the light emitting region and has a high electron mobility. The material for forming such an electron transport layer is not particularly limited as long as it can perform the above function, and any material can be selected and used from known materials.
有機層３は、蒸着法、転写法などの乾式プロセスによって成膜してもよいし、スピンコート法、スプレーコート法、ダイコート法、グラビア印刷法など、湿式プロセスによって成膜してもよい。
有機層３の厚さは限定するものはないが、例えば５０～２０００ｎｍであり、好ましくは１００～１０００ｎｍである。有機層３の厚さが５０ｎｍより薄いと突き抜け電流による内部ＱＥの低下や損失性表面カップリング（lossy surface Coupling）など、金属によるSPPカップリング以外の消光が起こる。有機層３の厚さが１０００ｎｍより厚いと駆動電圧が上昇する。 Theorganic layer 3 may be formed by a dry process such as an evaporation method or a transfer method, or may be formed by a wet process such as a spin coating method, a spray coating method, a die coating method, or a gravure printing method.
The thickness of theorganic layer 3 is not limited, but is, for example, 50 to 2000 nm, and preferably 100 to 1000 nm. If the thickness of the organic layer 3 is less than 50 nm, quenching other than SPP coupling by metal, such as reduction of internal QE due to punch-through current or lossy surface coupling, occurs. When the thickness of the organic layer 3 is greater than 1000 nm, the drive voltage increases.
有機層３の厚さは限定するものはないが、例えば５０～２０００ｎｍであり、好ましくは１００～１０００ｎｍである。有機層３の厚さが５０ｎｍより薄いと突き抜け電流による内部ＱＥの低下や損失性表面カップリング（lossy surface Coupling）など、金属によるSPPカップリング以外の消光が起こる。有機層３の厚さが１０００ｎｍより厚いと駆動電圧が上昇する。 The
The thickness of the
次に、本実施形態の有機ＥＬ素子の作用効果を、図３を用いて模式的に説明する。図３に矢印で示した光の伝播の仕方は、作用効果の原理をわかりやすく説明するために摸式的に示したものである。
Next, the function and effect of the organic EL element of this embodiment will be schematically described with reference to FIG. The light propagation method indicated by the arrows in FIG. 3 is schematically shown in order to easily understand the principle of the effect.
有機層３に含まれる発光層のＡ点で発光した光のうち、陰極４側に進んだ光（矢印Ａ１）は陰極４の表面４Ａに捕捉され、ＳＰＰモード光となる。このＳＰＰモード光は表面４Ａに沿って移動し（矢印Ａ２）、放射起点部４ａ１（４ａ）で放射され、当該放射起点部を中心とした球面波もしくは円筒波となる。この球面波もしくは円筒波として取り出された光は、有機層３等を透過して（矢印Ｂ１、Ｂ２、Ｂ３）、基板外に取り出される。
ここで、有機層３のＡ点で発光した光は全方位に進むので矢印Ａ１以外の方向（例えば、陽極側）に進む光も当然存在する。矢印Ａ１は本発明の作用効果を説明するために、そのうちの一部の光の伝播を摸式的に示しているに過ぎない。矢印Ａ２及び矢印Ｂ１～Ｂ３で示した光についても一部の光の伝播を摸式的に示しているに過ぎない。これは、放射起点部から放射された光についても同様である。 Of the light emitted from the point A of the light emitting layer included in theorganic layer 3, the light (arrow A1) traveling to the cathode 4 side is captured by the surface 4A of the cathode 4 and becomes SPP mode light. The SPP mode light moves along the surface 4A (arrow A2) and is emitted from the radiation starting point 4a1 (4a), and becomes a spherical wave or a cylindrical wave centered on the radiation starting point. The light extracted as the spherical wave or cylindrical wave passes through the organic layer 3 and the like (arrows B1, B2, B3) and is extracted out of the substrate.
Here, since the light emitted from the point A of theorganic layer 3 travels in all directions, there is naturally light traveling in a direction other than the arrow A1 (for example, the anode side). The arrow A1 merely schematically shows the propagation of part of the light in order to explain the effects of the present invention. The light indicated by the arrow A2 and the arrows B1 to B3 is only schematically showing the propagation of part of the light. The same applies to the light emitted from the radiation starting point.
ここで、有機層３のＡ点で発光した光は全方位に進むので矢印Ａ１以外の方向（例えば、陽極側）に進む光も当然存在する。矢印Ａ１は本発明の作用効果を説明するために、そのうちの一部の光の伝播を摸式的に示しているに過ぎない。矢印Ａ２及び矢印Ｂ１～Ｂ３で示した光についても一部の光の伝播を摸式的に示しているに過ぎない。これは、放射起点部から放射された光についても同様である。 Of the light emitted from the point A of the light emitting layer included in the
Here, since the light emitted from the point A of the
放射起点部４ａ１（４ａ）で放射され、矢印Ｂ１～Ｂ３で示した方向に伝播する光のうち、光Ｂ１は基板に対して垂直に基板側に進む光であり、有機層３と陽極２との界面及び陽極２と基板１との界面でも屈折することなく、誘電体層７内、基板１内を進み、外部に取り出される。
Of the light radiated from the radiation starting point 4a1 (4a) and propagating in the directions indicated by the arrows B1 to B3, the light B1 is light that travels perpendicularly to the substrate toward the substrate, and the organic layer 3 and the anode 2 At this interface and the interface between the anode 2 and the substrate 1, the light passes through the dielectric layer 7 and the substrate 1 without being refracted, and is taken out to the outside.
光Ｂ２及び光Ｂ３は回折レンズ５により、放射起点部４ａ１（４ａ）の中心線Ｃ１（図１参照）上の焦点に集光するように回折される。ここで、光Ｂ２及び光Ｂ３は有機層３から進み、回折レンズ５を通過する際に、回折レンズ５による回折により、基板１への入射角が小さい角度に変わる。通常、基板（例えば、ガラス）と空気との界面では臨界角以上の角度で入射すると全反射となる。しかし、この回折レンズ５での回折により基板１への入射角が小さい角度に変わるので、基板と空気との界面での全反射を避けられる光が増えて光取り出し効率が向上する。すなわち、回折レンズ５を備える構成を有することにより、光取り出し効率が向上する。
このように、本発明の有機ＥＬ素子では、有機層に含まれる発光層で発光した光が、陰極表面にＳＰＰモード光として捕捉されても、そのＳＰＰモード光は陰極表面の放射起点部で放射されて取り出すことができる。さらに、その陰極表面から取り出した光を、回折レンズ５で基板の正面方向へ屈折させて基板の正面方向への光の取り出し量を増大させることができる。 The light B2 and the light B3 are diffracted by thediffractive lens 5 so as to be condensed at the focal point on the center line C1 (see FIG. 1) of the radiation starting point portion 4a1 (4a). Here, when the light B <b> 2 and the light B <b> 3 travel from the organic layer 3 and pass through the diffraction lens 5, the incident angle on the substrate 1 is changed to a small angle due to diffraction by the diffraction lens 5. In general, when the light is incident at an angle greater than the critical angle at the interface between the substrate (eg, glass) and air, total reflection occurs. However, since the incident angle on the substrate 1 is changed to a small angle by the diffraction by the diffractive lens 5, the light that can avoid total reflection at the interface between the substrate and air is increased, and the light extraction efficiency is improved. That is, by having a configuration including the diffractive lens 5, light extraction efficiency is improved.
As described above, in the organic EL device of the present invention, even if the light emitted from the light emitting layer included in the organic layer is captured as SPP mode light on the cathode surface, the SPP mode light is emitted at the radiation starting point on the cathode surface. Can be taken out. Further, the light extracted from the cathode surface can be refracted in the front direction of the substrate by thediffraction lens 5 to increase the amount of light extracted in the front direction of the substrate.
このように、本発明の有機ＥＬ素子では、有機層に含まれる発光層で発光した光が、陰極表面にＳＰＰモード光として捕捉されても、そのＳＰＰモード光は陰極表面の放射起点部で放射されて取り出すことができる。さらに、その陰極表面から取り出した光を、回折レンズ５で基板の正面方向へ屈折させて基板の正面方向への光の取り出し量を増大させることができる。 The light B2 and the light B3 are diffracted by the
As described above, in the organic EL device of the present invention, even if the light emitted from the light emitting layer included in the organic layer is captured as SPP mode light on the cathode surface, the SPP mode light is emitted at the radiation starting point on the cathode surface. Can be taken out. Further, the light extracted from the cathode surface can be refracted in the front direction of the substrate by the
図４は、回折レンズの輪帯部の間隔に係り、輪帯部の粗密の程度が異なる例の平面模式図を示す。（ａ）は粗い（間隔が大きい）場合であり、（ｃ）は密な（間隔が小さい）場合であり、（ｂ）はその中間の場合である。
FIG. 4 shows a schematic plan view of an example in which the degree of density of the annular zone differs depending on the interval of the annular zone of the diffractive lens. (A) is a rough case (large interval), (c) is a dense case (small interval), and (b) is an intermediate case.
図５に、回折レンズ５の輪帯部５ａと陽極２の輪帯部２ａの位相が逆（逆位相）の場合について、（ａ）は断面模式図を、（ｂ）は平面模式図を示す。ここで逆位相の場合とは、図１において、輪帯部５ａと輪帯部２ａの位置が入れ替わった場合である。この場合、回折レンズ５の円形の中心部を占めるのは回折レンズ５の輪帯部５ａである。円形の中心部を占める回折レンズ５の輪帯部５ａの中心が陰極４の放射起点部４ａの中心線上に配置される。この「逆位相」の場合に対して、図１の場合を「同位相」という。図１の場合は、円形の中心部を占めるのが陽極２の輪帯部２ａである場合であって、円形の中心部を占める陽極２の輪帯部２ａの中心が陰極４の放射起点部４ａの中心線上に配置される。但し、「逆位相」の場合の“円形の中心部を占める回折レンズ５の輪帯部５ａの中心”も、「同位相」の場合の“円形の中心部を占める陽極２の輪帯部２ａの中心”も、いずれも「回折レンズの中心」である。
5A and 5B show a cross-sectional schematic view and FIG. 5B a schematic plan view when the phase of the annular zone 5a of the diffractive lens 5 and the annular zone 2a of the anode 2 are reversed (reverse phase). . Here, the case of the opposite phase is a case where the positions of the annular portion 5a and the annular portion 2a are interchanged in FIG. In this case, the annular zone 5 a of the diffractive lens 5 occupies the circular central portion of the diffractive lens 5. The center of the annular zone 5 a of the diffractive lens 5 occupying the center of the circle is arranged on the center line of the radiation starting point 4 a of the cathode 4. In contrast to this “reverse phase” case, the case of FIG. 1 is called “in-phase”. In the case of FIG. 1, it is the case where the annular zone 2 a of the anode 2 occupies the circular center portion, and the center of the annular zone 2 a of the anode 2 occupying the circular center portion is the radiation origin portion of the cathode 4. 4a is arranged on the center line. However, in the case of “reverse phase”, the “center of the annular zone 5a of the diffractive lens 5 occupying the circular center” is also the “annular zone 2a of the anode 2 occupying the circular central portion in the case of“ in phase ”. “Center of” is also “center of diffraction lens”.
回折レンズ５を透過した光を中心線上の焦点に集光させるためには、輪帯部５ａの幅（間隔）はそれぞれ、回折レンズ５の中心から周辺にいくほど小さくなるように形成されていることが好ましい。輪帯部５ａをこのように形成することによって、回折レンズの外周に入射した光ほど（例えば図３のＢ２よりＢ３の入射光線のほうが）大きく屈曲されて、レンズは集光作用が働く。
ただし、重なる位置に配置された放射起点と回折レンズ同士が接近しており（例えば、図１のように有機層３のみを介し、放射起点４ａと回折レンズ５が近接している場合）、且つレンズ透過光の焦点距離を無限遠とする場合はこの限りではない。すなわち、このような場合においては、放射起点部４ａから回折レンズ５への入射光の多くは、ほぼ基板面に平行な方向を向いている。そのため、回折レンズ５は基板面内方向の光を基板面に対し垂直に回折させられればよく、輪帯部５ａとして、幅（間隔）が一定のものを用いることができる。 In order to collect the light transmitted through thediffractive lens 5 at the focal point on the center line, the width (interval) of the annular zone 5a is formed so as to decrease from the center of the diffractive lens 5 to the periphery. It is preferable. By forming the annular zone 5a in this way, the light incident on the outer periphery of the diffractive lens is bent more greatly (for example, the incident light beam B3 than B2 in FIG. 3), and the lens has a condensing function.
However, the radiation starting point and the diffractive lens arranged at the overlapping position are close to each other (for example, when theradiation starting point 4a and the diffractive lens 5 are close to each other through only the organic layer 3 as shown in FIG. 1), and This is not the case when the focal length of the lens transmitted light is set to infinity. That is, in such a case, most of the incident light from the radiation starting point 4a to the diffractive lens 5 is directed in a direction substantially parallel to the substrate surface. Therefore, the diffractive lens 5 only needs to be able to diffract light in the in-plane direction perpendicular to the substrate surface, and the annular zone 5a having a constant width (interval) can be used.
ただし、重なる位置に配置された放射起点と回折レンズ同士が接近しており（例えば、図１のように有機層３のみを介し、放射起点４ａと回折レンズ５が近接している場合）、且つレンズ透過光の焦点距離を無限遠とする場合はこの限りではない。すなわち、このような場合においては、放射起点部４ａから回折レンズ５への入射光の多くは、ほぼ基板面に平行な方向を向いている。そのため、回折レンズ５は基板面内方向の光を基板面に対し垂直に回折させられればよく、輪帯部５ａとして、幅（間隔）が一定のものを用いることができる。 In order to collect the light transmitted through the
However, the radiation starting point and the diffractive lens arranged at the overlapping position are close to each other (for example, when the
本発明の有機ＥＬ素子の回折レンズは、有機層の陰極の反対側であれば、いずれの位置に備えてもよい。本実施形態では、回折レンズは陽極内に設けられた構成であるが、有機層内や基板内等の他の層もしくは構成要素の内部に備えてよいし、層と層の界面に備える構成でもよいし、基板の外表面に備える構成であってもよい。
The diffraction lens of the organic EL element of the present invention may be provided at any position as long as it is on the opposite side of the organic layer from the cathode. In this embodiment, the diffractive lens is provided in the anode. However, the diffractive lens may be provided in another layer or component such as in the organic layer or in the substrate, or may be provided in the interface between the layers. Alternatively, a configuration provided on the outer surface of the substrate may be employed.
例えば、図６に示す本発明の他の実施形態に係る有機ＥＬ素子は、基板１と陽極２との間に回折レンズ１５を備える構成の一例である。この場合、回折レンズ１５は屈折率の高い誘電体の輪帯部１５ａとそれより屈折率の低い誘電体の輪帯部１５ｂとが交互に並ぶ等の構成に形成されている。誘電体の輪帯部１５ａの屈折率が低く、輪帯部１５ｂがそれより屈折率が高いという逆位相の構成であってもよい。
For example, an organic EL element according to another embodiment of the present invention shown in FIG. 6 is an example of a configuration in which a diffraction lens 15 is provided between the substrate 1 and the anode 2. In this case, the diffractive lens 15 is formed such that dielectric ring zones 15a having a high refractive index and dielectric ring zones 15b having a low refractive index are alternately arranged. An anti-phase configuration in which the refractive index of the dielectric annular zone 15a is low and the refractive index of the annular zone 15b is higher than that may be used.
また例えば、図７に示す本発明のさらに他の実施形態に係る有機ＥＬ素子は、基板１の外表面１Ａに回折レンズ２５を備える構成の一例である。この場合、回折レンズ２５は屈折率の高い誘電体の輪帯部２５ａとそれより屈折率の低い誘電体の輪帯部２５ｂとが交互に並ぶ等の構成に形成されている。誘電体の輪帯部２５ａの屈折率が低く、輪帯部２５ｂがそれより屈折率が高いという逆位相の構成であってもよい。
For example, the organic EL element according to still another embodiment of the present invention shown in FIG. 7 is an example of a configuration in which the diffraction lens 25 is provided on the outer surface 1A of the substrate 1. In this case, the diffractive lens 25 is formed such that dielectric ring zones 25a having a high refractive index and dielectric ring zones 25b having a low refractive index are alternately arranged. An antiphase configuration may be employed in which the refractive index of the dielectric annular zone 25a is low and the refractive index of the annular zone 25b is higher than that.
（画像表示装置）
次に、上記の本発明の一実施形態である有機ＥＬ素子１０を備えた画像表示装置について説明を行う。本発明の画像表示装置は本発明の他の実施形態の有機ＥＬ素子を備えてもよい。
図８は、上記の有機ＥＬ素子を備えた画像表示装置の一例を説明した図である。
図８に示した画像表示装置１００は、いわゆるパッシブマトリクス型の画像表示装置である。有機ＥＬ素子１０の他に、陽極配線１０４、陽極補助配線１０６、陰極配線１０８、絶縁膜１１０、陰極隔壁１１２、封止プレート１１６およびシール材１１８を備えている。 (Image display device)
Next, an image display apparatus including theorganic EL element 10 according to the embodiment of the present invention will be described. The image display apparatus of the present invention may include the organic EL element according to another embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of an image display device including the organic EL element.
Theimage display device 100 shown in FIG. 8 is a so-called passive matrix image display device. In addition to the organic EL element 10, an anode wiring 104, an anode auxiliary wiring 106, a cathode wiring 108, an insulating film 110, a cathode partition 112, a sealing plate 116, and a sealing material 118 are provided.
次に、上記の本発明の一実施形態である有機ＥＬ素子１０を備えた画像表示装置について説明を行う。本発明の画像表示装置は本発明の他の実施形態の有機ＥＬ素子を備えてもよい。
図８は、上記の有機ＥＬ素子を備えた画像表示装置の一例を説明した図である。
図８に示した画像表示装置１００は、いわゆるパッシブマトリクス型の画像表示装置である。有機ＥＬ素子１０の他に、陽極配線１０４、陽極補助配線１０６、陰極配線１０８、絶縁膜１１０、陰極隔壁１１２、封止プレート１１６およびシール材１１８を備えている。 (Image display device)
Next, an image display apparatus including the
FIG. 8 is a diagram illustrating an example of an image display device including the organic EL element.
The
本実施の形態において、有機ＥＬ素子１０の基板１上には、複数の陽極配線１０４が形成されている。陽極配線１０４は、一定の間隔を隔てて平行に配置される。陽極配線１０４は、透明導電膜により構成され、例えばＩＴＯ（Indium Tin Oxide）を用いることができる。陽極配線１０４の厚さは例えば、１００ｎｍ～１５０ｎｍとすることができる。そして、それぞれの陽極配線１０４の端部の上には、陽極補助配線１０６が形成される。陽極補助配線１０６は陽極配線１０４と電気的に接続されている。このように構成することにより、陽極補助配線１０６は、基板１の端部側において外部配線と接続するための端子として機能する。これにより、外部に設けられた図示しない駆動回路から陽極補助配線１０６を介して陽極配線１０４に電流を供給することができる。陽極補助配線１０６は、例えば、厚さ５００ｎｍ～６００ｎｍの金属膜によって構成される。
In the present embodiment, a plurality of anode wirings 104 are formed on the substrate 1 of the organic EL element 10. The anode wirings 104 are arranged in parallel at a constant interval. The anode wiring 104 is made of a transparent conductive film, and for example, ITO (Indium Tin Oxide) can be used. The thickness of the anode wiring 104 can be set to 100 nm to 150 nm, for example. An anode auxiliary wiring 106 is formed on the end of each anode wiring 104. The anode auxiliary wiring 106 is electrically connected to the anode wiring 104. With this configuration, the anode auxiliary wiring 106 functions as a terminal for connecting to the external wiring on the end side of the substrate 1. As a result, a current can be supplied to the anode wiring 104 via the anode auxiliary wiring 106 from a drive circuit (not shown) provided outside. The anode auxiliary wiring 106 is made of a metal film having a thickness of 500 nm to 600 nm, for example.
有機ＥＬ素子１０上には、複数の陰極配線１０８が設けられている。複数の陰極配線１０８は、それぞれが平行となるよう、かつ、陽極配線１０４と直交するように配設されている。陰極配線１０８には、Ａｌ又はＡｌ合金を使用することができる。陰極配線１０８の厚さは、例えば、１００ｎｍ～１５０ｎｍである。陰極配線１０８の端部には、陽極配線１０４に対する陽極補助配線１０６と同様に、図示しない陰極補助配線が設けられ、陰極配線１０８と電気的に接続されている。よって、陰極配線１０８と陰極補助配線との間に電流を流すことができる。
A plurality of cathode wirings 108 are provided on the organic EL element 10. The plurality of cathode wirings 108 are arranged so as to be parallel to each other and orthogonal to the anode wiring 104. For the cathode wiring 108, Al or an Al alloy can be used. The thickness of the cathode wiring 108 is, for example, 100 nm to 150 nm. A cathode auxiliary wiring (not shown) is provided at the end of the cathode wiring 108, similarly to the anode auxiliary wiring 106 for the anode wiring 104, and is electrically connected to the cathode wiring 108. Therefore, a current can flow between the cathode wiring 108 and the cathode auxiliary wiring.
更に基板１上には、陽極配線１０４を覆うように絶縁膜１１０が形成される。絶縁膜１１０には、陽極配線１０４の一部を露出するように矩形状の開口部１２０が設けられている。複数の開口部１２０は、陽極配線１０４の上にマトリクス状に配置されている。この開口部１２０において、陽極配線１０４と陰極配線１０８の間に有機ＥＬ素子１０が設けられる。すなわち、それぞれの開口部１２０が画素となる。従って、開口部１２０に対応して表示領域が形成される。ここで、絶縁膜１１０の膜厚は、例えば、２００ｎｍ～１００ｎｍとすることができる。開口部１２０の大きさは、例えば、１００μｍ×１００μｍとすることができる。
Further, an insulating film 110 is formed on the substrate 1 so as to cover the anode wiring 104. A rectangular opening 120 is provided in the insulating film 110 so as to expose a part of the anode wiring 104. The plurality of openings 120 are arranged in a matrix on the anode wiring 104. In the opening 120, the organic EL element 10 is provided between the anode wiring 104 and the cathode wiring 108. That is, each opening 120 becomes a pixel. Accordingly, a display area is formed corresponding to the opening 120. Here, the film thickness of the insulating film 110 can be set to, for example, 200 nm to 100 nm. The size of the opening 120 can be, for example, 100 μm × 100 μm.
有機ＥＬ素子１０は、開口部１２０において陽極配線１０４と陰極配線１０８の間に位置している。そしてこの場合、有機ＥＬ素子１０の陽極２が陽極配線１０４と接触し、陰極４が陰極配線１０８と接触する。有機ＥＬ素子１０の厚さは、例えば、１５０ｎｍ～２００ｎｍとすることができる。
The organic EL element 10 is located between the anode wiring 104 and the cathode wiring 108 in the opening 120. In this case, the anode 2 of the organic EL element 10 is in contact with the anode wiring 104 and the cathode 4 is in contact with the cathode wiring 108. The thickness of the organic EL element 10 can be set to, for example, 150 nm to 200 nm.
絶縁膜１１０の上には、複数の陰極隔壁１１２が陽極配線１０４と垂直な方向に沿って形成されている。陰極隔壁１１２は、陰極配線１０８の配線同士が導通しないように、複数の陰極配線１０８を空間的に分離するための役割を担っている。従って、隣接する陰極隔壁１１２の間にそれぞれ陰極配線１０８が配置される。陰極隔壁１１２の大きさとしては、例えば、高さが２μｍ～３μｍ、幅が１０μｍのものを用いることができる。
A plurality of cathode partition walls 112 are formed on the insulating film 110 along a direction perpendicular to the anode wiring 104. The cathode partition 112 plays a role for spatially separating the plurality of cathode wirings 108 so that the wirings of the cathode wirings 108 do not conduct with each other. Accordingly, the cathode wiring 108 is disposed between the adjacent cathode partition walls 112. As the size of the cathode partition 112, for example, the one having a height of 2 μm to 3 μm and a width of 10 μm can be used.
基板１は、封止プレート１１６とシール材１１８を介して貼り合わせられている。これにより、有機ＥＬ素子１０が設けられた空間を封止することができ、有機ＥＬ素子１０が空気中の水分により劣化するのを防ぐことができる。封止プレート１１６としては、例えば、厚さが０．７ｍｍ～１．１ｍｍのガラス基板を使用することができる。
The substrate 1 is bonded through a sealing plate 116 and a sealing material 118. Thereby, the space in which the organic EL element 10 is provided can be sealed, and the organic EL element 10 can be prevented from being deteriorated by moisture in the air. As the sealing plate 116, for example, a glass substrate having a thickness of 0.7 mm to 1.1 mm can be used.
このような構造の画像表示装置１００において、図示しない駆動装置により、陽極補助配線１０６、図示しない陰極補助配線を介して、有機ＥＬ素子１０に電流を供給し、発光層を発光させることができる。そして基板１から基板１を通し、光を出射させることができる。そして、上述の画素に対応した有機ＥＬ素子１０の発光、非発光を制御装置により制御することにより、画像表示装置１００に画像を表示させることができる。
In the image display device 100 having such a structure, a current can be supplied to the organic EL element 10 via the anode auxiliary wiring 106 and the cathode auxiliary wiring (not shown) by a driving device (not shown) to cause the light emitting layer to emit light. Then, light can be emitted from the substrate 1 through the substrate 1. An image can be displayed on the image display device 100 by controlling the light emission and non-light emission of the organic EL element 10 corresponding to the above-described pixel by the control device.
（照明装置）
次に、上記の本発明の一実施形態である有機ＥＬ素子１０を用いた照明装置について説明を行う。本発明の画像表示装置は本発明の他の実施形態の有機ＥＬ素子を備えてもよい。
図９は、上記の有機ＥＬ素子１０を備える照明装置の一例を説明した図である。
図９に示した照明装置２００は、上述した有機ＥＬ素子１０と、有機ＥＬ素子１０の基板１（図１参照）に隣接して設置され陽極２（図１参照）に接続される端子２０２と、陰極４（図１参照）に接続される端子２０３と、端子２０２と端子２０３とに接続し有機ＥＬ素子１０を駆動するための点灯回路２０１とから構成される。 (Lighting device)
Next, the illuminating device using theorganic EL element 10 which is one embodiment of the present invention will be described. The image display apparatus of the present invention may include the organic EL element according to another embodiment of the present invention.
FIG. 9 is a diagram illustrating an example of an illumination device including theorganic EL element 10 described above.
Thelighting device 200 shown in FIG. 9 includes the organic EL element 10 described above, and a terminal 202 that is installed adjacent to the substrate 1 (see FIG. 1) of the organic EL element 10 and connected to the anode 2 (see FIG. 1). The terminal 203 is connected to the cathode 4 (see FIG. 1), and the lighting circuit 201 is connected to the terminal 202 and the terminal 203 to drive the organic EL element 10.
次に、上記の本発明の一実施形態である有機ＥＬ素子１０を用いた照明装置について説明を行う。本発明の画像表示装置は本発明の他の実施形態の有機ＥＬ素子を備えてもよい。
図９は、上記の有機ＥＬ素子１０を備える照明装置の一例を説明した図である。
図９に示した照明装置２００は、上述した有機ＥＬ素子１０と、有機ＥＬ素子１０の基板１（図１参照）に隣接して設置され陽極２（図１参照）に接続される端子２０２と、陰極４（図１参照）に接続される端子２０３と、端子２０２と端子２０３とに接続し有機ＥＬ素子１０を駆動するための点灯回路２０１とから構成される。 (Lighting device)
Next, the illuminating device using the
FIG. 9 is a diagram illustrating an example of an illumination device including the
The
点灯回路２０１は、図示しない直流電源と図示しない制御回路を内部に有し、端子２０２と端子２０３を通して、有機ＥＬ素子１０の陽極層２と陰極４との間に電流を供給する。そして、有機ＥＬ素子１０を駆動し、発光層を発光させて、基板１から支持基板１０１を通し、光を出射させ、照明光として利用する。発光層は白色光を出射する発光材料より構成されていてもよく、また緑色光（Ｇ）、青色光（Ｂ）、赤色光（Ｒ）を出射する発光材料を使用した有機ＥＬ素子１０をそれぞれ複数個設け、その合成光が白色となるようにしてもよい。
The lighting circuit 201 has a DC power supply (not shown) and a control circuit (not shown) inside, and supplies a current between the anode layer 2 and the cathode 4 of the organic EL element 10 through the terminal 202 and the terminal 203. Then, the organic EL element 10 is driven, the light emitting layer emits light, light is emitted from the substrate 1 through the support substrate 101, and is used as illumination light. The light emitting layer may be made of a light emitting material that emits white light, and each of the organic EL elements 10 using light emitting materials that emit green light (G), blue light (B), and red light (R). A plurality of them may be provided so that the combined light is white.
（有機ＥＬ素子の製造方法）
次に、本発明の有機ＥＬ素子の製造方法について説明する。
はじめに、図１に示した有機ＥＬ素子の製造方法について説明する。
まず、基板１上に、陽極２を形成する。この陽極２の形成方法は特に限定されるものではないが、例えば、抵抗加熱蒸着法、電子ビーム蒸着法、スパッタリング法、イオンプレーティング法、ＣＶＤ法などを用いることができる。 (Manufacturing method of organic EL element)
Next, the manufacturing method of the organic EL element of this invention is demonstrated.
First, a method for manufacturing the organic EL element shown in FIG. 1 will be described.
First, theanode 2 is formed on the substrate 1. The method for forming the anode 2 is not particularly limited, and for example, a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, a CVD method, or the like can be used.
次に、本発明の有機ＥＬ素子の製造方法について説明する。
はじめに、図１に示した有機ＥＬ素子の製造方法について説明する。
まず、基板１上に、陽極２を形成する。この陽極２の形成方法は特に限定されるものではないが、例えば、抵抗加熱蒸着法、電子ビーム蒸着法、スパッタリング法、イオンプレーティング法、ＣＶＤ法などを用いることができる。 (Manufacturing method of organic EL element)
Next, the manufacturing method of the organic EL element of this invention is demonstrated.
First, a method for manufacturing the organic EL element shown in FIG. 1 will be described.
First, the
陽極２を形成した後に、陽極２の表面処理を行うことで、オーバーコートされる層の性能（陽極２との密着性、表面平滑性、ホール注入障壁の低減化など）を改善することができる。表面処理を行うには高周波プラズマ処理を始めとしてスパッタリング処理、コロナ処理、ＵＶオゾン照射処理、紫外線照射処理、または酸素プラズマ処理などがある。
By performing the surface treatment of the anode 2 after forming the anode 2, the performance of the overcoated layer (adhesion with the anode 2, surface smoothness, reduction of hole injection barrier, etc.) can be improved. . The surface treatment includes high-frequency plasma treatment, sputtering treatment, corona treatment, UV ozone irradiation treatment, ultraviolet irradiation treatment, oxygen plasma treatment, and the like.
更に、陽極２の表面処理の表面処理を行う代わりに、もしくは表面処理に追加して、図示しない陽極バッファ層を形成することで表面処理と同様の効果が期待できる。そして、陽極バッファ層をウェットプロセスにて塗布して作製する場合には、スピンコート法、キャスティング法、マイクログラビアコート法、グラビアコート法、バーコート法、ロールコート法、ワイアーバーコート法、ディップコート法、スプレーコート法、スクリーン印刷法、フレキソ印刷法、オフセット印刷法、インクジェットプリント法等の塗布法などを用いて成膜することができる。
Furthermore, the same effect as the surface treatment can be expected by forming an anode buffer layer (not shown) instead of or in addition to the surface treatment of the surface treatment of the anode 2. When the anode buffer layer is applied by a wet process, spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating The film can be formed using a coating method such as a spray method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, or an inkjet printing method.
陽極バッファ層をドライプロセスにて作製する場合は、特開２００６－３０３４１２号公報に例示のプラズマ処理などを用いて成膜することができる。この他にも金属単体あるいは金属酸化物、金属窒化物等を成膜する方法が挙げられる。具体的な成膜方法としては、電子ビーム蒸着法、スパッタリング法、化学反応法、コーティング法、真空蒸着法などを用いることができる。
When the anode buffer layer is produced by a dry process, the anode buffer layer can be formed by using a plasma treatment or the like exemplified in Japanese Patent Application Laid-Open No. 2006-303412. In addition, a method of forming a film of a single metal, a metal oxide, a metal nitride, or the like can be given. As a specific film formation method, an electron beam evaporation method, a sputtering method, a chemical reaction method, a coating method, a vacuum evaporation method, or the like can be used.
次に、陽極２の輪帯部２ａを形成するには例えば、特許文献１０に記載しているようにフォトリソグラフィを用いた方法が使用できる。これを行うには、まず陽極２の上にポジ型レジスト液を塗布し、スピンコート等により余分なレジスト液を除去して、レジスト層を形成する。
Next, for example, a method using photolithography as described in Patent Document 10 can be used to form the annular zone 2 a of the anode 2. In order to do this, first, a positive resist solution is applied onto the anode 2, and the excess resist solution is removed by spin coating or the like to form a resist layer.
そして、輪帯部２ａを形成するための所定のパターンが描画されたマスクをかぶせ、紫外線（ＵＶ）、電子線（ＥＢ）等により露光を行うと、レジスト層に輪帯部２ａに対応した所定のパターンが露光される。そして現像液を用いて露光されたパターンの部分のレジスト層を除去する。これにより露光されたパターンの部分に対応して、陽極２の表面が露出する。
Then, when a mask on which a predetermined pattern for forming the annular zone 2a is applied and exposure is performed with ultraviolet rays (UV), electron beams (EB), etc., the resist layer has a predetermined corresponding to the annular zone 2a. The pattern is exposed. Then, the resist layer in the exposed pattern portion is removed using a developer. Thus, the surface of the anode 2 is exposed corresponding to the exposed pattern portion.
残存したレジスト層をマスクとして、露出した陽極２の部分をエッチング除去して輪帯部２ａを形成する。エッチング方法としては、ドライエッチングとウェットエッチングの何れをも使用することができる。この際に等方性エッチングと異方性エッチングを組合せることで、輪帯部２ａの形状の制御を行うことができる。ドライエッチングとしては、誘導結合プラズマや容量結合プラズマによる反応性イオンエッチング（ＲＩＥ：Reactive Ion Etching）等が利用できる。ウェットエッチングとしては、塩化鉄水溶液をはじめとする金属塩の溶液や、希塩酸や希硫酸をはじめとする酸への浸漬を行う方法などが利用できる。このエッチングにより上記パターンに対応して、基板１の表面が露出する。
Using the remaining resist layer as a mask, the exposed portion of the anode 2 is removed by etching to form the annular portion 2a. As an etching method, either dry etching or wet etching can be used. In this case, the shape of the annular zone 2a can be controlled by combining isotropic etching and anisotropic etching. As the dry etching, reactive ion etching (RIE: Reactive Ion Etching) using inductively coupled plasma or capacitively coupled plasma can be used. As the wet etching, a solution of a metal salt such as an iron chloride aqueous solution or a method of immersing in an acid such as dilute hydrochloric acid or dilute sulfuric acid can be used. By this etching, the surface of the substrate 1 is exposed corresponding to the pattern.
次に、残存したレジスト層をマスクとして、誘電体からなる輪帯部５ａを形成し、回折レンズ５とする。回折レンズ５は隣接する輪帯部２ａ間を充填する構成である。この回折レンズ５の形成も陽極２の形成と同様に限定するものではないが、例えば、抵抗加熱蒸着法、電子ビーム蒸着法、スパッタリング法、イオンプレーティング法、ＣＶＤ法などを用いることができる。
Next, using the remaining resist layer as a mask, a ring zone portion 5 a made of a dielectric is formed to form a diffraction lens 5. The diffractive lens 5 is configured to fill between adjacent ring zones 2a. The formation of the diffractive lens 5 is not limited to the formation of the anode 2. For example, a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, a CVD method, or the like can be used.
次に、レジスト層を除去した後、陽極２及び回折レンズ５上に、有機ＥＬ材料からなる発光層を含む有機層３を形成する。ここで、有機層３を形成する下地となる陽極２及び回折レンズ５の表面が凹凸状の場合は、平坦化するような研磨加工、エッチング処理などを適宜行ってもよい。
有機層３の形成には従来公知の方法を用いることができ限定するものではないが、例えば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法等の方法を用いることができる。 Next, after removing the resist layer, anorganic layer 3 including a light emitting layer made of an organic EL material is formed on the anode 2 and the diffraction lens 5. Here, when the surfaces of the anode 2 and the diffractive lens 5 serving as a base on which the organic layer 3 is formed are uneven, polishing or etching for flattening may be appropriately performed.
For forming theorganic layer 3, a conventionally known method can be used and is not limited. For example, a method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method can be used.
有機層３の形成には従来公知の方法を用いることができ限定するものではないが、例えば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法等の方法を用いることができる。 Next, after removing the resist layer, an
For forming the
次に、有機層３の表面に、この後に形成する陰極４の放射起点部４ａに対応する位置に凸部３ｂを有するように凹凸構造を形成する。この凹凸形成には例えば、フォトリソグラフィを用いた方法を使用できる。これを行うにはまず有機層３の上にポジ型レジスト液を塗布し、スピンコート等により余分なレジスト液を除去して、レジスト層を形成する。
Next, a concavo-convex structure is formed on the surface of the organic layer 3 so as to have a convex portion 3b at a position corresponding to the radiation starting point portion 4a of the cathode 4 to be formed later. For example, a method using photolithography can be used for forming the unevenness. To do this, first, a positive resist solution is applied on the organic layer 3, and the excess resist solution is removed by spin coating or the like to form a resist layer.
そして、凸部３を形成するための所定のパターンが描画されたマスクをかぶせ、紫外線（ＵＶ）、電子線（ＥＢ）等により露光を行うと、レジスト層に放射起点部４ａに対応した所定のパターンが露光される。そして現像液を用いて露光されたパターンの部分のレジスト層１１ａを除去する。これにより露光されたパターンの部分に対応して、有機層３の表面が露出する。
Then, when a mask on which a predetermined pattern for forming the convex part 3 is drawn is put on and exposed by ultraviolet rays (UV), electron beams (EB), etc., the resist layer has a predetermined corresponding to the radiation starting point part 4a. The pattern is exposed. Then, the resist layer 11a in the exposed pattern portion is removed using a developer. As a result, the surface of the organic layer 3 is exposed corresponding to the exposed pattern portion.
次に、残存したレジスト層をマスクとして、露出した有機層３の部分をエッチング除去して凸部３ｂを形成する。エッチングとしては、ドライエッチングとウェットエッチングの何れをも使用することができる。またこの際に等方性エッチングと異方性エッチングを組合せることで、凸部３ｂの形状の制御を行うことができる。ドライエッチングとしては誘導結合プラズマ、容量結合プラズマを用いた反応性イオンエッチング（ＲＩＥ：Reactive Ion Etching）や、酸素プラズマによるアッシング処理等が利用できる。ウェットエッチングとしては、希塩酸や希硫酸などのほか、各種の有機溶媒への浸漬を行う方法などが利用できる。このエッチングにより上記パターンに対応して、放射起点部４ａに対応する凸部３ｂを含む凹凸構造を有機層３の表面に形成することができる。
フォトリソグラフィは１μｍ程度までは位置合わせ精度があるため、陰極の放射起点部と回折レンズとが平面視して重なるように形成することが可能となる。 Next, using the remaining resist layer as a mask, the exposed portion of theorganic layer 3 is removed by etching to form a convex portion 3b. As the etching, either dry etching or wet etching can be used. In this case, the shape of the convex portion 3b can be controlled by combining isotropic etching and anisotropic etching. As dry etching, reactive ion etching (RIE: Reactive Ion Etching) using inductively coupled plasma or capacitively coupled plasma, ashing treatment using oxygen plasma, or the like can be used. As the wet etching, there can be used a method of immersing in various organic solvents in addition to dilute hydrochloric acid and dilute sulfuric acid. By this etching, a concavo-convex structure including the convex portions 3 b corresponding to the radiation starting point portions 4 a can be formed on the surface of the organic layer 3 corresponding to the pattern.
Since photolithography has alignment accuracy up to about 1 μm, it can be formed such that the radiation starting point of the cathode and the diffraction lens overlap in plan view.
フォトリソグラフィは１μｍ程度までは位置合わせ精度があるため、陰極の放射起点部と回折レンズとが平面視して重なるように形成することが可能となる。 Next, using the remaining resist layer as a mask, the exposed portion of the
Since photolithography has alignment accuracy up to about 1 μm, it can be formed such that the radiation starting point of the cathode and the diffraction lens overlap in plan view.
次に、陰極材料を有機層３上に蒸着して、有機層３の凹凸構造を追従させて放射起点部４ａを有する陰極４を形成する。
Next, a cathode material is vapor-deposited on the organic layer 3, and the cathode 4 having the radiation starting point portion 4a is formed by following the uneven structure of the organic layer 3.
以上の工程により、有機ＥＬ素子１０を製造することができる。これら一連の工程後、有機ＥＬ素子１０を長期安定的に用い、有機ＥＬ素子１０を外部から保護するための保護層や保護カバー（図示せず）を装着することが好ましい。保護層としては、高分子化合物、金属酸化物、金属フッ化物、金属ホウ化物、窒化ケイ素、酸化ケイ素等のシリコン化合物などを用いることができる。そして、これらの積層体も用いることができる。保護カバーとしては、ガラス板、表面に低透水率処理を施したプラスチック板、金属などを用いることができる。この保護カバーは、熱硬化性樹脂、光硬化性樹脂、フリットガラス等で基板１と貼り合わせて密閉する方法を採ることが好ましい。この際に、基板１と前記保護カバーの間にスペーサを配置することで所定の空間を維持することができ、有機ＥＬ素子１０が傷つくのを防止できるため好ましい。
そして、この空間に窒素、アルゴン、ヘリウムのような不活性なガスを封入すれば、上側の陰極４の酸化を防止しやすくなる。特にヘリウムを用いた場合、熱伝導が高いため、電圧印加時に有機ＥＬ素子１０より発生する熱を効果的に保護カバーに伝えることができるため、好ましい。更に酸化バリウム等の乾燥剤をこの空間内に設置することにより上記一連の製造工程で吸着した水分が有機ＥＬ素子１０にダメージを与えることを抑制しやすくなる。 Theorganic EL element 10 can be manufactured by the above process. After these series of steps, it is preferable to use the organic EL element 10 stably for a long period of time and to attach a protective layer and a protective cover (not shown) for protecting the organic EL element 10 from the outside. As the protective layer, polymer compounds, metal oxides, metal fluorides, metal borides, silicon compounds such as silicon nitride and silicon oxide, and the like can be used. And these laminated bodies can also be used. As the protective cover, a glass plate, a plastic plate whose surface is subjected to low water permeability treatment, a metal, or the like can be used. The protective cover is preferably bonded to the substrate 1 with a thermosetting resin, a photocurable resin, frit glass or the like and sealed. At this time, it is preferable to arrange a spacer between the substrate 1 and the protective cover because a predetermined space can be maintained and the organic EL element 10 can be prevented from being damaged.
If an inert gas such as nitrogen, argon or helium is sealed in this space, it becomes easy to prevent oxidation of theupper cathode 4. In particular, when helium is used, heat conduction is high, and thus heat generated from the organic EL element 10 when voltage is applied can be effectively transmitted to the protective cover, which is preferable. Furthermore, by installing a desiccant such as barium oxide in this space, it becomes easy to suppress the moisture adsorbed in the series of manufacturing steps from damaging the organic EL element 10.
そして、この空間に窒素、アルゴン、ヘリウムのような不活性なガスを封入すれば、上側の陰極４の酸化を防止しやすくなる。特にヘリウムを用いた場合、熱伝導が高いため、電圧印加時に有機ＥＬ素子１０より発生する熱を効果的に保護カバーに伝えることができるため、好ましい。更に酸化バリウム等の乾燥剤をこの空間内に設置することにより上記一連の製造工程で吸着した水分が有機ＥＬ素子１０にダメージを与えることを抑制しやすくなる。 The
If an inert gas such as nitrogen, argon or helium is sealed in this space, it becomes easy to prevent oxidation of the
以上の有機ＥＬ素子の製造方法では陽極側から作製する方法を説明したが、トップエミッション型の有機ＥＬ素子の場合等では、陰極側から作製してもよい。
In the above method for producing an organic EL element, the method for producing from the anode side has been described. However, in the case of a top emission type organic EL element, it may be produced from the cathode side.
図６で示した有機ＥＬ素子の製造方法においては例えば、基板１上に、フォトリソグラフィ技術を用いて、２種類の誘電体層を交互に公知の成膜技術で成膜することにより、回折レンズ１５を形成することができる。他の構成については、上述の製造方法と同様な手法により形成することができる。
In the method of manufacturing the organic EL element shown in FIG. 6, for example, a diffractive lens is formed by alternately forming two types of dielectric layers on a substrate 1 by a known film forming technique using a photolithography technique. 15 can be formed. About another structure, it can form by the method similar to the above-mentioned manufacturing method.
図７で示した有機ＥＬ素子の製造方法においては例えば、陰極側から作製して、基板の外表面上に、フォトリソグラフィ技術を用いて、２種類の誘電体層を交互に公知の成膜技術で成膜することにより、回折レンズ２５を形成することができる。他の構成については、上述の製造方法と同様な手法により形成することができる。
In the method of manufacturing the organic EL element shown in FIG. 7, for example, a known film forming technique is used in which two types of dielectric layers are alternately formed on the outer surface of the substrate by using a photolithography technique. The diffractive lens 25 can be formed by forming a film. About another structure, it can form by the method similar to the above-mentioned manufacturing method.
本発明の有機ＥＬ素子の実施例について以下に説明する。
Examples of the organic EL device of the present invention will be described below.
図１０及び図１１は、本発明の有機ＥＬ素子の効果を確認するために、例として図１で示したような陽極内に回折レンズを備える実施形態の場合について、有限差分時間領域（ＦＤＴＤ：Finite Difference Time Domain Method）法を用いて、全放射強度に対する基板中への光の放射強度を光取り出し効率としてコンピュータシミュレーション計算した結果を示す。ＦＤＴＤ法は、電磁界の時間変化を記述するＭａｘｗｅｌｌの方程式を空間的・時間的に差分化し、空間の各点における電磁界の時間変化を追跡する解析手法である。より具体的には、発光層における発光を微小ダイポールからの放射と捉えて、その放射(電磁界)の時間変化を追跡するという計算手法を採る。シミュレーション結果は、基板まで取り出された光に対する光取り出し効率を計算した結果を示すものである。
FIGS. 10 and 11 show a finite difference time domain (FDTD: FDTD) in the case of an embodiment including a diffractive lens in the anode as shown in FIG. 1 as an example in order to confirm the effect of the organic EL element of the present invention. The result of computer simulation calculation using the light intensity of light into the substrate with respect to the total radiation intensity as the light extraction efficiency using the Finite Difference Time Domain Method) method is shown. The FDTD method is an analysis method for tracking the time change of the electromagnetic field at each point in space by differentiating Maxwell's equation describing the time change of the electromagnetic field spatially and temporally. More specifically, a calculation method is adopted in which light emission in the light emitting layer is regarded as radiation from a minute dipole, and time variation of the radiation (electromagnetic field) is tracked. The simulation result shows the result of calculating the light extraction efficiency with respect to the light extracted up to the substrate.
ここで、回折レンズの輪帯部を幅が異なるものとするモデル構造とした場合、計算の負荷が大きくなる。そこで、計算の負荷を軽減しつつ本発明の効果の傾向を確認する目的で、シミュレーションで用いた回折レンズのモデルでは、輪帯部の幅が同じであって、輪帯部の密度が粗いもの、高いもの（多いもの）、それらの中間のものの３種類を用いた。輪帯部の幅が一定の場合でも、放射起点部４ａからレンズ周辺部に入射した光は輪帯部５ａによって回折・屈曲され中心線上に集光されるため、本発明の作用効果を奏する。
本実施形態ではボトムエミッション型の有機ＥＬ素子のシミュレーションを行っているが、トップエミッション型の有機ＥＬ素子の場合も光の取出す向きが異なるのみであり、本発明の作用効果を奏する。 Here, when a ring structure of the diffractive lens has a different structure, the calculation load increases. Therefore, for the purpose of confirming the trend of the effect of the present invention while reducing the calculation load, the model of the diffraction lens used in the simulation has the same width of the annular zone and the density of the annular zone is rough. Three types, high (many) and intermediate between them, were used. Even when the width of the annular zone is constant, the light incident on the lens peripheral portion from the radiationstarting point portion 4a is diffracted and bent by the annular zone 5a and collected on the center line, so that the operational effect of the present invention is achieved.
In this embodiment, a simulation of a bottom emission type organic EL element is performed, but the top emission type organic EL element also differs only in the direction of light extraction, and exhibits the effects of the present invention.
本実施形態ではボトムエミッション型の有機ＥＬ素子のシミュレーションを行っているが、トップエミッション型の有機ＥＬ素子の場合も光の取出す向きが異なるのみであり、本発明の作用効果を奏する。 Here, when a ring structure of the diffractive lens has a different structure, the calculation load increases. Therefore, for the purpose of confirming the trend of the effect of the present invention while reducing the calculation load, the model of the diffraction lens used in the simulation has the same width of the annular zone and the density of the annular zone is rough. Three types, high (many) and intermediate between them, were used. Even when the width of the annular zone is constant, the light incident on the lens peripheral portion from the radiation
In this embodiment, a simulation of a bottom emission type organic EL element is performed, but the top emission type organic EL element also differs only in the direction of light extraction, and exhibits the effects of the present invention.
図１０及び図１１はそれぞれ、垂直方向のダイポールからの放射光（主に、基板に対して平行方向に伝播する光（以下、ヨコ伝播光ということがある））の光取り出し効率と、水平方向のダイポールからの放射光（主に、基板に対して垂直方向に伝播する光（以下、タテ伝播光ということがある））の光取り出し効率の計算結果を示す。
10 and 11 respectively show the light extraction efficiency of light emitted from a dipole in the vertical direction (mainly light propagating in a direction parallel to the substrate (hereinafter sometimes referred to as horizontal propagation light)) and the horizontal direction. The calculation result of the light extraction efficiency of the light radiated from the dipole (mainly, the light propagating in the direction perpendicular to the substrate (hereinafter sometimes referred to as vertical propagation light)) is shown.
図１０及び図１１において、「陰極凹凸+回折レンズ（粗）」が示すのは、陰極の放射起点部と、回折レンズ（直径Ｌ（図２参照）が３．０８μｍ）とが上記の「同位相」である構成の場合である。このとき回折レンズは幅が４４０ｎｍの輪帯部を４本（本数は２ａ及び５ａの両方の本数を含めたものであり、中心部も１本の輪帯部として数えた。以下も同様である。）有する場合である。「陰極凹凸+回折レンズ（中間）」が示すのは、陰極の放射起点部と、回折レンズ（直径Ｌ（図２参照）が３．６３μｍ）とが上記の「同位相」である構成の場合である。このとき回折レンズは幅が３３０ｎｍの輪帯部を６本有する場合である。「陰極凹凸+回折レンズ（多）」が示すのは、陰極の放射起点部と、回折レンズ（直径Ｌ（図２参照）が３．３μｍ）とが上記の「同位相」である構成の場合である。このとき回折レンズは幅が２２０ｎｍの輪帯部を８本有する場合である。図１０及び図１１において「逆位相」が示すのは、陰極の放射起点部と、回折レンズ（直径Ｌ（図２参照）が３．０８μｍ）とが、上記「陰極凹凸+回折レンズ（粗）」の「逆位相」である構成の場合である。このとき回折レンズは幅が４４０ｎｍの輪帯部を４本有する場合である。
図１０及び図１１において「回折レンズのみ」が示すのは、「陰極凹凸+回折レンズ（粗）」と同じ構成の回折レンズを有するが、陰極が放射起点部を有さない構成の場合であって、比較例として載せたものである。また、「標準」が示すのは、放射起点部を有さない層状の陰極、有機層、陽極が順に積層され、回折レンズを有さない構成（ベタ構造）の場合であって、比較例として載せたものである。 10 and 11, “cathode concavity and convexity + diffraction lens (coarse)” indicates that the cathode radiation starting point portion and the diffraction lens (diameter L (see FIG. 2) is 3.08 μm) are the same as those described above. This is the case of the configuration of “phase”. At this time, the diffractive lens includes four ring zones having a width of 440 nm (the number includes both 2a and 5a, and the central portion is also counted as one ring zone. The same applies to the following. .) This is the case. The “cathode concavity and convexity + diffractive lens (intermediate)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.63 μm) are in the above-mentioned “in phase”. It is. In this case, the diffractive lens has six ring zones having a width of 330 nm. The “cathode concavity and convexity + diffraction lens (multiple)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.3 μm) are in the above “in phase” It is. In this case, the diffractive lens has eight ring zones with a width of 220 nm. In FIG. 10 and FIG. 11, “reverse phase” indicates that the emission starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.08 μm) are the above-mentioned “cathode unevenness + diffraction lens (coarse)”. This is a case of a configuration that is “opposite phase”. In this case, the diffractive lens has four ring zones having a width of 440 nm.
In FIG. 10 and FIG. 11, “diffractive lens only” indicates a case where a diffractive lens having the same configuration as “cathode unevenness + diffractive lens (rough)” is included, but the cathode does not have a radiation starting point portion. These are listed as comparative examples. In addition, “standard” indicates a case in which a layered cathode without an emission starting portion, an organic layer, and an anode are laminated in order and does not have a diffractive lens (solid structure). It is what I put.
図１０及び図１１において「回折レンズのみ」が示すのは、「陰極凹凸+回折レンズ（粗）」と同じ構成の回折レンズを有するが、陰極が放射起点部を有さない構成の場合であって、比較例として載せたものである。また、「標準」が示すのは、放射起点部を有さない層状の陰極、有機層、陽極が順に積層され、回折レンズを有さない構成（ベタ構造）の場合であって、比較例として載せたものである。 10 and 11, “cathode concavity and convexity + diffraction lens (coarse)” indicates that the cathode radiation starting point portion and the diffraction lens (diameter L (see FIG. 2) is 3.08 μm) are the same as those described above. This is the case of the configuration of “phase”. At this time, the diffractive lens includes four ring zones having a width of 440 nm (the number includes both 2a and 5a, and the central portion is also counted as one ring zone. The same applies to the following. .) This is the case. The “cathode concavity and convexity + diffractive lens (intermediate)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.63 μm) are in the above-mentioned “in phase”. It is. In this case, the diffractive lens has six ring zones having a width of 330 nm. The “cathode concavity and convexity + diffraction lens (multiple)” shows a case where the radiation starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.3 μm) are in the above “in phase” It is. In this case, the diffractive lens has eight ring zones with a width of 220 nm. In FIG. 10 and FIG. 11, “reverse phase” indicates that the emission starting point of the cathode and the diffraction lens (diameter L (see FIG. 2) is 3.08 μm) are the above-mentioned “cathode unevenness + diffraction lens (coarse)”. This is a case of a configuration that is “opposite phase”. In this case, the diffractive lens has four ring zones having a width of 440 nm.
In FIG. 10 and FIG. 11, “diffractive lens only” indicates a case where a diffractive lens having the same configuration as “cathode unevenness + diffractive lens (rough)” is included, but the cathode does not have a radiation starting point portion. These are listed as comparative examples. In addition, “standard” indicates a case in which a layered cathode without an emission starting portion, an organic layer, and an anode are laminated in order and does not have a diffractive lens (solid structure). It is what I put.
図１２は、シミュレーションで用いた実施形態の有機ＥＬ素子のモデル構造を示す断面図である。図１と同じ構造であり、符号の図示を省略する。
基板１はガラスからなるとして、屈折率としては１．５を用いた。陽極２はＩＴＯからなるとして、屈折率としては５５０ｎｍで１．８２+０．００９ｉとし、その他の波長はローレンツモデルで外挿した。回折レンズ５はＳＯＧからなるとして、屈折率としては１．２５を用いた。有機層３の屈折率としては１．７２を用いた。陰極４はアルミニウム（Ａｌ）からなるとして、屈折率としては５５０ｎｍで０．６４９＋４．３２ｉを用い、その他の波長はドルーデモデルで外挿した。以後、特に断りが無い場合、ガラス、有機層、アルミニウムの屈折率はそれぞれ上記の値を用いている。
陽極２（又は回折レンズ５）、有機層３の層状部３ａ、陰極４の層厚はそれぞれ、１５０ｎｍ、１５０ｎｍ、１５０ｎｍとした。回折レンズ５は隣同士の回折レンズ間に隙間がないように、平面視で六方細密状に配置した。
放射起点４ａは、すべての回折レンズ５に重なる位置に配置され、平面視で放射起点４ａの中心線上に回折レンズ５の中心が配置される構成である。凹部の深さは１００ｎｍ、直径は１００ｎｍとした。 FIG. 12 is a cross-sectional view showing a model structure of the organic EL element of the embodiment used in the simulation. The structure is the same as in FIG.
Thesubstrate 1 is made of glass, and a refractive index of 1.5 is used. The anode 2 is made of ITO, the refractive index is 1.82 + 0.009i at 550 nm, and other wavelengths are extrapolated by the Lorentz model. The diffractive lens 5 is made of SOG, and a refractive index of 1.25 is used. As the refractive index of the organic layer 3, 1.72 was used. The cathode 4 is made of aluminum (Al), the refractive index is 0.649 + 4.32i at 550 nm, and the other wavelengths are extrapolated by the Drude model. Thereafter, unless otherwise noted, the above values are used for the refractive indexes of glass, organic layer, and aluminum, respectively.
The layer thicknesses of the anode 2 (or the diffractive lens 5), thelayered portion 3a of the organic layer 3, and the cathode 4 were 150 nm, 150 nm, and 150 nm, respectively. The diffractive lenses 5 are arranged in a hexagonal fine shape in plan view so that there is no gap between adjacent diffractive lenses.
Theradiation starting point 4a is arranged at a position overlapping all the diffraction lenses 5, and the center of the diffraction lens 5 is arranged on the center line of the radiation starting point 4a in plan view. The depth of the recess was 100 nm and the diameter was 100 nm.
基板１はガラスからなるとして、屈折率としては１．５を用いた。陽極２はＩＴＯからなるとして、屈折率としては５５０ｎｍで１．８２+０．００９ｉとし、その他の波長はローレンツモデルで外挿した。回折レンズ５はＳＯＧからなるとして、屈折率としては１．２５を用いた。有機層３の屈折率としては１．７２を用いた。陰極４はアルミニウム（Ａｌ）からなるとして、屈折率としては５５０ｎｍで０．６４９＋４．３２ｉを用い、その他の波長はドルーデモデルで外挿した。以後、特に断りが無い場合、ガラス、有機層、アルミニウムの屈折率はそれぞれ上記の値を用いている。
陽極２（又は回折レンズ５）、有機層３の層状部３ａ、陰極４の層厚はそれぞれ、１５０ｎｍ、１５０ｎｍ、１５０ｎｍとした。回折レンズ５は隣同士の回折レンズ間に隙間がないように、平面視で六方細密状に配置した。
放射起点４ａは、すべての回折レンズ５に重なる位置に配置され、平面視で放射起点４ａの中心線上に回折レンズ５の中心が配置される構成である。凹部の深さは１００ｎｍ、直径は１００ｎｍとした。 FIG. 12 is a cross-sectional view showing a model structure of the organic EL element of the embodiment used in the simulation. The structure is the same as in FIG.
The
The layer thicknesses of the anode 2 (or the diffractive lens 5), the
The
図１０に示す通り、ヨコ伝播光については、「標準」構成では５４０ｎｍ以下の波長の光取り出し効率が非常に低下する。「回折レンズのみ」構成では全波長範囲で光取り出し効率が低い。
これに対して、本発明の実施例である、「陰極凹凸+回折レンズ（粗）」構成、「陰極凹凸+回折レンズ（中間）」構成、及び、「陰極凹凸+回折レンズ（多）」構成のいずれの構成も、全波長範囲において、「回折レンズのみ」構成の場合よりも光取り出し効率が高い。これらのいずれの実施例についても、５４０ｎｍ以下の波長の光取り出し効率が「標準」構成に比べて改善されている。
特に、「陰極凹凸+回折レンズ（多）」構成は、「回折レンズのみ」構成に比べて、全波長範囲で、光取り出し効率が＋１０数％～２倍以上の改善が見られた。「標準」構成に比べても５７０ｎｍ～６２０ｎｍの範囲では同程度であるが、他の波長範囲ではかなり優位である。特に４５０ｎｍ～５５０ｎｍでは＋３０％～１０倍程度の改善が見られ、７００ｎｍ～７５０ｎｍでは＋１０％以上の改善が見られた。
このように、「回折レンズ」構成と「陰極凹凸」構成とを組み合わせることによって、光取り出し効率が大幅に改善することがわかった。
回折レンズの輪帯部の粗密が粗くなるほど、すなわち、「陰極凹凸+回折レンズ（多）」構成、「陰極凹凸+回折レンズ（中間）」構成、「陰極凹凸+回折レンズ（粗）」構成の順に、改善の程度は低くなる。
「逆位相」構成は、４５０ｎｍ～６７０ｎｍの波長範囲で「回折レンズのみ」構成より光取り出し効率が改善され、５４０ｎｍ以下の波長範囲で「標準」構成より改善されている。
これらは、理論的には予測することが困難であり、シミュレーションを行って初めて知ることができたものである。 As shown in FIG. 10, with respect to the horizontal propagation light, the light extraction efficiency with a wavelength of 540 nm or less is greatly reduced in the “standard” configuration. The “diffractive lens only” configuration has low light extraction efficiency over the entire wavelength range.
In contrast, the “cathode unevenness + diffractive lens (rough)” configuration, the “cathode unevenness + diffraction lens (intermediate)” configuration, and the “cathode unevenness + diffraction lens (multiple)” configuration, which are embodiments of the present invention In any of the configurations, the light extraction efficiency is higher in the entire wavelength range than in the case of the “diffractive lens only” configuration. For any of these examples, the light extraction efficiency for wavelengths below 540 nm is improved compared to the “standard” configuration.
In particular, the “cathode concavity and convexity + diffraction lens (multiple)” configuration improved light extraction efficiency by +10 several percent to 2 times or more over the entire wavelength range as compared with the “diffractive lens only” configuration. Compared to the “standard” configuration, it is similar in the range of 570 nm to 620 nm, but is significantly superior in other wavelength ranges. In particular, an improvement of about + 30% to 10 times was observed at 450 nm to 550 nm, and an improvement of + 10% or more was observed at 700 nm to 750 nm.
Thus, it has been found that the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration.
The roughness of the annular zone of the diffractive lens increases, that is, the “cathode uneven + diffractive lens (multiple)” configuration, the “cathode uneven + diffractive lens (middle)” configuration, and the “cathode uneven + diffractive lens (rough)” configuration. In turn, the degree of improvement decreases.
The “reverse phase” configuration improves the light extraction efficiency over the “diffractive lens only” configuration in the wavelength range of 450 nm to 670 nm, and improves over the “standard” configuration in the wavelength range of 540 nm or less.
These are theoretically difficult to predict and can only be known after simulation.
これに対して、本発明の実施例である、「陰極凹凸+回折レンズ（粗）」構成、「陰極凹凸+回折レンズ（中間）」構成、及び、「陰極凹凸+回折レンズ（多）」構成のいずれの構成も、全波長範囲において、「回折レンズのみ」構成の場合よりも光取り出し効率が高い。これらのいずれの実施例についても、５４０ｎｍ以下の波長の光取り出し効率が「標準」構成に比べて改善されている。
特に、「陰極凹凸+回折レンズ（多）」構成は、「回折レンズのみ」構成に比べて、全波長範囲で、光取り出し効率が＋１０数％～２倍以上の改善が見られた。「標準」構成に比べても５７０ｎｍ～６２０ｎｍの範囲では同程度であるが、他の波長範囲ではかなり優位である。特に４５０ｎｍ～５５０ｎｍでは＋３０％～１０倍程度の改善が見られ、７００ｎｍ～７５０ｎｍでは＋１０％以上の改善が見られた。
このように、「回折レンズ」構成と「陰極凹凸」構成とを組み合わせることによって、光取り出し効率が大幅に改善することがわかった。
回折レンズの輪帯部の粗密が粗くなるほど、すなわち、「陰極凹凸+回折レンズ（多）」構成、「陰極凹凸+回折レンズ（中間）」構成、「陰極凹凸+回折レンズ（粗）」構成の順に、改善の程度は低くなる。
「逆位相」構成は、４５０ｎｍ～６７０ｎｍの波長範囲で「回折レンズのみ」構成より光取り出し効率が改善され、５４０ｎｍ以下の波長範囲で「標準」構成より改善されている。
これらは、理論的には予測することが困難であり、シミュレーションを行って初めて知ることができたものである。 As shown in FIG. 10, with respect to the horizontal propagation light, the light extraction efficiency with a wavelength of 540 nm or less is greatly reduced in the “standard” configuration. The “diffractive lens only” configuration has low light extraction efficiency over the entire wavelength range.
In contrast, the “cathode unevenness + diffractive lens (rough)” configuration, the “cathode unevenness + diffraction lens (intermediate)” configuration, and the “cathode unevenness + diffraction lens (multiple)” configuration, which are embodiments of the present invention In any of the configurations, the light extraction efficiency is higher in the entire wavelength range than in the case of the “diffractive lens only” configuration. For any of these examples, the light extraction efficiency for wavelengths below 540 nm is improved compared to the “standard” configuration.
In particular, the “cathode concavity and convexity + diffraction lens (multiple)” configuration improved light extraction efficiency by +10 several percent to 2 times or more over the entire wavelength range as compared with the “diffractive lens only” configuration. Compared to the “standard” configuration, it is similar in the range of 570 nm to 620 nm, but is significantly superior in other wavelength ranges. In particular, an improvement of about + 30% to 10 times was observed at 450 nm to 550 nm, and an improvement of + 10% or more was observed at 700 nm to 750 nm.
Thus, it has been found that the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration.
The roughness of the annular zone of the diffractive lens increases, that is, the “cathode uneven + diffractive lens (multiple)” configuration, the “cathode uneven + diffractive lens (middle)” configuration, and the “cathode uneven + diffractive lens (rough)” configuration. In turn, the degree of improvement decreases.
The “reverse phase” configuration improves the light extraction efficiency over the “diffractive lens only” configuration in the wavelength range of 450 nm to 670 nm, and improves over the “standard” configuration in the wavelength range of 540 nm or less.
These are theoretically difficult to predict and can only be known after simulation.
図１１に示す通り、タテ伝播光について、「陰極凹凸+回折レンズ（多）」構成は「回折レンズのみ」構成に比べて、全波長範囲で、光取り出し効率が＋１０％以上の改善が見られた。「標準」構成に比べて５００ｎｍ～６８０ｎｍの波長範囲で改善が見られた。「回折レンズのみ」構成では全波長範囲で「標準」構成よりも光取り出し効率が低かった。
このように、「回折レンズ」構成と「陰極凹凸」構成とを組み合わせることによって、光取り出し効率が大幅に改善することがわかった。
この効果は、理論的には予測することが困難であり、シミュレーションを行って初めて知ることができたものである。 As shown in FIG. 11, with regard to the vertically propagating light, the “cathode unevenness + diffractive lens (multiple)” configuration shows an improvement in light extraction efficiency of + 10% or more in the entire wavelength range as compared with the “diffractive lens only” configuration. It was. Improvements were seen in the wavelength range of 500 nm to 680 nm compared to the “standard” configuration. The “diffractive lens only” configuration had lower light extraction efficiency over the entire wavelength range than the “standard” configuration.
Thus, it has been found that the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration.
This effect is theoretically difficult to predict and can only be known after simulation.
このように、「回折レンズ」構成と「陰極凹凸」構成とを組み合わせることによって、光取り出し効率が大幅に改善することがわかった。
この効果は、理論的には予測することが困難であり、シミュレーションを行って初めて知ることができたものである。 As shown in FIG. 11, with regard to the vertically propagating light, the “cathode unevenness + diffractive lens (multiple)” configuration shows an improvement in light extraction efficiency of + 10% or more in the entire wavelength range as compared with the “diffractive lens only” configuration. It was. Improvements were seen in the wavelength range of 500 nm to 680 nm compared to the “standard” configuration. The “diffractive lens only” configuration had lower light extraction efficiency over the entire wavelength range than the “standard” configuration.
Thus, it has been found that the light extraction efficiency is greatly improved by combining the “diffractive lens” configuration and the “cathode unevenness” configuration.
This effect is theoretically difficult to predict and can only be known after simulation.
１ 基板 １Ａ 外表面 ２ 陽極 ３ 有機層 ４ 陰極 ４ａ 放射起点部 ５、１５、２５ 回折レンズ １０ 有機ＥＬ素子 １００ 画像表示装置 ２００ 照明装置
1 Substrate 1A Outer surface 2 Anode 3 Organic layer 4 Cathode 4a Radiation origin 5, 15, 25 Diffraction lens 10 Organic EL element 100 Image display device 200 Lighting device
Claims (8)
- 光透過電極と、有機ＥＬ材料からなる発光層を含む有機層と、反射電極とを順に具備し、
前記反射電極は、その有機層側の表面に周期的に配置される複数の放射起点部を有するものであり、
前記有機層の反射電極とは反対側に複数の回折レンズを備えてなり、
前記放射起点部は、平面視して前記回折レンズに重なる位置に配置されることを特徴とする有機ＥＬ素子。 A light transmissive electrode, an organic layer including a light emitting layer made of an organic EL material, and a reflective electrode are sequentially provided.
The reflective electrode has a plurality of radiation starting points arranged periodically on the surface of the organic layer side,
A plurality of diffractive lenses on the opposite side of the organic layer from the reflective electrode;
The organic EL element, wherein the radiation starting point portion is disposed at a position overlapping the diffraction lens in plan view. - 前記光透過電極の前記有機層とは反対側に基板を有し、
前記基板側から外部に光を取り出すように構成されており、
前記光透過電極が陽極であり、前記反射電極が陰極であり、
前記複数の回折レンズを前記基板の外表面から前記有機層との間に備えることを特徴とする請求項１に記載の有機ＥＬ素子。 Having a substrate on the opposite side of the light transmissive electrode from the organic layer;
It is configured to extract light from the substrate side to the outside,
The light transmitting electrode is an anode, and the reflective electrode is a cathode;
The organic EL element according to claim 1, wherein the plurality of diffractive lenses are provided between an outer surface of the substrate and the organic layer. - 前記回折レンズが前記光透過電極内に配置されることを特徴とする請求項１または２のいずれかに記載の有機ＥＬ素子。 The organic EL element according to claim 1, wherein the diffractive lens is disposed in the light transmission electrode.
- 前記回折レンズは、同心円状の誘電体からなる輪帯部を複数有してなることを特徴とする請求項１からのいずれか一項に記載の有機ＥＬ素子。 2. The organic EL element according to claim 1, wherein the diffractive lens has a plurality of annular zones made of concentric dielectrics.
- 前記回折レンズは、その中心が平面視して前記放射起点部の中心線上に配置されるように設けられていることを特徴とする請求項１～４のいずれか一項に記載の有機ＥＬ素子。 The organic EL element according to any one of claims 1 to 4, wherein the diffractive lens is provided so that a center thereof is disposed on a center line of the radiation starting point portion in plan view. .
- 前記放射起点部は、前記反射電極の前記有機層側の表面に形成された凹部であることを特徴とする請求項１～５のいずれか一項に記載の有機ＥＬ素子。 6. The organic EL element according to claim 1, wherein the radiation starting point is a recess formed on a surface of the reflective electrode on the organic layer side.
- 請求項１～６のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする画像表示装置。 An image display device comprising the organic EL element according to any one of claims 1 to 6.
- 請求項１～６のいずれか一項に記載の有機ＥＬ素子を備えたことを特徴とする照明装置。 An illumination device comprising the organic EL element according to any one of claims 1 to 6.
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