WO2014069573A1 - Élément el organique et dispositif d'affichage d'image et dispositif d'éclairage le comportant - Google Patents

Élément el organique et dispositif d'affichage d'image et dispositif d'éclairage le comportant Download PDF

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WO2014069573A1
WO2014069573A1 PCT/JP2013/079560 JP2013079560W WO2014069573A1 WO 2014069573 A1 WO2014069573 A1 WO 2014069573A1 JP 2013079560 W JP2013079560 W JP 2013079560W WO 2014069573 A1 WO2014069573 A1 WO 2014069573A1
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layer
organic
electrode
refractive index
light
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PCT/JP2013/079560
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Japanese (ja)
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祐介 山▲崎▼
祥貴 下平
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昭和電工株式会社
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    • 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
    • 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
    • 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

Definitions

  • 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. 2012-241334 filed in Japan on October 31, 2012 and Japanese Patent Application No. 2013-137529 filed in Japan on June 28, 2013. The contents are incorporated herein.
  • An organic EL (electroluminescence) element has features such as a wide viewing angle, high-speed response, and clear self-luminous display. It is expected as a pillar for next-generation lighting devices and image display devices because of its thin and light weight and low power consumption.
  • 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 having a transparent electrode, an organic layer including a light emitting layer, and a metal electrode in this order on a transparent substrate.
  • the light perpendicularly incident on the transparent substrate is transmitted through the transparent substrate and taken out of the element.
  • a small incident angle that is less than the critical angle at the interface between a transparent substrate (for example, glass (typical refractive index: 1.52)) and air (refractive index: 1.0).
  • Light incident at (the angle formed by the normal of the light beam and the incident surface) is 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.
  • a transparent electrode for example, indium tin oxide alloy (ITO (typical refractive index: 1.82)
  • a transparent substrate for example, glass (typical) made of a transparent conductive oxide.
  • the light incident on the interface with a refractive index of 1.52)) having an incident angle larger than the critical angle is totally reflected at the interface and is not taken out of the device, but can be finally absorbed by the material.
  • this light is called waveguide mode light, and the loss due to this is called waveguide loss.
  • light emitted from the light-emitting layer is incident on the metal cathode and combined with free electrons of the metal electrode, and light captured on the surface of the metal cathode as surface plasmon polariton (SPP) is also external to the device. And can be finally absorbed by the material.
  • SPP mode light the resulting loss is referred to as plasmon 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. Reducing these losses and improving the light extraction efficiency has become a major issue.
  • 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 lower refractive index than the organic light emitting layer and the transparent electrode in the organic light emitting layer and the transparent electrode. It is disclosed.
  • Patent Documents 4 and 5 disclose a configuration in which a cavity is provided in a transparent electrode 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. With this effect, the ratio of light that causes total reflection can be reduced by changing the incident angle of the guided mode light to a small angle.
  • Patent Documents 6 to 9 As a method for extracting SPP mode light trapped on the surface of the metal cathode, a configuration in which a periodic uneven structure is formed on the surface of the cathode is known (Patent Documents 6 to 9).
  • the present invention has been made in view of the above circumstances, and provides 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.
  • the purpose is to do.
  • the present inventors first assume a two-step light extraction mechanism in which SPP mode light is extracted as propagating light into an organic layer, and then the propagating light is extracted outside the device without being converted into guided mode light.
  • SPP mode light is extracted as propagating light into an organic layer
  • the propagating light is extracted outside the device without being converted into guided mode light.
  • the organic EL device of the present invention has a structure in which an organic layer including a light emitting layer is sandwiched between a first electrode and a second electrode.
  • the two-step light extraction mechanism described above generates the SPP mode light
  • the second electrode side structure of the Otto type arrangement Non-Patent Document 1 that extracts the generated SPP mode light as propagating light into the organic layer.
  • the first electrode side structure that takes out the propagating light to the outside without using the guided mode light.
  • the inventors of the present invention by simulation, have a second pole-side structure with an Otto-type arrangement and an interface that is perpendicular or nearly perpendicular to the substrate that refracts or directs the propagating light extracted into the organic layer to the substrate side.
  • the inventors have found that the second electrode structure and the first electrode side structure have a remarkable effect that cannot be predicted from the effect of improving the light extraction efficiency of the single electrode side structure. I let you.
  • An organic EL device comprising, on a substrate, an anode, an organic layer including a light emitting layer made of an organic EL material, and a cathode in order, and taking out light from the anode side to the outside.
  • the cathode further comprises a low refractive index layer and a metal layer on the opposite side of the organic layer in order, and the anode has an inner surface formed by a dielectric layer having a refractive index lower than the refractive index of the anode.
  • the organic layer has a layered portion disposed between the anode and the dielectric layer and the cathode, and the cathode is a light-transmitting conductive material.
  • An organic EL element wherein the refractive index of the low refractive index layer is lower than the refractive index of the organic layer.
  • An organic EL device comprising a first electrode, an organic layer including a light emitting layer, and a second electrode in this order, and a thickness of the second electrode on the surface opposite to the organic layer.
  • An organic EL element characterized in that the refractive index is lower than the refractive index of the organic layer.
  • An organic EL element comprising a first electrode, an organic layer including a light emitting layer, and a second electrode in this order, and further, a thickness of the second electrode on the surface opposite to the organic layer.
  • a low refractive index layer having a thickness of 20 nm to 300 nm and a metal layer in order, and the first electrode has a plurality of first electrode protrusions connected to each other by a first electrode layered portion;
  • An organic E comprising a conductive material, wherein the refractive index of the low refractive index layer is lower than the refractive index of the organic layer.
  • Organic EL element. (6) The organic EL element according to any one of (1) to (5), wherein a refractive index of the low refractive index layer is further lower than a refractive index of the second electrode.
  • the organic EL element according to (6) wherein a refractive index of the second electrode is lower than a refractive index of the organic layer.
  • the low refractive index layer is made of a material having a refractive index smaller by 0.2 or more than at least one of the second electrode and the organic layer.
  • the first electrode hole portion or the first electrode convex portion is periodically arranged in at least one direction within the substrate surface, and the metal layer (dielectric constant ⁇ 1 ) and the low refractive index layer (dielectric)
  • the real part of the rate ⁇ 2 ) and the period (p) in the one direction of the first electrode hole part or the first electrode convex part are as follows for a certain integer N (1 ⁇ N ⁇ 3):
  • ⁇ is the maximum peak wavelength of the photoluminescence spectrum of the light emitting layer.
  • the organic EL device according to (10), wherein the period is 500 nm to 4000 nm.
  • An image display device comprising the organic EL element according to any one of (1) to (11).
  • a lighting device comprising the organic EL element according to any one of (1) to (11).
  • 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.
  • (A) is a perspective view for demonstrating an example of the organic EL element which concerns on 1st embodiment of this invention
  • (b) demonstrates an example of the organic EL element which concerns on 2nd embodiment of this invention. It is a perspective view for doing.
  • the portion of the Otto structure is illustrated separately.
  • It is a cross-sectional schematic diagram for demonstrating an example of the organic EL element which concerns on 3rd Embodiment of this invention.
  • FIG. 5 shows the simulation results of the intensity distribution of the magnetic field of the emitted light from the dipole in the vertical direction for the organic EL element of the first embodiment of the present invention by the FDTD method.
  • Each of (a) to (f) has a pitch of 200 nm. 300 nm, 500 nm, 900 nm, 2000 nm, and 4000 nm.
  • the organic EL element of the first embodiment of the present invention shows the simulation result by the FDTD method of the intensity distribution of the electric field of the radiated light from the horizontal dipole, and (a) to (f) each have a pitch of 200 nm. 300 nm, 500 nm, 900 nm, 2000 nm, and 4000 nm.
  • FIG. 3 is a schematic sectional view of a structure.
  • the organic EL element of this invention may be provided with the layer which is not described below in the range which does not impair the effect of this invention.
  • An organic EL element 10 shown in FIGS. 1A and 1B includes an anode 2 that is an example of a first electrode, an organic layer 3 that includes a light-emitting layer made of an organic EL material, and a cathode that is an example of a second electrode. 4 are arranged in order, and light is extracted from the anode 2 side to the outside. Further, the organic EL element 10 includes a low refractive index layer 5 and a metal layer 6 in this order on the opposite side of the cathode 4 from the organic layer 3.
  • the anode 2 includes a plurality of anode holes 2A.
  • the inner side surface 2a of the anode hole 2A is covered with a dielectric layer 7 which is an example of the inner surface covering part of the anode hole.
  • the dielectric layer 7 is configured to be scattered in an island shape in the layer of the anode 2.
  • the dielectric layer 7 is made of a material having a refractive index different from that of the anode 2.
  • the organic layer 3 has a layered portion (organic layered portion) disposed between the anode 2 and the dielectric layer 7 and the cathode 4.
  • the cathode 4 is made of a transparent conductive material (translucent conductive material).
  • the refractive index of the low refractive index layer 5 is lower than the refractive index of the organic layer 3.
  • the dielectric layer 7 may have a structure covering a part of the surface of the anode 2 on the organic layer side in addition to the inner surface 2a of the anode hole 2A.
  • the anode hole portion 2A is not limited to a hole that penetrates the anode 2, and the anode hole portion 2A may be a hole that does not penetrate the anode 2.
  • FIGS. 1A and 1B are examples of a bottom emission structure in which the substrate 1 is disposed on the anode 2 side.
  • FIG. 1A shows an organic EL element in which the dielectric layer is made of a material having a refractive index higher than that of the anode.
  • the top emission structure is a case where the substrate 1 is disposed on the metal layer 6 side.
  • the organic EL device of the present invention may employ either a bottom emission structure or a top emission structure.
  • a bottom emission structure in which the substrate 1 is present on the anode 2 side will be described as an example.
  • the refractive index of the organic layer refers to the average refractive index of all the layers including the light emitting layer made of the organic EL material.
  • the shape of anode hole portion 2A has the effect of refracting light toward the substrate side on the inner side surface.
  • the dielectric layer is made of a material having a refractive index higher than that of the anode, it is preferable that the top surface area on the cathode 4 side is smaller than the bottom area on the substrate 1 side from the viewpoint of refracting the guided mode light more vertically. In the example shown in FIG.
  • the inner side surface is arranged to be perpendicular to the substrate surface, but the invention is not limited to this configuration.
  • the angle of the inner side surface 2a of the anode hole 2A with respect to the substrate surface is preferably 45 to 90 °, more preferably 60 to 90 °, and even more preferably 75 to 90 °.
  • the dielectric layer is made of a material having a refractive index lower than that of the anode
  • a shape in which the top surface area on the cathode 4 side is larger than the bottom area on the substrate 1 side is preferable from the viewpoint of refracting the guided mode light more vertically.
  • the angle of the inner side surface 2a of the anode hole portion 2A with respect to the substrate surface is preferably 90 ° to 135 °, more preferably 90 ° to 120 °, and still more preferably 90 ° to 105 °.
  • the propagating light re-radiated from the light emitting position toward the anode side and the propagating light from the SPP mode light is incident on the inner side 2a of the anode hole from the outside. Incident light is refracted to the substrate side and is easily taken out from the outer surface of the substrate.
  • the shape of the anode hole portion 2A is not particularly limited as long as it exhibits the effect of diffraction or the effect of the photonic crystal. Not.
  • the inner side surface 2a of the anode hole portion 2A is nearly perpendicular to the substrate surface. This is because the refractive index modulation becomes steep in the in-plane direction of the substrate across the inner side surface 2a of the anode hole 2A due to the inner surface 2a of the anode hole 2A being perpendicular to the substrate surface.
  • the photonic crystal has a wider band gap frequency range in which light cannot propagate in the in-plane direction of the substrate, and can be extracted from the organic layer 3 to the outside more efficiently.
  • the refractive index is sharply modulated even in the diffraction grating, the diffraction efficiency of light toward the substrate is improved, and similarly, the light extraction to the outside of the element is improved.
  • the bottom emission structure has been described above as an example, the same applies to the top emission structure.
  • the refractive index of the low refractive index layer is lower than the refractive index of the organic layer.
  • n L , n C , and n O refractive indexes of the low refractive index layer, the cathode, and the organic layer
  • B pattern n L ⁇ n O ⁇ n C
  • n L ⁇ There are three cases: n C ⁇ n O (hereinafter referred to as “C pattern”) and n C ⁇ n L ⁇ n O (hereinafter referred to as “D pattern”).
  • C pattern n C ⁇ n O
  • D pattern n C ⁇ n L ⁇ n O
  • the configuration of the metal layer / low refractive index layer / cathode is Otto arrangement.
  • the configuration of metal layer / low refractive index layer / cathode is Otto arrangement, and the configuration of metal layer / low refractive index layer + cathode / organic layer is also Otto arrangement.
  • the configuration of the metal layer / low refractive index layer + cathode / organic layer is an Otto type arrangement.
  • the most preferable B to D pattern is the C pattern.
  • the configuration of the metal layer / low refractive index layer / cathode (transparent conductive layer) is Otto arrangement, and the configuration of metal layer / low refractive index layer + cathode (transparent conductive layer) / organic layer.
  • the Otto arrangement re-radiation of SPP mode light is most likely to occur from the metal layer.
  • the refractive index increases in the order of the low refractive index layer, the cathode (transparent conductive layer), and the organic layer, total reflection does not occur at each interface, and the re-radiated SPP mode light is extracted as it is to the substrate side.
  • the low refractive index layer may be air or SOG (spin on glass), and the cathode (transparent conductive layer) may be a transparent conductive material layer such as ITO.
  • the configuration of metal layer / low refractive index layer / cathode (transparent conductive layer) is Otto arrangement. Therefore, re-radiation of SPP mode light occurs from the metal layer.
  • the refractive index of the organic layer is an intermediate value between the low refractive index layer and the cathode (transparent conductive layer)
  • some of the re-emitted SPP mode light is at the cathode (transparent conductive layer) / organic layer interface. And the remaining light is transmitted through the organic layer.
  • the configuration of the metal layer / low refractive index layer / cathode (transparent conductive layer) is not an Otto type arrangement.
  • the configuration of the metal layer / low refractive index layer + cathode (transparent conductive layer) / organic layer is an Otto type arrangement, re-emission of SPP mode light occurs from the metal layer. Therefore, the re-emission of SPP mode light is less than in the case of the B pattern.
  • a cathode for example, ITO
  • an organic layer are selected so as to satisfy n C ⁇ n O depending on the magnitude of the refractive index, and the refractive index n L is n C and n O as a low refractive index layer.
  • SOG satisfying the refractive index of the B pattern may be employed.
  • n O ⁇ n C ⁇ n L (hereinafter referred to as “E pattern”) and in the case of n C ⁇ n O ⁇ n L (hereinafter also referred to as “F pattern”), the Otto type arrangement is not achieved.
  • the metal layer / low refractive index layer / cathode is in an Otto type arrangement. Therefore, re-emission of SPP mode light occurs from the metal layer, but since the refractive index of the organic layer is lower than that of the low refractive index layer, most of the re-emitted SPP mode light is of the cathode (transparent conductive layer) / organic layer. It is totally reflected at the interface, and it is difficult to extract to the waveguide mode on the anode side.
  • the substrate When applied to the bottom emission type, the substrate is a light-transmitting substrate, and is usually preferably 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. It does not have 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. Further, the transmittance is more preferably 70% or more.
  • a glass plate, a polymer plate, etc. are mentioned. Examples of the glass plate 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, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
  • 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.
  • an opaque one can also be used.
  • a substrate made of a material such as the above or a material such as stainless steel, or a substrate normally used in other top emission type organic EL elements can be used.
  • the thickness of the substrate 1 is not particularly limited depending on the required mechanical strength, but is preferably 0.01 mm to 10 mm, more preferably 0.05 mm to 2 mm.
  • 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. 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 (High Occupied Molecular Orbital) level does not become excessive.
  • the material of the anode 2 is not particularly limited as long as it is a translucent and conductive material.
  • the anode 2 can be formed on the substrate 1 by, for example, a sputtering method, a vacuum deposition method, a coating method, a CVD method, an ion plating method, or the like.
  • the thickness of the anode 2 is not particularly limited. For example, it is 10 to 2000 nm, preferably 50 to 1000 nm. If the thickness is less than 10 nm, the sheet resistance of the anode 2 increases. If the thickness is more than 2000 nm, the flatness of the organic layer 3 cannot be maintained, and the transmittance of the anode 2 decreases.
  • the dielectric layer 7 covers the inner side surface 2 a of the anode hole 2 A of the anode 2 and is made of a material having a refractive index different from that of the anode 2.
  • the reason why the dielectric layer 7 is made of such a structure and material is to improve the light extraction efficiency.
  • Light incident on the inner side surface 2a of the anode hole 2A (the interface between the anode 2 and the dielectric layer 7 extending in a direction perpendicular or nearly perpendicular to the substrate surface of the substrate 1) is incident on the substrate 1 side at this interface. Refract.
  • the incident angle of the waveguide mode light By changing the incident angle of the waveguide mode light to a small angle, the proportion of light that causes total reflection is reduced, and the light extraction efficiency is improved (see FIGS. 1A and 1B).
  • the material of the dielectric layer 7 is not particularly limited as long as it is a light-transmitting material having a refractive index different from that of the anode.
  • the material of the anode 2 is an indium tin oxide alloy (ITO (refractive index 1.82)), for example, as a low refractive index material, spin-on-glass (SOG (an example of refractive index: 1.25)), fluorine Metal fluorides such as magnesium fluoride (MgF 2 (typical refractive index: 1.38)), organic fluorine compounds such as polytetrafluoroethylene (PTFE (typical refractive index: 1.35)), silicon dioxide ( Examples include SiO 2 (typical refractive index: 1.45)), various low-melting glasses, and porous materials.
  • ITO indium tin oxide alloy
  • SOG an example of refractive index: 1.25
  • fluorine Metal fluorides such as magnesium fluoride (MgF 2 (typical refractive index: 1.38)
  • silicon compounds such as silicon nitride (Si 3 N 4 ) (typical refractive index: 2.0), titanium oxide (TiO 2 ) (typical refractive index: 2 .5) and other metal oxides, aluminum nitride (AlN) (typical refractive index: 2.2) and other metal nitrides, and depending on the refractive index of the material of the anode 2, aluminum oxynitride Polymer compounds such as (AlON) (typical refractive index: 1.8), metal oxynitrides such as silicon oxynitride, and polyethylene naphthalate (typical refractive index: 1.8) And SOG (having a refractive index of 1.8 or more).
  • the thickness of the dielectric layer 7 is not particularly limited. For example, it is 10 to 2000 nm, preferably 50 to 1000 nm. When the thickness is less than 10 nm, the volume of the dielectric layer 7 with respect to the anode is reduced, and the guided mode light is hardly refracted or diffracted. On the other hand, if it is thicker than 2000 nm, it becomes difficult to maintain the flatness of the organic layer 3.
  • the dielectric layer 7 may be an insulator or may have conductivity.
  • the dielectric layer 7 is a conductor
  • a conductive path such as anode 2 / dielectric layer 7 / organic layer 3 / cathode 4 is generated in addition to the conductive path of anode 2 / organic layer 7 / cathode 4.
  • the in-plane luminance distribution in the organic layer 3 becomes uniform, and the luminance of the element can be improved.
  • the dielectric layer 7 is an insulator
  • a conductive path that passes through the dielectric 7 does not occur. Therefore, the brightness of the shortest straight line connecting the dielectric 7 and the cathode 4 is lowered.
  • the in-plane luminance of the organic layer 3 can be made uniform by laying a conductive buffer layer on the dielectric layer 7.
  • various surface treatments for the purpose of improving the film quality can be performed on the anode 2 and the anode-side surfaces of the dielectric layer 7.
  • the dielectric layer 7 is an insulator, by forming a conductive film as the surface treatment, the in-plane luminance in the organic layer can be made uniform and the luminance can be improved as described above. .
  • the cathode 4 is an electrode for injecting electrons into the light emitting layer, and it is preferable to use a material made of a metal, an alloy, a conductive compound, or a mixture thereof having a small work function. It is preferable to use a material having a work function of 1.9 eV or more and 5 eV or less so that the difference from the LUMO (Lowest Unoccupied Molecular Orbital) level of the organic layer 3 in contact with the anode 2 does not become excessive.
  • LUMO Local Unoccupied Molecular Orbital
  • the thickness of the cathode 4 is not particularly limited, but is, for example, 30 nm to 1 ⁇ m, preferably 50 to 500 nm. When the thickness is less than 30 nm, the sheet resistance increases and the drive voltage increases. When the thickness is greater than 1 ⁇ m, heat, radiation damage, and mechanical damage due to film stress during film formation accumulate in the electrode and the organic layer.
  • the organic layer 3 is disposed between the anode 2 and the dielectric layer 7 and the cathode 4.
  • the organic layer 3 shown in FIGS. 1A and 1B has a configuration composed of only an organic layer layered portion, but at least a part of the organic layer 3 only needs to be composed of a layered portion, and is composed of only the layered portion. It is not limited to the case.
  • 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, and its ionization energy is usually as small as 5.5 eV or less.
  • a material which transports holes to the light emitting layer with lower electric field strength is preferable.
  • 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 hole transport layer is a layer that transports holes to the light emitting region and has a high hole mobility.
  • the material to be formed as such a hole 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 electron injection layer is a layer that assists injection of electrons 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 particularly limited, but is, for example, 50 to 2000 nm, and preferably 100 to 1000 nm. If the thickness is less than 50 nm, quenching other than SPP coupling due to metal such as a decrease in internal quantum efficiency due to punch-through current and lossy surface coupling occurs, and if it is thicker than 1000 nm, the driving voltage increases.
  • the low refractive index layer 5 is provided on the opposite side of the cathode 4 from the organic layer 3, and is preferably made of a material having a refractive index lower than that of the translucent conductive material constituting the cathode 4.
  • the material for the low refractive index layer 5 is not particularly limited as long as it is a material having a lower refractive index than the translucent conductive material constituting the cathode 4.
  • SOG satisfying this refractive index condition, metal fluoride such as magnesium fluoride (MgF 2 (typical refractive index: 1.38)), polytetrafluoroethylene (PTFE (typical refractive index: 1.35), etc. )) And the like, silicon dioxide (SiO 2 (typical refractive index: 1.45)), various low-melting-point glasses, porous materials, and the like.
  • the low refractive index layer 15 may be a layer including an air layer.
  • the low refractive index layer is preferably made of a material that is 0.2 or more smaller than at least one of the second electrode and the organic layer. This is because the second electrode or the organic layer corresponds to an Otto type high refractive index layer, and if the refractive index difference between the low refractive index layer and the high refractive index layer is 0.2 or more in the Otto type arrangement, the SPP Since the in-plane component of the wave number of the mode light becomes small, the dispersion curve of the propagation light in the high refractive index layer and the SPP mode light crosses, and the extraction efficiency of the SPP mode light into the high refractive index layer by the Otto type arrangement Because it goes up.
  • the thickness of the low refractive index layer 5 is preferably 20 nm or more and 300 nm or less. When the thickness is 20 nm or less, the film thickness of the low refractive index layer 5 is too thin, so that the metal layer and the high refractive index layer come close to each other and the in-plane wave number component of the SPP mode light becomes large. When the in-plane wavenumber component increases, the dispersion curve does not intersect with the dispersion curve of propagating light in the high refractive index layer, and SPP mode light becomes difficult to be extracted into the high refractive index layer.
  • the thickness is 300 nm or more, the film thickness of the low refractive index layer 15 is too thick, so that the evanescent wave does not reach the metal layer 16 and the SPP mode light is hardly extracted into the high refractive index layer. More preferably, it is 200 nm or less.
  • the metal layer 6 is provided on the opposite side of the cathode 4 from the organic layer 3 via a low refractive index layer 5.
  • any material or plasmon resonance can be used as long as plasmon resonance is generated by the light emitted from the light emitting layer.
  • a material in which the real part of the complex dielectric constant is negative and the absolute value of the real part has a large value is preferable. Examples of such materials include simple substances such as gold, silver, copper, zinc, aluminum, and magnesium, alloys of gold and silver, alloys of silver and copper, and alloys such as brass.
  • the metal layer 6 may have a laminated structure of two or more layers. The thickness of the metal layer 6 is not particularly limited.
  • the thickness is 20 to 2000 nm, preferably 50 to 500 nm.
  • the thickness is less than 20 nm, the reflectance is lowered and the front luminance is lowered.
  • the thickness is more than 500 nm, heat, radiation damage, and mechanical damage due to film stress during film formation accumulate in the electrode and the organic layer.
  • positioning of the organic EL element of this invention is demonstrated.
  • the following is a principle explanation based on the calculation formula, and therefore, the first electrode and the second electrode are not associated with either the anode or the cathode, respectively, and are described as the first electrode and the second electrode.
  • SPP surface plasmon polariton
  • ⁇ is an incident angle of incident light from the high refractive index dielectric layer to the low refractive index dielectric layer. Therefore, by changing the incident angle ⁇ , the dispersion curve of the SPP and the evanescent wave due to total reflection (hereinafter, simply referred to as “evanescent wave”, all of which are caused by total reflection) are linearly distributed.
  • incident angle ⁇ is the radiation angle of the SPP when viewed from the metal layer side.
  • the dispersion curve of the SPP and the dispersion line of the evanescent wave intersect each other. This means that only the SPP radiated at a predetermined angle is in a state where energy can be exchanged when the SPP and the evanescent wave resonate. And it becomes possible to take out SPP as propagation light via an evanescent wave.
  • a predetermined incident angle SPP dispersion curve and Light incident on the interface between the high refractive index layer and the low refractive index layer from the high refractive index layer at an angle having an intersection with the dispersion line of the evanescent wave generates an evanescent wave.
  • the evanescent wave excites SPP mode light on the metal surface.
  • the SPP mode light excited on the metal surface can be extracted into the organic layer as propagating light radiated at a predetermined angle via the evanescent wave generated in the Otto arrangement structure.
  • the organic EL element by introducing the Otto arrangement structure, it is possible to extract SPP mode light generated on the surface of the metal layer as propagating light propagating through the organic layer at a predetermined angle.
  • the excitation / extraction of the SPP mode light via the evanescent wave occurs when the thin film satisfies the formula (1). This is because if the low refractive index layer is too thick, the evanescent wave from the organic layer does not reach the metal layer, and the evanescent wave and the SPP mode light cannot exchange energy.
  • the light extracted from the SPP is emitted at a predetermined angle corresponding to the intersection of the SPP dispersion curve and the evanescent wave dispersion line.
  • the effect of the first electrode side structure of the organic EL element of the present invention will be described below.
  • the light propagating in the organic layer is refracted or diffracted toward the substrate side so that the incident angle to the interface between the first electrode and the substrate or the substrate and the outside (for example, air) becomes small.
  • An interface having a refractive index perpendicular to or nearly perpendicular to the substrate surface was introduced. More specifically, by providing a hole in the first electrode and covering the inner surface of the hole with a dielectric layer made of a material having a refractive index different from that of the first electrode, the first electrode is perpendicular to the substrate surface.
  • an interface between the first electrode and the dielectric layer is introduced as an interface having a refractive index close to perpendicular.
  • the first electrode can be used as an interface having a refractive index that is perpendicular or nearly perpendicular to the substrate surface.
  • An interface with the dielectric layer may be introduced.
  • the first electrode side structure may be a structure having periodicity in the in-plane direction of the substrate or a non-periodic structure having no periodicity.
  • the first electrode side structure has periodicity, that is, when the dielectric layers having different refractive indexes and the first electrode are periodically arranged one-dimensionally or two-dimensionally in the in-plane direction of the substrate, the refraction effect is improved.
  • the diffraction effect by the transmission diffraction grating hereinafter simply referred to as “diffraction grating”
  • the photonic crystal light propagation in a specific direction / frequency
  • the waveguide mode light can be extracted to the substrate side.
  • the period (pitch) of the refractive index modulation structure of the first electrode side structure When the period (pitch) of the refractive index modulation structure of the first electrode side structure is larger than the wavelength of the emitted light, refraction at the medium interface having a different refractive index becomes the dominant mechanism and light is extracted. Conceivable. On the other hand, when the period (pitch) of the refractive index modulation structure of the first electrode is equal to or less than the wavelength of the emitted light, the effect of the diffraction grating and the effect of the photonic crystal become the dominant mechanism, and light is extracted. It is thought that.
  • FIG. 2 is a schematic cross-sectional view of an organic EL element having a second electrode side structure having an Otto type arrangement. First, the principle of extracting SPP mode light as guided mode light by the second electrode side structure will be described with reference to FIG. In FIG. 2, the first electrode side structure is omitted.
  • n sub is the refractive index of the substrate
  • n OLED is the average refractive index of the first electrode
  • ⁇ 1 is the dielectric constant of the metal layer
  • ⁇ 2 is the dielectric constant of the low refractive index layer
  • k sp is the wave vector of SPP mode light
  • k 0 is the wave number of light in vacuum
  • ⁇ is the propagation angle of light propagating in the high refractive index layer.
  • the wave number k sp of the SPP mode light is given by the equations (2) to (5).
  • Equation (11) the in-plane components of the wave vector coincide between the SPP mode light and the extracted light, that is, Equation (11) must be satisfied. is there. From the equations (5) and (6), the SPP mode light is extracted as propagating light at an angle satisfying the following equation (7).
  • FIG. 3 is a schematic cross-sectional view of a part of the first electrode side structure provided with a transmissive diffraction grating. It is assumed that light extracted from the SPP mode light at a predetermined angle ⁇ is diffracted by a diffraction grating having a grating interval (refractive index modulation period) p.
  • the condition for diffracting to the substrate side at a predetermined angle ⁇ sub with respect to the substrate surface is that the difference between the in-plane wave number of incident light incident on the diffraction grating and the in-plane wave number of diffracted light is an integral multiple of 2 ⁇ / p. It is. Therefore, it can be expressed by the following formula (8).
  • N 0, ⁇ 1,...
  • OLED stack indicates a layer through which guided mode light including the first electrode and the organic layer propagates.
  • the specific layer structure depends on the specific structure of the present invention. Further, the position where the “diffraction grating” is provided also depends on the specific configuration of the present invention. Equation (9) is obtained from Equation (7) and Equation (8).
  • ⁇ is the wavelength in vacuum of the light diffracted by the diffraction grating.
  • the term “wavelength” represents the wavelength in vacuum.
  • the condition under which total reflection does not occur at the interface between the substrate and air is to satisfy equation (10). Therefore, by providing a diffraction grating whose grating interval satisfies the following formula (11), total reflection does not occur at the interface between the substrate and air. As a result, the light extraction efficiency is improved.
  • N in Equation (11) may be a positive integer.
  • the expression (11) approximately satisfies the following expression (1).
  • the maximum peak wavelength of the emission spectrum of the light emitting layer is adopted as ⁇ in Equation (1).
  • the maximum peak wavelength the maximum peak wavelength of the photoluminescence spectrum can be used.
  • N is a diffraction order and is an arbitrary integer, but if the diffraction order is too large, the directivity of the diffracted light decreases. Therefore, it is preferable to select the pitch p and the wavelength ⁇ so that N satisfying the formula (1) is in the range of 1 ⁇ N ⁇ 3.
  • the above theoretical analysis is a one-dimensional analysis.
  • a one-dimensional diffraction grating structure a diffraction grating structure in which the grating is arranged at regular intervals in a predetermined direction
  • a diffraction effect based on this analysis is obtained.
  • the one-dimensional diffraction grating structure does not have a grating structure in a direction orthogonal to the one direction, and therefore does not produce a diffraction effect for light in the orthogonal direction (light component).
  • the two-dimensional diffraction grating structure has a diffraction grating structure in another direction in the substrate surface. Therefore, a diffraction effect is added also in that direction.
  • the two-dimensional diffraction grating structure has a larger diffraction effect than the one-dimensional diffraction grating structure. Therefore, in the organic EL element having a configuration satisfying the expression (1) in a predetermined cross section, the light extraction efficiency can be improved regardless of whether the configuration is a one-dimensional diffraction grating structure or a two-dimensional diffraction grating structure. .
  • a photonic crystal is a structure whose refractive index is periodically different, in particular, a structure whose period is equal to or less than a wavelength. This periodic structure forms a forbidden band (photonic band gap) in which light in a specific wavelength range cannot exist.
  • the first electrode side structure of the present invention is a periodic refractive index modulation structure and the period is equal to or less than the wavelength
  • the first electrode side structure is a one-dimensional or two-dimensional photonic crystal (respectively a substrate). It can be regarded as a photonic crystal structure in which lattices are arranged at regular intervals in a predetermined direction or two directions in a plane.
  • a one-dimensional photonic crystal In a one-dimensional photonic crystal, light having a wavelength corresponding to the photonic band gap cannot propagate in one direction having a periodic structure. For this reason, the propagation of light is redistributed in directions other than in-plane, and the light can be extracted to the substrate side.
  • the one-dimensional photonic crystal structure does not have a periodic structure in a direction orthogonal to the one direction. Therefore, there is no photonic band gap in this direction, and there is no extraction effect due to this, or if any, it is very small.
  • the two-dimensional photonic crystal structure has a lattice structure in two different directions in the plane. Therefore, a photonic band gap is formed in these two directions, and light cannot propagate. Therefore, in the two-dimensional photonic crystal, the direction in which light cannot propagate in the plane increases, so that light is extracted to the substrate more efficiently than the one-dimensional structure.
  • the first electrode side structure is a non-periodic structure having no periodicity
  • the light incident on the first electrode structure is diffracted at random positions and phases, so that the light is emitted at a specific radiation angle. Are not radiated. Therefore, by having such a structure on the first electrode side, relatively uniform (highly diffusible) orientation characteristics can be obtained. That is, in the case where the first electrode side structure is a periodic structure, it is possible to obtain an alignment characteristic in which the light intensity at a specific radiation angle is increased by the effect of strengthening the emitted light by the diffraction grating. On the other hand, when the first electrode structure is an aperiodic structure, relatively uniform alignment characteristics can be obtained. Therefore, the first electrode side structure can be selected as a periodic structure or an aperiodic structure as necessary.
  • FIGS. 1A and 1B The light propagation method indicated by the arrows in FIGS. 1A and 1B is schematically shown for easy understanding of the principle of the action effect by refraction.
  • the way of light propagation varies depending on the magnitude relationship between the refractive index of the dielectric layer 7 and the refractive index of the anode 2, and FIG. 1A is an explanatory diagram when the former is higher than the refractive index of the latter, and FIG. It is explanatory drawing when the former is lower than the refractive index of the latter.
  • the refractive index of the dielectric layer 7 does not depend on the magnitude relationship between the refractive index of the dielectric layer 7 and the refractive index of the anode 2.
  • the light traveling toward the cathode 4 is incident at the interface between the cathode 4 and the low refractive index layer 5 at a large incident angle greater than the critical angle ( Arrow A1)
  • an evanescent wave (arrow A2) is generated in the low refractive index layer 5.
  • the generated evanescent wave oozes out to the interface between the metal layer 6 and the low refractive index layer 5, and the surface plasmon polariton SPP (arrow A3) is excited.
  • a light emission point (or light emission location) Ao indicates a light emission point at a position overlapping the anode 2 in plan view (hereinafter, light emission at this point is referred to as “out light emission”). There are times.)
  • the light emission point Ai indicates a light emission point at a position overlapping the anode hole portion in plan view (hereinafter, light emission at this point may be referred to as “in light emission”).
  • the light emission point Ae indicates light emission at a boundary position between “in light emission” and “out light emission” (hereinafter, light emission at this point may be referred to as “in-out edge light emission”).
  • in-out edge light emission For “in light emission” and “in-out edge light emission”, an arrow indicating total reflection at the interface between the cathode 4 and the low refractive index layer 5 is omitted.
  • the light propagation after SPP (arrow A3) excitation is also applied to “in emission” and “in-out end emission”. Is the same as in the case of “out emission”. Since the current flows between the cathode and the anode, in this case, the light emission point Ao is located in a route having a higher current density than the light emission point Ai. Many.
  • the cathode layer structure (the cathode 4, the low refractive index layer 5, and the metal layer 6) is used as shown in FIG.
  • the light extracted to the point propagates like AD1, and is extracted to the substrate 1. That is, the light AD 1 traveling through the organic layer 3 from the point A is refracted at the interface between the organic layer 3 and the dielectric layer 7 and passes through the dielectric layer 7. Further, the light is refracted and travels toward the substrate 1 at the interface between the anode 2 and the dielectric layer 7 (the inner surface 2a of the anode hole 2A).
  • the substrate 1 After being refracted at the interface between the anode 2 and the substrate 1, it can be taken out through the substrate 1.
  • the interface between the dielectric layer 7 and the anode 2 the interface between the dielectric layer 7 and the anode 2 (the inner side surface 2a of the anode hole 2A (the anode 2 extending perpendicularly to the substrate surface of the substrate 1).
  • the angle of incidence of the light AD1 on the substrate 1 changes to a smaller angle (an angle closer to the direction perpendicular to the substrate surface of the substrate 1).
  • the light is incident at an angle greater than the critical angle at the interface between the substrate (for example, glass) and the air, total reflection occurs. . Therefore, light that does not undergo total reflection at the interface between the substrate and air increases, and light extraction efficiency is improved. That is, the light extraction efficiency is improved by having the configuration including the inner side surface 2a of the anode hole portion 2A.
  • the vicinity of the shortest distance between the cathode 4 and the anode 2 has the highest current density and the amount of light emission increases.
  • the light emission at the point P of the light emitting layer included in the organic layer 3 is “out light emission” in which the amount of light emission increases, and the light emission at this point is schematically shown.
  • the light PD1 is light traveling toward the substrate side in a direction perpendicular to the substrate. It proceeds through the substrate 1 without being refracted at the interface with the substrate 1 and is taken out to the outside.
  • the light PD 2 is refracted at the inner side surface 2 a of the anode hole 2 A (the interface between the anode 2 and the dielectric layer 7 extending perpendicularly to the substrate surface of the substrate 1) and transmits through the anode 2. Further, after being refracted at the interface between the anode 2 and the substrate 1, it can be taken out through the substrate 1.
  • the incident angle to the substrate 1 is small due to refraction at the interface between the dielectric layer 7 and the anode 2 (inner side surface 2 a of the anode hole 2 A). It changes to an angle (an angle closer to the direction perpendicular to the substrate surface of the substrate 1).
  • Total reflection occurs when incident at an angle greater than the critical angle at the interface between the anode 2 and the substrate (for example, glass) 1 and at the interface between the substrate 1 and air.
  • the incident angle to the substrate 1 is changed to a small angle due to refraction at the inner surface 2a of the anode hole portion 2A, light that does not undergo total reflection at the interface between the substrate and air increases, and light extraction efficiency is improved.
  • the excited SPP mode light A3 is extracted into the organic layer 3 through resonance with the evanescent wave as shown in FIG.
  • the process is the same as that in the case where the dielectric layer 7 is made of a material higher than the refractive index of the anode 2 (FIG. 1A).
  • the light extracted to the organic layer propagates like the light AD1 shown in FIG. That is, the light AD1 traveling through the organic layer 3 from the point A is refracted at the interface between the dielectric layer 7 and the anode 2 (the inner surface 2a of the anode hole 2A) and travels through the dielectric layer 7.
  • the angle of incidence on the interface between the anode 2 and the substrate 1 and the outer surface of the substrate 1 changes to a smaller angle due to refraction at the interface between the dielectric layer 7 and the anode 2.
  • Total reflection at these interfaces is suppressed, and the light beam AD1 can be prevented from becoming guided mode light or substrate mode light, thereby improving the light extraction efficiency.
  • the light PD1 is light traveling toward the substrate side in a direction perpendicular to the substrate. It proceeds through the substrate 1 without being refracted at the interface with the substrate 1 and is taken out to the outside.
  • the light PD2 is refracted at the inner side surface 2a of the anode hole portion 2A (the interface between the anode 2 and the dielectric layer 7 extending perpendicularly to the substrate surface of the substrate 1), and is transmitted through the dielectric layer 7. Further, after being refracted at the interface between the dielectric layer 7 and the substrate 1, it is taken out through the substrate 1.
  • the angle of incidence on the substrate 1 is small due to refraction at the interface between the anode 2 and the dielectric layer 7 (inner side surface 2 a of the anode hole 2 A). (An angle closer to the direction perpendicular to the substrate surface of the substrate 1). Total reflection occurs when incident at an angle greater than the critical angle at the interface between the anode 1 and the substrate (for example, glass) 1 and at the interface between the substrate 1 and air.
  • the incident angle on the substrate 1 is changed to a small angle due to refraction at the inner side surface 2a of the anode hole portion 2A, the light that can avoid total reflection at the interface between the substrate and air is increased and the light extraction efficiency is improved. To do.
  • the anode hole 2a is periodically arranged in at least one direction in the plane of the substrate 11 with a period equal to or less than the wavelength of the emitted light.
  • the function and effect of the diffraction grating will be schematically described with reference to FIG.
  • the light propagation method indicated by the arrows in FIG. 4 is schematically shown in order to explain the principle of the action and effect of the diffraction grating. The principle described below does not depend on the magnitude relationship between the refractive indexes of the dielectric layer 7 and the anode 2.
  • the light traveling to the cathode 4 side enters the interface between the cathode 4 and the low refractive index layer 5 at a large incident angle greater than the critical angle (arrow B1)
  • an evanescent wave (arrow B2) is generated in the low refractive index layer 5.
  • the generated evanescent wave oozes out to the interface between the metal layer 6 and the low refractive index layer 5, and the surface plasmon polariton SPP (arrow B3) is excited.
  • the excited SPP is radiated to the cathode 4 at a predetermined angle (arrow B5) through resonance with the evanescent wave (arrow B4), and is extracted to the organic layer 3 as propagating light.
  • the light extracted from the cathode side structure (cathode 4, low refractive index layer 5, metal layer 6) to point B of the organic layer 3 propagates through the organic layer 3 and enters the diffraction grating.
  • the incident light is diffracted by the diffraction grating in a predetermined direction (a direction satisfying the Nth order strengthening condition).
  • the diffracted light is emitted while interfering with the diffracted light at each diffraction point, so that the light is directed very strongly at a predetermined angle.
  • arrows BD1 and BD2 light incident on the interface between the substrate 1 (for example, glass) and air at an incident angle equal to or less than the critical angle is directly extracted outside.
  • the material of the metal layer and the low refractive index layer and the period of the diffraction grating should be selected so as to satisfy the formula (1). preferable.
  • the generated SPP light can be efficiently extracted from the substrate 1 by the diffraction grating, and the light extraction efficiency can be improved.
  • the intensity of the diffracted light is higher as the order N is smaller, it is preferable to select the period of the diffraction grating and the like so as to satisfy the formula (1) for N as small as possible.
  • the organic EL element 10 of the first embodiment of the present invention when the anode hole portion 2A is periodically arranged at a period equal to or less than the wavelength of the emitted light in at least one direction within the surface of the substrate 1, As described above, it can be considered that a diffraction grating is formed, and on the other hand, it can be considered that a photonic crystal is formed.
  • the effect by the photonic crystal will be schematically described with reference to FIG.
  • the light propagation method indicated by the arrows in FIG. 5 is schematically shown in order to explain the principle of action and effect by the photonic crystal.
  • the light traveling to the cathode 4 side enters the interface between the cathode 4 and the low refractive index layer 5 at a large incident angle greater than the critical angle (arrow C1)
  • an evanescent wave (arrow C2) is generated in the low refractive index layer 5.
  • the generated evanescent wave swells to the interface between the metal layer 6 and the low refractive index layer 5, and the surface plasmon polariton SPP (arrow C3) is excited.
  • the excited SPP is radiated to the cathode 4 at a predetermined angle (arrow C5) through resonance with the evanescent wave (arrow C4), and taken out to the organic layer 3 as propagating light.
  • the periodic structure is formed by the dielectric layer 7 that covers the anode 2 and the inner surface 2a of the anode hole.
  • the photonic band gap can be generated parallel to the substrate surface. The direction is the arrow CD2.
  • the organic EL element of the present invention When there is no photonic crystal structure, most of the light extracted into the organic layer 3 is totally reflected at the interface between the anode 2 (or the dielectric layer 7) and the substrate 1 to become guided mode light, or the substrate 1 And is totally reflected on the outer surface of the air interface, and becomes a substrate mode.
  • the light propagation direction in the organic layer is changed by the photonic crystal structure to a direction close to perpendicular to the substrate surface, so that total reflection is suppressed and the light extraction efficiency to the outside is improved.
  • FIG. 6 is a schematic cross-sectional view for explaining an example of the organic EL element according to the second embodiment of the present invention.
  • the dielectric layers are scattered in islands in the anode layer
  • the anode protrusions are scattered in islands in the dielectric layer 7.
  • the plurality of anode convex portions are connected to each other by the anode layered portion.
  • the organic EL element 20 shown in FIG. 6 includes an anode (first electrode) 22, an organic layer 23 including a light emitting layer, and a cathode (second electrode) 24 in this order on a substrate 21.
  • the organic EL element 20 includes a low refractive index layer 25 and a metal layer 26 in this order on the opposite side of the second electrode 24 from the organic layer 23.
  • the anode 22 includes a plurality of anode convex portions 22B connected to each other by an anode layered portion 22c.
  • the organic layer 23 has a layered portion disposed between the anode 22 and the dielectric layer 27 and the second electrode 24.
  • the cathode 24 is made of a translucent conductive material.
  • the refractive index of the low refractive index layer 25 is lower than the refractive index of the organic layer 23.
  • FIG. 6 shows an example of a bottom emission structure in which the substrate 21 is disposed on the anode 22 side.
  • the top emission structure is a case where the substrate 21 is disposed on the metal layer 26 side.
  • a bottom emission structure in which the substrate 21 exists on the anode 22 side will be described as an example.
  • the refractive index of the organic layer 23 refers to the average refractive index of all layers including the light emitting layer.
  • the period (pitch) in which the adjacent anode convex portions 22B are arranged in at least one direction within the substrate surface is equal to or greater than the wavelength of the emitted light
  • the shape of the anode convex portion 22B is an effect of refracting light toward the substrate side on the outer surface There is no particular limitation as long as it plays.
  • the dielectric layer is made of a material having a refractive index higher than that of the anode
  • a shape in which the bottom area on the cathode 24 side is smaller than the bottom area on the substrate 21 side is preferable from the viewpoint of refracting the guided mode light more vertically.
  • the outer surface is configured to be arranged perpendicular to the substrate surface, but is not limited to this configuration.
  • the angle of the outer surface 22b of the adjacent anode projection 22B with respect to the substrate surface is preferably 45 to 90 °, more preferably 60 to 90 °, and even more preferably 75 to 90 °.
  • the propagating light re-radiated from the light emitting position toward the anode side and the guided mode light and the SPP mode light is incident on the outer surface 22b of the anode convex portion from the outside. Incident light is refracted to the substrate side and is easily taken out from the outer surface of the substrate.
  • the dielectric layer is made of a material having a refractive index lower than that of the anode, a shape in which the bottom area on the cathode 24 side is larger than the bottom area on the substrate 21 side is preferable from the viewpoint of refracting the guided mode light more vertically.
  • the angle of the outer surface 22b of the adjacent anode projection 22B with respect to the substrate surface is preferably 90 ° to 135 °, more preferably 90 ° to 120 °, and still more preferably 90 ° to 105 °.
  • the shape of the anode protrusions A22B is not particularly limited as long as the effect of diffraction and the effect of photonic crystals are exhibited.
  • the outer surface 22b of the anode convex portion 22B is nearly perpendicular to the substrate surface. This is because the refractive index modulation becomes steep in the in-plane direction of the substrate crossing the outer surface 22b of the anode protrusion 22B because the outer surface 22b of the anode protrusion 22B is perpendicular to the substrate surface.
  • the photonic crystal When the refractive index is sharply modulated, the photonic crystal has a wider band gap frequency range where light cannot propagate in the in-plane direction of the substrate, and can be extracted from the organic layer 23 to the outside more efficiently. Further, when the refractive index is sharply modulated even in the diffraction grating, the diffraction efficiency of light toward the substrate is improved, and similarly, the light extraction to the outside of the element is improved.
  • the same effect can be obtained when the size and the period of the hole and the protrusion are equal between the case of having the anode hole of the first embodiment and the case of having the anode protrusion of the second embodiment.
  • FIG. 7 is a schematic perspective view of the first embodiment and the second embodiment.
  • the anode convex portion according to the second embodiment is provided and the period and size of the anode hole portion or convex portion are not changed, the same refraction effect is obtained. Therefore, also in 2nd Embodiment, the effect similar to the effect of 1st Embodiment is acquired.
  • FIG. 8 is a schematic cross-sectional view for explaining an example of the organic EL element according to the third embodiment of the present invention.
  • An organic EL device 30 according to the third embodiment of the present invention includes, on a substrate 31, an anode (first electrode) 32, an organic layer 33 including a light emitting layer, and a cathode (second electrode) 34 in this order. ing. Furthermore, the organic EL element 30 includes a low refractive index layer 35 and a metal layer 36 in this order on the opposite side of the second electrode 34 from the organic layer 33.
  • the anode 32 includes a plurality of anode hole portions 32A.
  • the inner surface 32a of the anode hole portion 32A is covered with a substrate convex portion 31B which is another example of the anode hole inner surface covering portion.
  • the substrate convex portions 31B are scattered in the layer of the anode 32 in an island shape.
  • the organic layer 33 has a layered portion disposed between the anode 32 and the substrate convex portion 31 ⁇ / b> B and the cathode 34.
  • the cathode 34 is made of a transparent conductive material (translucent conductive material), and the refractive index of the low refractive index layer 45 is lower than the refractive index of the organic layer 33.
  • the substrate convex portion 31B may have a structure that covers a part of the organic layer side surface of the anode 32 in addition to the inner side surface 32a of the anode hole portion 32A.
  • the anode hole portion 32 ⁇ / b> A is not limited to a hole that penetrates the anode 32, and the anode hole portion 3 ⁇ / b> A may be a hole that does not penetrate the anode 32.
  • FIG. 9 is a schematic cross-sectional view for explaining an example of the organic EL element according to the fourth embodiment of the present invention.
  • the substrate protrusions are scattered in islands in the anode layer
  • anode protrusions are scattered in the substrate recesses, and a plurality of anode protrusions are formed.
  • the parts are connected to each other by the anode layered part.
  • the organic EL element 40 shown in FIG. 9 includes an anode (first electrode) 42, an organic layer 43 including a light emitting layer, and a cathode (second electrode) 44 in this order on a substrate 41.
  • the organic EL element 40 includes a low refractive index layer 45 and a metal layer 46 in this order on the opposite side of the second electrode 44 from the organic layer 43.
  • the anode 42 includes a plurality of anode convex portions 42B connected to each other by an anode layered portion 42c.
  • the organic layer 43 has a layered portion disposed between the anode 42 and the second electrode 44.
  • the cathode 44 is made of a translucent conductive material.
  • the refractive index of the low refractive index layer 45 is lower than the refractive index of the organic layer 43.
  • FIG. 10 is a diagram illustrating an example of an image display device including the organic EL element. Further, the organic EL element may have a bottom emission structure or a top emission structure, but the following description will be made with an example of a bottom emission structure.
  • An image display device 100 shown in FIG. 10 is a so-called passive matrix type image display device.
  • anode wiring 104 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, and a cathode partition 112 are provided. , A sealing plate 116 and a sealing material 118.
  • a plurality of anode wirings 104 are formed on the substrate 1 of the image display device 100.
  • 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.
  • the anode auxiliary wiring 106 functions as a terminal for connecting to the external wiring on the end portion side of the substrate 1, and the drive circuit (not shown) provided outside via the anode auxiliary wiring 106.
  • a current can be supplied to the anode wiring 104.
  • 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 and is electrically connected to the cathode wiring 108. Therefore, a current can flow between the cathode wiring 108 and the cathode auxiliary wiring.
  • 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.
  • 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.
  • the film thickness of the insulating film 110 can be, for example, 200 nm to 100 nm, and the size of the opening 120 can be, for example, 100 ⁇ m ⁇ 100 ⁇ m.
  • 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 orthogonal to the anode wiring 104 in plan view.
  • 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 to each other through a sealing plate 116 and a sealing material 118.
  • 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 atmosphere.
  • the sealing plate 116 for example, a glass substrate having a thickness of 0.7 mm to 1.1 mm can be used.
  • the sealing plate 116 may not be transparent when light is extracted from the substrate 1 side as in the case of a bottom emission type element.
  • the sealing plate 116 needs to be transparent with respect to at least a part of the emission wavelength region.
  • 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. 11 is a diagram illustrating an example of a lighting device including the organic EL element.
  • the organic EL element may have a bottom emission structure or a top emission structure, but in the following, an example of a bottom emission structure will be described.
  • the lighting device 200 shown in FIG. 11 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 is caused to emit light, light is emitted from the substrate 1, and 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 anode 2 is formed on the substrate 1.
  • the formation method of this anode 2 is not specifically limited.
  • 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 performance of the overcoated layer (adhesion with the anode 2, surface smoothness, reduction of hole injection barrier, etc.) can be improved.
  • Specific examples of the surface treatment include 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.
  • the anode buffer layer can be prepared by applying a wet process.
  • Specific film forming methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating. And coating methods such as a method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, and an ink jet 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.
  • Specific examples of the film forming method include an electron beam evaporation method, a sputtering method, a chemical reaction method, a coating method, and a vacuum evaporation method.
  • a method using photolithography can be used to form the anode hole 2A.
  • a positive resist solution is applied onto the anode 2 and the excess resist solution is removed by spin coating or the like, thereby forming a resist layer 9.
  • a mask (not shown) on which a predetermined pattern for forming the anode hole 2A is formed is covered, and exposure is performed with ultraviolet rays (UV), electron beams (EB), or the like.
  • UV ultraviolet rays
  • EB electron beams
  • FIG. 12C the resist layer 9 is exposed to a predetermined pattern corresponding to the anode hole 2A (exposed portion 9a).
  • the resist layer 9 in the exposed pattern portion is removed using a developer.
  • the surface of the anode 2 is exposed corresponding to the exposed pattern portion (FIG. 12D).
  • the exposed portion of the anode 2 is removed by etching to form an anode hole portion 2A.
  • etching either dry etching or wet etching can be used.
  • the shape of the anode hole portion 2A can be controlled by combining isotropic etching and anisotropic etching.
  • dry etching reactive ion etching (RIE) or inductively coupled plasma etching can be used.
  • RIE reactive ion etching
  • wet etching a method of immersing in 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.
  • anode convex part of 2nd Embodiment you may be the same as the process of forming the said anode hole part 2A.
  • etching the anode it is possible to connect the anode projections by leaving the anode layer-like portion without suppressing the etching to expose the substrate and to establish conduction between the anode projections.
  • the remaining resist layer is removed with a resist removing solution or the like (FIG. 12 (f)), and then the dielectric layer 7 is formed (FIG. 12 (g)).
  • the dielectric layer 7 is configured to fill the anode hole 2A and cover the inner surface 2a of the anode hole 2A.
  • a configuration in which only a part is filled and the inner side surface 2a of the anode hole 2A is covered (a part of the bottom surface of the anode hole 2A is exposed) may be employed.
  • the method for forming the dielectric layer 7 is not particularly limited as with the method for forming the anode 2.
  • a resistance heating vapor deposition method 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 dielectric layer 7 covers the upper surface of the anode 2 (the surface opposite to the substrate other than the anode hole 2A)
  • the dielectric layer 7 may be exposed by partially removing the surface by etching back. This etch back process is necessary to form a conductive path between the anode and the cathode when the dielectric layer 7 is an insulator.
  • an etch back processing method for example, an etching method or a polishing method used for forming the anode hole 2A can be used. Furthermore, after the dielectric layer 7 is formed, various surface treatments for the purpose of improving the film quality can be performed on the anode 2 and the anode-side surfaces of the dielectric layer 7. As the surface treatment method, the same method as described in the surface treatment after forming the anode 2 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 dielectric layer 7.
  • polishing or etching for flattening may be appropriately performed.
  • a conventionally known method can be used to form the organic layer 3 and is not particularly limited. For example, methods such as a vacuum deposition method, a spin coating method, a casting method, and an LB method can be used.
  • the formation conditions are adjusted depending on whether the anode hole 2A is completely filled or partially filled.
  • the dielectric layer 7 covering the inner surface 2a of the anode hole is formed as described above, and the layered organic layer 3 is further formed to produce a structure corresponding to FIG.
  • a cathode 4 is formed on the organic layer 3.
  • the method for forming the cathode 4 can be the same as the method for forming the anode 2 and is not particularly limited.
  • 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.
  • a low refractive index layer 5 is formed on the cathode 4.
  • the formation of the low refractive index layer 5 can be performed using the same method as the formation of the dielectric layer 7, and is not particularly limited.
  • 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 low-refractive index layer 5 is a low-refractive index layer including an air layer, for example, after the SOG layer is formed, the SOG material is left at a predetermined position in the SOG layer using photolithography.
  • the low refractive index layer is formed by etching away the SOG layer so that the portion where the SOG layer is removed becomes an air layer.
  • a metal layer 6 is formed on the low refractive index layer 5.
  • the formation of the metal layer 6 is not particularly limited. For example, vapor deposition or sputtering can be used.
  • the organic EL element 10 can be manufactured by the above process. Moreover, after these series of processes, 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.
  • a 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.
  • a metal having a higher ionization tendency than the metal layer 6 may be used as the protective layer as the sacrificial layer.
  • 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 or a photocurable resin and sealed.
  • a spacer 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 the upper metal layer 6 from being oxidized. 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. Further, 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.
  • the metal layer 16 is formed on the substrate 11.
  • the formation method of the metal layer 16 is not specifically limited, For example, a vapor deposition method and sputtering can be used.
  • a low refractive index layer 15 is formed on the metal layer 16.
  • the method for forming the low refractive index layer 15 is not particularly limited. 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 low-refractive index layer 15 is a low-refractive index layer including an air layer, for example, after the SOG layer is formed, the SOG material is left at a predetermined position using photolithography in the SOG layer.
  • the low refractive index layer is formed by etching away the SOG layer so that the portion where the SOG layer is removed becomes an air layer.
  • the cathode 14 is formed on the low refractive index layer 15.
  • the method for forming the cathode 14 is not particularly limited.
  • 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 13 is formed on the cathode 14.
  • a conventionally known method can be used as a method for forming the organic layer 13.
  • methods such as a vacuum deposition method, a spin coating method, a casting method, and an LB method can be used.
  • the anode 12 is formed on the organic layer 13.
  • the formation of the anode 12 is not particularly limited.
  • 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 anode 12.
  • 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 mentioned.
  • Specific film forming methods include an electron beam evaporation method, a sputtering method, a chemical reaction method, a coating method, and a vacuum evaporation method. The method etc. can be used.
  • a method using photolithography can be used to form the anode hole portion 12A.
  • a positive resist solution is applied onto the anode 12, and the excess resist solution is removed by spin coating or the like to form a resist layer 19.
  • FIG. 13 (g) is obtained.
  • a predetermined pattern corresponding to the anode hole 12A is exposed to the resist layer 19 (exposed portion 19a).
  • the resist layer 19 in the exposed pattern portion is removed using a developer.
  • the surface of the anode 12 is exposed corresponding to the exposed pattern portion (FIG. 13H).
  • the exposed resist layer 19 is used as a mask to remove the exposed portion of the anode 12 to form an anode hole portion 12A.
  • the etching either dry etching or wet etching can be used.
  • the shape of the anode hole portion 12A can be controlled by combining isotropic etching and anisotropic etching.
  • dry etching reactive ion etching (RIE) or inductively coupled plasma etching can be used.
  • RIE reactive ion etching
  • wet etching a method of immersing in dilute hydrochloric acid or dilute sulfuric acid can be used. By this etching, the surface of the organic layer 13 is exposed corresponding to the pattern.
  • the dielectric layer 17 is formed.
  • the resist layer 19 may be removed before and after the formation of the dielectric layer 17.
  • the dielectric layer 17 is configured to fill the anode hole portion 12A and cover the inner side surface 12a of the anode hole portion 12A.
  • covers may be sufficient.
  • the formation method of the dielectric layer 17 is not limited as in the formation of the anode 12. 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 various coating methods can be used.
  • the dielectric layer 17 is formed by the above formation method, when the dielectric layer 17 covers the upper surface of the anode 12 (the surface opposite to the substrate 11 other than the anode hole portion 12A), the dielectric layer The upper surface of the anode 2 may be exposed by removing a portion 17 by etching back.
  • FIG. 14 shows the result of energy dissipation calculation in which the intensity of light emitted from the organic layer is developed with the wave number component in the organic EL element surface direction.
  • the horizontal axis represents the wave number of the light emitted from the organic layer, the organic EL element surface direction component divided by the vacuum wave number k 0 , that is, the effective refractive index, and the vertical axis represents the light intensity of the wave number, that is, the development.
  • the coefficient is shown.
  • the calculation was performed separately for the TM polarization component and the TE polarization component.
  • This calculation shows the result of an organic EL element in which a flat anode, an organic layer, and a cathode (metal) are laminated on glass. In this case, the peak area on the highest wavenumber side of TM polarized light represents the intensity of the SPP mode light, but it can be seen that most of the light emitted from the organic layer is captured as the SPP mode light.
  • FIG. 15 shows the dependence of the intensity of the light emitted from the organic layer (TM polarization component) by the energy dissipation calculation in the Otto configuration on the thickness of the low refractive index layer.
  • the refractive index of the low refractive index layer 5 is 1.38
  • FIG. 15A shows the cathode and the reflective layer as Al
  • FIG. 15B shows the cathode and the reflective layer as Ag.
  • the change of the peak will be described below with reference to FIGS.
  • the light is completely trapped on the surface of the reflective layer as SPP mode light.
  • the SPP mode light and the waveguide mode light are mixed due to the Otto type arrangement. This means that the extracted SPP mode light becomes waveguide mode light, and is recaptured as SPP mode light in the reflective layer again by interface reflection.
  • the peak width becomes gradually narrower.
  • the film thickness of the low refractive index layer becomes sufficiently large, it becomes as shown in FIG.
  • the Otto type arrangement is used, the evanescent wave at the light emitting point does not reach the reflective layer and is not captured as SPP mode light.
  • the emitted light is captured as guided mode light. That is, when the film thickness of the low refractive index layer exceeds a certain thickness, the trapped light is only guided mode light, so the ease of attenuation does not change and the peak width also does not change.
  • surface plasmon polariton (SPP) trapped on the surface of the reflective layer can be taken out by an evanescent wave generated by light totally reflected at the interface between the cathode and the low refractive index layer. That is, the wave number of this evanescent wave needs to have an intersection with the wave number k SPP of the surface plasmon polariton (SPP) generated on the surface of the reflective layer.
  • the wave number k SPP of the surface plasmon polariton (SPP) generated on the reflective layer surface can be expressed by the following equation (13).
  • ⁇ 1 is the dielectric constant of the reflective layer
  • ⁇ 2 is the dielectric constant of the low refractive index layer
  • k 0 is the wave number of light in vacuum at the maximum peak wavelength of light emitted from the light emitting layer.
  • the real part can be expressed by the following equation (14).
  • SPP surface plasmon polariton
  • the intensity of the surface plasmon polariton (SPP) at the position propagated through the thickness (h 2 ) of the low refractive index layer is approximately when the reflection at each interface is negligible. It becomes.
  • ⁇ SPP is a value obtained by dividing the real part of the in-plane direction component of the surface plasmon polariton (SPP) wave number by the wave number k 0 of light in vacuum.
  • FIG. 18A is a graph showing Expression (16) in the case where the reflective layer is Al and (b) is Ag as the reflective layer.
  • the intensity of the surface plasmon polariton (SPP) generated on the reflection layer surface at the interface between the low refractive index layer and the cathode is 0 in the equation (16). It can be seen that the peak width is saturated to a constant value at a thickness of the low refractive index layer of .4 or less. That is, when the expression (16) is 0.4 or less, it can be said that the intensity of the surface plasmon polariton (SPP) that oozes out to the interface between the low refractive index layer and the cathode is reduced, and the light extraction effect by the Otto type arrangement is reduced. In other words, it can be seen that the light extraction effect by the Otto type arrangement can be sufficiently obtained when the thickness of the low refractive index layer satisfies the expression (16) of 0.4 or less.
  • FIG. 19 shows the dependence of the light extraction efficiency on the distance (pitch) between adjacent anode portions using the finite difference time domain method (FDTD (Finite Difference Time Domain) Method) with respect to the effect of the organic EL element of the present invention.
  • FDTD Finite Difference Time Domain
  • the result of computer simulation is shown.
  • Maxwell's equation describing the time change of the electromagnetic field is differentiated spatially and temporally, and the time change of the electromagnetic field at each point in the space is tracked. More specifically, the light emission in the light emitting layer is regarded as radiation from a minute dipole, and the time change of the radiation (electromagnetic field) is traced.
  • the simulation result shows the result of calculating the light extraction up to the substrate.
  • ⁇ on the horizontal axis is the wavelength
  • ⁇ on the vertical axis is the relative intensity.
  • FIG. 20 is a cross-sectional view showing a model structure of an organic EL element used in the simulation.
  • the refractive index values used for the calculation are as follows.
  • the substrate 1 is made of glass, and a refractive index of 1.52 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 dielectric layer 7 is made of SOG (spin on glass), and a refractive index of 1.25 is used.
  • the cathode 4 was made of ITO, and the same one as the anode was used.
  • the low refractive index layer 5 is composed of an air layer, and a refractive index of 1.00 is used. Assuming that the metal layer 6 is made of aluminum (Al), the refractive index is 0.649 + 4.32i at 550 nm, and other wavelengths are extrapolated by the Drude model.
  • the thicknesses of the anode 2, the dielectric layer 7, the organic layer 3 composed of layered portions, the cathode 4, the low refractive index layer 5, and the metal layer 6 were 150 nm, 150 nm, 100 nm, 50 nm, 50 nm, and 100 nm, respectively.
  • the period P (distance between the centers) of adjacent anode hole portions was in the range of 500 nm to 900 nm and calculated every 100 nm.
  • the diameter D of the anode hole 2A in each period P was set to 1/2 of the period P.
  • a structure having a cathode side structure with an Otto type arrangement and no first electrode side structure for extracting propagating light to the outside without using it as a guided mode light hereinafter referred to as an Otto type arrangement only structure.
  • the cathode side structure with Otto type arrangement and the structure without the first electrode side structure to extract the propagating light to the outside without using the guided mode light hereinafter sometimes referred to as standard structure). did.
  • the standard structure means a structure in which an anode layer, an organic layer, and a cathode metal layer are formed in this order on a glass substrate.
  • the standard structure was such that the substrate was made of glass, the anode was made of ITO, the organic layer was sandwiched, and the cathode was made of Al.
  • Refractive indexes of 1.52, 1.82 + 0.009i, 1.72, and 0.649 + 4.32i were used, respectively, and the anode, organic layer, and cathode layer thicknesses were 150 nm, 100 nm, and 100 nm, respectively. It was.
  • FIG. 19 (a) and 19 (b) respectively show the radiation intensity ⁇ of the radiated light from the horizontal dipole (light propagating in the direction perpendicular to the substrate (hereinafter also referred to as vertical propagation light)), A radiation intensity ⁇ of light emitted from a dipole in the vertical direction (light propagating mainly in a direction parallel to the substrate (hereinafter sometimes referred to as horizontal propagation light)) is shown.
  • FIG. 19A vertical propagation light
  • the radiation intensity is higher by 30% or more than in the case of the structure of only the Otto type arrangement over the entire visible light range in any case of this embodiment. was gotten. Furthermore, over the entire range of visible light, the result was that the radiation intensity was about 10 times that of the standard structure.
  • the improvement of the radiation intensity of several tens of percent in the case of the present invention compared to the case of the structure having only the Otto type arrangement is due to the refraction effect on the inner side surface 2a of the anode hole portion 2A.
  • the improvement of the radiation intensity in the case of this embodiment is about an order of magnitude, because the cathode side structure of the Otto type arrangement and the refraction effect on the inner side surface 2a of the anode hole 2A.
  • the pitch dependence of the anode portion is observed at a wavelength of 650 nm or less.
  • the radiation intensity was higher by about 20% in the case of 900 nm pitch than in the case of 500 nm pitch.
  • FIG. 21 shows an FDTD in which the dipole as the light source is random (dipole moment is random in the x, y, and z directions) in order to simulate a more realistic light emission phenomenon for the organic EL element of this embodiment.
  • the result of having simulated the light extraction efficiency using the method is shown.
  • FIG. 19 a case where the period P is every 100 nm in the range of 500 nm to 900 nm, a structure having only an Otto type arrangement, and a standard structure are shown. In any case, it can be seen that a remarkable synergistic effect is obtained by combining the cathode side structure of the Otto type arrangement and the anode side structure over the entire visible light range.
  • FIG. 22 is a simulation in which the materials of the cathode 4 and the low refractive index layer 5 of the element of FIG. 20 are changed with respect to the simulation of FIG.
  • the cathode 4 is made of a-ITO (amorphous ITO)
  • the refractive index is 2.08 + 0.0013i at 550 nm
  • the low refractive index layer 5 is made of SOG. 25 was used.
  • the case where the period P of the adjacent anode hole part was 200 nm, 300 nm, 500 nm, 900 nm, 2000 nm, 4000 nm, and 8000 nm was calculated.
  • the diameter D of the anode hole portion 2A in each case was 100 nm, 150 nm, 250 nm, 450 nm, 1000 nm, 2000 nm, and 4000 nm, which are 1 ⁇ 2 of the period P, respectively.
  • a simulation was also performed on an element having the same standard structure as in FIG. 19 and an element structure of the present embodiment and only an Otto type arrangement.
  • the organic EL device of this embodiment has an improved light extraction efficiency as a whole in the period P (200 to 8000 nm) between all anode portions, as compared with the structure having only the Otto type arrangement and the standard structure.
  • the light extraction efficiency is increased when the period P of the anode hole portion is 500 nm to 4000 nm.
  • the light extraction efficiency is remarkably increased when the period P between the anode holes is in the range of 900 to 2000 nm. This result cannot be predicted based on the single structure of the cathode-side structure and the anode-side structure of the Otto type arrangement, but was revealed for the first time by the simulation of the present invention.
  • FIGS. 23A to 23F are the elements of the embodiment used in FIG. 22 described above, from the dipoles in the vertical direction when the period P is 200 nm, 300 nm, 500 nm, 900 nm, 2000 nm, and 4000 nm, respectively.
  • the simulation result by the FDTD method of the intensity distribution of the magnetic field of synchrotron radiation is shown.
  • the wavelength of the emitted light was 620 nm.
  • the substrate is located on the upper side, corresponding to the magnetic field strength distribution of the substrate, anode, organic layer, cathode, low refractive index layer, metal layer, and air in order from the top, and the magnetic field strength increases from blue to red. It is shown that.
  • the shape of each layer is also displayed superimposed on the magnetic field distribution.
  • FIGS. 24A to 24F show simulation results by the FDTD method of the intensity distribution of the electric field of the radiated light from the horizontal dipole for the element of the same embodiment as FIG.
  • the display method is the same as in FIG.
  • the wavelength of the emitted light was 620 nm.
  • FIG. 25A shows an element having a standard structure, and shows a simulation result by the FDTD method of the intensity distribution of the magnetic field of the emitted light from the dipole in the vertical direction.
  • the wavelength of the emitted light was 620 nm.
  • the substrate is located on the upper side, corresponding to the magnetic field strength distribution of the substrate, the anode, and the cathode in order from the top, indicating that the magnetic field strength is strong from blue to red.
  • the right end indicates the light emission position.
  • the substrate 1 is made of glass
  • the anode 2 is made of ITO
  • the organic layer 3 is sandwiched
  • the cathode 4 is made of Al.
  • Refractive indexes are 1.52, 1.74 + 0.013i (Lorentz model), 1.72, 0.810 + 4.86i (Drude model), respectively, and the anode, organic layer, and cathode layer thicknesses are used. Are 150 nm, 100 nm, and 100 nm, respectively.
  • FIG. 25 (a) shows that the SPP is strongly trapped (localized) at the interface between the cathode and the organic layer. It can be seen that it is difficult to emit SPP with the standard structure.
  • FIG. 25B shows the simulation result by the FDTD method of the intensity distribution of the magnetic field of the emitted light from the dipole in the vertical direction for the structure having only the Otto type arrangement.
  • FIG. 24C is an enlarged view of the vicinity of the light emitting layer, and the drawing on the right is a schematic cross-sectional view of the layer structure of the element, in order from the top, substrate, anode, organic layer, cathode, low refractive index layer, metal layer. , Represents that it corresponds to air.
  • the propagation of SPP mode light hardly occurs and is extracted to the organic layer. However, it can be seen that the light in the organic layer is confined as guided mode light, and not so much extracted into the substrate.
  • the second electrode side structure and the first electrode side structure provided with an interface that is perpendicular or nearly perpendicular to the substrate are independent of the second electrode side structure and the first electrode side structure. It turns out that the remarkable effect which cannot be predicted from the improvement effect of light extraction efficiency is produced.
  • the external quantum efficiency of the device was measured using an integrating sphere.
  • the standard structure (solid structure) was 16.9%, but in the case of the present invention, it was 47.3%, which was 2.80 times as large as the standard structure (solid structure). .

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  • Electroluminescent Light Sources (AREA)

Abstract

L'invention concerne un élément EL organique qui est équipé d'une première électrode, d'une couche organique contenant une couche électroluminescente et d'une seconde électrode, disposées dans cet ordre. L'élément EL organique est caractérisé : en ce qu'il est équipé d'une couche à faible indice de réfraction de 20-300 nm d'épaisseur et d'une couche métallique disposées dans cet ordre sur le côté de la seconde électrode opposé à la couche organique ; en ce que la première électrode comporte une pluralité de trous de première électrode, dont les surfaces internes sont couvertes par une couche diélectrique ayant un indice de réfraction différent de l'indice de réfraction de la première électrode ; en ce que la couche organique a une partie de couche agencée entre la seconde électrode et la première électrode et la couche diélectrique ; en ce que la seconde électrode comprend un matériau conducteur émetteur de lumière ; et en ce que l'indice de réfraction de la couche à faible indice de réfraction est inférieur à l'indice de réfraction de la couche organique.
PCT/JP2013/079560 2012-10-31 2013-10-31 Élément el organique et dispositif d'affichage d'image et dispositif d'éclairage le comportant WO2014069573A1 (fr)

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WO2017176888A1 (fr) * 2016-04-05 2017-10-12 Corning Incorporated Diode électroluminescente organique (oled) à motifs à extraction de lumière améliorée
WO2017186941A1 (fr) * 2016-04-29 2017-11-02 Commissariat A L'energie Atomique Et Aux Energies Alternatives Dispositif optoelectronique organique matriciel
WO2018167177A1 (fr) 2017-03-15 2018-09-20 Commissariat A L'energie Atomique Et Aux Energies Alternatives Diode electroluminescente organique a rendement optimise par confinement de plasmons et dispositif d'affichage comprenant une pluralite de telles diodes
WO2018176763A1 (fr) * 2017-03-29 2018-10-04 京东方科技集团股份有限公司 Dispositif électroluminescent organique et son procédé de fabrication, et appareil d"affichage
CN109390478A (zh) * 2017-08-07 2019-02-26 固安翌光科技有限公司 一种有机电致发光器件
CN112599698A (zh) * 2020-12-11 2021-04-02 合肥视涯技术有限公司 一种改善光晕的有机发光显示面板

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CN109075265A (zh) * 2016-04-05 2018-12-21 康宁公司 具有增强光提取的图案化有机发光二极管(oled)
WO2017176888A1 (fr) * 2016-04-05 2017-10-12 Corning Incorporated Diode électroluminescente organique (oled) à motifs à extraction de lumière améliorée
US10741784B2 (en) 2016-04-05 2020-08-11 Corning Incorporated Patterned organic light emitting diode (OLED) with enhanced light extraction
US20190165299A1 (en) * 2016-04-05 2019-05-30 Corning Incorporated Patterned organic light emitting diode (oled) with enhanced light extraction
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CN110431683A (zh) * 2017-03-15 2019-11-08 原子能和辅助替代能源委员会 具有等离激元约束优化的输出的有机发光二极管以及包括多个这种二极管的显示设备
FR3064114A1 (fr) * 2017-03-15 2018-09-21 Commissariat A L'energie Atomique Et Aux Energies Alternatives Diode electroluminescente organique a rendement optimise par confinement de plasmons et dispositif d'affichage comprenant une pluralite de telles diodes
WO2018176763A1 (fr) * 2017-03-29 2018-10-04 京东方科技集团股份有限公司 Dispositif électroluminescent organique et son procédé de fabrication, et appareil d"affichage
US10553812B2 (en) 2017-03-29 2020-02-04 Boe Technology Group Co., Ltd. Organic electroluminescent device and manufacturing method thereof, display device
CN109390478A (zh) * 2017-08-07 2019-02-26 固安翌光科技有限公司 一种有机电致发光器件
CN112599698A (zh) * 2020-12-11 2021-04-02 合肥视涯技术有限公司 一种改善光晕的有机发光显示面板

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