JP2019016478A - Organic el element, lighting device including the same, planar light source, and display device - Google Patents

Abstract

To provide an organic EL element capable of realizing high light extraction efficiency, a lighting device including the same, a planar light source, and a display device.SOLUTION: An organic EL element includes a light-transmitting substrate, a light-transmitting first electrode, a functional layer including a light-emitting layer, a patterning portion, and a second electrode in this order, and the functional layer is in contact with the patterning portion and the second electrode, and the patterning portion is made of lithium fluoride, and the patterning portion has a convex portion on the side of the second electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic electroluminescence (EL) element with improved light extraction efficiency, and an illumination device, a planar light source, and a display device including the organic EL element.

  In recent years, light-emitting elements (organic EL elements) that utilize the organic EL phenomenon have attracted a great deal of attention as next-generation light-emitting devices used in lighting devices, display devices, and the like. The organic EL element is capable of surface emission, can be operated at a low temperature, can be reduced in cost, can be reduced in weight, and can be made into a flexible element. There are advantages such as low angular dependence, low power consumption, and the ability to fabricate extremely thin elements.

  An organic EL element generally includes an anode, a cathode, and an organic EL layer sandwiched between the anode and the cathode. Here, the organic EL layer includes a light emitting layer containing an organic light emitting material. If necessary, the organic EL layer may further include an electron transport layer, an electron injection layer, a hole transport layer, a hole injection layer and the like.

  An organic EL element includes a transparent substrate such as a glass substrate, an anode made of a transparent conductive material such as ITO (indium tin oxide), an organic EL layer, and a cathode made of metal in this order. You may have the bottom emission structure to take out. Alternatively, the organic EL element may have a top emission structure in which a cathode, an organic EL layer, and an anode made of a transparent conductive material are provided on the substrate in this order, and light is extracted from the side opposite to the substrate side. .

  Although an organic EL element has the above-mentioned advantages, it has a problem that light extraction efficiency is low. The light extraction efficiency is the ratio of the total energy amount of light emitted into the atmosphere from the light extraction surface (for example, the substrate surface in the case of the bottom emission type) to the total energy amount of light generated in the light emitting layer. For example, since light generated in the light emitting layer is radiated in all directions, most of the light becomes a waveguide mode in which total reflection is repeated at the interface between two layers having different refractive indexes. For this reason, the light extraction efficiency in the target direction decreases due to the change to heat in the waveguide mode and the emission of light from the side surface of the element.

  In the organic EL element, since the distance between the light emitting layer and the metal cathode is short, a part of the light from the light emitting layer is converted to surface plasmon on the surface of the cathode and lost. This also reduces the light extraction efficiency. Since the light extraction efficiency affects the brightness of a display device, an illuminating device or the like provided with an organic EL element, various methods have been studied for improving the light extraction efficiency.

  As one of the methods for improving the light extraction efficiency, an organic EL element using a glass substrate provided with a condensing layer having a condensing property has been proposed. For example, Japanese Patent Laid-Open No. 2003-86353 discloses a light condensing layer composed of a light converging structure such as a microlens and a transparent resin covering the light converging structure (see Patent Document 1). . In this proposal, the transparent resin has a higher refractive index than the light collecting structure. By providing the condensing layer on the glass substrate, total reflection occurring on the surface of the glass substrate is suppressed, and the light extraction efficiency is improved.

  Further, as one method for improving the light extraction efficiency, a method using surface plasmon resonance has been proposed. For example, Japanese Patent No. 4762542 discloses a method of providing a one-dimensional or two-dimensional periodic microstructure on the surface of a metal layer (cathode) (see Patent Document 2). In this proposal, the periodic microstructure functions as a diffraction grating. Thereby, the energy converted into surface plasmon on the cathode surface is reconverted into light, and the light extraction efficiency is improved.

Japanese Patent Laid-Open No. 2006-173986 includes a transparent substrate, a transparent electrode, an organic layer, and a back electrode in this order. The back electrode is composed of a metal region and a dielectric region, and the dielectric region is made of quartz (SiO ₂ ). The produced organic EL element is proposed (refer patent document 3). In this proposal, the dielectric region made of quartz has concave portions of various shapes formed in the metal region, and the interface between the back electrode and the organic layer is a reflective surface having irregularities. The energy converted into surface plasmons is reconverted into light on the reflective surface having irregularities, thereby improving the light extraction efficiency. However, this proposal does not disclose or suggest whether a similar effect can be obtained when a dielectric region other than quartz is used. In addition, this proposal does not disclose or suggest the problem of color shift caused by the difference in orientation distribution depending on the wavelength.

JP 2003-86353 A Japanese Patent No. 4762542 JP 2006-173986 A

  However, even if the above-mentioned condensing layer is provided on the glass substrate, total reflection occurs at the interface between the condensing layer and the glass substrate, and thus it cannot be said that the light extraction efficiency from the organic EL element is sufficiently high. In addition, when the above-described periodic fine structure is provided in the metal layer, a leakage current is generated due to the uneven structure of the metal layer, and uneven light emission is generated due to nonuniformity of each layer stacked on the metal layer, In addition, there is a problem that the stability over time of the organic EL element is lowered. For this reason, even if a theoretically efficient periodic fine structure is provided in the metal layer, the organic EL element cannot always be manufactured stably. On the other hand, an organic EL element having further improved light extraction efficiency is demanded for power saving of the organic EL lighting device and / or manufacture of a flexible organic EL lighting device.

  An object of this invention is to provide the organic EL element which can implement | achieve high light extraction efficiency. Furthermore, an object of this invention is to provide the illuminating device, planar light source, and display apparatus containing this organic EL element.

The organic EL device according to the first embodiment of the present invention includes a light transmissive substrate, a light transmissive first electrode, a functional layer including a light emitting layer, a patterning unit, and a second electrode in this order. The functional layer is in contact with the patterning portion and the second electrode, the patterning portion is made of lithium fluoride, and the patterning portion has a convex portion on the second electrode side. Here, the area ratio Ap of the patterning portion is
0.02 ≦ Ap ≦ 0.1 (Formula 1)
It is desirable to satisfy. Furthermore, the patterning portion may have a height of 10 nm or more. In addition, a light extraction lens layer may be further included on the surface of the light transmissive substrate opposite to the surface on which the first electrode is provided.

In the first embodiment of the organic EL element according to the first embodiment of the present invention, the patterning portion is composed of a plurality of independent protrusions, each of the plurality of protrusions has a circular bottom shape, The convex portions may be arranged in a square lattice shape or a hexagonal lattice (regular triangular lattice) shape. Here, the distance W1 between the convex portions of the patterning portion is 500 nm ≦ W1 ≦ 2500 nm (Formula 2)
It is desirable to satisfy the relationship.

In the second embodiment of the organic EL element according to the first embodiment of the present invention, the patterning portion has a plurality of first protrusions having a stripe shape extending in the first direction, and a stripe shape extending in the second direction. The first direction may be a direction intersecting with the second direction. Here, the distance W2 between the convex portions of the patterning portion 108 is 500 nm ≦ W2 ≦ 2500 nm (Formula 3)
It is desirable to satisfy the relationship. Furthermore, the patterning portion may have a height of 10 nm or more. In addition, a light extraction lens layer may be further included on the surface of the light transmissive substrate opposite to the surface on which the first electrode is provided.

  The illumination device according to the second embodiment of the present invention includes the organic EL element according to the first embodiment. A planar light source according to the third embodiment of the present invention includes the organic EL element according to the first embodiment. A display device according to a fourth embodiment of the present invention includes the organic EL element according to the first embodiment.

  By adopting the above configuration, an organic EL element having high light extraction efficiency can be provided. Furthermore, by using this organic EL element, it is possible to provide an illumination device, a planar light source, and a display device having excellent characteristics.

It is a schematic sectional drawing of the organic EL element which concerns on the 1st Embodiment of this invention. It is a schematic top view which shows arrangement | positioning of the patterning part in one structural example of the organic EL element which concerns on the 1st aspect of the 1st Embodiment of this invention. It is a schematic sectional drawing which shows arrangement | positioning of the patterning part in one structural example of the organic EL element which concerns on the 1st implementation mode of the 1st Embodiment of this invention along the cutting line III-III. It is a schematic top view which shows arrangement | positioning of the patterning part in another structural example of the organic EL element which concerns on the 1st aspect of the 1st Embodiment of this invention. It is a schematic top view which shows arrangement | positioning of the patterning part in one structural example of the organic EL element which concerns on 2nd aspect of 1st Embodiment of this invention. It is a schematic sectional drawing which shows arrangement | positioning of the patterning part in one structural example of the organic EL element which concerns on the 2nd implementation mode of the 1st Embodiment of this invention along the cutting plane line VI-VI. It is a schematic sectional drawing which shows one modification of the organic EL element which concerns on the 1st Embodiment of this invention. It is a schematic sectional drawing which shows another modification of the organic EL element which concerns on the 1st Embodiment of this invention. It is a perspective view for demonstrating the detail of the arrangement conditions of the patterning part in one structural example of the organic EL element which concerns on the 1st aspect of the 1st Embodiment of this invention. It is sectional drawing for demonstrating the detail of the arrangement conditions of the patterning part in one structural example of the organic EL element which concerns on the 1st aspect of the 1st Embodiment of this invention along the cutting line XX. It is a perspective view for demonstrating the detail of the arrangement conditions of the patterning part in one structural example of the organic EL element which concerns on the 2nd aspect of the 1st Embodiment of this invention. It is sectional drawing for demonstrating the detail of the arrangement conditions of the patterning part in one structural example of the organic EL element which concerns on the 2nd implementation mode of the 1st Embodiment of this invention along the cutting line XII-XII. It is a schematic sectional drawing which shows one structural example of the illuminating device of the 2nd Embodiment of this invention, and the planar light source of 3rd Embodiment. It is a schematic sectional drawing which shows one structural example of the display apparatus of the 4th Embodiment of this invention.

  The present invention will be described with reference to the drawings. The present invention includes an organic EL element, a lighting device including the organic EL element, a planar light source, and a display device. Note that the present invention is not limited to the embodiments described below. Various changes or modifications can be made to the present invention based on the knowledge of those skilled in the art. Embodiments to which such changes or modifications are added are also included in the scope of the present invention.

(I) Organic EL Element The organic EL element of the first embodiment of the present invention includes a substrate, a first electrode, a functional layer, a patterning unit, and a second electrode in this order. One structural example of the organic EL element 100 of this embodiment is shown in FIG. The organic EL element 100 according to this embodiment includes a light transmissive substrate 102, a light transmissive first electrode 104, a functional layer 106 including a light emitting layer, a patterning unit 108 made of lithium fluoride, and a second electrode 110. It has a structure laminated in this order. The organic EL element of the present invention has a bottom emission structure in which light 150 is extracted from the light transmissive substrate 102 side.

  The organic EL element according to the first embodiment of the first embodiment of the present invention includes a patterning unit 108 including a plurality of independent protrusions 202. The convex portion 202 (that is, the patterning portion 108) is formed on the surface of the functional layer 106 on the second electrode 110 side. Each of the plurality of convex portions 202 has a substantially cylindrical shape having a circular bottom surface. In an area where the patterning portion 108 is not formed, the upper surface 204 of the functional layer 106 (hereinafter, may be referred to as “functional layer surface 204”) is in contact with the second electrode 110. In one configuration example of the first aspect of the present embodiment shown in FIG. 2, the plurality of convex portions 202 are arranged in a hexagonal lattice (regular triangular lattice) shape. That is, each of the plurality of convex portions 202 is arranged at the center of a regular hexagon formed by the six closest convex portions 202. In other words, the convex part 202 is arrange | positioned in the vertex and center of a regular hexagon laid without gap.

  3 is a cross-sectional view taken along a cutting line III-III passing through the centers of two adjacent convex portions 202 shown in FIG. As shown in FIG. 3, the upper surface 204 of the functional layer exists between two adjacent convex portions 202 on the surface of the functional layer 106 on the second electrode 110 side. In the present embodiment, the shape of the convex part 202 constituting the patterning part 108 is transferred to the second electrode 110 side. Specifically, the convex portion 202 is transferred to the concave portion 208 of the second electrode 110, and the upper surface 204 of the functional layer may be referred to as a lower surface 206 of the second electrode 110 (hereinafter referred to as “second electrode lower surface 206”). ). In other words, the second electrode 110 has the concave portion 208 at a position corresponding to the convex portion 202 constituting the patterning portion 108. In addition, as long as the convex part 202 which comprises the patterning part 108 is transcribe | transferred to the recessed part 208 of the 2nd electrode 110, the patterning part 108 is provided in the upper surface (surface on the opposite side to the functional layer 106) of the 2nd electrode 110. The shape of the convex part 202 which comprises may not be formed.

  FIG. 4 is a top view showing another configuration example of the organic EL element according to the first mode of the first embodiment of the present invention, in which the plurality of convex portions 202 constituting the patterning unit 108 are in different arrangement states. is there. In this configuration example, the plurality of convex portions 202 are arranged in a square lattice pattern. That is, each of the plurality of convex portions 202 extends in the first direction and extends in a second direction orthogonal to the first direction and a plurality of straight lines arranged at a predetermined interval d, and is arranged at an interval d. Arranged at intersections with a plurality of straight lines. In other words, the convex part 202 is arrange | positioned in the vertex of the square laid without gap.

  The organic EL element according to the second embodiment of the first embodiment of the present invention includes a plurality of first protrusions 222 having a stripe shape extending in the first direction and a plurality of stripe shapes extending in the second direction. It has the patterning part 108 which consists of the 2nd convex part 224. FIG. Here, the first direction is a direction intersecting the second direction, preferably a direction orthogonal to the second direction. FIG. 5 is a configuration example in which the first direction is a direction orthogonal to the second direction, and the interval between the two adjacent first convex portions 222 is equal to the interval between the two adjacent second convex portions. FIG. The first convex portion 222 and the second convex portion 224 (that is, the patterning portion 108) are formed on the surface of the functional layer 106 on the second electrode 110 side. In the area where the patterning portion 108 is not formed, the upper surface 204 of the functional layer 106 is in contact with the second electrode 110. In the configuration example shown in FIG. 5, the upper surface 204 of the functional layer 106 is composed of a plurality of separated areas. One area of the upper surface 204 of the functional layer 106 surrounded by the two adjacent first protrusions 222 and the two adjacent second protrusions 224 has a square shape.

  FIG. 6 is a cross-sectional view taken along a cutting line VI-VI extending in the second direction through the center of two adjacent second convex portions 224 shown in FIG. As shown in FIG. 6, on the surface of the functional layer 106 on the second electrode 110 side, the upper surface of the functional layer is surrounded by the two adjacent first convex portions 222 and the two adjacent second convex portions 224. 204 exists. In the present embodiment, the shapes of the first and second convex portions 222 and 224 constituting the patterning unit 108 are transferred to the second electrode 110 side. Specifically, the first convex portion 222 and the second convex portion 224 are transferred to the concave portion 208 of the second electrode 110, and the upper surface 204 of the functional layer is transferred to the lower surface 206 of the second electrode 110 (hereinafter referred to as “second electrode”). Transferred to the lower surface 206). In other words, the second electrode 110 has the concave portion 208 at a position corresponding to the first convex portion 222 and the second convex portion 224 constituting the patterning portion 108. In addition, as long as the 1st convex part 222 and the 2nd convex part 224 which comprise the patterning part 108 are transcribe | transferred to the recessed part 208 of the 2nd electrode 110, it is the upper surface (the side opposite to the functional layer 106) of the 2nd electrode 110. The shape of the convex portion 202 constituting the patterning portion 108 may not be formed on the surface).

  The specific shapes of the patterning unit 108 and the second electrode 110 in the present invention will be described in detail in the following “patterning unit” and “second electrode” sections.

  The first electrode 104 is a light-transmitting electrode that serves as an anode. The functional layer 106 includes a light emitting layer. The second electrode 110 is an electrode serving as a counter electrode of the first electrode 104 and serves as a cathode.

  In the present specification, “light-transmitting” means a property (translucency) that is transparent to light. The light transmissive material used in the present invention preferably transmits light from the ultraviolet region to the infrared region. In the wavelength region, the average transmittance is preferably 50% or more at 350 nm to 800 nm, and more preferably 80% or more.

  As shown in FIG. 7, one modified example of the organic EL element according to the first embodiment of the present invention includes a condensing lens layer 302 on the surface of the light transmissive substrate 102 opposite to the first electrode 104. A light extraction lens layer 310 including a light transmissive layer 304 may be further included.

  As shown in FIG. 8, another modification of the organic EL element according to the first embodiment of the present invention may further include a barrier layer 320 and / or a light scattering layer 330. The barrier layer 320 is a layer for preventing intrusion of moisture or the like harmful to the first electrode 104, the functional layer 106, and the second electrode 110. In order to express this function more effectively, it is desirable to provide a barrier layer 320 between the light transmissive substrate 102 and the first electrode 104 as shown in FIG. Also in this configuration example, as shown in FIG. 7, a light extraction lens layer 310 may further be included.

  Next, each part which comprises the organic EL element 100 is demonstrated in detail.

[Light transmissive substrate]
The light transmissive substrate 102 is a plate-like member that transmits predetermined light (preferably light in the visible region). The material is not particularly limited as long as it is conventionally used for organic EL elements such as glass and plastic. The light transmissive substrate 102 is preferably a glass plate, a plate made of a polymer, a film, or the like.

  Examples of glasses that can be used include soda lime glass, barium strontium containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass, and the like.

  Examples of polymers that can be used include, for example, the following materials: polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN); polyolefins such as polyethylene, polypropylene, polymethylpentene; cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose esters such as cellulose acetate phthalate, cellulose nitrate, or derivatives thereof; polyvinylidene chloride; polyvinyl alcohol; polyethylene vinyl alcohol; syndiotactic polystyrene Polycarbonate; polyetherketone; polyimide; polyethersulfone (PES); polypheny Nsurufido; including cycloolefin resins such as norbornene resins; polysulfones; polyetherimides; polyether ketone imide; polyarylate, acrylic resins such as polymethylmethacrylate (PMMA).

  When a polymer plate or a polymer film is used as the light transmissive substrate 102, a polymer plate with a barrier coating or a polymer film with a barrier coating in which a barrier coating described below is previously provided on the surface of the polymer plate or polymer film may be used. it can. The barrier coating can be formed from the same material as the barrier layer 320 described below.

[Barrier layer]
The barrier layer 320 is an optional component of the organic EL element of the present invention. The barrier layer 320 has a function of suppressing entry of moisture, oxygen, and the like that cause deterioration of the organic EL element 100 (particularly, the functional layer 106). The barrier layer 320 may be an inorganic film or a hybrid film including both an inorganic film and an organic film. Examples of the inorganic material for forming the barrier layer 320 include silicon oxide, silicon dioxide, silicon nitride, and the like. The hybrid coating is useful in eliminating the mechanical fragility of the inorganic coating. The hybrid film preferably has a structure in which an inorganic film and an organic film are laminated. Examples of organic materials used in the hybrid coating include polyvinyl alcohol resins, acrylic resins, and the like. There are no particular restrictions on the number of inorganic and organic coatings in the hybrid coating and the order of lamination. More preferably, the hybrid coating has a structure in which inorganic coatings and organic coatings are alternately laminated.

The barrier layer 320 has a water vapor permeability (25 ± 0.5 ° C., 90 ± 2) measured by a method according to JIS K 7129-1992, which is 1.0 × 10 ⁻² g / (m ² · 24 h) or less. % RH). More preferably, the barrier layer 320 has a water vapor transmission rate of 1.0 × 10 ⁻⁵ g / (m ² · 24 h) or less. Furthermore, the barrier layer 320 preferably has an oxygen permeability of 1.0 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, which is measured by a method according to JIS K 7126-1987. Most preferably, the barrier layer 320 has an oxygen permeability of 1.0 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, and 1.0 × 10 ⁻³ g / (m ² · 24 h) or less. Having both water vapor permeability.

  The barrier layer 320 can be formed using any means conventionally used in this technical field. Examples of means that can be used include vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, plasma CVD, Including laser CVD method, thermal CVD method and the like.

[Light scattering layer]
The light scattering layer 330 is an optional component of the organic EL element of the present invention. Fine particles may be added to the light scattering layer 330.

  The fine particles added for the purpose of imparting light scattering properties may be inorganic fine particles, organic fine particles, or a combination thereof. Organic fine particles that can be used include fine particles composed of acrylic polymers, styrene polymers, styrene-acrylic polymers and cross-linked products thereof, melamine-formaldehyde condensates, polyurethanes, polyesters, silicones, fluoropolymers, and copolymers thereof. . Inorganic fine particles that can be used are: clay compound particles such as smectite, kaolinite, talc; fine particles composed of inorganic oxides such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, strontium oxide; carbonic acid Fine particles composed of inorganic compounds such as calcium, barium carbonate, barium chloride, barium sulfate, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide; and two or more types It contains fine particles made of a glass material obtained by sintering an inorganic oxide. A combination of two or more kinds of organic fine particles and / or inorganic fine particles may be used.

  Further, fine particles may be added to the light scattering layer 330 for the purpose of adjusting the refractive index. The fine particles added for the purpose of adjusting the refractive index include fine particles made of an inorganic oxide such as titanium oxide or zirconia.

(First electrode 104: anode)
When the first electrode 104 is used as an anode, the first electrode 104 is formed from a material having a large work function. Materials that can be used include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. The materials for forming the first electrode 104 used as the anode are: antimony-doped (added) tin oxide (ATO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), conductive metal oxides such as indium zinc oxide (IZO); metals such as gold, silver, chromium and nickel; mixtures of these metals and conductive metal oxides; copper iodide, copper sulfide, etc. Inorganic conductive materials; including organic conductive materials such as polyaniline, polythiophene, and polypyrrole. The first electrode 104 may be a stacked body. For example, the first electrode 104 may be a stacked body of layers made of the above materials. In the present invention, the first electrode 104 is preferably formed using a conductive metal oxide. In view of productivity, high conductivity, transparency, etc., it is particularly preferable to form the first electrode 104 using ITO.

  In the case where light emitted from the side of the first electrode 104 used as the anode is extracted, the first electrode 104 preferably has a light transmittance greater than 50%. The first electrode 104 preferably has a sheet resistance of several hundred Ω / □ or less. Furthermore, although it depends on the material to be used, the first electrode 104 has a film thickness usually in the range of 10 nm to 1000 nm, preferably in the range of 10 nm to 200 nm.

[Functional layer]
The functional layer 106 provided between the first electrode 104 and the second electrode 110 includes at least a light emitting layer. The functional layer may further include a hole injection layer, a hole transport layer, an electron transport layer, and / or an electron injection layer.

  The first electrode 104, the functional layer 106, and the second electrode 110 can have various stacked structures. Specific examples of the laminated structure that can be adopted include, but are not limited to, the following layer configurations (a) to (p), for example. In the following layer configuration, the “anode” may be the first electrode 104, and the “cathode” may be the second electrode 110. The symbol “/” indicates that two layers are stacked adjacent to each other.

(A) Anode / light emitting layer / cathode (b) Anode / hole injection layer / light emitting layer / cathode (c) Anode / hole injection layer / light emitting layer / electron injection layer / cathode (d) Anode / hole injection layer / Emission layer / electron transport layer / cathode (e) anode / hole injection layer / emission layer / electron transport layer / electron injection layer / cathode (f) anode / hole transport layer / emission layer / cathode (g) anode / Hole transport layer / light emitting layer / electron injection layer / cathode (h) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (i) Anode / hole transport layer / light emitting layer / electron transport layer / electron injection Layer / cathode (j) anode / hole injection layer / hole transport layer / light emitting layer / cathode (k) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode (l) anode / Hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode (m) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (n) anode / Emission layer / electron injection layer / cathode (o) anode / emission layer / electron transport layer / cathode (p) anode / emission layer / electron transport layer / electron injection layer / cathode

  Hereinafter, each layer constituting the functional layer 106 will be described.

(Light emitting layer)
The light emitting layer is a layer that emits light by recombination of electrons and holes injected from the electrodes. The portion that emits light may be within the layer of the light emitting layer, or may be the interface between the light emitting layer and the adjacent layer.

  The light emitting layer may contain a light emitting host compound and a light emitting dopant compound such as a phosphorescent dopant and a fluorescent dopant. Examples of the light-emitting host compound include those having a basic skeleton such as a carbazole derivative, a triarylamine derivative, an aromatic derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, and an oligoarylene compound, or a carboline derivative or diazacarbazole. Including derivatives. Luminescent dopant compounds include, for example, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, Includes stilbene dyes, polythiophene dyes, rare earth complexes, and the like.

  The light emitting layer may be a single layer or a laminate of a plurality of layers. The light emitting layer which is a single layer may be at least one of a blue light emitting layer, a green light emitting layer and a red light emitting layer. In the present specification, “blue light emitting layer” means a monochromatic light emitting layer having an emission maximum wavelength of 430 nm or more and 480 nm or less, and “green light emitting layer” means a monochromatic light emitting layer having an emission maximum wavelength of 510 nm or more and 550 nm or less. The “red light emitting layer” means a monochromatic light emitting layer having an emission maximum wavelength of 600 nm or more and 640 nm or less. You may use the light emitting layer which has light emission maximum wavelengths other than the above.

  One structural example of the light emitting layer which is a multilayered laminate is a white light emitting layer including three colors (a blue light emitting sublayer, a green light emitting sublayer, and a red light emitting sublayer). “Blue”, “green” and “red” relating to the light-emitting sublayer mean that the light emission maximum wavelength is provided. In the light-emitting layer that is a multilayer structure, a non-light-emitting intermediate layer may be provided between two light-emitting sublayers.

  The light emitting layer of the organic EL device 100 of the present invention is preferably a white light emitting layer. That is, the organic EL element 100 of the present invention is particularly effective when the light emitting layer of the organic EL element is a white light emitting layer. Moreover, it is preferable that the illuminating device, planar light source, and display apparatus of this invention contain a white light emitting layer. Therefore, it is preferable that the illuminating device, the planar light source, and the display device of the present invention have at least part of an organic EL element including a white light emitting layer.

  The total film thickness of the light emitting layer is not particularly limited. The light emitting layer preferably has a thickness in the range of 2 nm to 5 μm, more preferably in the range of 2 nm to 200 nm, and particularly preferably in the range of 10 nm to 20 nm. A film thickness within the above range contributes to improving the uniformity of the film, preventing unnecessary application of a high voltage during light emission, and improving the stability of the emission color with respect to the drive current.

(Injection layer: hole injection layer, electron injection layer)
The injection layer is a layer provided between the electrode and the light emitting layer as necessary in order to lower the driving voltage, improve the light emission luminance, and the like.

(Hole injection layer)
The hole injection layer may be provided between the anode and the light-emitting layer (for example, the layer configuration (b) to (e) described above), or between the anode and the hole transport layer (for example, the above-described layer configuration (b) to (e)). (Layer configuration (j) to (m)) may be provided. Materials for forming the hole injection layer include: phthalocyanines typified by copper phthalocyanine; oxides typified by vanadium oxide; amorphous carbon; conductive polymers such as polyaniline (emeraldine) and polythiophene.

(Electron injection layer)
The electron injection layer may be provided between the cathode and the light-emitting layer (for example, the above layer configuration (c), (g), (k), and (n)), or the cathode and the electron transport layer. (For example, the layer configurations (e), (i), (m), and (p) described above). Materials for forming the electron injection layer are: metals typified by strontium and aluminum; alkali metal compounds typified by lithium fluoride; alkaline earth metal compounds typified by magnesium fluoride; typified by aluminum oxide Including oxides.

  When the electron injection layer is provided in the present invention, the electron injection layer is preferably formed of lithium fluoride. This is because the patterning portion 108 in contact with the electron injection layer is formed of lithium fluoride. Then, by forming the electron injection layer with lithium fluoride, the adhesion between the patterning portion 108 which is a thin film and the electron injection layer (functional layer 106) can be improved, and the patterning portion 108 can be formed more stably. It becomes possible. In particular, in the organic EL element of the first embodiment, since the patterning unit 108 is divided into a plurality of minute areas, an electron injection layer made of lithium fluoride is effective.

  Although depending on the material used, the hole injection layer and the electron injection layer preferably have a film thickness in the range of 0.1 nm to 5 μm.

(Transport layer: electron transport layer, electron transport layer)
The transport layer is a layer provided between the electrode and the light-emitting layer as necessary for transporting holes or electrons.

(Hole transport layer)
The hole transport layer may be provided between the anode and the light emitting layer (for example, the above layer configuration (f) to (i)), or between the hole injection layer and the light emitting layer (for example, the above). The layer configurations (j) to (m)) may be provided. The hole transport material for forming the hole transport layer desirably has a high hole transfer rate. In addition, the hole transport material may have properties that facilitate hole injection or provide a barrier to electron transfer.

  The hole transport material may be organic or inorganic. Non-limiting examples of hole transport materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, It includes styryl anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, and conductive polymer oligomers such as aniline copolymers and thiophene oligomers. The hole transport layer may include one or more hole transport materials.

  The hole transport layer may include one or more hole transport materials. Alternatively, the hole transport layer may be a single layer or may have a laminated structure composed of a plurality of sublayers. The hole transport layer can be formed using a technique well known in the art such as a vacuum evaporation method. The hole transport layer usually has a thickness in the range of 5 nm to 5 μm, preferably in the range of 5 nm to 200 nm.

(Electron transport layer)
The electron transport layer may be provided between the cathode and the light emitting layer (for example, in the above layer configuration (d), (h), (l), and (o)), or the electron injection layer and the light emitting layer. (For example, the above-described layer configuration (e), (i), (m), and (p)). The electron transport material for forming the electron transport layer desirably has a high electron moving speed. In addition, the electron transport material may have properties that facilitate electron injection or serve as a barrier to hole transfer.

  Non-limiting examples of electron transport materials are nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, anthraquinodimethane derivatives, anthrone derivatives, oxadiazole derivatives, thiadiazole Including derivatives. Here, the oxadiazole derivative may have a quinoxaline ring known as an electron withdrawing group. Alternatively, a polymer material having a partial structure selected from the group consisting of nitro-substituted fluorene, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, anthraquinodimethane, anthrone, oxadiazole, and thiadiazole. It may be used as an electron transport material.

  Non-limiting examples of electron transport materials include metal complexes of 8-quinolinol derivatives. Non-limiting examples of 8-quinolinol derivatives that can be used include 8-quinolinol, 5,7-dichloro-8-quinolinol, 5,7-dibromo-8-quinolinol, 2-methyl-8-quinolinol, 5- Methyl-8-quinolinol) aluminum. Central metals that can be used include Al, Zn, In, Mg, Cu, Ca, Sn, Ga, and Pb. Metal complexes of 8-quinolinol derivatives include tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, tris ( Examples include, but are not limited to, 2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, and bis (8-quinolinol) zinc (Znq).

  Non-limiting examples of electron transport materials include phthalocyanine derivatives and metal complexes thereof. The phthalocyanine derivative may have a substituent such as an alkyl group or a sulfonic acid group. Although depending on the layer configuration, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can be used as the electron transporting material.

  The electron transport layer may include one or more kinds of electron transport materials. Alternatively, the electron transport layer may be a single layer or may have a laminated structure including a plurality of sublayers. The electron transport layer can be formed using a technique well known in the art such as a vacuum evaporation method. The electron transport layer usually has a thickness in the range of 5 nm to 5 μm, preferably in the range of 5 nm to 200 nm.

[Patterning part]
As shown in FIGS. 3 and 6, the patterning portion 108 made of lithium fluoride is formed on the surface of the functional layer 106 on the second electrode 110 side. As shown in FIGS. 2 and 4, in the first embodiment, the patterning unit 108 includes a plurality of convex portions 202 having a circular bottom shape. In the first embodiment, the upper surface 204 of the functional layer 106 is in contact with the second electrode 110 (more specifically, the lower surface 206 of the second electrode 110) in an area where the patterning unit 108 is not present. As shown in FIG. 5, in the second embodiment, the patterning unit 108 includes a plurality of first convex portions 222 having a stripe shape extending in the first direction and a plurality of stripe shapes extending in the second direction. The second convex portion 224 is included. Here, the first direction is a direction intersecting the second direction, preferably a direction orthogonal to the second direction. Also in the second embodiment, the upper surface 204 of the functional layer 106 is in contact with the second electrode 110 (more specifically, the lower surface 206 of the second electrode 110) in an area where the patterning unit 108 does not exist. .

  First, the first embodiment will be described with reference to FIGS. 2 to 4, 9 and 10. FIG. 2 is a top view showing one configuration example of the organic EL element of the first embodiment, and FIG. 3 shows the organic EL element of the first embodiment along the section line III-III in FIG. It is sectional drawing which shows one structural example of these. As shown in FIG. 3, the convex portion 202 of the patterning unit 108 corresponds to the concave portion 208 of the second electrode 110, and the upper surface 204 of the functional layer 106 corresponds to the lower surface 206 of the second electrode 110. In other words, the second electrode 110 has a plurality of concave portions 208 at positions where the plurality of convex portions 202 of the patterning unit 108 are formed.

  In the present embodiment, the plurality of convex portions 202 constituting the patterning portion 108 are arranged in a hexagonal lattice (regular triangular lattice). The plurality of convex portions 202 have a substantially cylindrical shape having a circular bottom surface. The upper bottom surface of the substantially cylindrical shape may be a curved surface that is highest at the center and lowers toward the peripheral edge due to the influence of the boundary conditions of mask vapor deposition described later. Therefore, in each of the plurality of convex portions 202, in the cross section passing through the diameter of the lower bottom surface (for example, the cross section 602 shown in FIG. 9), the point of the upper bottom surface that is equidistant from the side surface and the vertex 402 that is the highest point Are substantially the same. For example, in the cross section in FIG. 10, a point on the upper bottom surface that is equidistant from two intersections between a line having a height of H1a / 2 and both side surfaces of the convex portion 202 can be regarded as the vertex 402.

The patterning unit 108 needs to satisfy the following conditions. First, the area ratio Ap of the patterning unit 108 is 0.02 or more and 0.1 or less. In other words, the area ratio Ap of the patterning unit 108 is as follows (Formula 1):
0.02 ≦ Ap ≦ 0.1 (Formula 1)
Meet. Here, the area ratio Ap of the patterning unit 108 is the ratio of the area of the upper surface of the functional layer 106 in contact with the patterning unit 108 to the total area of the measurement region. In other words, the area ratio Ap of the patterning unit 108 is a ratio of the area of the patterning unit 108 (specifically, the total area of the convex portions 202) to the total area of the measurement region in a top view.

  The area ratio Ap of the patterning unit 108 can be obtained by observing desired regions of the functional layer 106 and the patterning unit 108 with a scanning probe microscope (for example, AFM5400 manufactured by Hitachi High-Tech Science Corporation). In the present invention, it is desirable to observe a region including three or more convex portions 202. In the present invention, 10 or more regions are observed, the area ratio Ap obtained in each region is obtained, and whether (Equation 1) is satisfied using the arithmetic average value of the area ratio Ap for each obtained region is determined. Can be determined.

  Next, conditions regarding the arrangement of the convex portions 202 of the patterning unit 108 in the organic EL element according to the first embodiment of the first embodiment will be described. FIG. 9 is a perspective view showing one configuration example of the organic EL element 100 of the first embodiment, and FIG. 10 is a cross-sectional view of the organic EL element 100 of the first embodiment along the cutting line XX. It is sectional drawing which shows one structural example. In this invention, the convex part adjacent to one convex part 202a shown in FIG. 9 means the six convex parts 202b-g. The cutting line XX corresponds to a straight line passing through each vertex of the convex portions 202c and 202e adjacent to one convex portion 202a. In other words, the cutting line XX is a straight line passing through the vertex 402a of the convex portion 202a and the vertices 402c and 402e of the two convex portions 202c and 202e. The cross section 602 is orthogonal to the main surface of the light transmissive substrate 102.

  One convex portion 202a has a vertex 402a having a maximum height from the bottom surface of the functional layer 106. The height of the vertex 402a from the bottom surface of the functional layer 106 is defined as H10. In addition, in the cross section shown in FIG. 10, the upper surface 204a of the functional layer 106 is flat between the two convex portions 202c and 202e adjacent to the convex portion 202a. The height of the upper surface 204 of the functional layer 106 is defined as H11. And the value of H10-H11 is defined as the height H1a of the convex part 202a. In other words, the difference between the minimum value and the maximum value when the functional layer 106 in which the patterning portion 108 is formed is observed along the cutting line XX corresponds to the height H1a of the convex portion 202a. In the present invention, the cross section corresponding to the cross section 602 is observed for 10 or more convex portions 202, and the arithmetic average value of the obtained height H1a is obtained as the height H1 of the patterning portion 108. H1 is preferably 10 nm or more. When H1 has a numerical value in the above range, the recess 208 of the second electrode 110 stacked on the patterning unit 108 and the lower surface 206 of the second electrode 110 existing at the position of the upper surface 204 of the functional layer 106 are provided. The height difference can be maintained. This is important in obtaining the effect of re-radiation by surface plasmon conversion in the second electrode 110. The measurement of the height H1 can be performed by top surface observation using a scanning probe microscope, cross-sectional observation using an electron microscope, or the like.

Further, as shown in FIG. 10, the horizontal distance between the vertex 402a of one convex portion 202a and the vertex 402c of the adjacent convex portion 202c is defined as a width W1c. Similarly, a horizontal distance between the vertex 402a and the vertex 402e between the convex portion 202c and the adjacent convex portion 202e on the opposite side is defined as a width W1e. Here, the “horizontal distance” means a distance in a direction parallel to the main surface of the light transmissive substrate 102. In this embodiment, it is desirable that the arithmetic average value W1 of W1c and W1e (hereinafter sometimes referred to as “distance between protrusions W1”) is in the range of 500 nm to 2500 nm. In other words, in the present embodiment, the inter-convex distance W1 is expressed by the following (Equation 2).
500 nm ≦ W1 ≦ 2500 nm (Formula 2)
It is desirable to satisfy. By setting such an inter-convex distance W1, it is possible to give the second electrode 110 a shape that reflects light emitted from the functional layer 106 toward the light-transmissive substrate 102 with high efficiency. Become. In the present invention, the cross section corresponding to the cross section 602 is observed for 10 or more convex portions 202, W1c and W1e obtained in each cross section are obtained, and each cross section is substituted into the formula W1 = (W1c + W1e) / 2. The distance W1 between the convex portions is obtained. And the arithmetic mean value of W1 obtained can be calculated | required, and the distance W1 between convex parts of the patterning part 108 can be determined. The inter-convex distance W <b> 1 within the above-described range is important in obtaining the effect of re-radiation by the surface plasmon conversion in the second electrode 110. The determination of the inter-convex distance W1 can be performed by top surface observation using a scanning probe microscope, cross-section observation using an electron microscope, or the like.

  In the present invention, as long as the area ratio of the patterning portion 108 and the distance W1 between the protrusions are within the above-described range, the plurality of protrusions 202 of the patterning portion 108 may be arranged periodically or randomly. May be.

  When the patterning unit 108 satisfies the condition of (Formula 1), the upper surface 204 of the functional layer 106 (that is, the lower surface 206 of the second electrode 110), which is a carrier injection surface from the second electrode 110 to the functional layer 106. Can have a sufficient area. Specifically, since the patterning unit 108 has a height H1 of 10 nm or more, the patterning unit 108 functions as an insulating unit when a voltage is applied between the first electrode 104 and the second electrode 110. In other words, the area where the patterning unit 108 is formed is a non-light-emitting area where carrier injection from the second electrode 110 to the functional layer 106 does not occur. On the other hand, the upper surface 204 of the functional layer 106 (that is, the lower surface 206 of the second electrode 110) functions as a carrier injection surface, and an area corresponding to the upper surface 204 of the functional layer 106 in the top view is a light emitting area. Therefore, when the patterning unit 108 has an area ratio satisfying (Equation 1), a light emitting area having a sufficient area can be obtained.

  Furthermore, when the patterning unit 108 satisfies the conditions of (Expression 1) and (Expression 2), it is possible to realize effective light reflection at the second electrode 110. Specifically, part of the light emitted from the functional layer 106 and reaching the second electrode 110 generates surface plasmons in the second electrode 110. Since the second electrode 110 of the present embodiment has the concave portion 208 corresponding to the patterning portion 108 that satisfies the height H1 of 10 nm or more and the inter-convex distance W1 of 500 nm or more and 2500 nm or less, the generated surface plasmon is reconverted. Then, it is re-emitted as light directed to the light-transmitting substrate 102. For this reason, the amount of light emission per current density increases, and the light emission efficiency increases. In addition, the upper surface 204 of the functional layer 106 (that is, the lower surface 206 of the second electrode 110) is a smooth surface and has a high reflectance. Therefore, part of the light emitted from the functional layer 106 and reaching the second electrode 110 is reflected toward the light transmissive substrate 102. Further, the light emitted from the functional layer 106 and reaching the second electrode 110 through the patterning unit 108 is also reflected toward the light transmissive substrate 102 through the patterning unit 108. Here, since the patterning unit 108 is made of lithium fluoride having high transmittance in the visible light region, the amount of light absorbed by the patterning unit 108 is small.

  As described above, since a light-emitting area having a sufficient area can be obtained and reflection at the second electrode 110 can be effectively performed, high light extraction efficiency can be obtained in the organic EL element of this embodiment. . In addition, since the plurality of concave portions 208 are formed in the second electrode 110 by the plurality of convex portions 202 constituting the patterning portion 108, the second electrode 110 can be compared with the case where the planar second electrode is used. The direction in which the reflected light is directed varies. The presence of reflected light directed in various directions is effective in suppressing color shift caused by the difference in orientation distribution depending on the wavelength.

  FIG. 4 is a top view showing another configuration example of the organic EL element according to the first embodiment of the first embodiment. In this configuration example, the patterning unit 108 includes a plurality of convex portions 202 arranged in a square lattice pattern. The area ratio, the height H1, and the inter-convex distance W1 of the patterning unit 108 can be determined in the same manner as in the above-described first configuration example, and are within the same ranges as in the first configuration example. The organic EL element of this configuration example is also effective for high light extraction efficiency and suppression of color shift, as in the first configuration example.

  Next, the second embodiment will be described with reference to FIGS. 5, 6, 11 and 12. FIG. 5 is a top view showing a configuration example of the organic EL element of the second embodiment, and FIG. 6 is a configuration of the organic EL element of the second embodiment along the cutting line VI-VI in FIG. It is sectional drawing which shows an example. As shown in FIG. 5, the patterning unit 108 includes a plurality of stripe-shaped first protrusions 222 extending in the first direction and a plurality of stripe-shaped second protrusions 224 extending in the second direction. In the configuration example of FIG. 5, the first direction is a direction orthogonal to the second direction. The cutting line VI-VI is a straight line extending in a second direction that is equidistant from two adjacent second convex portions 224. As shown in FIG. 6, the first convex portion 222 and the second convex portion 224 of the patterning portion 108 correspond to the concave portion 208 of the second electrode, and the upper surface 204 of the functional layer 106 is on the lower surface 206 of the second electrode 110. Correspond. In other words, the second electrode 110 has a plurality of recesses 208 at positions where the plurality of first protrusions 222 and the second protrusions 224 of the patterning unit 108 are formed.

  The plurality of first protrusions 222 and second protrusions 224 constituting the patterning unit 108 in this embodiment have a substantially prismatic shape having a rectangular bottom surface. The upper surface of the substantially prismatic shape may be a curved surface that is highest at the center and lowers toward the peripheral edge due to the influence of the boundary conditions of mask vapor deposition described later. Therefore, in each of the plurality of first protrusions 222 extending in the first direction, a cross section orthogonal to the first direction (for example, in the cross section 604 shown in FIG. The vertex 402, which is a high point, is substantially the same, for example, in the cross section in Fig. 12, which is equidistant from two intersections between the line having a height of H1a / 2 and both side surfaces of the first convex portion 222. A point on the upper surface can also be regarded as the vertex 402. The same applies to the plurality of second convex portions 224.

  The patterning unit 108 of this embodiment needs to satisfy the condition of (Equation 1) as in the first embodiment.

  Next, conditions regarding the arrangement of the first and second protrusions 222 and 224 of the patterning unit 108 in the organic EL element according to the second embodiment of the first embodiment will be described. FIG. 11 is a perspective view illustrating a configuration example of the organic EL element 100 according to the second embodiment, and FIG. 12 illustrates a configuration example of the organic EL element 100 according to the second embodiment along the cutting line XII-XII. FIG. The cutting line XII-XII is a straight line extending in the second direction that is equidistant from the two adjacent second convex portions 224. The cross section 604 is perpendicular to the first direction and is orthogonal to the main surface of the light transmissive substrate 102.

  One first convex portion 222a has a vertex 402a having a maximum height from the bottom surface of the functional layer 106. The height of the vertex 402a from the bottom surface of the functional layer 106 is defined as H10. In addition, in the cross section shown in FIG. 12, the upper surface of the functional layer 106 is flat between the two first convex portions 222c and the first convex portions 222e adjacent to the first convex portion 222a. It has surfaces 204c and 204e. The height of the upper surface 204 of the functional layer 106 is defined as H11. And the value of H10-H11 is defined as the height H1a of the 1st convex part 222a. In other words, the difference between the minimum value and the maximum value when the functional layer 106 on which the patterning portion 108 is formed is observed along the cutting line XX corresponds to the height H1a of the first convex portion 222a. To do.

  Further, as shown in FIG. 12, the horizontal distance between the vertex 402a of one first convex portion 222a and the vertex 402c of the adjacent first convex portion 222c is defined as a width W2c. Similarly, a horizontal distance between the vertex 402a and the vertex 402e between the first convex portion 222e opposite to the first convex portion 222c is defined as a width W2e. Here, the “horizontal distance” means a distance in a direction parallel to the main surface of the light transmissive substrate 102. The inter-convex distance W2 in this embodiment is an arithmetic average value of W2c and W2e (that is, W2 = (W2c + W2e) / 2).

  Also for the second convex portion 224, the height H1a and the inter-convex distance W1 can be measured by the same procedure as described above.

  In the present invention, the height H1a is measured at the ten or more first convex portions 222 and the ten or more second convex portions 224, and the arithmetic average value of the obtained height H1a is obtained to obtain the patterning portion 108. The height is H1. H1 is preferably 10 nm or more. When H1 has a numerical value in the above range, the recess 208 of the second electrode 110 stacked on the patterning unit 108 and the lower surface 206 of the second electrode 110 existing at the position of the upper surface 204 of the functional layer 106 are provided. The height difference can be maintained. This is important in obtaining the effect of re-radiation by surface plasmon conversion in the second electrode 110. The measurement of the height H1 can be performed by top surface observation using a scanning probe microscope, cross-sectional observation using an electron microscope, or the like.

Similarly, in the present invention, the inter-convex distance W2 is measured at 10 or more first convex portions 222 and 10 or more second convex portions 224, and the arithmetic average value of the obtained inter-convex distance W2 is measured. Is determined as the distance W2 between the convex portions of the patterning portion 108. In the present embodiment, it is desirable that the inter-convex distance W2 is in the range of 500 nm to 2500 nm. In other words, in the present embodiment, the inter-convex distance W2 is expressed by the following (Equation 3).
500 nm ≦ W2 ≦ 2500 nm (Formula 3)
It is desirable to satisfy. By setting such an inter-convex distance W2, it is possible to give the second electrode 110 a shape that reflects light emitted from the functional layer 106 toward the light transmissive substrate 102 with high efficiency. Become. The determination of the inter-convex distance W2 can be performed by top surface observation using a scanning probe microscope, cross-section observation using an electron microscope, or the like.

  Also in this embodiment, when the patterning unit 108 satisfies the condition of (Equation 1), the upper surface 204 of the functional layer 106 (that is, the second electrode) that is a carrier injection surface from the second electrode 110 to the functional layer 106. The lower surface 206) of 110 can have a sufficient area. Specifically, since the patterning unit 108 has a height H1 of 10 nm or more, the patterning unit 108 functions as an insulating unit when a voltage is applied between the first electrode 104 and the second electrode 110. In other words, the area where the patterning unit 108 is formed is a non-light-emitting area where carrier injection from the second electrode 110 to the functional layer 106 does not occur. On the other hand, the upper surface 204 of the functional layer 106 (that is, the lower surface 206 of the second electrode 110) functions as a carrier injection surface, and an area corresponding to the upper surface 204 of the functional layer 106 in the top view is a light emitting area. Therefore, when the patterning unit 108 has an area ratio satisfying (Equation 1), a light emitting area having a sufficient area can be obtained.

  Furthermore, when the patterning unit 108 satisfies the conditions of (Expression 1) and (Expression 3), it is possible to realize effective light reflection at the second electrode 110. Specifically, part of the light emitted from the functional layer 106 and reaching the second electrode 110 generates surface plasmons in the second electrode 110. Since the second electrode 110 of the present embodiment has the concave portion 208 corresponding to the patterning portion 108 that satisfies the height H1 of 10 nm or more and the inter-convex distance W2 of 500 nm or more and 2500 nm or less, the generated surface plasmon is reconverted. Then, it is re-emitted as light directed to the light-transmitting substrate 102. For this reason, the amount of light emission per current density increases, and the light emission efficiency increases. In addition, the upper surface 204 of the functional layer 106 (that is, the lower surface 206 of the second electrode 110) is a smooth surface and has a high reflectance. Therefore, part of the light emitted from the functional layer 106 and reaching the second electrode 110 is reflected toward the light transmissive substrate 102. Further, the light emitted from the functional layer 106 and reaching the second electrode 110 through the patterning unit 108 is also reflected toward the light transmissive substrate 102 through the patterning unit 108. Here, since the patterning unit 108 is made of lithium fluoride having high transmittance in the visible light region, the amount of light absorbed by the patterning unit 108 is small.

  As described above, since a light-emitting area having a sufficient area can be obtained and reflection at the second electrode 110 can be effectively performed, high light extraction efficiency can be obtained in the organic EL element of this embodiment. . In addition, since the plurality of concave portions 208 are formed in the second electrode 110 by the plurality of convex portions 202 constituting the patterning portion 108, the second electrode 110 can be compared with the case where the planar second electrode is used. The direction in which the reflected light is directed varies. The presence of reflected light directed in various directions is effective in suppressing color shift caused by the difference in orientation distribution depending on the wavelength.

(Second electrode: cathode)
As described above, the shape of the patterning unit 108 is transferred to the second electrode 110. Specifically, as shown in FIG. 2 and FIG. 3, or FIG. 5 and FIG. 6, the shape of the convex part 202, the first convex part 222, and the second convex part 224 of the patterning part 108 is the second Transferred to the recess 208 of the electrode 110. The lower surface 206 of the second electrode 110 is formed in an area where the patterning unit 108 does not exist (that is, an area where the upper surface 204 of the functional layer 106 is exposed). The shape of the patterning unit 108 is transferred to at least the surface of the second electrode 110 on the light transmissive substrate 102 side. The shape of the patterning unit 108 may or may not be reflected on the surface of the second electrode 110 opposite to the light transmissive substrate 102 (so-called upper surface). The interface between the second electrode 110 to which the lower surface 206 and the recess 208 are transferred, the functional layer 106, and the patterning unit 108 enables efficient extraction of light from the light-transmissive substrate 102 by high-efficiency reflection. . In this specification, “reflection” at the interface between the second electrode 110 and the functional layer 106 is as follows: (1) A part of light emitted from the light emitting layer of the functional layer 106 is the second electrode 110 on the light transmitting substrate 102 side. (2) means that the generated surface plasmon is reconverted and light is emitted to the light transmitting substrate 102 side (suppression of surface plasmon absorption).

  When the second electrode 110 is used as a cathode, the second electrode 110 is formed from a material having a small work function. Materials that can be used preferably include metals having a work function of 4.5 eV or less (hereinafter referred to as “electron-injecting metals”). Examples of electron injecting metals include lithium, sodium, potassium, magnesium, aluminum, indium, rare earth metals, and the like. The material that can be used may be an alloy or mixture of two or more electron injecting metals. Examples of such materials include sodium-potassium alloys, magnesium / aluminum mixtures, magnesium / indium mixtures, lithium / aluminum mixtures and the like. Alternatively, in order to achieve both electron injection properties and durability against oxidation, the second electrode 110 that is a cathode using a mixture of an electron injection metal and a metal or metal oxide having a larger work function. May be formed. Examples of such materials include magnesium / copper (4.65 eV) mixtures, magnesium / silver (4.64 eV) mixtures, aluminum / aluminum oxide mixtures, and the like.

  The second electrode 110 preferably has a sheet resistance of several hundred Ω / □ or less. The second electrode 110 usually has a film thickness in the range of 10 nm to 5 μm, preferably in the range of 40 nm to 200 nm.

[Light extraction lens layer]
Optionally, a light extraction lens layer 310 having a light scattering or condensing function may be provided on the surface of the light transmissive substrate 102 opposite to the surface on which the first electrode 104 is provided. As shown in FIGS. 7 and 8, the light extraction lens layer 310 includes a light transmissive layer 304 having light transmissive properties, and a condensing lens layer 302 provided on the surface of the light transmissive layer 304. Good. Here, a so-called condensing sheet may be used as the condensing lens layer 302. Alternatively, the light extraction lens layer 310 may include a light transmissive layer having a microlens array formed on the surface (not shown). By providing the light extraction lens layer 310, the light can be condensed in a specific direction, for example, the light extraction direction of the organic EL element (direction 112 in FIG. 1), and the luminance in the specific direction can be increased.

  The light extraction lens layer 310 (specifically, the light transmissive layer 304 and the condensing lens layer 302) can be formed using the above-described light transmissive resin.

  Alternatively, the light scattering effect of the light extraction lens layer 310 can be improved by adding fine particles to the light transmissive resin. The fine particles that can be added can be selected from the group consisting of one or more types of inorganic fine particles, one or more types of organic fine particles, and combinations thereof. Organic fine particles that can be used include acrylic polymers, styrene polymers, styrene-acrylic polymers and cross-linked products thereof, melamine-formalin condensates, polyurethane-based polymers, polyester-based polymers, silicone-based polymers, fluorine-based polymers, and copolymers of these. Includes polymeric materials such as coalescence. Non-limiting examples of materials for forming inorganic particulates are: clay compounds such as smectite, kaolinite, talc; inorganics such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, strontium oxide Oxides; inorganic compounds such as calcium carbonate, barium carbonate, barium chloride, barium sulfate, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide; and two or more A glass material obtained by sintering the inorganic oxide.

[Sealing member]
The display area of the organic EL element 100 is preferably covered with a sealing member. As long as the sealing member can cover the display area of the organic EL element 100, the sealing member may be concave or flat. For example, the display region may be sealed by bonding the sealing member and the electrode and / or the supporting substrate with an adhesive.

There are no requirements for optical transparency and electrical insulation for the sealing member. However, like the barrier layer 320, the sealing member preferably has a low water vapor permeability and a low oxygen permeability. The sealing member has a water vapor permeability (25 ± 0.5 ° C., 90 ± 2) measured by a method according to JIS K 7129-1992, which is 1.0 × 10 ⁻² g / (m ² · 24 h) or less. % RH) and / or an oxygen permeability of 1.0 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, measured by a method according to JIS K 7126-1987. .

  Non-limiting examples of sealing members include glass plates, polymer plates and films, metal plates and films, and the like. Glasses that can be used include, among others, soda lime glass, barium-strontium containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass, and the like. Polymers that can be used include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone, and the like. Metals that can be used include stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, tantalum, and alloys containing them.

  Non-limiting examples of adhesives used for sealing include: photocurable or thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers; 2-cyanoacrylates, etc. Moisture curable adhesives; chemical curable adhesives such as two-component epoxy adhesives; hot melt adhesives such as polyamide, polyester, polyolefin, etc .; UV curable adhesives including cationic curable epoxy resins.

  Here, in order to prevent deterioration of the organic EL element 100 due to heating, it is desirable to perform sealing using an adhesive that can be adhesively cured in a temperature range from room temperature to 80 ° C. In the sealing step, the adhesive may be applied using a commercially available dispenser or a printing technique such as screen printing.

  It is preferable to inject a gas phase or liquid phase inactive substance into the gap between the sealing member and the display area of the organic EL element 100. Non-limiting examples of inert materials include inert gases such as nitrogen and argon, and inert liquids such as fluorinated hydrocarbons and silicone oils. In addition, the gap between the sealing member and the display area of the organic EL element 100 can be evacuated.

  Optionally, a hygroscopic member containing a hygroscopic compound may be disposed in the gap between the sealing member and the display region of the organic EL element 100. Alternatively, sealing may be performed using an adhesive containing a hygroscopic compound. Non-limiting examples of hygroscopic compounds are: metal oxides such as sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide; sulfates such as sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate; Metal halides such as calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide; perchloric acids such as barium perchlorate and magnesium perchlorate Including. Of these, anhydrous salts are preferably used for sulfates, metal halides, and perchloric acids.

<Method for producing organic EL element>
This invention includes the manufacturing method of the said organic EL element. This manufacturing method is
(A) preparing a light transmissive substrate 102;
(B) forming a first electrode 104 on the light transmissive substrate 102;
(C) forming a functional layer 106 on the first electrode 104;
(D) forming a patterning portion 108 on the functional layer 106;
(E) The process of forming the 2nd electrode 110 on the functional layer 106 and the patterning part 108 may be included.

  Step (A) is a step of selecting a light-transmitting substrate 102 formed of an appropriate material, and subjecting the light-transmitting substrate 102 to cleaning and / or necessary pretreatment as necessary. Cleaning and / or necessary pretreatment is usually performed on the substrate of the organic EL device, and is not particularly limited.

  Step (B) is a step of forming the first electrode 104 used as an anode. Step (B) can be performed using any method known in the art. For example, considering the suitability with the material constituting the first electrode 104, the step (B) is performed by (1) a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, and (2) CVD, plasma. It can implement by the method selected suitably from well-known methods, such as chemical methods, such as CVD method. For example, when the first electrode 104 is formed using ITO, the step (B) can be performed by a direct current sputtering method, a high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  Note that in the step (B), the first electrode 104 may be patterned using chemical etching using a photolithography method or the like, or physical etching using a laser or the like. Alternatively, the patterned first electrode 104 may be formed by a vacuum deposition method through a mask, a sputtering method through a mask, a lift-off method, or the like.

  Step (C) is a step of forming the functional layer 106 including a light emitting layer. Step (C) can be performed using any method known in the art. For example, step (C) may be performed using a vacuum deposition method or the like.

  Step (D) is a step of forming the patterning portion 108. Step (D) can be performed by a vacuum vapor deposition method using a mask.

  Step (E) is a step of forming the second electrode 110 used as a cathode. The second electrode 110 can be formed using any technique known in the art such as a vacuum evaporation method or a sputtering method. A lower surface 206 and a plurality of concave portions 208 are formed on the lower surface of the second electrode 110 formed in this step, reflecting the planar shape of the functional layer 106 and the convex shape of the patterning portion 108. By having such a shape, the light emitted from the functional layer 106 can be “reflected” with high efficiency and emitted from the light-transmitting substrate 102 side.

(II) Illumination device and planar light source The present invention includes an illumination device (second embodiment) and a planar light source (third embodiment) including the organic EL element of the first embodiment. For example, in the case of a lighting device including a light transmissive substrate, an anode, a functional layer, a cathode, a hygroscopic member, and a sealing member from the light emitting side, the first portion of the present invention is provided in a portion from the light transmissive substrate to the cathode. The organic EL element of the embodiment can be used. More specifically, one configuration example of the illumination device according to the second embodiment of the present invention illustrated in FIG. 13 includes a light-transmitting substrate 102, a first electrode (anode) 104, and a functional layer from the light emission side. 106, a patterning unit 108, a second electrode (cathode) 110, an external connection terminal 112, a hygroscopic member (desiccant) 1202, and a sealing member 1204. In this configuration example, the configuration from the light transmissive substrate 102 to the second electrode (cathode) 110 corresponds to the organic EL element 100 described above. Here, the external connection terminal 112 is a member for connecting the second electrode 110 and a power source. The external connection terminal 112 can be formed using a conductive material having low water vapor permeability and low oxygen permeability, such as a transparent conductive oxide. The planar light source according to the third embodiment of the present invention can also have the same configuration as the illumination device according to the second embodiment. The illumination device according to the second embodiment of the present invention and the planar light source according to the third embodiment of the present invention add an appropriate process to the method for manufacturing the organic EL element according to the first embodiment of the present invention described above. Can be manufactured.

(III) Display Device The present invention includes a display device (fourth embodiment) including the organic EL element of the first embodiment. The display device of the present invention includes a display device including a color filter glass substrate (including a glass substrate and a color filter layer), a protective layer, an anode, an organic layer including a white organic EL light emitting layer, and a cathode from the display side of the device. . In the display device of the present invention, the anode part may include a driving part such as a silicon driving substrate. More specifically, the configuration example of the display device illustrated in FIG. 14 includes, from the display side of the device, a light transmissive substrate 102, a color filter layer (for example, an RGB color filter layer) 1302, and a first electrode (anode) 104. , A functional layer 106, a patterning unit 108, and a second electrode (cathode) 110. In the configuration example of FIG. 14, portions other than the color filter layer 1302 correspond to the organic EL element of the first embodiment. The display device of the fifth embodiment of the present invention can be manufactured by adding an appropriate process to the method for manufacturing the organic EL element of the first embodiment. For example, the color filter layer 1302 can be formed using any method known in the art, such as a spin coating method or an evaporation method.

  An example embodying the above-described embodiment will be described together with a comparative example as a comparison target. In the following examples, the structure of the patterning unit 108 was measured using a scanning probe microscope. In the example according to the organic EL element of the first embodiment, the area ratio Ap of the patterning unit 108, the height of the projection 202 of the patterning unit 108, and the distance between two adjacent projections 202 of the patterning unit 108 Was measured. Specifically, after obtaining images of one convex portion 202a and two convex portions 202c and 202e adjacent thereto at 10 randomly selected locations, the height H1a of the convex portion 202a was obtained. Moreover, the distance (W1c, W1e) between the adjacent convex parts 202c and 202e was measured, and the distance W1 between convex parts was calculated | required. The arithmetic average values of the measured values of H1a and W1 at 10 locations were set as the height H1 of the patterning portion 108 and the distance W1 between the convex portions, respectively.

    In the example relating to the organic EL element of the second embodiment, the area ratio Ap of the patterning unit 108, the height H1a of the patterning unit 108, and the inter-convex distance W2 of the patterning unit 108 were measured. Specifically, for 10 first convex portions 222 selected at random, after obtaining images of one first convex portion 222a and two first convex portions 222c and 222e adjacent thereto, the first convex portions 222a are obtained. The height H1a of the portion 222 was obtained. Moreover, the distance (W2c, W2e) between the adjacent 1st convex parts 222c and 222e was measured, and the distance W2 between convex parts was calculated | required. Similarly, the height H1a and the inter-convex distance W2 were obtained for ten first convex portions 224 selected at random. The arithmetic average value of the measured values of H1a and W2 at a total of 20 locations was defined as the height H1 of the patterning portion 108 and the distance W2 between the convex portions.

  Further, in the following embodiments, description will be made based on the characteristic values of the structure of the patterning unit 108, but the convex part of the patterning unit 108 and the upper surface 204 of the functional layer 106 are respectively the concave part 208 and the lower surface of the second electrode 110. 206 was confirmed to be transferred.

<Example 1>
A non-alkali glass plate having a size of 30 mm × 40 mm and a thickness of 0.7 mm was washed to prepare a light transmissive substrate 102.

  Next, an ITO film having a film thickness of 100 nm is deposited on the surface of the light-transmitting substrate 102 by sputtering, and then the ITO film is patterned to form a first electrode 104 (anode) having light transmittance. Thus, a light transmissive anode substrate was obtained.

Subsequently, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer are deposited on the surface of the first electrode 104 simultaneously by using two identical light-transmitting anode substrates. Then, the functional layer 106 was formed. More specifically, the following constituent layers were deposited in this order to form the functional layer 106 having the layer constitution (i).
(1) Hole transport layer:
4,4 ′, 4 ″ -tris (9-carbazole) triphenylamine (film thickness 35 nm);
(2) Light emitting layer:
4,4 ′, 4 ″ -tris (9-carbazole) triphenylamine (film thickness 15 nm) doped with tris (2-phenylpyridinato) iridium (III) complex, and tris [1-phenylisoquinoline-C2 , N] laminated structure of 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (film thickness 15 nm) doped with an iridium (III) complex;
(3) Electron transport layer:
1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (film thickness 65 nm); and (4) Electron injection layer:
Lithium fluoride (film thickness 1.5 nm).

  Lithium fluoride was deposited by a vapor deposition method through a metal mask having a plurality of circular openings arranged in a square lattice pattern to form a patterning portion 108 composed of a plurality of projections 202 having a set height of 30 nm. . One of the two substrates processed at the same time was observed with a scanning probe microscope, and the shape of the patterning portion 108 was confirmed. The patterning unit 108 was confirmed to have the pattern shown in FIG. 4 in which the convex portions 202 are arranged in a square. Here, the area ratio Ap of the patterning portion 108 was 10.0%. Further, the height H1 of the patterning portion 108 was 30.5 nm. The inter-convex distance W1 was 850 nm.

  Subsequently, aluminum was deposited on the functional layer 106 and the patterning portion 108 by vapor deposition to form a second electrode 110 having a thickness of 100 nm.

  Separately, a PET film was prepared as a light transmissive layer 304 made of a light transmissive sheet. A condensing lens layer 302 composed of a hemispherical microlens having a diameter of 5 μm and a cross prism structure having an apex angle of 89 degrees having a pitch of 5 μm is formed on one surface of the light transmitting layer 304, thereby obtaining a light extraction lens layer 310. It was. Subsequently, the other surface of the light transmissive layer 304 was bonded to the light transmissive substrate 102 via an adhesive to obtain the organic EL element 100 having the light extraction lens layer 310 shown in FIG. At this time, the condensing lens layer 302 is the outermost surface on the light extraction side.

<Example 2>
The procedure of Example 1 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning unit 108 was confirmed to have the pattern shown in FIG. 4 in which the convex portions 202 are arranged in a square. Here, the area ratio Ap of the patterning portion 108 was 2.0%. Further, the height H1 of the patterning portion 108 was 30.2 nm. The inter-convex distance W1 was 2500 nm.

<Example 3>
The procedure of Example 1 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning unit 108 was confirmed to have the pattern shown in FIG. 4 in which the convex portions 202 are arranged in a square. Here, the area ratio Ap of the patterning portion 108 was 7.1%. Further, the height H1 of the patterning portion 108 was 30.6 nm. The inter-convex distance W1 was 500 nm.

<Example 4>
The procedure of Example 1 is repeated except that the metal mask used in forming the patterning portion 108 is changed to a metal mask having a plurality of circular openings arranged in a hexagonal lattice, and the organic EL element 100 is repeated. Got. The patterning part 108 confirmed that the convex part 202 had the pattern shown in FIG. 2 arranged in a hexagonal lattice shape. Here, the area ratio Ap of the patterning portion 108 was 8.9%. Further, the height H1 of the patterning portion 108 was 30.2 nm. The inter-convex distance W1 was 840 nm.

<Example 5>
The procedure of Example 4 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning part 108 confirmed that the convex part 202 had the pattern shown in FIG. 2 arranged in a hexagonal lattice shape. Here, the area ratio Ap of the patterning portion 108 was 4.4%. Further, the height H1 of the patterning portion 108 was 30.4 nm. The inter-convex distance W1 was 900 nm.

<Example 6>
The procedure of Example 1 was repeated to form the first electrode 104 and the functional layer 106 on the light transmissive substrate 102.

  Lithium fluoride is deposited on the functional layer 106 by vapor deposition through a metal mask having a plurality of openings having stripe shapes extending in the first direction, and a plurality of first protrusions 222 having a set height of 30 nm. Formed. Subsequently, lithium fluoride is deposited on the functional layer 106 and the first protrusion 222 by an evaporation method through a metal mask having a plurality of openings having a stripe shape extending in the second direction, and a set height of 30 nm is obtained. A plurality of second convex portions 224 having the above were formed to obtain the patterning portion 108. Here, the second direction is a direction orthogonal to the first direction. One of the two substrates processed at the same time was observed with a scanning probe microscope, and the shape of the patterning portion 108 was confirmed. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 10.0%. Further, the height H1 of the patterning portion 108 was 30.0 nm. The inter-convex distance W2 was 893 nm.

  Then, the 2nd electrode 110 and the light extraction lens layer 310 were formed in the procedure similar to Example 1, and the organic EL element 100 was obtained.

<Example 7>
The procedure of Example 6 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 2.0%. Further, the height H1 of the patterning portion 108 was 30.2 nm. The inter-convex distance W2 was 2273 nm.

<Example 8>
The procedure of Example 6 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 9.5%. Further, the height H1 of the patterning portion 108 was 30.5 nm. The inter-convex distance W2 was 500 nm.

<Example 9>
The procedure of Example 6 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 7.8%. Further, the height H1 of the patterning portion 108 was 30.3 nm. The inter-convex distance W2 was 2500 nm.

<Comparative Example 1>
The procedure of Example 1 was repeated except that the patterning portion 108 was not formed, and the organic EL element 100 was obtained. The interface between the functional layer 106 and the second electrode 110 was flat.

<Comparative Example 2>
The procedure of Example 1 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning unit 108 was confirmed to have the pattern shown in FIG. 4 in which the convex portions 202 are arranged in a square. Here, the area ratio Ap of the patterning portion 108 was 10.2%. Further, the height H1 of the patterning portion 108 was 30.2 nm. The inter-convex distance W1 was 2800 nm.

<Comparative Example 3>
The procedure of Example 1 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning unit 108 was confirmed to have the pattern shown in FIG. 4 in which the convex portions 202 are arranged in a square. Here, the area ratio Ap of the patterning portion 108 was 1.6%. Further, the height H1 of the patterning portion 108 was 30.1 nm. The inter-convex distance W1 was 353 nm.

<Comparative example 4>
The procedure of Example 4 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning part 108 confirmed that the convex part 202 had the pattern shown in FIG. 2 arranged in a hexagonal lattice shape. Here, the area ratio Ap of the patterning portion 108 was 11.9%. Further, the height H1 of the patterning portion 108 was 30.0 nm. The inter-convex distance W1 was 400 nm.

<Comparative Example 5>
The procedure of Example 4 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. The patterning part 108 confirmed that the convex part 202 had the pattern shown in FIG. 2 arranged in a hexagonal lattice shape. Here, the area ratio Ap of the patterning portion 108 was 1.3%. Further, the height H1 of the patterning portion 108 was 30.6 nm. The inter-convex distance W1 was 2800 nm.

<Comparative Example 6>
The procedure of Example 6 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 1.5%. Further, the height H1 of the patterning portion 108 was 30.3 nm. The inter-convex distance W2 was 2620 nm.

<Comparative Example 7>
The procedure of Example 6 was repeated except that the metal mask used for forming the patterning portion 108 was changed, and the organic EL element 100 was obtained. It was confirmed that the patterning unit 108 had the pattern shown in FIG. 5 composed of the first convex part 222 and the second convex part 224 orthogonal to each other. Here, the area ratio Ap of the patterning portion 108 was 10.5%. Further, the height H1 of the patterning portion 108 was 30.1 nm. The inter-convex distance W2 was 400 nm.

<Evaluation>
A constant current with a current density of 20 mA / cm ² was passed from a direct current (DC) power source to the organic EL elements of Examples 1 to 9 and Comparative Examples 1 to 7, and the total emitted light emitted was measured with an integrating sphere. The ratio of the amount of total emitted light of Examples 1-9 and Comparative Examples 2-7 to the amount of total emitted light of Comparative Example 1 having no patterning portion 108 was calculated to obtain the light extraction efficiency ratio.

  The characteristic values and evaluation results of the structures of the patterning portions 108 of Examples 1 to 10 and Comparative Examples 1 to 7 are summarized in Tables 1 to 3.

  As shown in Tables 1 to 3, the organic EL elements of Examples 1 to 5 having the patterning portion 108 having a shape satisfying (Formula 1) and (Formula 2), and (Formula 1) and (Formula 3) The organic EL elements of Examples 6 to 9 having the patterning portion 108 having a shape satisfying (1) have a high light extraction efficiency ratio of 1.52 to 1.81. This is presumably because the structure of the surface on the functional layer 106 side of the second electrode 110 where irregularities were formed by the patterning portion 108 suppressed surface plasmon absorption and improved the reflectance.

  It is known that surface plasmons are attenuated when propagating through a portion having the same height over a certain distance. However, in the organic EL elements of Examples 1 to 5 according to the first embodiment of the present invention, the second electrode 110 has the recess 208 and the lower surface 206 that satisfy (Expression 1) and (Expression 2). It has parts with different heights that exist within a certain distance. Therefore, it is considered that the surface plasmon causing the attenuation does not occur on the surface of the second electrode 110 on the functional layer 106 side, and the surface plasmon can be reconverted and emitted as light. Similarly, in the organic EL elements of Examples 6 to 9 according to the second embodiment of the present invention, the second electrode 110 has the recess 208 and the lower surface 206 that satisfy (Expression 1) and (Expression 3). , Having different height parts that exist within a certain distance. Therefore, it is considered that the surface plasmon causing the attenuation does not occur on the surface of the second electrode 110 on the functional layer 106 side, and the surface plasmon can be reconverted and emitted as light.

  Furthermore, the light that has traveled from the functional layer 106 to the lower surface 206 of the second electrode 110 is directly reflected to the light-transmitting substrate 102 side. In the present invention, it is presumed that the lower surface 206 can directly reflect some light.

  On the other hand, the organic EL device of Comparative Example 2 showed an insufficient light extraction efficiency ratio of 1.32. This result is considered to be due to the fact that the area ratio Ap of the patterning portion 108 is too high and the distance W1 between the convex portions of the patterning portion 108 is too large. Specifically, the area of the carrier injection interface where the functional layer 106 and the second electrode 110 are in contact with each other is reduced, leading to a decrease in light emission luminance, and the distance W1 between the convex portions of the patterning portion 108 is too large. Further, it is considered that surface plasmon propagation and attenuation occurred in the lower surface 206 of the second electrode 110.

  The organic EL element of Comparative Example 3 exhibited a light extraction efficiency ratio as low as 1.07. This result is considered to be caused by the fact that the area ratio Ap of the patterning portion 108 is too small and the distance between the convex portions of the patterning portion 108 is too small. Specifically, the area occupied by the patterning portion 108 is small, the propagation and attenuation of surface plasmons within the lower surface 206 of the second electrode 110, and the distance W1 between the convex portions of the patterning portion 108 is greater than the emission wavelength. It is estimated that the plasmon suppression effect was not obtained.

  The organic EL elements of Comparative Examples 4 and 7 exhibited insufficient light extraction efficiency ratios of 1.15 and 1.31, respectively. This result is considered to be due to the fact that the area ratio Ap of the patterning portion 108 is too high and the distance between the convex portions of the patterning portion 108 is too small. Specifically, the area of the carrier injection interface where the functional layer 106 and the second electrode 110 are in contact with each other is reduced, resulting in a decrease in emission luminance, and the distance between the convex portions of the patterning unit 108 is longer than the emission wavelength. It is estimated that the plasmon suppression effect was not obtained.

  The organic EL elements of Comparative Examples 5 and 6 exhibited low light extraction efficiency ratios of 1.05 and 1.07. This result is considered to result from the fact that the area ratio Ap of the patterning portion 108 is too small and the distance between the convex portions of the patterning portion 108 is too large. Specifically, it is considered that propagation and attenuation of surface plasmons occurred in the lower surface 206 of the second electrode 110 because the area occupied by the patterning portion 108 is small and the distance between the convex portions of the patterning portion 108 is large. .

DESCRIPTION OF SYMBOLS 100 Organic EL element 102 Light transmissive substrate 104 1st electrode 106 Functional layer 108 Patterning part 110 2nd electrode 112 External connection terminal 202 Convex part 204 Upper surface of functional layer 206 Lower surface of 2nd electrode 208 Recessed part 222 of 2nd electrode 222 First convex portion 224 Second convex portion 302 Condensing lens layer 304 Light transmitting layer 310 Light extraction lens layer 320 Barrier layer 330 Light scattering layer 402 Apex of convex portion 1202 Hygroscopic member 1204 Sealing member 1302 Color filter layer

Claims (11)

  A light transmissive substrate, a light transmissive first electrode, a functional layer including a light emitting layer, a patterning unit, and a second electrode are included in this order, and the functional layer is formed on the patterning unit and the second electrode. The organic EL device is in contact with each other, wherein the patterning portion is made of lithium fluoride, and the patterning portion has a convex portion on the second electrode side. The area ratio Ap of the patterning portion is
0.02 ≦ Ap ≦ 0.1 (Formula 1)
The organic EL element according to claim 1, wherein:   The patterning portion is composed of a plurality of independent convex portions, each of the plurality of convex portions has a circular bottom shape, and the plurality of convex portions are arranged in a square lattice shape or a hexagonal lattice shape. The organic EL element according to claim 1 or 2. The distance W1 between the convex portions of the patterning portion is 500 nm ≦ W1 ≦ 2500 nm (Formula 2)
The organic EL device according to claim 3, wherein the relationship is satisfied.   The patterning portion includes a plurality of first protrusions having a stripe shape extending in a first direction and a plurality of second protrusions having a stripe shape extending in a second direction, and the first direction is: The organic EL element according to claim 1, wherein the organic EL element is in a direction intersecting with the second direction. The distance W2 between the convex portions of the patterning portion is 500 nm ≦ W2 ≦ 2500 nm (Formula 3)
The organic EL element according to claim 5, wherein the relationship is satisfied.   The organic EL element according to claim 1, wherein the patterning portion has a height of 10 nm or more.   8. The organic EL element according to claim 1, further comprising a light extraction lens layer on a surface opposite to the surface on which the first electrode of the light transmissive substrate is provided. 9.   An illumination device comprising the organic EL element according to claim 1.   A planar light source comprising the organic EL device according to claim 1.   A display device comprising the organic EL element according to claim 1.