JP2019079725A - Organic el element, lighting device including organic el element, surface light source, and display device - Google Patents

Abstract

To provide an organic EL element capable of achieving high light extraction efficiency.SOLUTION: An organic EL element of the present embodiment includes in the following order, a light transmissive substrate, and a light transmissive structure layer, a light transmissive first electrode, a functional layer including a luminescent layer and a second electrode which are provided on the substrate. The structure layer has a plurality of projections and a flat part on a surface on the second electrode side; and each projection is surrounded by the flat part; and a distance between tops of two neighboring projections is not less than 0.5 μm and not more than 5 μm and an area ratio Ap of the projections satisfies a predetermined relationship. The present embodiment incorporates a lighting device including the above-described organic EL element, a surface light source and a display device.SELECTED DRAWING: Figure 1

Description

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

  In recent years, a light emitting element (organic EL element) using an organic EL phenomenon has attracted much attention as a next-generation light emitting device used for a lighting device, a display device, and the like. The organic EL element is capable of surface light emission, capable of low temperature operation, capable of cost reduction, capable of weight reduction, capable of producing a flexible element, It has advantages such as low corner dependence, low power consumption, and the ability to produce extremely thin devices.

  An organic EL element generally comprises an anode, a cathode, and an organic EL layer (functional layer) sandwiched between the anode and the cathode. Here, the organic EL layer includes a light emitting layer containing an organic light emitting material. As 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.

  The organic EL element comprises 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 on a transparent substrate such as a glass substrate, and light is emitted from the substrate side. You may have a bottom emission structure to take out. Alternatively, the organic EL element may include a cathode, an organic EL layer, and an anode made of a transparent conductive material in this order on a substrate, and may have a top emission structure for extracting light from the side opposite to the substrate side.

  Although the organic EL element has the above-mentioned advantages, it has a problem that the light extraction efficiency is low. The light extraction efficiency is the ratio of the total energy amount of light emitted from the light extraction surface (for example, the substrate surface in the case of bottom emission type) to the atmosphere to the total energy amount of light generated in the light emitting layer. For example, since light generated in the light emitting layer is emitted in all directions, much of the light becomes a guided mode which repeats total reflection at the interface of two layers having different refractive indices. For this reason, the change to heat in the guided mode and the emission of light from the side of the element lower the light extraction efficiency in the intended direction.

  Further, in the organic EL element, since the distance between the light emitting layer and the metal cathode is short, 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 illumination device or the like provided with an organic EL element, various methods have been studied to improve the light extraction efficiency.

  As one of methods for improving the light extraction efficiency, an organic EL element using a glass substrate provided with a light collecting layer having a light collecting property has been proposed. For example, Japanese Patent Application Laid-Open No. 2003-86353 discloses a light collecting layer comprising a light collecting structure such as a microlens and a transparent resin covering the light collecting structure (see Patent Document 1). . In this proposal, the transparent resin has a higher refractive index than the light-condensing structure. By providing the light collecting 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 of methods 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 fine structure on the surface of a metal layer (cathode) (see Patent Document 2). In this proposal, the periodic microstructures function as diffraction gratings. As a result, the energy converted to surface plasmons on the cathode surface is reconverted to light, and the light extraction efficiency is improved.

  Furthermore, Patent Document 3 discloses an organic EL element in which the back electrode of the organic EL element includes a metal region and a dielectric region, and a part of the metal regions are connected to each other. . In this organic EL element, the reduction of surface plasmon absorption is realized without providing the uneven structure on the back electrode.

JP 2003-86353 A Patent 4762542 specification JP, 2016-173986, A

  However, even if the above-described light collecting layer is provided on a glass substrate, total reflection occurs at the interface between the light collecting layer and the glass substrate, so that the light extraction efficiency from the organic EL element can not be said to be sufficiently high. In the case where the above-described periodic fine structure is provided in the metal layer, 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. And there is also a problem that the stability over time of the organic EL element is lowered. For this reason, even if the periodic fine structure having high theoretical efficiency is provided in the metal layer, the organic EL element can not always be manufactured stably. In addition, towards the power saving of the organic EL lighting device and / or the manufacture of the flexible organic EL lighting device, there is a demand for an organic EL element having further improved light extraction efficiency.

  An object of the present invention is to provide an organic EL element which can realize high light extraction efficiency. Another object of the present invention is to provide a lighting device, a planar light source and a display including the organic EL element.

A first aspect of the present invention is an organic EL element. The organic EL element includes a light transmitting substrate, a light transmitting structural layer provided on the substrate, a light transmitting first electrode, a functional layer including a light emitting layer, and a second electrode in this order. The structural layer has a plurality of projections and a flat portion on the surface on the second electrode side, and one projection is surrounded by the flat portion, and the distance between the tops of two adjacent projections is It is characterized in that it is 0.5 μm or more and 5 μm or less, and the convex portion area ratio Ap satisfies the relationship of the following (Expression 1).
0.12 ≦ protrusion area ratio Ap ≦ 0.64 (Expression 1)

  However, the convex portion area ratio Ap is a ratio of the sum of the projected areas of the convex portions in the predetermined area to the predetermined area in the display region of the organic EL element.

  Specifically, an area of a predetermined area in the display area of the organic EL element (in this specification, this is referred to as an area X) is set. The sum of the projection areas of the respective convex portions in the region X is obtained. The convex portion area ratio Ap is a ratio [the following (Expression 1a)] of the sum of the projected areas of the convex portions to the predetermined area.

  However, the area X is an area having a predetermined area in the display area of the organic EL element.

  In the organic EL element of the present invention, where the width of one convex portion (A) selected from the plurality of convex portions is w1a, the w1a is in the range of 400 nm to 1000 nm.

Furthermore, in the organic EL element of the present invention, the width of the convex portion (A) is w1a, and the width of the two flat portions between the two convex portions adjacent to the convex portion and the convex portion (A) is In the case of w1b and w1c respectively, it is characterized in that the relationship of the following equation 2 is satisfied.
0.5 ≦ w1a / [(w1b + w1c) / 2] ≦ 4.0 (equation 2)

  The organic EL element of the present invention is characterized in that the apparent height of one convex portion (A) selected from the plurality of convex portions is 50 nm to 300 nm.

  The organic EL device of the present invention may further include a barrier layer and / or a light scattering layer between the light transmitting substrate and the structural layer. The organic EL device of the present invention may further include a light extraction lens layer on the surface of the light transmitting substrate opposite to the surface provided with the structural layer.

  The second aspect of the present invention relates to a lighting device including the organic EL element of the present invention. The third aspect of the present invention relates to a planar light source including the organic EL element of the present invention. A fourth aspect of the present invention relates to a display including the organic EL element of the first aspect.

  The organic EL element of the present invention can enhance the light extraction efficiency. Furthermore, by using the organic EL element of the present invention, a lighting device, a planar light source and a display device having excellent characteristics can be provided.

It is a schematic sectional drawing which shows the organic EL element which concerns on the 1st side of this invention. It is a figure which shows the structure layer of the organic EL element of this invention, (a) is a top view, (b) is sectional drawing along cutting-plane line IIb-IIb. It is sectional drawing which shows another example of the organic EL element of this invention. It is sectional drawing which shows another example of the organic EL element of this invention, (a) is an example containing a barrier layer, (b) is an example containing a barrier layer and a light-scattering layer. (A) is a top view which shows an example of the structural layer of the organic EL element of this invention, (b) is a top view which shows another example of the structural layer of the organic EL element of this invention. It is a perspective sectional view which shows the structural layer of the organic EL element of this invention. It is a perspective sectional view which shows the structural layer of the organic EL element of this invention. FIG. 8 is a cross-sectional view of a structural layer of the organic EL element of the present invention cut along the cutting line VIII-VIII in FIG. 7. It is a top view which shows another example of the structural layer of the organic EL element of this invention. It is a top view which shows another example of the structural layer of the organic EL element of this invention. It is a schematic sectional drawing which shows an example of the illuminating device of the 2nd side of this invention, and the planar light source of a 3rd side. It is a schematic sectional drawing which shows an example of the display apparatus of the 4th side of this invention.

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

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

  The organic EL element of the present invention has a structural layer 104. As shown in FIG. 2A, the structural layer 104 has a plurality of convex portions 202 having a square bottom shape on the surface on the second electrode side, and flat portions 204 around the plurality of convex portions 202. Have. In the example shown in FIG. 2, the plurality of convex portions 202 are arranged in a square lattice shape. That is, each of the plurality of convex portions 202 is arranged at an apex portion of a square formed by the closest four convex portions 202. The structural layer of the organic EL element of the present invention is characterized in that it has a structure in which the plurality of convex portions 202 are surrounded by the flat portion 204.

  The more specific structure of the organic EL element of this invention is demonstrated using FIG.2 (b). FIG. 2B is a cross-sectional view taken along the cutting line IIb-IIb of FIG. In the present invention, the structural layer 104 has, on the surface on the side of the first electrode 106, a plurality of convex portions 202 facing in the direction of the first electrode. Further, the shapes of the plurality of convex portions 202 and the flat portion 204 therearound are maintained for the first electrode 106, the functional layer 108, and the second electrode 110 on the structural layer 104, respectively. The shape transferred from the convex portion and the flat portion of the structural layer 104 to the second electrode 110 can be maintained on both the surface on the substrate side of the second electrode 110 and the surface opposite thereto. Further, the shape of the second electrode 110 may be formed only on the surface on the functional layer 108 side of the second electrode 110 as long as the shape of the structural layer 104 is maintained by the second electrode. Here, the shape of the convex portion of the structural layer is transferred to the concave portion 206 on the surface on the functional layer 108 side of the second electrode, and the flat portion 204 of the structural layer is a flat portion on the second electrode (second The flat portion of the electrode 208 is transferred. As shown in FIG. 2A, the second electrode 110 having the shape of the concave portion 206 and the flat portion 208 of the second electrode efficiently transmits the light 210 emitted from the functional layer 108 to the light transmissive substrate 102. It can be taken out as light 212 to the side.

  The specific shapes of the convex portion 202 and the flat portion 204 of the structural layer 104 in the present invention, and the specific shape of the concave portion 206 of the second electrode 110 and the flat portion 208 of the second electrode are the following “structural layers”. And in the "second electrode" section.

  In the present embodiment, the first electrode 106 is an electrode having light transmittance and serving as an anode. The functional layer 108 includes a light emitting layer. The second electrode 110 is an electrode serving as a counter electrode of the first electrode 106 and serves as a cathode.

  As used herein, "light transmitting" means the property of being transparent to light (light transmitting). The light transmissive material used in the present invention preferably transmits light in 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. 3, another example of the organic EL device according to the first aspect of the present invention is a condensing lens layer 302 and a light transmitting layer on the surface of the light transmitting substrate 102 opposite to the structural layer 104. It further includes a light extraction lens layer 310 including the layer 304.

  The organic EL device of the present invention may further include a barrier layer 402 as shown in FIG. 4 (a). The barrier layer 402 is a layer for preventing entry of moisture and 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 402 between the light transmitting substrate 102 and the first electrode 106 as shown in FIG. 4A. As shown in FIG. 4 (b), still another example of the organic EL device of the present invention further includes a light scattering layer 404. The light scattering layer 404 is preferably provided between the light transmitting substrate 102 and the structural layer 104, as shown in FIG. 4 (b). Also in this example, as shown in FIGS. 4A and 4B, the light extraction lens layer 310 may be further included.

  In the present specification, a portion including the light transmitting substrate 102, the structural layer 104, and the first electrode 106 is also referred to as a "light extraction substrate 120". Also, in the present specification, the light extraction lens layer 310, the barrier layer 402, and the light scattering layer 404, which are optional elements, can be included in the light extraction substrate 120.

  Next, each part of the organic EL element 100 will be described in detail.

[Light transmitting 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 transmitting substrate 102 is preferably a glass plate or a plate or a film made of a polymer.

  Examples of the glass include, for example, soda lime glass, glass containing barium and strontium, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass and the like.

  Examples of polymers are, 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 acetate phthalate, cellulose esters such as cellulose nitrate or derivatives thereof; polyvinylidene chloride; polyvinyl alcohol; polyethylene vinyl alcohol; syndiotactic polystyrene; polycarbonate; Ether ketone; polyimide; polyether sulfone (PES); polyphenylene sulfide; Sulfonic acids; and the like cycloolefin resins such as norbornene resins, acrylic resins such as polymethyl methacrylate (PMMA); polyetherimides; polyether ketone imide; polyarylate.

[Barrier layer]
The barrier layer 402 is an optional element of the organic EL device of the present invention. The barrier layer 402 has a function of suppressing the entry of moisture, oxygen, or the like that causes deterioration of the organic EL element 100 (in particular, the functional layer 108). The barrier layer 402 may be a hybrid coating comprising an inorganic coating or both an inorganic coating and an organic coating. The film thickness of the barrier layer 402 is preferably 5 nm to 100 nm.

  The inorganic substance for forming the barrier layer 402 includes silicon oxide, silicon dioxide, silicon nitride and the like. Hybrid coatings are useful in eliminating the mechanical fragility of inorganic coatings. The hybrid coating preferably has a structure in which an inorganic coating and an organic coating are laminated. Organic substances used in the hybrid coating include polyvinyl alcohol resins, acrylic resins and the like. The number of inorganic coatings and organic coatings in the hybrid coating and the stacking order are not particularly limited. More preferably, the hybrid coating has a structure in which an inorganic coating and an organic coating are alternately laminated.

The barrier layer 402 has a water vapor transmission rate (25 ± 0.5 ° C., 90 ± 2) of 1.0 × 10 ⁻² g / (m ² · 24 h) or less, which is measured according to JIS K 7129-1992. It is preferable to have% RH). More preferably, the barrier layer 402 has a water vapor transmission rate of not more than 1.0 × 10 ⁻⁵ g / (m ² · 24 h). Furthermore, the barrier layer 402 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 402 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 Have both water vapor transmission rates.

  Barrier layer 402 can be formed using any means commonly used in the art. These means include, for example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, atmospheric pressure plasma polymerization, plasma CVD, laser CVD Methods, thermal CVD methods, etc.

  When a polymer plate or a polymer film is used as the light transmitting substrate 102 in the organic EL device of the present invention, the surface of the polymer plate or the polymer film may have a barrier coating. This barrier coating can function as a barrier layer 402.

[Light scattering layer]
The light scattering layer 404 is an optional element of the organic EL device of the present invention. The light scattering layer 404 is formed by total reflection at the interface of each layer due to the difference in the refractive index of each layer existing between the functional layer 108 including the light emitting layer and the light transmitting substrate 102 in the light emission of the organic EL element. It has a function of reducing the loss of light and improving the light extraction efficiency. The thickness of the light scattering layer 404 is preferably 0.5 μm to 5 μm.

  The light scattering layer 404 is required to be light transmissive. The light scattering layer 404 can be prepared by adding fine particles to the light transmitting resin. Light transmitting resins are: low density polyethylene, high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-norbornene copolymer, ethylene Polyolefin resins such as dimethanooctahydronaphthalene copolymer [ethylene-domon (DMON) copolymer], polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer; polyethylene terephthalate, polybutylene terephthalate Polyester resins such as polyethylene naphthalate; Amide resins such as nylon-6, nylon-6,6, meta-xylene diamine-adipic acid condensation polymer; Imido-based acrylic resins such as polymethyl methacryl imide; Acrylic resins such as acrylate; styrene-acrylonitrile resins such as styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer; polystyrene; polyacrylonitrile; cellulose resins such as triacetate cellulose and diacetate cellulose; polychloride Halogen-containing resins such as vinyl, polyvinylidene chloride, polyvinylidene fluoride and polytetrafluoroethylene; hydrogen bonding resins such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer; ionomer resins; polycarbonate resins, polysulfone resins, polyether sulfone resins , Engineering plastics such as polyetheretherketone resin, polyphenylene oxide resin, polymethylene oxide resin, polyarylate resin, liquid crystal resin, etc. Including click-based resin. The fine particles may be inorganic fine particles, organic fine particles or a combination thereof. The organic fine particles include fine particles consisting of acrylic polymers, styrene polymers, styrene-acrylic polymers and crosslinked products thereof, melamine-formaldehyde condensates, polyurethanes, polyesters, silicones, fluorine-based polymers, and copolymers of these. Inorganic fine particles include: clay compound particles such as smectite, kaolinite and talc; fine particles comprising inorganic oxide such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, strontium oxide, etc .; calcium carbonate, barium carbonate Particles comprising an inorganic compound such as barium chloride, barium sulfate, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium nitrate, strontium hydroxide and the like; and two or more inorganic oxides It contains fine particles of a glass material obtained by sintering. A combination of two or more organic and / or inorganic particles may be used.

  A buffer layer (not shown) may be provided between the light scattering layer 404 and the structural layer 104 for embedding the unevenness on the surface of the light scattering layer 404 to improve the smoothness. The buffer layer may also contain fine particles for adjusting the refractive index. The buffer layer is required to be light transmitting, and the same light transmitting resin as the light scattering layer can be used. The fine particles for adjusting the refractive index include fine particles made of an inorganic oxide such as titanium oxide or zirconia.

  In addition, the light scattering layer 404 may be a light transmitting layer having a surface having an uneven shape, and a layer for buffering the uneven shape and further adjusting a refractive index may be stacked thereon. As these, the materials described in the light transmitting resin and the fine particles described above can be used.

[Structure layer]
The organic EL element of the present invention has a structural layer 104. In the present invention, the structural layer 104 includes a plurality of convex portions 202 protruding toward the first electrode on the surface on the side of the first electrode 106 and an adjacent convex portion of the plurality of convex portions 202. There is a flat portion 204 between them (see, for example, FIGS. 2 (a) and 2 (b)). The shapes of the convex portion 202 and the flat portion 204 are transferred and maintained to the first electrode 106, the functional layer 108, and the second electrode 110 stacked on the structural layer 104. In the present invention, the structural layer 104 preferably has a thickness (including a convex portion) of 0.1 μm to 5 μm.

  Below, the organic EL element of this invention is demonstrated in detail taking the organic EL element shown to Fig.2 (a) and FIG.2 (b) as an example. In this embodiment (the first embodiment), the structural layer 104 includes a convex portion 202 having a square bottom shape and a flat portion 204 surrounding the convex portion 202.

  As shown in FIGS. 2A to 2B, the structural layer 104 has a plurality of convex portions 202 and flat portions on the surface on the second electrode 110 side (that is, the interface with the first electrode 106). It has 204. The plurality of projections 202 have a square bottom in the example of the first embodiment. Moreover, the convex part 202 has a gentle curved surface (namely, does not have a ridgeline) toward a top part from a bottom (refer FIGS. 5-8). In the example of the first embodiment, the plurality of convex portions 202 are arranged in a square lattice shape. That is, each of the plurality of convex portions 202 is arranged at a vertex of a square formed by the four convex portions 202 closest to each other. Each of the plurality of convex portions 202 is in contact with the flat portion 204 at the periphery. That is, each of the convex portions is surrounded by the flat portion 204. As described above, in the organic EL element of the present invention, the plurality of convex portions 202 are not in contact with the adjacent convex portions, and are characterized by being isolated and present in the display region of the organic EL element. is there.

  In the present invention, the convex portion 202 preferably occupies an area of 60% or more, preferably 80% or more of the portion corresponding to the display area of the structural layer 104.

  The structural layer 104 according to the first embodiment will be described in more detail with reference to FIGS. 5 (a) and 5 (b). FIG. 5A is a view of the display region of the organic EL element as viewed from the top, and is in the same form as FIG. 2A. In FIG. 5A, the convex portions 202 are arranged on the structural layer in a square lattice shape. Moreover, in FIG. 5A, the convex part 202 is shown by the shape (square which is a shape of a bottom face) projected on the structure layer.

In the organic EL element of the present invention, the convex portion 202 and the flat portion 204 need to satisfy the following first condition (formula 1). That is, the area ratio (convex area ratio) Ap of the convex part 202 needs to be 0.12 or more and 0.64 or less.
0.12 ≦ protrusion area ratio Ap ≦ 0.64 (Expression 1)

  However, the convex portion area ratio Ap is a ratio of the sum of the projected areas of the convex portions in the predetermined area to the predetermined area in the display region of the organic EL element.

  The convex portion area ratio Ap will be described below. First, a region (region X) of a predetermined area in the display region of the organic EL element is set. The sum of the projected areas of the convex portions in the region X is obtained. The convex portion area ratio Ap is a ratio [the following (Expression 1a)] of the sum of the projected areas of the convex portions to the predetermined area.

  However, the area X is an area having a predetermined area in the display area of the organic EL element.

  Thus, the convex portion area ratio Ap is a ratio of the sum of the projection areas of the convex portions in the region X to the area of the region X in the display region of the organic EL element. In other words, when the organic EL element is viewed from the top of the display area, it is the ratio of the total projected area of the projections to the area of the area X.

  Specifically, as shown in FIG. 5A, the region X510 on the structural layer 104 is determined, and the area is determined. Next, the projected areas of the plurality of convex portions 202 in the region X510 are determined, and the sum thereof is determined. The ratio of the sum of the projected areas to the area of the region X510 is defined as a convex portion area ratio Ap. In the present specification, the “projected shape” of the convex portion 202 refers to the shape of the convex portion projected onto the structural layer when the convex portion 202 on the structural layer 104 is viewed from directly above. Specifically, in the case of a convex portion having a square bottom as shown in FIGS. 2 (a) and 2 (b), it means a shape projected on a square as shown in FIG. 5 (a). In the present specification, the “projected area” of the convex portion 202 refers to the area within the “projected shape” of the convex portion 202 described above (a region in which the convex portion 202 such as FIG. 5A is hatched). .

  In the present invention, it is desirable to set a plurality of the areas X. Preferably, ten or more regions X are set. It is desirable to set the area X so that there is no bias in the entire area of the display area on the structural layer 104. In the present invention, the plurality of regions X may have the same area as the regions 510 and 512 of FIG. 5 (a). Alternatively, the plurality of regions X may have different areas. Further, it is desirable that the region X includes three or more convex portions 202. Each of the regions X preferably has an area of 50 μm □ (□ is a square), preferably 2 μm to 10 μm, provided that each of the regions X includes three or more convex portions 202.

  In the present invention, as shown in FIG. 5A, the structural layer 104 in which the convex portions 202 are regularly arranged in a square lattice shape is particularly preferable. However, in addition to the structural layer 104 having the convex portions 202 regularly arranged as shown in FIG. 5A, the structural layer 104 may be one in which the convex portions 202 are randomly arranged. For example, as shown in FIG. 5B, the structural layer 104 may have convex portions 202 randomly arranged and flat portions 204 around the convex portions 202. Also, for example, the regions X 510 ′ and 512 ′ can be set. As described above, even in the case where the convex portions 202 are randomly arranged, it is necessary that the conditions of the region X and the convex portions 202 as described in the regularly arranged convex portions 202 be satisfied. Furthermore, in the present invention, the structural layer 104 may include both a region including regularly arranged protrusions and a region having randomly arranged protrusions.

  The convex portion area ratio Ap can be obtained by observing a desired region of the functional layer 104 with a scanning probe microscope (for example, AFM 5400 manufactured by Hitachi High-Tech Science Co., Ltd.). In the present invention, the flat portion 204 refers to a portion parallel to the surface of the light transmitting substrate 102 from which light is emitted. The convex portion 202 refers to a region other than the flat portion 204 which protrudes on the surface on the functional layer side of the structural layer 104. In the flat portion 204, the distribution in the height direction has a height distribution of plus or minus 10 nm with respect to the average value of the lowest position and the highest position in the region excluding the convex portion 202 of the structural layer 104. It may be done. Further, it is particularly preferable that all the flat portions 204 have the same height from the surface on which the convex portion 202 of the structural layer 104 is not provided.

  In the present invention, ten or more regions X are observed, and a convex portion area ratio obtained in each region X is determined. Next, the arithmetic mean value of the convex part area ratio for each of the obtained regions X is obtained, and it is determined whether or not (Expression 1) is satisfied.

  That the convex portion 202 satisfies the condition of (Expression 1) is that (i) on the surface on the functional layer side of the second electrode 110, surface plasmons propagating through the flat portion 208 of the second electrode are reconverted at the concave portion 206; It is important to obtain the effect of re-radiating as light and (ii) the effect of direct reflection due to high reflectivity at the flat portion 208 of the second electrode.

  The shape of the structural layer 104 including the convex portion 202 and the flat portion 204 is transferred to the layer formed thereon (that is, the first electrode 106, the functional layer 108, and the second electrode 110), and the shape is maintained. Be done. For example, the second electrode 110 has a recess 206 corresponding to the convex portion 202 and the flat portion 204 of the structural layer 104 at the interface between the second electrode 110 and the functional layer 108, and the flat portion 208 of the second electrode. Have.

  It is preferable that the convex part 202 and the flat part 204 provided in the structural layer 104 satisfy the conditions described below with reference to FIGS. 6 to 8 in addition to the condition of the above (formula 1).

  The first additional condition is that, in the structural layer 104, the distance between the apexes of the adjacent projections 202 is within a predetermined range. Specifically, the distance between the apexes of adjacent convex portions 202 is preferably in the range of 0.5 μm to 5 μm, preferably 0.5 μm to 3 μm. By setting the distance between the apexes, the concave portion 206 of the second electrode 110 has a shape capable of reflecting the light emitted from the functional layer 108 toward the light transmitting substrate 102 with high efficiency.

  Between the vertices will be described with reference to FIG. The vertex “adjacent to” one vertex of the convex portion 202a means the vertex of the convex portions 202b, 202c, 202d and 202h and the vertex of the convex portions 202e, 202f, 202i and 202j through the flat portion 204. . In the present invention, the distance between the apex of the convex portion 202a and each of the apexes of the convex portions 202b to j is in the range of 0.5 μm to 5 μm, preferably 0.5 μm to 3 μm.

  In the present invention, it is preferable to satisfy both the condition of the above (formula 1) and the distance between the apexes.

  Next, with reference to FIG. 7 and FIG. 8, the relationship between the convex part 202 of the structural layer 104 and the flat part 204 is demonstrated. FIG. 7 is a perspective sectional view showing the structural layer 104 including the convex portion 202 and the flat portion 204 similar to FIG. FIG. 7 shows a cutting line VIII-VIII (702) for cutting out a part of the structural layer 104. FIG. 8 is a cross-sectional view taken along the line VIII-VIII (702) of FIG. The cutting line VIII-VIII (702) is a straight line passing through the apexes of the convex portion 202a and the convex portions 202b and 202c. A cross section cut along a cutting line VIII-VIII (702) is perpendicular to the main surface of the light transmitting substrate 102.

  In the present invention, when considering the relationship between the convex portion 202 and the flat portion 204 of the structural layer 104, as shown in FIG. 7, (i) convex portions 202a and adjacent convex portions 202b centering on the convex portions 202a. And 202c, and (ii) the flat portion 204a between the convex portion 202a and the convex portion 202b and the flat portion 204b between the convex portion 202a and the convex portion 202c.

  Next, referring to FIG. 8, the convex portion 202 a has a vertex 802 a. The apex 802 a is the position of the convex portion 202 a whose height from the bottom surface 804 of the structural layer 104 is the largest. In the present invention, the height from the bottom surface 804 to the apex 802 a of the structural layer 104 is defined as H10. Further, as shown in FIG. 8, the height from the bottom surface 804 of the flat portion 204a between the convex portion 202a and the convex portion 202b is defined as H11. In the first embodiment, the height from the bottom surface 804 of the flat portion 204a between the convex portion 202a and the convex portion 202c is also H11. Then, the height obtained by subtracting the value of H11 from the value of H10 is defined as the “apparent height” H1a of the convex portion 202a. Further, the width of the convex portion 202a (the horizontal distance between the flat portion 204a and the flat portion 204b) is defined as the width w1a of the convex portion 202a. In the present invention, as described above, the heights H11 of the flat portions 204a and 204b may not be the same value due to variations in the flat portions. In that case, the arithmetic mean of both heights may be taken as the height H11 of the flat portion. In the present invention, the apex of the convex portion 202 (for example, the apex 802a in FIG. 8) is preferably at the center (or the center of gravity) of the bottom. However, in the present invention, the apex of the projection 202 does not have to be at the center (or the center of gravity) of the bottom of the projection. The apex of the convex portion 202 may be within the range of the bottom surface.

  In the present invention, the width w1a of the convex portion 202a is preferably 400 nm or more and 1000 nm or less. If the width w1a of the convex portion 202a is a numerical value within the above range, the width w1a can be maintained at the same size as the emission wavelength from the functional layer. This is important to obtain the effect of re-emission of light due to re-conversion of surface plasmons at the second electrode 110.

  As shown in FIG. 8, the horizontal distance between the flat portion 204a and the flat portion 204b is defined as the width w1b of the flat portion 204a and the width w1c of the flat portion 204b, respectively. Here, the width w1a, the width w1b, and the width w1c in the present invention are distances along the cutting line of interest (in the example of FIG. 8, the cutting line VIII-VIII of FIG. 7). In the present invention, the cutting line is preferably a straight line connecting the apex of one convex portion and the apexes of two convex portions adjacent thereto.

In the present invention, the ratio of the width w1a of the projection 202a to the arithmetic mean value w1f [w1f = (w1b + w1c) / 2] of the horizontal distance between the flat portion 204a and the flat portion 204b is 0.5 or more and 4.0 or less Is preferred. That is, it is preferable that w1a and w1f satisfy the following (formula 2).
0.5 ≦ w1a / w1f ≦ 4.0 (Equation 2)

  The ratio of w1a to w1f being within the above range means that the electromagnetic wave propagating in the horizontal direction in the second electrode of the organic EL element is re-converted as light by reconversion of surface plasmon at the boundary point between the flat portion and the concave portion. It is important in obtaining the effect to be emitted. That is, on the surface of the second electrode 110 to which the shape of the structural layer 104 is transferred, an electromagnetic wave propagating in the horizontal direction of the organic EL element in the flat portion 208 of the second electrode is at the boundary portion between the flat portion 208 and the recess 206 By reconversion of surface plasmons, it is possible to obtain an effect of being re-emitted as light.

  The apparent height H1a of the convex portion 202 of the structural layer 104 is preferably in the range of 50 nm or more and 300 nm or less. When H 1 a has a numerical value in the above range, the depth of the recess 206 of the second electrode 110 can be maintained in a range effective for reconversion of surface plasmons. This is important to obtain the effect of re-emission of light due to re-conversion of surface plasmons. In addition, when H1a has a numerical value in the above range, the uniformity of the surface of a layer (for example, a light emitting layer or the like) included in the functional layer 108 can be maintained, and light emission defects due to leakage current can be prevented. .

  The values of the apparent height H1a of the convex portion 202 and the dimensions (w1a, w1b, and w1c) necessary for calculation of (Expression 2) are scanning probe microscopes (for example, AFM 5400 manufactured by Hitachi High-Tech Science Co., Ltd. It can be determined using For example, ten or more measurement points corresponding to FIGS. 7 and 8 on the structural layer 104 may be provided, and H1a, w1a, w1b, and w1c may be measured at each measurement point. Preferably, ten or more measurement points are set in each of ten or more regions X on the structural layer 104 (such as the regions X 510 and 512 described above). A plurality of measurement points may be provided in the same area X. In addition, it is desirable that the measurement points be set so that there is no bias in the entire display region of the structural layer 104. In the present specification, when the area X is referred to as a concept including measurement points, it is referred to as an "area".

In order to examine whether the condition of the above (formula 2) is satisfied or not, first, w1a, w1b, and w1c are measured at the ten or more measurement points. Next, the dimensions of w1a, w1b, and w1c obtained in each measurement are substituted into the following (Equation 3) to determine the value of w1a / w1f at each measurement point.
w1a / w1f = w1a / [(w1b + w1c) / 2] (Equation 3)

  The arithmetic mean value of the ratio of the obtained 10 or more (formula 3) is determined. It is determined whether the obtained average value satisfies (Expression 2).

  In the present invention, as described above, the convex area ratio and the arithmetic average of w1a / w1f are determined based on the numerical values measured in each of ten or more “areas”. In the present invention, it is only necessary that the arithmetic mean satisfies the above (formula 1) and (formula 2). That is, the ten or more “areas” described above do not have to satisfy the conditions of the convex portion area ratio Ap of (Expression 1) and w1a / w1f of (Expression 2). Among the ten or more “areas”, there may exist one that does not satisfy either or both of (Expression 1) and (Expression 2). In such a case, the “areas” satisfying both (Formula 1) and (Formula 2) may be periodically arranged on the structural layer 104 or may be randomly arranged. In the present invention, the “area” satisfying both (Formula 1) and (Formula 2) is preferably 50 to 100%, more preferably 80% to 100% with respect to the entire area of the display region of the structural layer 104. %. Most preferably, the “area” satisfying both (Formula 1) and (Formula 2) occupies 100% on the structural layer 104.

  In the present invention, for the conditions of (formula 1) and (formula 2), it is sufficient to satisfy (formula 1), but it is particularly preferable to satisfy the conditions of both (formula 1) and (formula 2).

  The first embodiment described above has been described based on the structural layers specifically shown in FIGS. 2 and 5-8. However, the present invention is not limited to the structural layer having the convex portion 202 and the flat portion 204 whose shapes are specifically shown in FIGS. 2 and 5 to 8. In particular, the shapes of the convex portion 202 and the flat portion 204 according to the present invention are not particularly limited as long as the shape transferred to the second electrode 110 efficiently reflects the light emitted from the functional layer 108 to the light transmissive substrate 102 side. It is not limited.

  For example, the convex portion may have a circular bottom surface and a hemispherical convex portion. As an example of another convex part, the shape of a polygon whose base is not quadrangular, but triangular, pentagonal, hexagonal or the like can be mentioned. In the present invention, the arrangement of the protruding portion and the protruding portion of the protruding portion may be any shape as long as the above-described conditions (H1a, w1a, w1a / w1f, etc.) are satisfied.

  For example, the shape and arrangement of the protrusions may be those of the second embodiment as shown in FIG. 9 or the third embodiment as shown in FIG. Specifically, the convex portion 202 of the structural layer 104 shown in FIG. 9 has the same shape as the convex portion 202 shown in FIG. Further, in the convex portion of the structural layer 104 shown in FIG. 9, one convex portion 202 is surrounded by the flat portion 204, and the six convex portions around each convex portion 202 are the vertices of a regular hexagon. Located in

  The convex portion 202 of the structural layer 104 shown in FIG. 10 has a bottom surface of a true circular shape and a convex portion of a hemispherical shape. Further, in the convex portion of the structural layer 104 shown in FIG. 10, one convex portion 202 is surrounded by the flat portion 204, and the six convex portions around each of the convex portions 202 are the vertices of a hexagon. Located in Here, in the third embodiment, as shown in FIG. 10, there is a row (dotted line row represented by p1 in FIG. 10) passing through the top of the longitudinal convex portion and adjacent to this row A distance between a grain apex and a line passing through the line (dotted line indicated by p2 in FIG. 10) is defined as x, and two adjacent lines in the horizontal direction orthogonal to the two lines in the vertical direction The distance between the dotted row) represented by q1 and q2 in FIG. 10 is defined as y. In a third embodiment, the ratio of x to y is not 1: 1. The ratio of x to y is x: y = 32: 23 to 32:29, preferably 31:25 to 31:26.

  In addition, the convex part of FIG. 10 may be a convex part of a shape as shown to Fig.2 (a) or FIG. In the present invention, in particular, it is preferable that the protruding portion of the convex portion 202 be a convex curved surface (curved surface without a ridge line as shown in FIGS. 5 to 8) or a hemispherical shape.

  In the present invention, as shown in FIG. 7, the cutting lines for determining the widths w1a, w1b and w1c are preferably taken in a direction parallel to one side of the periphery of the display area of the organic EL element. If the measured values do not have the same value depending on the direction of the cross section in which the width w1b and the width w1c are measured (for example, the arrangement of protrusions shown in FIGS. 9 and 10, random arrangement, etc.), the width w1a, the width w1b and The cutting line for obtaining the width w1c is preferably taken such that two adjacent convex portions are as close as possible with one convex portion as the center.

  The structural layer 104 is light transmissive. The structural layer 104 preferably contains a light transmitting resin. The light transmitting resin is low density polyethylene, high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-norbornene copolymer, ethylene Polyolefin resins such as dimethanooctahydronaphthalene copolymer [ethylene-domon (DMON) copolymer], polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer; polyethylene terephthalate, polybutylene terephthalate Polyester resins such as polyethylene naphthalate; Amide resins such as nylon-6, nylon-6,6, meta-xylene diamine-adipic acid condensation polymer; Imido-based acrylic resins such as polymethyl methacryl imide; Acrylic resins such as acrylate; styrene-acrylonitrile resins such as styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer; polystyrene; polyacrylonitrile; cellulose resins such as triacetate cellulose and diacetate cellulose; polychloride Halogen-containing resins such as vinyl, polyvinylidene chloride, polyvinylidene fluoride and polytetrafluoroethylene; hydrogen bonding resins such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer; ionomer resins; polycarbonate resins, polysulfone resins, polyether sulfone resins , Engineering plastics such as polyetheretherketone resin, polyphenylene oxide resin, polymethylene oxide resin, polyarylate resin, liquid crystal resin, etc. Including click-based resin.

  Fine particles may be added to the structural layer 104 for the purpose of adjusting the refractive index and / or imparting light scattering properties. 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.

  The particulates added for the purpose of imparting light scattering properties may be from inorganic particulates, organic particulates or a combination thereof. The organic fine particles include fine particles consisting of acrylic polymers, styrene polymers, styrene-acrylic polymers and crosslinked products thereof, melamine-formaldehyde condensates, polyurethanes, polyesters, silicones, fluorine-based polymers, and copolymers of these. Inorganic fine particles include clay compound particles such as smectite, kaolinite and talc; fine particles comprising inorganic oxide such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide and strontium oxide; calcium carbonate, barium carbonate Particles comprising an inorganic compound such as barium chloride, barium sulfate, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium nitrate, strontium hydroxide and the like; and two or more inorganic oxides It contains fine particles of a glass material obtained by sintering. A combination of two or more organic and / or inorganic particles may be used.

[electrode]
Hereinafter, the first electrode 106 and the second electrode 110 will be described. Here, the case where the first electrode 106 is used as an anode and the second electrode 110 is used as a cathode will be described. However, the present invention is not limited to this case. In the present invention, the first electrode 106 may be used as a cathode and the second electrode 110 may be used as an anode. In this case, it is preferable to use the first electrode 106 as a light transmitting cathode and the second electrode 110 as a reflective anode.

(First electrode 106: anode)
When the first electrode 106 is used as an anode, the first electrode 106 is formed of a material having a large work function. Materials that can be used include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. The material for forming the first electrode 106 used as an anode is: antimony doped tin oxide (ATO), fluorine doped tin oxide (FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), conductive metal oxides such as zinc indium oxide (IZO); metals such as gold, silver, chromium, 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, polypyrrole and the like. The first electrode 106 may be a laminate. For example, the first electrode 106 may be a stack of layers made of the above materials. In the present invention, it is preferable to form the first electrode 106 using a conductive metal oxide. It is particularly preferable to form the first electrode 106 using ITO in terms of productivity, high conductivity, transparency and the like.

  In the case of extracting light emitted from the side of the first electrode 106 used as an anode, it is desirable that the first electrode 106 have a light transmittance of greater than 50%. Further, the first electrode 106 preferably has a sheet resistance of several hundred ohms / square or less. Furthermore, although depending on the material to be used, the first electrode 106 usually has a thickness in the range of 10 nm to 1000 nm, preferably in the range of 10 nm to 200 nm.

(Second electrode: cathode)
As described above, the shape of the structural layer 104 is transferred to the second electrode 110. Specifically, as shown in FIGS. 2A and 2B, the shapes of the convex portion 202 and the flat portion 204 of the structural layer 104 are the same as those of the second electrode 1101 concave portion 206 and the second electrode. They are respectively transferred to the flat portions 208. The shape of the structural layer 104 is transferred at least to the surface of the second electrode 110 on the light transmitting substrate 102 side (the interface between the second electrode 110 and the functional layer 108). The shape of the structural layer 104 may or may not be transferred to the surface of the second electrode 110 opposite to the light transmitting substrate 102 (so-called upper surface). The interface between the functional layer 108 and the second electrode 110 having the concave portion 206 and the flat portion 208 of the second electrode can efficiently reflect light from the light transmitting substrate 102 by reflecting light with high efficiency. Make it In the present specification, “reflection” at the interface between the second electrode 110 and the functional layer 108 is: (1) part of the light emitted from the light emitting layer of the functional layer 108 is the second electrode 110 and the light transmitting substrate 102 side It means both being reflected to the side (normal reflection) and (2) the generated surface plasmons being reconverted, and light being 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 of a material having a small work function. Materials which can be used as the cathode desirably include metals having a work function of 4.5 eV or less (hereinafter referred to as “electron-injectable 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 as the cathode may be an alloy or mixture of two or more electron injecting metals. Examples of such materials include sodium-potassium alloys, magnesium / aluminium mixtures, magnesium / indium mixtures, lithium / aluminium mixtures, and the like. Alternatively, in order to achieve both electron injecting property and durability against oxidation etc., a second electrode 110 which is a cathode, using a mixture of an electron injecting 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 ohms / square or less. The second electrode 110 generally has a thickness in the range of 10 nm to 5 μm, preferably in the range of 40 nm to 200 nm.

[Function layer]
The functional layer 108 provided between the first electrode 106 and the second electrode 110 at least includes 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 106, the functional layer 108, and the second electrode 110 can have various stacked structures. Specific examples of the laminated structure that can be adopted include, for example, the following layer structures (a) to (p), but are not limited thereto. In the following layer structure, the “anode” may be the first electrode 106, and the “cathode” may be the second electrode 110. Also, 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 / Emitting 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 / luminescent layer / electron injection layer / cathode (h) anode / hole transport layer / luminescent layer / electron transport layer / cathode (i) anode / hole transport layer / luminescent 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 / emission layer / electron transport layer / cathode (m) anode / hole injection layer / hole transport layer / emission layer / electron transport layer / electron injection layer / cathode (n) anode / Light emitting layer / electron injection layer / cathode (o) anode / light emitting layer / electron transport layer / cathode (p) anode / light emitting layer / electron transport layer / electron injection layer / cathode

  Hereinafter, each layer of the functional layer 108 will be described.

(Emitting layer)
The light emitting layer is a layer in which electrons and holes injected from the electrode recombine to emit light. The part that emits light may be in the layer of the light emitting layer, or may be an interface between the light emitting layer and a layer adjacent to the light emitting layer.

  The light emitting layer may contain a light emitting host compound and a light emitting dopant compound such as a phosphorescent dopant or a fluorescent dopant. The light-emitting host compound is, for example, one 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 or an oligoarylene compound, or a carboline derivative or a diazacarbazole Including derivatives and the like. The light emitting dopant compound includes, for example, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, It includes stilbene dyes, polythiophene dyes, rare earth complexes and the like.

  The light emitting layer may be a single layer or a laminate of multiple 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 a light emitting maximum wavelength of 430 nm or more and 480 nm or less, and "green light emitting layer" means a single light emitting layer having a light emitting maximum wavelength of 510 nm or more and 550 nm or less By "red light emitting layer" is meant a monochromatic light emitting layer having a light emission maximum wavelength of 600 nm or more and 640 nm or less. A light emitting layer having a light emission maximum wavelength other than the above may be used.

  One example of a light emitting layer which is a laminate including a plurality of layers is a white light emitting layer including three colors (blue light emitting sublayer, green light emitting sublayer, and red light emitting sublayer). The terms "blue", "green" and "red" pertaining to the light emitting sublayer mean having the emission maximum wavelength described above. In a light emitting layer which is a laminate including a plurality of layers, 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 of this invention, a planar light source, and a display apparatus contain a white light emitting layer. Therefore, the lighting device, the planar light source and the display device of the present invention preferably have at least a part of the organic EL element including the 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. The film thickness within the above range contributes to the improvement of the film uniformity, the elimination of the need to apply a high voltage to the light emitting layer, and the improvement of the stability of the luminescent color 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 needed for the reduction of the driving voltage, the improvement of 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 above layer structure (b) to (e)), or between the anode and the hole transport layer (for example, the above It may be provided in layer structure (j)-(m)). Materials for forming the hole injection layer include: phthalocyanines represented by copper phthalocyanine; oxides represented 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, in the above layer structures (c), (g), (k) and (n)), or the cathode and the electron transport layer (E.g., the layer structures (e), (i), (m) and (p) above). Materials for forming the electron injection layer are: metals represented by strontium and aluminum; alkali metal compounds represented by lithium fluoride; alkaline earth metal compounds represented by magnesium fluoride; represented by aluminum oxide Including oxides and the like.

  Although depending on the material to be used, it is preferable that the hole injection layer and the electron injection layer have a thickness in the range of 0.1 nm or more and 5 μm or less.

(Transport layer: hole transport layer, electron transport layer)
The transport layer is a layer provided between the electrode and the light emitting layer as needed 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 structure (f) to (i)), or between the hole injection layer and the light emitting layer (for example, the above Layer structures (j) to (m)). It is desirable that the hole transport material for forming the hole transport layer have a high hole transfer rate. In addition, the hole transport material may have the property of promoting hole injection or blocking electron transfer.

  The hole transport material may be organic or inorganic. Non-limiting examples of hole transport materials are triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives 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 contain one or more hole transport materials.

  The hole transport layer may contain 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 techniques well known in the art, such as vacuum evaporation. The hole transport layer generally has a thickness of 5 nm or more and 5 μm or less, preferably 5 nm or more and 200 nm or less.

(Electron transport layer)
The electron transport layer may be provided between the cathode and the light emitting layer (for example, the above layer structures (d), (h), (l) and (o)), and the electron injection layer and the light emitting layer And (for example, the above-mentioned layer structures (e), (i), (m) and (p)). The electron transport material for forming the electron transport layer preferably has a high electron transfer rate. In addition, the electron transport material may have the property of promoting electron injection or blocking the hole transfer.

  Non-limiting examples of electron transport materials are nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide derivatives, freorenylidenemethane derivatives, anthraquinodimethane derivatives, anthrone derivatives, oxadiazole derivatives, thiadiazoles 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, thiopyrandioxide, carbodiimide, freorenylidenemethane, anthraquinodimethane, anthrone, oxadiazole, and thiadiazole And 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 are 8-quinolinol, 5,7-dichloro-8-quinolinol, 5,7-dibromo-8-quinolinol, 2-methyl-8-quinolinol, 5- Methyl-8-quinolinol) aluminum. Center metals that can be used include Al, Zn, In, Mg, Cu, Ca, Sn, Ga, and Pb. Metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, tris 2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, and bis (8-quinolinol) zinc (Znq), but is not limited thereto.

  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 structure, a 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 electron transport materials. Alternatively, the electron transport layer may be a single layer or may have a laminated structure composed of a plurality of sublayers. The electron transport layer can be formed using techniques well known in the art, such as vacuum evaporation. The electron transport layer generally has a thickness of 5 nm or more and 5 μm or less, preferably 5 nm or more and 200 nm or less.

[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 transmitting substrate 102 opposite to the surface on which the structural layer 104 is provided. As shown in FIG. 3 and FIG. 4, the light extraction lens layer 310 is also provided with a light transmitting layer 304 having a light transmitting property, and a condensing lens layer 302 provided on the surface of the light transmitting layer 304. Good. Here, a so-called light collecting sheet may be used as the light collecting lens layer 302. Alternatively, the light extraction lens layer 310 may be a light transmissive layer in which a microlens array is formed on the surface (not shown). By providing the light extraction lens layer 310, light can be collected in a specific direction, for example, the light extraction direction (the direction 112 in FIG. 1) of the organic EL element, and the luminance in the specific direction can be enhanced.

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

  Alternatively, fine particles may be added to the light transmitting resin to improve the light scattering effect of the light extraction lens layer 340. The particulates that can be added can be selected from the group consisting of one or more types of inorganic particulates, one or more types of organic particulates, and a combination thereof. Organic fine particles that can be used include acrylic polymers, styrene polymers, styrene-acrylic polymers and their cross-linked products, melamine-formalin condensates, polyurethane polymers, polyester polymers, silicone polymers, fluorine polymers, and their copolymer weights Including polymeric materials such as coalescing. Nonlimiting examples of materials for forming the inorganic fine particles are: clay compounds such as smectite, kaolinite and talc; inorganic substances such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide and 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 nitrate, strontium hydroxide and the like; And a glass material obtained by sintering an inorganic oxide of

[Sealing member]
The organic EL element 100 is preferably covered by a sealing member. The sealing member may be concave or flat as long as it can cover the side including the functional layer of the organic EL element 100. For example, the sealing member and the electrode and / or the supporting substrate may be bonded with an adhesive to perform sealing on the side including the functional layer of the organic EL element. The sealing member has a function of preventing moisture, oxygen and the like harmful to the layers (particularly the functional layer) of the organic EL element from invading the organic EL element.

There are no light transmission and electrical insulation requirements for the sealing member. However, the sealing member, like the barrier layer 402, preferably has low water vapor transmission and low oxygen transmission. The sealing member has a water vapor transmission rate (25 ± 0.5 ° C., 90 ± 2) of 1.0 × 10 ⁻² g / (m ² · 24 h) or less, which is measured according to JIS K 7129-1992. It is desirable to have 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 (% RH) and / or JIS K 7126-1987. .

  Non-limiting examples of sealing members include glass plates, plates and films of polymers, metal plates and films, and the like. Glass which can be used includes, in particular, soda lime glass, barium-strontium containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz glass and the like. Also, polymers which 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 are: Photocurable or thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers, methacrylic acid oligomers, etc .; such as 2-cyanoacrylate 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 etc.

  Here, in order to prevent the 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 inert substance into the gap between the sealing member and the side including the functional layer of the organic EL element 100. Non-limiting examples of inert substances include nitrogen, inert gases such as argon, and inert liquids such as fluorocarbons, silicone oils. Moreover, it is also possible to evacuate the gap between the sealing member and the side including the functional layer of the organic EL element 100.

  Optionally, a hygroscopic member containing a hygroscopic compound may be disposed in the gap between the sealing member and the side including the functional layer 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 and magnesium iodide; perchlorates such as barium perchlorate and magnesium perchlorate Including. Among these, as sulfates, metal halides and perchloric acids, anhydrides are preferably used.

<Method of manufacturing organic EL element>
The present invention includes a method of manufacturing the organic EL element. This manufacturing method is
(A) preparing a light transmitting substrate;
(B) forming a structural layer on the light transmitting substrate;
(C) forming a first electrode on the structural layer;
(D) forming a functional layer on the first electrode;
(E) forming a second electrode on the functional layer.

  Step (A) is a step of selecting the light transmitting substrate 102 formed of an appropriate material, and if necessary, performing the cleaning and / or necessary pretreatment on the light transmitting substrate 102. The cleaning and / or necessary pretreatment is usually performed on the substrate of the organic EL element, and is not particularly limited.

  The step (B) is a step of forming the structural layer 104 having a plurality of convex portions 202 and flat portions 204. This step can be performed using a technique such as a transfer method or a photolithography method. When the transfer method is used, the light transmitting resin for forming the above-described structural layer 104 is uniformly coated on the light transmitting substrate 102 prepared in the step (A), and a desired shape is formed on the resin. The shape transfer substrate having a shape (inverted shape) to be pressed is pressed, and the desired shape is transferred to the light transmitting resin. The layer of the light transmitting resin to which the desired shape has been transferred is cured by light or heat to form the structural layer 104 having the convex portion 202 of the desired shape and the flat portion 204.

  Step (C) is a step of forming a first electrode 106 used as an anode. Step (C) may be performed using any method known in the art, provided that the top surface shape of the structural layer 104 is reflected on the top surface of the first electrode 106. For example, in consideration of the compatibility with the material of the first electrode 106, the step (C) may be performed by (1) physical methods such as vacuum evaporation, sputtering, ion plating, etc., (2) CVD, plasma CVD It can implement by the method suitably selected from well-known methods, such as a chemical system, etc. For example, when forming the first electrode 106 using ITO, the step (C) can be performed by a direct current sputtering method, a high frequency sputtering method, a vacuum evaporation method, an ion plating method, or the like.

  In the step (C), the first electrode 106 may be patterned using chemical etching such as photolithography or physical etching such as laser. Alternatively, the patterned first electrode 106 may be formed by a vacuum evaporation method through a mask, a sputtering method through a mask, a lift-off method, or the like.

  Step (D) is a step of forming a functional layer 108 including a light emitting layer. Step (C) may be performed using any method known in the art, provided that the top surface shape of the first electrode 106 (that is, the top surface shape of the structural layer 104) is reflected on the top surface of the functional layer 108. It can be implemented. For example, step (D) may be performed using a vacuum evaporation method or the like.

  Process (E) is a process of forming the 2nd electrode 110 used as a cathode. The second electrode 110 can be formed using any technique known in the art, such as vacuum evaporation or sputtering. The lower surface of the second electrode 110 formed in this step (that is, the interface between the functional layer 108 and the second electrode 110) corresponds to the plurality of convex portions 202 and the flat portion 204 of the structural layer 104. And a flat portion 208 of the second electrode. By having such a shape, light emitted from the functional layer 108 can be “reflected” with high efficiency and emitted from the light transmitting substrate 102 side.

<Lighting device and planar light source>
The present invention includes a lighting device and a planar light source including the organic EL element described above. For example, in the case of a lighting device including a light transmitting substrate, an anode, a functional layer, a cathode, a moisture absorbing member, and a sealing member from the light emission side, the organic EL of the present invention The element can be used. FIG. 11 shows an example of a specific lighting device. In this example, from the light emission side, the light transmitting substrate 102, the structural layer 104, the first electrode (anode) 106, the functional layer 108, the second electrode (cathode) 110, the external connection terminal 112, the moisture absorbing member (desicant) 1202 and a sealing member 1204. In this example, the structure from the light transmitting 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 supply. 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. In addition, the planar light source of the present invention can be configured similarly to the illumination device. The production of the illumination device and the planar light source of the present invention can be carried out by adding known appropriate steps to the method of producing the organic EL element described above.

<Display device>
The present invention includes a display including the above-described organic EL element. The display device of the present invention can include 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 portion may include a drive portion such as a silicon drive substrate. FIG. 12 shows an example of a specific display device. This display device includes, from the display side of the device, a light transmitting substrate 102, a color filter layer (for example, an RGB color filter layer) 1302, a barrier layer 402, a structural layer 104, a first electrode (anode) 106, and a functional layer 108. , The second electrode (cathode) 110. In the example of FIG. 12, portions other than the color filter layer 1302 correspond to the above-described organic EL element. The production of the display device of the present invention can be carried out by adding appropriate steps to the above-mentioned method of producing an organic EL element. For example, the light transmitting substrate 102 may be prepared [step (A)], then the color filter layer 1302 and the barrier layer 402 may be formed, and the above steps (B) to (E) may be performed. The color filter layer 1302 can be formed using any method known in the art, such as spin coating or evaporation.

  An embodiment embodying the first aspect described above will be described below. Moreover, it describes also about a comparative example. In the following examples and comparative examples, the width and apparent height H1a of the projections 202 of the structural layer 104 and the projection area ratio Ap were measured and calculated using a scanning probe microscope. Specifically, after obtaining an image of one convex portion 202a and two convex portions 202b and 202c adjacent thereto at ten randomly selected points, the width w1a of the convex portion 202a and the apparent height H1a , And the average value of the widths (w1b, w1c) of the two flat portions 204a, 204b. In addition, the sum of the area of the region X and the projected area of the convex portion 202 in the region X was determined, and the convex portion area ratio Ap was determined. The arithmetic mean value of ten measured values was taken as the characteristic value of the fine structure of the structural layer 104. Further, although the following embodiments will be described based on the characteristic value of the fine structure of the structural layer 104, the fine structure of the structural layer 104 is reversed and transferred to the functional layer 108 side of the second electrode 110. confirmed.

Example 1
The non-alkali glass plate having dimensions of 30 mm × 40 mm and a thickness of 0.7 mm was washed to prepare a light transmitting substrate 102. A UV (ultraviolet) -curable acrylic resin (Liodurasu TYT manufactured by Toyo Ink Co., Ltd.) is applied onto the light transmitting substrate 102 using a spin coater, and then heated at 100 ° C. for 1 minute in a hot air oven A resin layer having a thickness of 1 μm was formed. Then, the film board which has a fine pattern was pressed on the surface of this resin layer, and UV light (150 mJ / cm < ² >) was irradiated in the state. Next, the film plate was peeled off to obtain a structural layer 104 having a convex portion 202 and a flat portion 204 on the top surface. The bottom of the convex portion 202 had a square shape. In addition, in the structural layer 104, it was confirmed that one convex portion 202 was surrounded by the flat portion 204 and had the pattern shown in FIG. Moreover, the convex part had the protrusion of the structure shown to FIGS. 5-8. The width w1a of the convex portion was 448 nm, the height H1a was 60 nm, and the convex portion area ratio was 0.41. The widths w1b and w1c of the flat portion 204 were 249 nm and 255 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 252 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value w1f of the width w1a of the convex portion and the width of the flat portion was 1.8.

  Next, an ITO film having a thickness of 100 nm was deposited on the surface of the structural layer 104 by sputtering, and then the ITO film was patterned to form a first electrode 106 (anode) having light transmittance. Thus, the light extraction substrate 120 was obtained.

  The functional layer 108 was formed by depositing the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer on the surface of the first electrode 106 by vapor deposition.

The materials of each layer in the functional layer 108 used in the present embodiment are as follows.
(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 Layered structure of 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene (film thickness 15 nm) doped with [, N] 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).

  Subsequently, aluminum was deposited on the surface of the functional layer 108 by vapor deposition to form a second electrode 110 having a thickness of 50 nm.

  Separately, a PET film was prepared as a light transmitting layer 304 made of a light transmitting sheet. A condensing lens layer 302 is formed on one surface of the light transmitting layer 304. The condensing lens layer 302 is composed of a 5 μm diameter hemispherical micro lens and a cross prism structure with an apex angle of 89 ° at 5 μm pitch. The Subsequently, the other surface of the light transmitting layer 304 was bonded to the light transmitting 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 film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 400 nm, the height H1a was 50 nm, and the convex portion area ratio Ap was 0.64. The widths w1b and w1c of the flat portion 204 were 101 nm and 99 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 100 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 4.0.

Example 3
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 415 nm, the height H1a was 50 nm, and the area ratio was 12.0%. The widths w1b and w1c of the flat portion 204 were 789 nm and 781 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 785 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 0.5.

Example 4
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 584 nm, the height H1a was 90 nm, and the convex portion area ratio Ap was 0.533. The widths w1b and w1c of the flat portion 204 were 215 nm and 217 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 216 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 2.7.

Example 5
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 1000 nm, the height H1a was 100 nm, and the convex portion area ratio Ap was 0.444. The widths w1b and w1c of the flat portion 204 were 503 nm and 497 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 500 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 2.0.

Example 6
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 1000 nm, the height H1a was 300 nm, and the convex portion area ratio Ap was 0.25. The widths w1b and w1c of the flat portion 204 were 985 nm and 1015 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 1000 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 1.0.

Example 7
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The bottom of the convex portion had a square shape. In addition, it is confirmed that the structure layer 104 has a pattern in which one convex portion 202 is surrounded by the flat portion 204, and six convex portions are positioned at each vertex of a regular hexagon with respect to one convex portion shown in FIG. did. The width w1a of the convex portion was 400 nm, the height H1a was 70 nm, and the convex portion area ratio Ap was 0.16. The widths w1b and w1c of the flat portion 204 were 610 nm and 590 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 600 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 0.7.

Example 8
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The bottom of the convex portion was a true circle and had a hemispherical shape. Further, the structural layer 104 had a structure shown in FIG. 10 in which one convex portion 202 is surrounded by the flat portion 204. Here, the ratio of the distance x between two columns (p1 and P2) in one direction shown in FIG. 10 and the distance y between two columns (q1 and q2) in the direction orthogonal thereto is x: y = 6 It confirmed that it had a pattern which becomes: 5. The width w1a of the convex portion was 400 nm, the height H1a was 70 nm, and the convex portion area ratio Ap was 0.44. The widths w1b and w1c of the flat portion 204 were 189 nm and 189 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 189 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 2.1. In the present example, the above H1a, w1a, w1b and w1c were measured in the cross section along the cutting line along IIb-IIb in FIG.

Example 9
The present embodiment is an example in the case where (Expression 1) is satisfied but (Expression 2) is not satisfied.

  The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The bottom of the convex portion had a perfect circular shape. Further, the structural layer 104 had a structure shown in FIG. 10 in which one convex portion 202 is surrounded by the flat portion 204. Here, the ratio of the distance x between two columns (p1 and P2) in one direction shown in FIG. 10 and the distance y between two columns (q1 and q2) in the direction orthogonal thereto is x: y = 6 It confirmed that it had a pattern which becomes: 5. The width w1a of the convex portion was 800 nm, the height H1a was 80 nm, and the convex portion area ratio Ap was 0.63. The widths w1b and w1c of the flat portion 204 were 182 nm and 178 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 180 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 4.4. In the present example, the above H1a, w1a, w1b and w1c were measured in the cross section along the cutting line along IIb-IIb in FIG.

Comparative Example 1
When forming the structural layer 104, the procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion was not pressed, to obtain the organic EL element 100. The top surface of the structural layer 104 was flat. In addition, the interface between the second electrode 110 and the functional layer 108 was also flat.

Comparative Example 2
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 290 nm, the height H1a was 320 nm, and the convex portion area ratio Ap was 0.687. The widths w1b and w1c of the flat portion 204 were 65 nm and 55 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 60 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 4.8.

Comparative Example 3
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 1060 nm, the height H1a was 45 nm, and the convex portion area ratio Ap 0.094. The widths w1b and w1c of the flat portion 204 were 2387 nm and 2393 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 2390 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 0.4.

Comparative Example 4
The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 240 nm, the height H1a was 40 nm, and the convex portion area ratio Ap was 0.095. The widths w1b and w1c of the flat portion 204 were 543 nm and 537 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 540 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 0.4.

Comparative Example 5
The procedure of Example 1 was repeated except that the film plate used in forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 1200 nm, the height H1a was 500 nm, and the convex portion area ratio Ap was 0.685. The widths w1b and w1c of the flat portion 204 were 248 nm and 252 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 250 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 4.8.

Comparative Example 6
The present comparative example is an example in the case where (Expression 1) is not satisfied but (Expression 2) is satisfied.

  The procedure of Example 1 was repeated except that the film plate for forming the convex portion and the flat portion used when forming the structural layer 104 was changed, to obtain an organic EL element 100. The width w1a of the convex portion was 400 nm, the height H1a was 250 nm, and the convex portion area ratio Ap was 0.11. The widths w1b and w1c of the flat portion 204 were 820 nm and 780 nm, respectively, and their arithmetic mean value w1f [(w1 b + w1 c) / 2)] was 800 nm. The ratio [w1a / (w1b + w1c) / 2)] of the arithmetic mean value of the width of the convex portion and the width of the flat portion was 0.5.

<Evaluation>
A constant current with a current density of 20 mA / cm ² was applied to the organic EL elements of Examples 1 to 6 and Comparative Examples 1 to 5 from a direct current (DC) power source, and total emitted light emitted was measured by an integrating sphere. Total emission light of Examples 1 to 6 and Comparative Examples 2 to 5 with respect to the amount of total emission light of Comparative Example 1 having the structural layer 104 (the interface between the flat second electrode 110 and the functional layer 108) having a flat upper surface The ratio of the amount of light was calculated to determine the light extraction efficiency ratio.

Further, the current density flowing when the forward voltage was applied stepwise to the organic EL element was measured, and subsequently, the current density flowing when applying the reverse voltage stepwise was measured. When a voltage of 1.0 V is applied in the forward direction, a current density smaller than 1.0 × 10 ⁻⁵ mA / cm ² is exhibited, and when a voltage of 1.0 V is applied in the reverse direction, 1.0 × The case where the current density was less than 10 ⁻⁵ mA / cm ² was determined as no leak current (“o”). When a voltage of 1.0 V was applied in the forward or reverse direction and the current density was greater than 1.0 × 10 ⁻⁵ mA / cm ² , it was determined that there was a leak current (“x”). Based on the above two evaluation items, the comprehensive judgment was determined according to the criteria in Table 1 below.

  The characteristic values and the evaluation results of the microstructures of the structural layers 104 of Examples 1 to 9 and Comparative Examples 1 to 6 are summarized in Table 2.

  As shown in Table 2, the organic EL devices of Examples 1 to 9 having the structural layer 104 satisfying (Expression 1) and (Expression 2) have high light extraction efficiency ratios of 1.51 to 1.76. Have. It is estimated that the structure of the interface between the second electrode 110 and the functional layer 108 transferred from the structural layer 104 suppresses surface plasmon absorption and improves the light reflectance of the second electrode 110. Be done.

  Surface plasmons are known to attenuate as they propagate through portions having the same height over a certain distance. However, in the present invention, since the structural layer 104 has the convex portion 202, the surface plasmon is reconverted to the light toward the light transmitting substrate 102 in the concave portion 206 of the second electrode to which this shape is transferred. Re-radiated. In addition, since the structural layer 104 has the convex portion 202, the first electrode 106 side of the structural layer 104 is not flat. Since the shape of the structural layer 104 is transferred at the interface between the second electrode 110 and the functional layer 108, the functional layer side of the second electrode 110 has a recess 206 and a flat portion 208 of the second electrode. Therefore, the electromagnetic wave propagated in the horizontal direction on the surface on the functional layer side of the flat portion 208 of the second electrode is reconverted at the boundary point with the concave portion 206 and reradiated as light toward the light transmissive substrate 102 . In addition, the flat portion 208 of the second electrode is a smooth surface and has high reflectivity. Therefore, part of the light that has reached the second electrode 110 from the functional layer 106 is reflected toward the light transmissive substrate 102 at the flat portion 208 of the second electrode.

  As described above, in the present invention, surface plasmons are reconverted at the second electrode 110, and in addition, light from the functional layer is efficiently reflected. Therefore, the organic EL device of the first aspect can realize high light extraction efficiency.

  On the other hand, the organic EL element of Comparative Example 2 exhibited a light extraction efficiency ratio as low as 0.42, and a leak current was also generated. The result is that (1) the convex portion 202 has a very sharp shape because the apparent height H1a of the convex portion 202 of the structural layer 104 is larger than the width w1a, (2) the structure layer 104 The apparent height H1a is larger than the film thickness of the functional layer 108, (3) the convex portion area ratio Ap of the structural layer 104 is large, and (4) the widths (w1b, w1c) of the flat portions 204 are It is estimated that this is due to the fact that it is smaller than the width (w1a) of the projection 202. Specifically, it is considered that a convex portion having a steep side surface is formed on the first electrode 106 above the convex portion 202, and the film thickness of the functional layer 108 on the slope is smaller than that of the other portion. . Then, the decrease in the film thickness of the functional layer 108 causes the carrier movement between the first electrode 106 and the second electrode 110 to be locally dominant, and the carriers reaching the counter electrode increase without contributing to light emission. Conceivable. In addition, it is estimated that the ratio of direct reflection of light at the second electrode 110 is reduced by the comparative example 2 having the features (1), (2) and (4) above.

  The organic EL device of Comparative Example 3 also exhibited an insufficient light extraction efficiency ratio of 1.13. As a result, (1) the apparent height H1a of the convex portion 202 of the structural layer 104 is too low, (2) the convex portion area ratio Ap of the structural layer 104 is small, and (3) the structural layer 104 It is considered that the width (w1b, w1c) of the flat portion 204 is larger than the width (w1a) of the convex portion 202. Specifically, due to the features (1) to (3) of the comparative example 3, in the structure to be transferred onto the second electrode, the depth of the recess 206 is insufficient, the area of the recess 206 is reduced, The width of the flat portion 208 of the two electrodes becomes larger than the width of the recess 206. For this reason, it is considered that the flat portion 208 of the second electrode has a substantially continuous shape. Therefore, it is estimated that the organic EL element of the comparative example 3 was not able to suppress surface plasmon absorption.

  The organic EL element of Comparative Example 4 exhibited an insufficient light extraction efficiency ratio of 1.05. As a result, (1) the width (w1a) of the convex portion 202 of the structural layer 104 is too small, and the apparent height H1a is too low, (2) the convex portion area ratio Ap of the structural layer 104 is small And (3) the width (w1b, w1c) of the flat portion 204 of the structure layer 104 is considered to be larger than the width (w1a) of the convex portion 202. Specifically, due to the features (1) to (3) of Comparative Example 4 described above, the depth of the recess 206 transferred onto the second electrode 110 becomes insufficient, and the width of the recess 206 becomes significantly smaller than the wavelength. The area in which the recess 206 is formed is reduced, and the width of the flat portion 208 of the second electrode is larger than the width of the recess. For this reason, it is considered that the flat portion 208 of the second electrode has a substantially continuous shape. Therefore, in the organic EL element of the comparative example 4, it is estimated that surface plasmon absorption was not able to be suppressed.

  The organic EL element of Comparative Example 5 exhibited a low light extraction efficiency ratio of 0.78, and also generated a leak current. As a result, (1) the width of the convex portion of the structure layer 104 is larger than the wavelength of light emitted from the functional layer, (2) the apparent height H1a of the structure layer 104 is the thickness of the functional layer 108 (3) the convex portion area ratio Ap of the structural layer 104 is large, and (4) the width (w1b, w1c) of the flat portion 204 of the structural layer 104 is larger than the width (w1a) of the convex portion 202. It is presumed that the cause is small. Specifically, according to the features (1) to (4) of the comparative example 5, the first electrode 106 has a convex portion having a steep side surface, and the functional layer of the portion where the convex portion is formed. It is considered that the film thickness of 108 is smaller than the other portions. Then, the decrease in the film thickness of the functional layer 108 causes the carrier movement between the first electrode 106 and the second electrode 110 to be locally dominant, and the carriers reaching the counter electrode increase without contributing to light emission. Conceivable. Moreover, it is thought that the effect which suppresses surface plasmon absorption fell by the characteristic of said (1). In addition, since the apparent height H1a of the convex portion 202 is higher than the width w1a of the convex portion 202 of the structural layer 104, reflection of direct reflection in the concave portion 206 of the second electrode 110 to which this shape is transferred is obtained. It is estimated that the rate has dropped.

  The organic EL element of Comparative Example 6 exhibited an insufficient light extraction efficiency ratio of 1.20, and also generated a leak current. The result is that (1) the convex portion 202 has a very sharp shape because the apparent height H1a of the convex portion 202 of the structural layer 104 is larger than the width w1a, (2) the structure layer 104 This is considered to be due to the fact that the convex portion area ratio Ap is small, and (3) the width (w1b, w1c) of the flat portion 204 of the structural layer 104 is larger than the width (w1a) of the convex portion 202. Specifically, it is considered that a convex portion having a steep side surface is formed on the first electrode 106 above the convex portion 202, and the film thickness of the functional layer 108 on the slope is smaller than that of the other portion. . Then, the decrease in the film thickness of the functional layer 108 causes the carrier movement between the first electrode 106 and the second electrode 110 to be locally dominant, and the carriers reaching the counter electrode increase without contributing to light emission. Conceivable. In addition, the area in which the recess 206 is formed is reduced, and the width of the flat portion 208 of the second electrode is larger than the width of the recess. For this reason, it is estimated that the organic EL element of the comparative example 6 was not able to suppress surface plasmon absorption.

100 organic EL element 102 light transmitting substrate 104 structural layer 106 first electrode 108 functional layer 110 second electrode 112 external connection terminal 120 light extraction substrate 202a, 202b, 202c, 202d, 202e, 202f convex portion of the structural layer 202h, 202i , 202j structural layer convex portion 204 structural layer flat portion 206 second electrode concave portion 208 second electrode flat portion 302 condenser lens layer 304 light transmitting layer 310 light extraction lens layer 402 barrier layer 404 light scattering layer 510, 512, 510 ', 512' A predetermined area (area X) including a convex portion and a flat portion
702 cutting line 802a, 802b, 802c apex of convex portion 1202 moisture absorbing member 1204 sealing member 1302 color filter layer

Claims (9)

A light transmitting substrate, a light transmitting structural layer provided on the substrate, a light transmitting first electrode, a functional layer including a light emitting layer, and a second electrode in this order,
The structural layer has a plurality of protrusions and flat portions on the surface on the second electrode side, one protrusion is surrounded by the flat portions, and the distance between the tops of two adjacent protrusions is 0. .5 .mu.m or more and 5 .mu.m or less, and an organic EL element having a convex portion area ratio Ap satisfying the formula (1).
0.12 ≦ protrusion area ratio Ap ≦ 0.64 (Expression 1)
(However, the projection area ratio Ap is the ratio of the sum of the projection areas of the projections in the predetermined area to the predetermined area in the display area of the organic EL element.)   The organic EL element according to claim 1, wherein w1a is in the range of 400 nm to 1000 nm, where w1a is the width of one convex portion (A) selected from the plurality of convex portions. When the width of the convex portion (A) is w1a, and the widths of two flat portions between the two convex portions adjacent to the convex portion (A) and the convex portion (A) are w1b and w1c, respectively. The organic EL device according to claim 1, wherein the following relationship (formula 2) is satisfied:
0.5 ≦ w1a / [(w1b + w1c) / 2] ≦ 4.0 (equation 2)   The organic EL device according to any one of claims 1 to 3, wherein an apparent height of one convex portion (A) selected from the plurality of convex portions is 50 nm to 300 nm.   The organic EL device according to any one of claims 1 to 4, further comprising a barrier layer and / or a light scattering layer between the light transmitting substrate and the structural layer.   The organic EL according to any one of claims 1 to 5, further comprising a light extraction lens layer on the light transmitting substrate and the surface of the light transmitting substrate opposite to the surface provided with the structural layer. element.   The illuminating device containing the organic EL element of any one of Claims 1-6.   The planar light source containing the organic EL element of any one of Claim 1 to 6.   The display apparatus containing the organic EL element of any one of Claims 1-6.

Images