WO2012169069A1

WO2012169069A1 - Organic electroluminescence panel

Info

Publication number: WO2012169069A1
Application number: PCT/JP2011/063379
Authority: WO
Inventors: 崇人小山田; 大志辻; 敏治内田
Original assignee: パイオニア株式会社
Priority date: 2011-06-10
Filing date: 2011-06-10
Publication date: 2012-12-13

Abstract

[Problem] To provide an organic EL panel capable of maintaining a light-extraction magnification while reducing the amount of materials used in an organic material layer. [Solution] An organic electroluminescence panel is provided with: a plurality of organic EL elements having a plurality of organic material layers each being laminated between a transparent first electrode and a light-reflective second electrode and each containing a light-emitting layer having at least one type of light-emitting color; and a transparent substrate for supporting the first electrodes of the organic EL elements. This organic electroluminescence panel is characterized in that each of the plurality of organic EL elements has a light-emitting region in which the first electrode, the organic material layer and the second electrode are continuously laminated so as to completely overlap with one another, and the light-emitting layer of the light-emitting region has a surface area between 0.9 cm² and 100 cm².

Description

Organic electroluminescence panel

The present invention relates to an organic electroluminescence panel (hereinafter referred to as an organic EL panel) in which a plurality of organic electroluminescence elements (hereinafter referred to as organic EL elements) are juxtaposed.

The organic EL element has a structure in which a plurality of organic material layers using an organic compound having charge transportability (hole or electron mobility) are stacked. For the organic material layer, in addition to the light emitting layer, a layer made of a material having a hole transport ability such as a hole injection layer or a hole transport layer, or a material having an electron transport ability such as an electron transport layer or an electron injection layer The layer which consists of is included.

There is a need for an element with excellent external light extraction efficiency that efficiently extracts lost light confined as guided light inside the multilayer structure of an organic EL element. For example, in Patent Document 1, in order to reduce the loss of light in a glass substrate, a microlens, a nanoparticle, a multilayer refractive index, a concavo-convex shape, or the like is processed on a substrate on a radiation surface, or a transparent plate obtained by processing them is laminated. Thus, a technique for improving light extraction and improving luminous efficiency is disclosed.

Patent Document 2 discloses a technique for reducing the loss of light in the element by introducing these processing techniques into the layer structure of the organic EL element.

JP 2011-003284 A JP-A-6-155101

In the field of such organic EL elements, particularly in the field of manufacturing an organic EL panel having a plurality of organic EL elements arranged on a substrate, in order to establish a low-cost production method, wet coating is used. Increasing adoption of film formation is occurring. Examples of the wet coating method include a spin method, a dip method, a roll method, and an ink jet method. Inkjet systems that can be finely and easily patterned are drawing attention. In a method for manufacturing an organic EL panel using an inkjet method, a process of forming a bank for each organic EL element may be employed in order to coat a light emitting layer and an organic material layer for each organic EL element on a substrate. Many.

However, in the technologies related to the organic EL elements disclosed in

Patent Documents

1 and 2, light loss of the organic EL element alone is taken into consideration, but not so-called energy saving such as material loss of the organic material layer and effective use. .

Therefore, an object of the present invention is to provide an organic electroluminescence panel capable of maintaining the light extraction magnification while suppressing the amount of the organic material layer used.

The organic electroluminescence panel according to the present invention includes a plurality of organic material layers each including a light emitting layer of at least one kind of light emitting color, which is disposed between a transmissive first electrode and a light reflective second electrode. A plurality of organic EL elements, and a transparent substrate that supports the first electrode of the organic EL element. The organic electroluminescence panel includes a light emitting region in which each of the plurality of organic EL elements is continuously overlapped and laminated with the first electrode, the organic material layer, and the second electrode. The light emitting layer has an area of 0.9 cm ² to 100 cm ² .

Thus, according to the present invention, the light extraction efficiency comparable to that of the conventional panel can be improved by using a specific area for the light emitting region of the element while the organic EL element is provided with the light extraction structure. .

It is a general | schematic fragmentary sectional view which shows the organic EL element of embodiment of this invention. It is a general | schematic fragmentary perspective view which shows an example of the organic electroluminescent panel of embodiment of this invention. It is a general | schematic fragmentary sectional view which shows an example of the organic electroluminescent panel of embodiment of this invention. It is a fragmentary top view which shows the organic EL element which has the rectangular light emission area | region of the experiment example by this invention. It is a graph (a) which shows the plot which calculated the total light beam magnification corresponding to the ITO film thickness X of the organic EL element of the experiment example by this invention, and the graph (b) which shows the curve which fitted the said plot. It is a graph which shows the plot which computed the total light beam magnification corresponding to the circular light emission area | region diameter of the organic EL element of the experiment example by this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[Organic EL device]
FIG. 1 is a schematic partial cross-sectional view showing an example of the organic EL element of the present embodiment. As shown in FIG. 1, the organic EL element includes, on a transparent substrate 1 such as glass, a transparent anode 2 (first electrode), a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, in order. The hole blocking layer 6, the electron transport layer 7, the electron injection layer 8, and the cathode 9 (second electrode) made of metal are laminated. The hole injection layer 3, the hole transport layer 4, the light emitting layer 5, the hole blocking layer 6, and the electron transport layer 7 are organic material layers OML. In the organic EL element, the organic material layer OML is disposed between the opposing anode and cathode, and a part of the hole injection layer 3 and the hole transport layer 4 are formed over the substrate 1. The hole injection layer 3 and the hole transport layer 4 prevent a short circuit between the anode 2 and the cathode 9. Any organic material layer such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer may be formed by a dry film formation method such as a vacuum deposition method or a wet coating method such as an ink jet method. Can be formed.

The organic EL element 11 has a light extraction structure 10 on the main surface opposite to the main surface that supports the anode 2 of the substrate 1, that is, on the light extraction surface side (front side). The light extraction structure 10 includes, for example, a microlens layer, a pyramid layer, an uneven layer, or a fine particle diffusion layer.

Organic EL element 11 includes a light emitting region 15. The light emitting region 15 is a region where the first electrode 2, the organic material layer OML, and the second electrode 9 are continuously overlapped and laminated, and includes the light emitting layer 5. In the example shown in FIG. 1, the light emitting region 15 has an area defined by its width W and length (not shown in the direction perpendicular to the drawing) when the anode 2 is rectangular.

Further, the separator of each layer shown in FIG. 1 is represented by “/”, and anode 2 / hole injection layer 3 / hole transport layer 4 / light emitting layer 5 / hole blocking layer 6 / electron transport layer 7 / electron injection In addition to the configuration of layer 8 / cathode 9 /, although not shown, anode 2, hole injection layer 3, light emitting layer 5, electron transport layer 7, electron injection layer 8, cathode 9 / hole transport layer 4, positive The structure in which the hole blocking layer 6 is omitted, and although not shown, the anode 2 / hole transport layer 4 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / hole injection layer 3, hole blocking Although not shown, the layer 6 is omitted, and although not shown, the hole injection layer 3, the hole transport layer 4, the hole blocking layer 6 of the anode 2 / light emitting layer 5 / electron transport layer 7 / electron injection layer 8 / cathode 9 / A configuration in which is omitted is also included in the present invention. Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. In any case, the present invention is not limited to these stacked structures, and includes a structure including at least a light-emitting layer or a charge transport layer that can also be used.

[Organic EL panel]
FIG. 2 is a schematic partial perspective view showing an example of the organic EL panel of the present embodiment.

As shown in FIG. 2, the organic EL panel has a transparent substrate 1 and a plurality of organic EL elements 11 arranged on the substrate. Each of the organic EL elements 11 includes a transmissive first electrode (anode 2) and a light-reflective second electrode (cathode 9), and a plurality of organic material layers OML arranged between the first and second electrodes. And have. The organic material layer OML includes at least one light emitting layer having a light emitting color. The portion of the organic material layer OML including the light emitting layer is disposed at a portion where the striped first electrode and the strip-shaped second electrode intersect. In the embodiment shown in FIG. 2, the light emitting region 15 is rectangular or rectangular, but is not limited thereto. For example, the shape of the light emitting region 15 may be a square, a polygon, a circle, an ellipse, or a rectangle, or may be any shape having a long span and a short span as viewed from the front side. The long and short passes are, for example, a long side and a short side in the case of a rectangle, and a long axis and a short axis in the case of an ellipse.

Each of the organic EL elements 11 is formed so that the area of the light emitting region 15 is 0.9 cm ² to 100 cm ² . The shorter width (shortest span) of the light emitting region 15 is in the range of 0.2 mm to 100 mm.

The light extraction structure 10 provided on the transparent substrate 1 is disposed on the main surface opposite to the main surface supporting the first electrode (anode 2) of the substrate 1, that is, on the light extraction surface side (front side). As shown in FIG. 3, the light extraction structure 10 includes (a) a microlens layer 10a, (b) a pyramid layer 10b, (c) an uneven layer 10c, or (d) a fine particle diffusion layer 10d.

[substrate]
As the substrate 1, a quartz or glass plate, a metal plate or a metal foil, a resin substrate to be bent, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic EL element may be deteriorated by the outside air that has passed through the substrate. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

[Anode and cathode]
The anode 2 that supplies holes to the layers up to the light emitting layer is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, or a metal such as indium and / or tin or zinc oxide (ITO or IZO). It is composed of an oxide, a metal halide such as copper iodide, carbon black, or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

The anode is usually formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode can also be formed by dispersing and coating the substrate. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate by electrolytic polymerization, or the anode can be formed by applying a conductive polymer on the substrate.

The anode usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

The thickness of the anode depends on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. If it may be opaque, the thickness of the anode is arbitrary, and the anode may be integrated with the substrate 1. Furthermore, different conductive materials may be laminated.

For the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve the hole injection property, the anode surface is subjected to ultraviolet (UV) treatment or ozone treatment, oxygen plasma or argon plasma surface treatment, etc. It is preferable to do.

As a material of the cathode 9 for supplying electrons to the layers up to the light emitting layer, a material used for the anode can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. A suitable metal such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

In addition, only 1 type may be used for the material of the

cathode

9, and 2 or more types may be used together by arbitrary combinations and a ratio. The thickness of the cathode is usually the same as that of the anode.

Further, for the purpose of protecting the cathode made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Furthermore, when the anode and the cathode are on the light emission extraction side (first electrode), the material and film thickness are selected so as to be transparent or translucent. In particular, for either the anode or the cathode, it is preferable to select a material having a transmittance of at least 10% at the emission wavelength obtained from the organic light emitting material. These electrodes may be patterned as necessary.

[Organic material layer]
The organic material layer constituting the main components of the hole injection layer 3, the hole transport layer 4, the light emitting layer 5, the electron transport layer 6 and the electron injection layer 7 has a charge transport property (hole and / or electron mobility). An organic compound having

Examples of phosphorescent organometallic complex compounds used for the light-emitting layer 5 include Bis ジウム (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium III, Tris (2-phenylpyridine), which are iridium complexes. ) Iridium (III) = (Ir (ppy) 3), Bis (2-phenylbenzothiazolato) (acetylacetonate) iridium (III), Osmium (II) bis (3-trifluoromethyl -5- (2-pyridyl)- pyrazolate) dimethylphenylphosphine, rare earth compound Tris (dibenzoylmethane) phenanthroline europium (III),

platinum complexes

2,3,7,8,12,13,17,18-Octaethyl-21H, 23H- porphine, platinum (II), etc. Can be mentioned.

Examples of the organic compound having an electron transporting property as a main component of the light emitting layer and the electron injection layer include polycyclic compounds such as p-terphenyl and quaterphenyl and derivatives thereof, naphthalene, tetracene, pyrene, coronene, chrysene, Condensed polycyclic hydrocarbon compounds such as anthracene, diphenylanthracene, naphthacene, phenanthrene and their derivatives, condensed heterocyclic compounds such as phenanthroline, bathophenanthroline, phenanthridine, acridine, quinoline, quinoxaline, phenazine and their derivatives, fluoro CEJN, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, oxadiazole, aldazine, bisbenzoxazoline, bissu Lil, pyrazine, cyclopentadiene, oxine, aminoquinoline, imine, diphenylethylene, vinyl anthracene, diaminocarbazole, pyran, may be mentioned thiopyran, polymethine, merocyanine, quinacridone, rubrene, and the like, and the like derivatives thereof.

Furthermore, as an organic compound having an electron transporting property, metal chelate complex compounds, particularly metal chelated oxanoid compounds, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis [benzo (f) -8-quinolinolato ] Zinc, bis (2-methyl-8-quinolinolato) (4-phenyl-phenolato) aluminum, tris (8-quinolinolato) indium, tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris Mention may also be made of metal complexes having at least one 8-quinolinolato or a derivative thereof such as (5-chloro-8-quinolinolato) gallium and bis (5-chloro-8-quinolinolato) calcium as a ligand.

As organic compounds having electron transport properties, oxadiazoles, triazines, stilbene derivatives, distyrylarylene derivatives, styryl derivatives, and diolefin derivatives can also be suitably used.

Further, as an organic compound that can be used as an organic compound having an electron transporting property, 2,5-bis (5,7-di-t-benzyl-2-benzoxazolyl) -1,3,4-thiazole, 4, 4'-bis (5,7-t-pentyl-2-benzoxazolyl) stilbene, 4,4'-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazoly Ru] stilbene, 2,5-bis (5.7-di-t-pentyl-2-benzoxazolyl) thiophene, 2,5-bis [5- (α, α-dimethylbenzyl) -2-benzoxa Zolyl] thiophene, 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazolyl] -3,4-diphenylthiophene, 2,5-bis (5- Methyl-2-benzoxazolyl) thiophene, 4,4 ′ -Bis (2-benzoxazolyl) biphenyl, 5-methyl-2- {2- [4- (5-methyl-2-benzoxazolyl) phenyl] vinyl} benzoxazole, 2- [2- (4 Benzoxazoles such as -chlorophenyl) vinyl] naphtho (1,2-d) oxazole, benzothiazoles such as 2,2 '-(p-phenylenedipinylene) -bisbenzothiazole, 2- {2- [4 There may also be mentioned-(2-benzimidazolyl) phenyl] vinyl} benzimidazole, 2- [2- (4-carboxyphenyl) vinyl] benzimidazole and the like.

Further, as an organic compound having an electron transporting property, 1,4-bis (2-methylstyryl) benzene, 1,4-bis (3-methylstyryl) benzene, 1,4-bis (4-methylstyryl) benzene, Distyrylbenzene, 1,4-bis (2-ethylstyryl) benzene, 1,4-bis (3-ethylstyryl) benzene, 1,4-bis (2-methylstyryl) -2-methylbenzene, 1,4 There may also be mentioned -bis (2-methylstyryl) -2-ethylbenzene.

Further, as an organic compound having an electron transporting property, 2,5-bis (4-methylstyryl) pyrazine, 2,5-bis (4-ethylstyryl) pyrazine, 2,5-bis [2- (1- Naphthyl) vinyl] pyrazine, 2,5-bis (4-methoxystyryl) pyrazine, 2,5-bis [2- (4-biphenyl) vinyl] pyrazine, 2,5-bis [2- (1-pyrenyl) vinyl ] Pyrazine etc. are mentioned.

Other organic compounds having electron transport properties include 1,4-phenylene dimethylidin, 4,4'-phenylene dimethylidin, 2,5-xylylene dimethylidin, and 2,6-naphthylene dimethylidene. Din, 1,4-biphenylenedimethylidin, 1,4-p-terephenylenedimethylidin, 9,10-anthracenediyldimethylidin, 4,4 '-(2,2-di-t-butylphenylvinyl Well-known ones conventionally used for producing organic EL devices, such as biphenyl and 4,4 ′-(2,2-diphenylvinyl) biphenyl, can be appropriately used.

An electron transporting organic material layer made of an organic semiconductor that is in contact with the interface of the organic material layer and is laminated between the second electrode and the organic material layer and doped with a metal acid salt compound having an electron donating metal as a counter cation. Can be provided. This reduces the energy barrier when electrons are injected from the cathode to the organic material layer by doping the organic material layer (electron transport layer or electron injection layer) on the cathode side with an electron-donating metal having a reducing action. This is because the diffusion of the electron donating metal into the organic material layer under high temperature storage can be suppressed. Since the organic material layer has already been reduced by the electron donating metal due to the metal salt compound with the doped electron donating metal as a counter cation, the electron injection energy barrier is small, compared with the conventional organic EL device. Drive voltage can be reduced. In this case, the electron-donating metal is not particularly limited as long as it is an alkali metal such as Cs, an alkaline earth metal such as Mg, or a transition metal containing a rare earth metal. In particular, a metal having a work function of 4.0 eV or less can be suitably used. Specific examples include Cs, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, La, Mg, Sm, Gd, Yb, Etc.

The concentration of the metal salt compound in the organic material layer is preferably 0.1 to 40% by weight. If it is less than 0.1% by weight, the concentration of the molecule reduced by the electron donating metal of the metal salt compound is too low, and the effect of doping is small. If it exceeds 40% by weight, the metal salt compound concentration in the film is organic. The molecular concentration is exceeded and the effect of doping is also reduced. The thickness of the organic material layer is not particularly limited, but is preferably 1 nm to 300 nm. If the thickness is less than 1 nm, the amount of reducing molecules present in the vicinity of the electrode interface is small, so that the effect of doping is small. If the thickness exceeds 300 nm, the entire organic layer is too thick, leading to an increase in driving voltage.

On the other hand, organic compounds having hole transporting properties include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N′-di (3-methyl Phenyl) -4,4′-diaminobiphenyl, 2,2-bis (4-di-p-tolylaminophenyl) propane, N, N, N ′, N′-tetra-p-tolyl-4,4′- Diaminobiphenyl, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N′-diphenyl-N, N′-di (4-methoxyphenyl) -4,4′-diaminobiphenyl, N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether, 4,4′-bis (diphenylamino) quadriphenyl, 4-N, N-diphenylamino- (2-diphenylvinyl) benzene, 3- Toxi-4′-N, N-diphenylaminostilbenzene, N-phenylcarbazole, 1,1-bis (4-di-p-triaminophenyl) -cyclohexane, 1,1-bis (4-di-p- Triaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) -phenylmethane, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino)- 4 ′-[4 (di-p-tolylamino) styryl] stilbene, N, N, N ′, N′-tetra-p-tolyl-4,4′-diamino-biphenyl, N, N, N ′, N ′ -Tetraphenyl-4,4'-diamino-biphenyl N-phenylcarbazole, 4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl, 4,4 ''-bis [N (1-naphthyl) -N-phenyl-amino] p-terphenyl, 4,4'-bis [N- (2-naphthyl) -N-phenyl-amino] biphenyl, 4,4'-bis [N- ( 3-Acenaphthenyl) -N-phenyl-amino] biphenyl, 1,5-bis [N- (1-naphthyl) -N-phenyl-amino] naphthalene, 4,4′-bis [N- (9-anthryl)- N-phenyl-amino] biphenyl, 4,4 ″ -bis [N- (1-anthryl) -N-phenyl-amino] p-terphenyl, 4,4′-bis [N- (2-phenanthryl)- N-phenyl-amino] biphenyl, 4,4′-bis [N- (8-fluoranthenyl) -N-phenyl-amino] biphenyl, 4,4′-bis [N- (2-pyrenyl) -N— Phenyl-amino] biphenyl, 4 , 4′-bis [N- (2-perylenyl) -N-phenyl-amino] biphenyl, 4,4′-bis [N- (1-coronenyl) -N-phenyl-amino] biphenyl, 2,6-bis (Di-p-tolylamino) naphthalene, 2,6-bis [di- (1-naphthyl) amino] naphthalene, 2,6-bis [N- (1-naphthyl) -N- (2-naphthyl) amino] naphthalene 4.4 ″ -bis [N, N-di (2-naphthyl) amino] terphenyl, 4.4′-bis {N-phenyl-N- [4- (1-naphthyl) phenyl] amino} biphenyl 4,4′-bis [N-phenyl-N- (2-pyrenyl) -amino] biphenyl, 2,6-bis [N, N-di (2-naphthyl) amino] fluorene, 4,4 ″- Bis (N, N-di-p-tolylamino) terfeny , Bis (N-1-naphthyl) (N-2-naphthyl) amine.

Further, as the hole injection layer, the hole transport layer, and the hole transport light emitting layer, those obtained by dispersing the above organic compound in a polymer or those polymerized can be used. So-called π-conjugated polymers such as polyparaphenylene vinylene and derivatives thereof, hole-transporting non-conjugated polymers represented by poly (N-vinylcarbazole), and sigma-conjugated polymers of polysilanes can also be used.

The hole injection layer is not particularly limited, but metal phthalocyanines such as copper phthalocyanine (CuPc: Copper Phthalocyanine) and metal-free phthalocyanines, carbon films, and conductive polymers such as polyaniline can be suitably used.

--- Experimental example-
The materials and members shown in Table 1 and Table 2 below were prepared. The materials for the light emitting layer, the hole transport layer, and the electron transport layer were manufactured by Luminescence Technology. The light extraction improving film as the light extraction structure was a light diffusion film (product name: Light Up NSH, manufactured by Kimoto Co., Ltd.).

[First Experimental Example]
An ITO anode (70 nm thickness) / hole transport layer (40 nm thickness) / CBP + Ir (phq) 2 tpy red light emitting layer (60 nm thickness) / electron transport layer (30 nm) on a glass substrate (0.7 mm plate thickness) by vacuum deposition. Thickness) / Al cathode (100 nm thickness) was used to produce the organic EL device of Example 1. Here, as shown in FIG. 4, the stripe of the ITO anode 2 has a width W of 0.9 cm, and the stripe of the intersecting Al cathode 9 has a width X of 1.0 cm. An organic EL element having an area of 0.9 cm ² was produced.

After film formation of each layer, the desiccant was sealed with a metal or glass sealing can in a glove box in an inert gas atmosphere from a vacuum vapor deposition machine. Thereafter, a light diffusion film (manufactured by Kimoto Co., Ltd.) was attached to the glass substrate surface (substrate surface opposite to the organic EL element) to complete the element of Example 1.

Similarly, the elements of Examples 2, 3 and 5 having the same configuration as Example 1 were prepared except that the light emitting layer was made of a light emitting layer (60 nm thickness each) made of a light emitting color material shown in Table 3 below.

Similarly, except that the light emitting layer is a light emitting layer (60 nm thickness) made of a light emitting color material shown in Table 3 below and the area of the rectangular light emitting region is 0.7 cm ² (the ITO anode stripe is 0.7 cm wide and intersecting Al The element of Example 4 having the same configuration as that of Example 1 was prepared.

Similarly, the light emitting layer is made of a light emitting color material (each 60 nm thick) made of a light emitting color material shown in Table 3 below, and the area of the rectangular light emitting region is 0.04 cm ² (the ITO anode stripe has a width of 0.2 cm and intersects). The elements of Comparative Examples 1 to 4 having the same configuration as in Example 1 were fabricated.

[First test]
The devices of Examples 1-5 and Comparative Examples 1-4, the current value 2.5 mA / cm ^2, respectively, or to drive at 7.5 mA / ^cm 2 (B only), the light emitting surface front direction 0 degrees (normal ) To 80 degrees, chromaticity and emission luminance were measured at an angular position of 5 degrees step. The chromaticity of each element is R (CIE: x0.61, y0.39), O (CIE: x0.57, y0.43), G (CIE: x0.31, y0.64), B (CIE: x0.13, y0.15). From the measured luminance value, the light extraction magnification in the front direction, the Lambertian divergence coefficient, and the light extraction magnification in the front direction with and without the light diffusion film were calculated.

Lambertian indicates the state of the light intensity distribution of the light emission pattern of the surface light source. When the light intensity in the normal direction (θ = 0 °) with respect to the light emitting surface is I0, the Lambertian light intensity distribution I (θ) Is an assumed distribution (completely diffusing surface light source) of I (θ) = I (0) cos θ.

The Lambertian divergence coefficient is assumed to be Lambertian (fully diffuse surface light source) because the light emission pattern of the surface light source measured from the element normal to the angle θ in the direction of angle θ is not necessarily Lambertian distribution. Then, the error from that, that is, the deviation from Lambertian I (θ) = cos θ is calculated as a coefficient.

Table 4 shows the calculation results of the test. The front light extraction magnification and the total luminous flux magnification are normalized by the measured values of 0.04 cm ² area elements in the elements of Examples 1 to 5 and Comparative Examples 1 to 4. The Lambertian divergence coefficient was obtained from (actually measured total luminous flux (= integral value of 5 ° step luminance measurement values)) / (total luminous flux calculated from Lambertian assumption from front luminance).

From the above results, the element of the example having an area of 0.9 cm ² where the area of the light emitting region is large has a larger front light extraction magnification and a Lambertian divergence coefficient, resulting in a higher total light beam magnification and higher light extraction efficiency. It was found that a high organic EL element can be obtained.

[Second Experimental Example]
As in Example 1, except that the light-emitting layer made of a light emitting color material of a light emitting layer in the following Table 5 (the 60nm thick), performed with an area 0.9 cm ² of the light emitting region having the same structure of Example 1 Devices of Examples 6 to 41 were produced. However, as shown in Table 5, the thickness X of the ITO anode was changed to 70 nm, 110 nm, and 155 nm for each of the RGB emission colors, and the film thickness Y of the electron transport layer (NBphen + CsxMoOx) was 30 nm, 50 nm, And it changed for every Example of 70 nm and each color, and the element was produced.

[Second test]
The same measurement as in the first experimental example was performed, and the light extraction magnification in the front direction, the Lambertian divergence coefficient, and the light extraction magnification in the front were calculated. Table 5 shows the measurement results. For each color element, the front light extraction magnification is normalized by the measured values of the elements having an ITO film thickness X = 70 nm and an electron transport layer film thickness Y = 30 nm. Further, the total luminous flux magnification was calculated by multiplying the value normalized by the front luminance of the ITO film thickness of 70 nm and the electron transport layer film thickness of 30 nm for each color element by the Lambertian divergence coefficient.

From the above results, it can be seen that an organic EL element having a high Lambertian divergence coefficient has a high front light extraction magnification when the light diffusion film is attached. It can also be seen that the total luminous flux ratio tends to be high when the electron transport film thickness Y is 50 nm or more. This is considered to be because the incident angle of light from the glass substrate to the light diffusion film was improved, and the amount of light taken in by the light diffusion film was increased.

From the measurement results in Table 5, the range of the Lambertian divergence coefficient in which the total luminous flux magnification is higher than the ITO film thickness X = 70 nm and the electron transport film thickness Y = 30 nm is 0.82 to 1.01 for the R color element, and the O color. It can be seen that the element is 0.83 to 1.04, the G color element is 0.86 to 1.18, and the B color element is 0.80 to 0.97. Therefore, the range of the Lambertian divergence coefficient is preferably 0.80 to 1.18 (union), more preferably 0.83 to 1.05 (average), and most preferably 0.86 to 0.8. It was revealed that the element having 97 (product set) has a high light extraction effect.

FIG. 5A shows a plot for calculating the total luminous flux magnification corresponding to the ITO film thickness X, and FIG. 5B shows a plot for calculating the average value of the total luminous flux magnification corresponding to the ITO film thickness X. The fitted curve (no particular formula) is shown. From the measurement results of FIG. 5A, the total luminous flux magnification is 0.9 times or more when the ITO film thickness X = 40 nm to 80 nm, and the total luminous flux magnification is the highest value when the ITO film thickness X = 60 nm to 50 nm. It became clear to show.

[Example 3]
As in Example 1, the light emitting layer was made of a light emitting layer (each 60 nm thick) made of a light emitting color material shown in Table 6 below, and the area of the light emitting region having the same configuration of Example 1 was 0.9 cm ^2. Devices of Examples 42 to 47 were produced. However, as shown in Table 6, the thickness X of the ITO anode was changed to 70 nm and 155 nm for each of the examples of R and B emission colors, and the thickness Y of the electron transport layer (NBphen + CsxMoOx) was 50 nm, respectively. A device using Al or Ag was prepared. The same measurement as in the first experimental example was performed for each. Table 6 shows the measurement results. The front light extraction magnification is normalized for each color element by the measured values of the ITO film thickness of 70 nm and the Al cathode element. Further, the total luminous flux magnification was calculated for each color element by multiplying the value normalized by the front brightness of the ITO film thickness of 70 nm and the Al cathode element by the Lambertian divergence coefficient.

From the above results, the light extraction magnification and the Lambertian divergence coefficient were improved because light loss due to multiple reflection was reduced in the highly reflective Ag cathode, and as a result, the total luminous flux magnification of the device was improved.

[Example 4]
As in Example 1, except that the light-emitting layer made of a light emitting color material of a light emitting layer in the following Table 7 (the 40nm thick), performed with an area 0.9 cm ² of the light emitting region having the same structure of Example 1 Devices of Examples 48 to 51 were produced. However, as shown in Table 7, the glass substrate thickness d was changed to 0.7 mm and 0.55 mm for each of the examples of R and B emission colors, and the ITO anode film thickness was 155 nm respectively, and the electron transport layer (NBphen + CsxMoOx ) Was made to be 50 nm, and an element using Ag as a cathode was manufactured. Measurements similar to those in the first experimental example were performed. Table 7 shows the measurement results. The front light extraction magnification is standardized by the measured value of the glass substrate 0.7 mm thick element for each color element. Further, the total luminous flux magnification was calculated for each color element by multiplying the value normalized by the front luminance of the glass substrate 0.7 mm thick element by the Lambertian divergence coefficient.

From the above results, as the glass film thickness becomes thinner, the radiation angle from the light emitting layer to the glass external emission surface becomes wider, the Lambertian divergence coefficient is improved, and as a result, the total luminous flux magnification of the device is improved. Since NBphen doped with CsxMoOx is used as the electron transport layer, even when Ag is used as the cathode, the increase in driving voltage can be made almost zero as compared with the Al cathode.

[Fifth Experimental Example]
A device similar to the device of Example 1 was fabricated except that the ITO anode was circular, the stripes of intersecting Al cathodes were 1.0 cm wide, and the red light emitting layer of the circular light emitting region was formed. The change in the ratio of the light extraction amount of the organic EL element when the diameter of the circular light emitting region was changed was verified.

FIG. 6 shows a plot in which the light extraction magnification corresponding to the circular light emitting region diameter d = 0.2 mm to 150 mm is calculated.

From the above results, it can be seen that the light extraction magnification tends to be saturated at 100 mm in any element having a circular light emitting region diameter. This indicates that there is no merit of forming a circular light emitting region having a larger diameter. A light-emitting region having a very large area may lead to deterioration of device characteristics due to electrical characteristics, process margin, uneven light emission, and the like. Therefore, the shorter width of the light emitting region (the shortest pass) is preferably 100 mm or less at which the light extraction magnification is saturated. The lower limit of the shorter width (shortest span) of the light emitting region is 0.2 mm or more. This is because in the light emitting region having a width of less than 0.2 mm, the ratio of the gap (non-light emitting portion) between adjacent light emitting regions is increased, leading to deterioration of element characteristics.

From the above results, the maximum value of the area of the light emitting region was set to 100 cm ² . In other words, when the shorter width of the cell is set to 100 mm, it is considered as a square, and a cell larger than this exceeds 100 mm in any direction, so the light extraction magnification is saturated, so there is no merit to enlarge the cell. Because. Since the minimum value of the area of the light emitting region is preferably 0.9 cm ² as apparent from the above experiment, the light emitting layer of each light emitting region of the organic EL element has an area of 0.9 cm ² to 100 cm ^2. did.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Light extraction structure

Claims

A plurality of organic EL elements each having an organic material layer including a light emitting layer of at least one kind of luminescent color, which is laminated between a transmissive first electrode and a light reflective second electrode;
A transparent substrate that supports the first electrode of the organic EL element,
Each of the plurality of organic EL elements has a light emitting region in which the first electrode, the organic material layer, and the second electrode are all continuously stacked.
The organic electroluminescence panel according to claim 1, wherein the light emitting layer in the light emitting region has an area of 0.9 cm 2 to 100 cm 2 .
2. The organic electroluminescence panel according to claim 1, wherein the shortest span of the light emitting region is in a range of 0.2 mm to 100 mm.
The organic electroluminescence panel according to claim 1 or 2, wherein the organic electroluminescence panel comprises a microlens layer, a pyramid layer, an uneven layer, or a fine particle diffusion layer and has a light extraction structure provided on the substrate.
An electron transporting organic material comprising an organic semiconductor in contact with the interface of the organic material layer and laminated between the second electrode and the organic material layer and doped with a metal salt compound having an electron donating metal as a counter cation The organic electroluminescence panel according to claim 1, further comprising a material layer.
The organic electroluminescence panel according to any one of claims 1 to 4, wherein the second electrode is made of Al, Ag, or an alloy thereof.