JP2012160476A - White organic electroluminescent element, image display element, and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an organic electroluminescent element which is free from chromaticity shifts, has high efficiency, and is suitable for white light emission.SOLUTION: The white organic electroluminescent element comprising light-emitting layers between an anode and a cathode is characterized in that: it comprises three or more light-emitting layers; the three or more light-emitting layers include two or more kinds of light-emitting layers having different emission peaks, and two or more light-emitting layers having the same emission peak; at least one kind of light-emitting layer contains a phosphorescent compound; and the three or more light-emitting layers are laminated in a regular cycle.

Description

  The present invention relates to an organic electroluminescent element having three or more light emitting layers between an anode and a cathode, and an image display element and an illumination device using the organic electroluminescent element, and particularly, white light emission with high luminous efficiency and no chromaticity deviation. The present invention relates to an organic electroluminescence device suitable for the above.

  Since the organic EL element is self-luminous, it has excellent visibility and can be driven at a low voltage of several volts to several tens of volts, so that the weight including the driving circuit can be reduced. Therefore, the organic EL element is expected to be used as a thin film display, illumination, and backlight.

  The organic EL element is also characterized by abundant color variations. Another feature is that various colors can be emitted by mixing colors combining a plurality of colors.

  Of the luminescent colors, the need for white light emission is particularly high, and it can also be used as a backlight. Furthermore, it is possible to divide into blue, green and red pixels using a color filter.

  There are the following two methods for performing such white light emission.

  1. One light emitting layer is doped with a plurality of light emitting compounds.

  2. A plurality of emission colors are combined from a plurality of emission layers.

  For example, when white is achieved by three colors of blue (B), green (G), and red (R), in the case of 1, when vacuum deposition is used as a device manufacturing method, BGR and 4 of the host compound are used. It becomes original vapor deposition and control becomes very difficult.

  In addition, there is a method in which BGR and a host compound are applied by dissolving or dispersing them in a solution, but at present, there is a problem that the coating type organic EL is inferior in durability to the vapor deposition type.

  On the other hand, a method of combining two light emitting layers has been proposed. In the case of using a vapor deposition type, it becomes easier compared to 1.

  As an organic EL element that emits such white light, two layers of a blue light-emitting layer that emits short wavelength light and a red light-emitting layer that emits long wavelength light are stacked so that white light is emitted as a mixed color of both light-emitting layers. What has been obtained has been proposed (see, for example, Patent Document 1).

  However, in the case of stacking two light emitting layers with different colors (different peak wavelengths), the film quality changes in the two light emitting layers as the driving time of the element, that is, the light emitting time and the applied voltage change. In addition, the emission center moves due to changes in the degree of hole and electron transport properties, and as a result, chromaticity is likely to change.

  In particular, when white is obtained as a mixed color of two light-emitting layers, the problem becomes obvious because white is more sensitive to chromaticity changes than other colors.

  In an organic EL device that emits mixed color light from a plurality of light emitting layers having different peak wavelengths, light emission with different peak wavelengths is performed as a method for minimizing chromaticity changes accompanying drive time and voltage changes. A structure in which three or more light emitting layers are alternately laminated is disclosed (for example, see Patent Document 2).

  In addition, in a stacked structure of two or more layers, a method for designing the film thickness of the light emitting layer and the ratio between the organic host material and the fluorescent material using the light emission efficiency as a parameter is disclosed (for example, see Patent Document 3).

  By alternately laminating them, there is an effect that even if the carrier injection balance is slightly deviated, color misregistration hardly occurs. However, it has been found that the luminous efficiency is low and there is energy transfer between layers, and there is a bias in whiteness, which is still insufficient as white light emission. In addition, there is still a problem that chromaticity shifts with voltage change.

JP-A-7-142169 JP 2003-187777 A JP 2004-63349 A

  An object of the present invention is to obtain an organic electroluminescence element suitable for white light emission with no chromaticity shift and high efficiency.

  One aspect of the present invention for achieving the above object of the present invention is an organic electroluminescence device having a light emitting layer between an anode and a cathode, the light emitting layer having three or more layers, and the three or more layers. The light emitting layer contains two or more light emitting layers having different light emission peaks, and two or more light emitting layers having the same light emission peak are contained, at least one light emitting layer contains a phosphorescent compound, and The organic light-emitting device is characterized in that the light emitting layers are laminated with a regular period.

That is, the said subject which concerns on this invention is solved by the following means.
1. In the organic electroluminescence device having a light emitting layer between an anode and a cathode, the light emitting layer has three or more light emitting layers, and the three or more light emitting layers include two or more kinds of light emitting layers having different emission peaks, and Two or more light emitting layers having the same emission peak are included, at least one light emitting layer contains a phosphorescent compound, and the light emitting layers are laminated with a regular period. White organic electroluminescence device.
2. 2. The white organic electroluminescence device according to claim 1, wherein the light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, and a blue light emitting layer from the cathode to the anode.
3. The first item, wherein the light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer and a yellow light emitting layer from the cathode to the anode. The white organic electroluminescent element as described in 2.
4). From the cathode to the anode, the light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, and a yellow light emitting layer. 2. The white organic electroluminescence device according to item 1, wherein
5. 2. The light emitting layer is laminated in the order of at least a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer, and a yellow light emitting layer from the cathode to the anode. The white organic electroluminescent element as described in 2.
6). From the cathode to the anode, the light emitting layer is at least in the order of a blue light emitting layer, a green light emitting layer, a red light emitting layer, a blue light emitting layer, a green light emitting layer, a red light emitting layer, a blue light emitting layer, a green light emitting layer and a red light emitting layer. 2. The white organic electroluminescence device according to item 1, which is laminated.
7). From the cathode to the anode, the light emitting layer is at least in the order of a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer and a yellow light emitting layer. 2. The white organic electroluminescence device according to item 1, which is laminated.
8). 2. The white organic electroluminescence device according to item 1, wherein there are two types of light emitting layers having different emission peaks, and each of the light emitting layers having the same emission peak has two or more layers.
9. All the light emitting layers which have a different light emission peak contain a phosphorescent compound, The white organic electroluminescent element as described in any one of Claims 1-8 characterized by the above-mentioned.
10. Any one of the light-emitting layers having different emission peaks contains a light-emitting dopant and a host compound, and all the light-emitting layers are composed of the same host compound. The white organic electroluminescent element as described.
11. Item 11. The white organic electroluminescence device according to item 10, wherein the excited triplet energy of the host compound is larger than the excited triplet energy of the phosphorescent compound.
12 The white organic electroluminescent element according to any one of items 1 to 11, wherein a hole blocking layer is provided between the light emitting layer and the cathode and in a layer adjacent to the light emitting layer.
13. 13. The white organic electroluminescent element according to any one of items 1 to 12, wherein an electron blocking layer is provided between the light emitting layer and the anode and adjacent to the light emitting layer.
14 An image display device comprising the white organic electroluminescence device according to any one of items 1 to 13.
15. An illumination device using the white organic electroluminescence element according to any one of Items 1 to 13.

  By the above means of the present invention, it is possible to provide an organic electroluminescence element suitable for white light emission with no chromaticity shift and high efficiency.

The figure which shows the layer structure of an organic EL element The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention The figure which shows the layer structure of the light emitting layer of the organic EL element of this invention Schematic diagram showing an example of a display device composed of organic EL elements Schematic diagram of the display unit Schematic diagram of pixels Schematic diagram of passive matrix type full color display device Schematic perspective view of lighting device Cross section of the lighting device

  The layer configuration of the organic electroluminescence element (organic EL element) of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  1 has a light emitting layer between a cathode and an anode, and the light emitting layer is sandwiched between an electron blocking layer and a hole blocking layer.

  These electron blocking layers or hole blocking layers are not necessarily required. However, with this structure, excitons generated by confining electron / hole carriers in the light emitting layer and recombination of electrons and holes are generated. Since these layers can be confined in the light emitting layer, it is preferable to provide these layers.

  Known materials can be used to form the electron blocking layer and the hole blocking layer.

  Since the electron blocking layer confines electrons so that electrons do not leak from the light emitting layer, the material forming the electron blocking layer preferably has a lower electron affinity than the material forming the light emitting layer.

  In addition, since the hole blocking layer confines holes so that holes do not leak from the light emitting layer, the material forming the hole blocking layer preferably has a higher ionization potential than the material forming the light emitting layer.

  Further, in order to confine triplet excitons generated by recombination of electrons and holes, the excitation triplet energy of the material forming the hole blocking layer and the electron blocking layer is the excitation triplet of the phosphorescent compound in the light emitting layer. It is preferably larger than the term energy.

  Furthermore, it is preferable to provide a hole transport layer and an electron transport layer so as to sandwich them. Known materials can be used for the hole transport layer and the electron transport layer. It is preferable to use a material having high conductivity in terms of driving voltage reduction.

  A configuration example of the light emitting layer will be described with reference to FIGS. Although the light-emitting layer 1-1 to the light-emitting layer 3-14 are shown, the present invention is not limited to these.

  The light emitting layer 1-1 to the light emitting layer 3-14 are obtained by extracting only the light emitting layer portion in the element structure 1.

  In the present invention, the light emitting layer is composed of at least 3 layers and has at least 2 types of light emitting layers having different emission peaks, preferably 3 or 4 types, and most preferably 3 types.

  In the present invention, a light emitting layer having a different emission peak means that the emission maximum wavelength differs by at least 10 nm or more when the emission peak is measured by PL.

  Note that PL measurement means that a vapor deposition film is produced on a quartz substrate with a composition using a light emitting dopant and a host compound in the light emitting layer, or a thin film is produced by spin coating or dipping for a wet process such as a polymer. Then, the emission maximum wavelength can be determined by measuring the emission of the obtained deposited film or thin film with a fluorometer.

  The color when the organic EL is turned on is not particularly limited, but is preferably white.

  For example, when there are two types of light emitting layers having different emission peaks, it is preferable to obtain a white color by combining the light emitting layers that emit blue and yellow or blue and green and red.

  For example, when there are three types of light emitting layers having different emission peaks, it is preferable to obtain white by a combination of emitting blue, green and red.

  In this way, it can be used for various light sources such as illumination and backlight.

  For example, when there are four light emitting layers having different emission peaks, white can be obtained by a combination of blue, blue green, yellow, and red. In addition, it is also possible to use another layer for correcting white color with three colors of blue, green, and red.

  The emission color is not limited to white.

  By making a single color (for example, blue, green, red) emit light with a plurality of light emitting layers having different emission peaks, it is possible to adjust the color more delicately.

  The order of arrangement of the plurality of light emitting layers may have a regular period or may be random.

  When the voltage (current) is applied to the organic EL element, it is preferable to arrange the organic EL elements so that the chromaticity shift is minimized with respect to the voltage (current) fluctuation.

  Preferably, it has a regular period. For example, the light emitting layers 1-1 to 1-6, 2-9, 2-23, 2-36, 3-9, 3 shown in FIGS. -12, 3-14.

  In this way, when the voltage (current) is changed, it is possible to make it difficult for the emission color to change even if the emission position is shifted in the thickness direction.

  On the other hand, when combining a plurality of emission colors from a plurality of light emitting layers, in order to minimize color misregistration, alternating, periodic, and random structures are stacked in multiple layers, at that time, because there are many contacts with adjacent layers, Opportunities for energy transfer at the interface increase, and the same problem as in the formation of a white element in one light emitting layer occurs.

  The energy transfer of the organic EL is mainly dominated by the Forster type, but the Forster type has a long energy transfer distance.

  The Förster energy transfer is basically an important factor that the overlap integral intensity of the emission spectrum of the donor molecule and the absorption spectrum of the acceptor molecule is large.

  In the case of a fluorescent compound, when the spectra overlap, the fluorescence quantum yield and the molar extinction coefficient are large, so that the excited singlet energy transfer distance increases.

In the phosphorescent compound, when T ← G absorption is observed, energy transfer occurs in the excited triplet as in the fluorescent compound (“Principles of Fluorescence Spectroscopy” written by Joseph R. Lakowicz regarding the Forster type energy transfer). Kluwer Academic Plenum Publishers p.368). However, since the molar extinction coefficient of T ← G absorption is much smaller than that of the fluorescent compound, the phosphorescent compound has an overwhelmingly shorter Forster energy transfer distance.

  In the present invention, by containing a phosphorescent compound in at least one of the light emitting layers, energy transfer between the layers can be reduced, and multilayering by thin layers can be realized.

  Since the energy transfer between the light emitting dopants to each adjacent light emitting layer proceeds in a Förster type, the arrangement order of the respective light emitting layers can be determined by a combination having a small Förster distance.

  Furthermore, current-voltage characteristics can be changed by selecting a host material.

  The total thickness of the light emitting layer is not particularly limited, but is preferably 5 to 100 nm. More preferably, it is 7 to 50 nm, and most preferably 10 to 40 nm.

  The thickness of each light emitting layer constituting the light emitting layer is preferably 1 to 20 nm, more preferably 2 to 10 nm.

  These can be selected depending on the element driving voltage, the chromaticity shift with respect to the voltage (current), the energy transfer, and the difficulty of production.

  In the present invention, it is necessary that at least one layer of the structure of the light emitting layer contains a phosphorescent compound, and it is preferable that all the light emitting layers contain a phosphorescent compound.

(Light emitting host and light emitting dopant)
The mixing ratio of the light-emitting dopant to the host compound as the main component in the light-emitting layer is preferably in the range of less than 0.1 to 30% by mass.

  However, in the present invention, it is necessary to use a phosphorescent compound (phosphorescent dopant) in at least one layer of the light emitting layer, and the light emitting dopant may be used by mixing a plurality of kinds of compounds, such as metal complexes and other A phosphorescent dopant having a structure may be used.

  The light-emitting dopant is roughly classified into two types, a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

  Representative examples of fluorescent dopants include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes. Stilbene dyes, polythiophene dyes, rare earth complex phosphors, and the like.

  A typical example of the phosphorescent dopant is preferably a complex compound containing a metal of Group 8, Group 9, or Group 10 in the periodic table of elements, more preferably an iridium compound or an osmium compound, and most preferably. Is an iridium compound.

  Specific examples of the phosphorescent dopant are compounds described in the following patent publications.

  WO 00/70655 pamphlet, JP 2002-280178, JP 2001-181616, JP 2002-280179, JP 2001-181617, JP 2002-280180, JP 2001-247859, JP 2002-299060, JP 2001-313178, JP 2002-302671, JP 2001-345183, JP 2002-324679, International Publication No. 02/15645 pamphlet, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-83684 A, JP 2002-540572 A, JP 2002-2002 A. No. 117978, JP 20 JP-A-2-338588, JP-A-2002-170684, JP-A-2002-352960, WO01 / 93642, JP-A-2002-50483, JP-A-2002-1000047, JP-A-2002. No. -173744, JP-A No. 2002-359082, JP-A No. 2002-17584, JP-A No. 2002-363552, JP-A No. 2002-184582, JP-A No. 2003-7469, JP-T-2002-525808. Gazette, JP2003-7471, JP2002-525833, JP2003-31366, JP2002-226495, JP2002-234894, JP2002-2335076 JP 2002-241751 A JP 2001-319779, JP 2001-319780, JP 2002-62824, JP 2002-1000047, JP 2002-203679, JP 2002-343572, JP 2002-203678 gazette etc.

  Some examples are shown below.

(Luminescent host compound)
The light-emitting host compound used in the present invention is not particularly limited in terms of structure, but typically, a carbazole derivative, a triarylamine derivative, an aromatic borane derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, Those having a basic skeleton such as an oligoarylene compound, or a carboline derivative or a diazacarbazole derivative (here, a diazacarbazole derivative is a compound in which at least one carbon atom of a hydrocarbon ring constituting a carboline ring of a carboline derivative is nitrogen Represents an atom substituted with an atom.) And the like.

  Of these, carboline derivatives, diazacarbazole derivatives and the like are preferably used.

  Specific examples of carboline derivatives, diazacarbazole derivatives and the like are given below, but the present invention is not limited thereto.

  The light emitting host used in the present invention may be a low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). .

  As the light-emitting host, a compound having a hole transporting ability and an electron transporting ability and preventing a long wavelength of light emission and having a high Tg (glass transition temperature) is preferable.

  As specific examples of the light-emitting host, compounds described in the following documents are suitable. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Next, other constituent layers of the organic EL element will be described.

《Hole blocking layer》
The hole blocking layer has the function of an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons but has a very small ability to transport holes, and blocks holes while transporting electrons. Thus, the probability of recombination of electrons and holes can be improved.

  Examples of the hole blocking layer include those disclosed in JP-A-11-204258, JP-A-11-204359, and “Organic EL device and its forefront of industrialization (issued by NTS, Inc. on November 30, 1998)”. The hole blocking (hole block) layer described in page 237 and the like can be applied as the hole blocking layer according to the present invention. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed.

《Electron blocking layer》
On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.

  The thickness of the hole blocking layer and the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably in the range of 5 to 30 nm.

《Hole transport layer》
The hole transport layer includes a material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material is not particularly limited, and is conventionally used as a hole charge injection / transport material in an optical transmission material or a well-known material used for a hole injection layer or a hole transport layer of an EL element. Any one can be selected and used.

  The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbenes Derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, and the like can be given.

  As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N ′ − (4-methoxyphenyl) -4,4′-diaminobiphenyl; N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type (MTDATA).

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material. The hole transport material preferably has a high Tg.

  The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, it is a grade in the range of 5-5000 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Further, a hole transport layer having a high p property doped with impurities can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided with a single layer or multiple layers.

  Conventionally, in the case of a single-layer electron transport layer and a plurality of layers, the following materials are used as the electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Are known.

  Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .

  Examples of materials used for this electron transport layer (hereinafter referred to as electron transport materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, carbodiimides, Examples include fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq3), 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, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu Metal complexes replaced with Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC. A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, it is a grade in the range of 5-5000 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  An impurity-doped electron transport layer having a high n property can also be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

  Next, an injection layer used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer >>: Electron injection layer, hole injection layer The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, between the anode and the light emitting layer or the hole transport layer, and You may exist between a cathode and a light emitting layer or an electron carrying layer.

  An injection layer is a layer provided between an electrode and an organic layer in order to lower drive voltage or improve light emission luminance. “Organic EL element and its forefront of industrialization (issued on November 30, 1998 by NTS Corporation) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium or aluminum Metal buffer layer represented by lithium fluoride, alkali metal compound buffer layer represented by lithium fluoride, alkaline earth metal compound buffer layer represented by magnesium fluoride, oxide buffer layer represented by aluminum oxide, etc. It is done.

  The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 to 100 nm, although it depends on the material.

  This injection layer can be formed by thinning the above material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an injection | pouring layer, Usually, it is a grade in the range of 5-5000 nm. The injection layer may have a single layer structure composed of one or more of the above materials.

"anode"
As the anode according to the organic EL device of the present invention, an electrode having a work function (4 eV or more) metal, alloy, electrically conductive compound and a mixture thereof as an electrode material is preferably used. Specific examples of such an electrode substance include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (100 μm or more) Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.

"cathode"
On the other hand, as the cathode according to the present invention, a cathode having a work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 to 1000 nm, preferably 50 to 200 nm. In order to transmit light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The substrate of the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is not particularly limited as long as it is transparent. A light transmissive resin film can be mentioned. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.

  Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose triacetate. Examples thereof include films made of (TAC), cellulose acetate propionate (CAP) and the like.

  An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and it is preferably a high barrier film having a water vapor transmission rate of 0.01 g / m 2 · day · atm or less. .

  The external extraction efficiency at room temperature for light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 2% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  When used in lighting applications, a film (such as an antiglare film) that has been roughened to reduce unevenness in light emission can be used in combination.

  When used as a multicolor display device, it is composed of organic EL elements having at least two different light emission maximum wavelengths. A suitable example for producing an organic EL element will be described.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, an organic material comprising an anode / hole injection layer / hole transport layer / light emitting layer (three layers or more) / hole blocking layer / electron transport layer / cathode buffer layer / cathode is used. A method for manufacturing an EL element will be described.

First, on a suitable substrate, a thin film made of a desired electrode material, for example, an anode material is formed by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm, An anode is produced. Next, a thin film containing an organic compound such as a hole injection layer, a hole transport layer, a light emitting layer (three or more layers), a hole blocking layer, an electron transport layer, or the like, which is an element material, is formed thereon.

As a method for thinning a thin film containing an organic compound, there are a spin coat method, a cast method, an ink jet method, a vapor deposition method, a printing method, etc., but a uniform film is easily obtained and pinholes are not easily generated. From the point of view, the vacuum deposition method or the spin coating method is particularly preferable. Further, different film forming methods may be applied for each layer. When employing a vapor deposition method for film formation, the vapor deposition conditions vary depending on the type of compound used, etc., but generally within a boat heating temperature range of 50 to 450 ° C. and a degree of vacuum of 10 ⁻⁶ to 10 ⁻² Pa. It is desirable that the deposition rate is appropriately selected within the range of 0.01 to 50 nm / second, within the range of the substrate temperature −50 to 300 ° C., and within the range of the film thickness 0.1 nm to 5 μm.

  After these layers are formed, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

<Display device>
The display device of the present invention will be described.

  The display device of the present invention may be single color or multicolor, but here, the multicolor display device will be described. In the case of a multicolor display device, a shadow mask is provided only at the time of forming a light emitting layer, and a film can be formed on one surface by a vapor deposition method, a casting method, a spin coating method, an ink jet method, a printing method, or the like.

  When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

  Further, it is also possible to reverse the production order and produce the cathode, the electron transport layer, the hole blocking layer, the light emitting layer (three layers or more), the hole transport layer, and the anode in this order.

  When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage in the range of 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

  The multicolor display device can be used as a display device, a display, and various light emission sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and the display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in a car. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. For example, but not limited to.

《Lighting device》
The lighting device of the present invention will be described.

  The organic EL element of the present invention may be used as an organic EL element having a resonator structure. The use of the organic EL element having such a resonator structure is as a light source for an optical storage medium, an electrophotographic copying machine, and the like. Light sources, optical communication processor light sources, optical sensor light sources, and the like.

  Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a type for directly viewing a still image or a moving image. It may be used as a display device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, it is possible to produce a full-color display device by using two or more organic EL elements of the present invention having different emission colors.

  Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.

  FIG. 10 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 11 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.

  In the figure, the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  When the organic EL device of the present invention is used as a white light emitting device, full color display can be performed by combination with a BGR color filter.

  Next, the light emission process of the pixel will be described.

  FIG. 12 is a schematic diagram of a pixel.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full-color display can be performed by using a white light emitting organic EL element as the organic EL element 10 divided into a plurality of pixels and combining it with a BGR color filter.

  In FIG. 12, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 13 is a schematic diagram of a display device using a passive matrix method. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  The organic EL element according to the present invention can also be applied to an organic EL element that emits substantially white light as a lighting device.

  In the white organic EL element concerning this invention, you may pattern by a metal mask, an inkjet printing method, etc. at the time of film forming as needed. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  Thus, in addition to the display device and display, the white light-emitting organic EL element of the present invention can be used as various light-emitting light sources, lighting devices, household lighting, interior lighting, and a kind of lamp such as an exposure light source. It is also useful for display devices such as backlights for liquid crystal display devices.

  Others such as backlights for watches, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

Example 1
<Preparation of organic EL elements 1-1 to 1-12>
(Preparation of organic EL element 1-1)
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) formed by depositing 100 nm of ITO (indium tin oxide) on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support base was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

  Next, after reducing the pressure of the vacuum chamber to 4 × 10 −4 Pa, the heating boat containing α-NPD was heated by heating, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / sec. Was provided. Next, as an electron blocking layer, a heating boat containing HTM1 was energized and heated to deposit 15 nm of HTM1 at a deposition rate of 0.1 nm / sec.

  Thereafter, as shown in Table 1, each composition of the light emitting layers A and B is used to form a light emitting layer of the light emitting layer 1-1 shown in FIG. -13 was deposited by 10 nm.

  Further, a heating boat containing Alq3 was energized and heated, and deposited on the hole layer at a deposition rate of 0.1 nmsec to provide an electron transport layer having a thickness of 30 nm. The substrate temperature during vapor deposition was room temperature.

  Then, 0.5 nm of lithium fluoride was vapor-deposited as a cathode buffer layer, and also aluminum 110nm was vapor-deposited, the cathode was formed, and the organic EL element 1-1 was produced.

(Production of organic EL elements 1-2 to 1-12)
In the same manner as in the organic EL element 1-1, each light emitting layer shown in Table 1 was laminated so as to have each layer configuration, and organic EL elements 1-2 to 1-12 were produced.

得られた有機ＥＬ素子を以下の方法で評価した。

The obtained organic EL element was evaluated by the following methods.

<External extraction quantum efficiency>
About the produced organic EL element, external extraction quantum efficiency (%) when a constant current of 2.5 mA / cm 2 was applied at 23 ° C. in a dry nitrogen gas atmosphere was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used.

<Chromaticity deviation>
In the CIE chromaticity diagram, the chromaticity shift represents a shift between chromaticity coordinates at 100 cd / m2 luminance and chromaticity coordinates at 5000 cd / m2 luminance.

  Measurement was performed using CS-1000 (manufactured by Minolta) at 23 ° C. in a dry nitrogen gas atmosphere.

  In addition, the excited triplet energy of the used host compound and dopant compound is described. The solvent was measured by ethanol: methanol = 1: 1, 77K. The measurement was performed with Hitachi F4500. The excited triplet energy was calculated from the peak resulting from the 0-0 band of the obtained phosphorescence spectrum.

  The obtained results are shown in Tables 1 and 2.

本発明の有機ＥＬ素子は高い外部取り出し量子効率と低い色度のずれを示すことが分かる。

It can be seen that the organic EL device of the present invention exhibits high external extraction quantum efficiency and low chromaticity shift.

Example 2
The non-light-emitting surface of the organic EL element 1-8 produced in Example 1 was covered with a glass case to obtain a lighting device. The illuminating device could be used as a thin illuminating device that emits white light with high luminous efficiency and long emission life. FIG. 14 is a schematic perspective view of the lighting device, and FIG. 15 is a cross-sectional view of the lighting device. In the figure, an organic EL element 101 has an organic EL layer 106 and a cathode 105 laminated on a glass substrate 107 with an ITO transparent electrode. In the lighting device 100, the organic EL element 101 is covered with a glass case 102, and a power line (anode) 103 and a power line (cathode) 104 are connected. The glass case 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

  The present invention has a structure in which three or more light emitting layers are provided, two or more light emitting layers having different light emission peaks, and two or more light emitting layers having the same light emission peak, and at least one light emitting layer is phosphorescent. It has been found that by containing a compound, there is no energy transfer even when it is multi-layered, color shift due to voltage change is less likely to occur, and luminous efficiency can be improved.

DESCRIPTION OF SYMBOLS 1 Display apparatus 3 Pixel 5 Scan line 6 Data line 11 Organic EL element 12 Drive transistor 13 Capacitor A Display part B Control part

Claims (15)

  In the organic electroluminescence device having a light emitting layer between an anode and a cathode, the light emitting layer has three or more light emitting layers, and the three or more light emitting layers include two or more kinds of light emitting layers having different emission peaks, and Two or more light emitting layers having the same emission peak are included, at least one light emitting layer contains a phosphorescent compound, and the light emitting layers are laminated with a regular period. White organic electroluminescence device.   The white organic electroluminescence device according to claim 1, wherein the light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, and a blue light emitting layer from the cathode to the anode.   The light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, and a yellow light emitting layer from the cathode to the anode. The white organic electroluminescent element as described in 2.   From the cathode to the anode, the light emitting layer is laminated in the order of at least a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, a yellow light emitting layer, a blue light emitting layer, and a yellow light emitting layer. The white organic electroluminescence device according to claim 1.   2. The light emitting layer is laminated in the order of at least a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer, and a yellow light emitting layer from the cathode to the anode. The white organic electroluminescent element as described in 2.   From the cathode to the anode, the light emitting layer is at least in the order of a blue light emitting layer, a green light emitting layer, a red light emitting layer, a blue light emitting layer, a green light emitting layer, a red light emitting layer, a blue light emitting layer, a green light emitting layer and a red light emitting layer. The white organic electroluminescence element according to claim 1, wherein the white organic electroluminescence element is laminated.   From the cathode to the anode, the light emitting layer is at least in the order of a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer, a yellow light emitting layer, a blue light emitting layer, a green light emitting layer and a yellow light emitting layer. The white organic electroluminescence element according to claim 1, wherein the white organic electroluminescence element is laminated.   2. The white organic electroluminescence device according to claim 1, wherein two light emitting layers having different light emission peaks are used, and two light emitting layers having the same light emission peak each have two or more layers.   All the light emitting layers which have a different light emission peak contain a phosphorescent compound, The white organic electroluminescent element as described in any one of Claims 1-8 characterized by the above-mentioned.   All the light emitting layers from which an emission peak differs contain a light emission dopant and a host compound, and all the light emitting layers are comprised with the same host compound, It is characterized by the above-mentioned. White organic electroluminescence element.   The white organic electroluminescence device according to claim 10, wherein the excited triplet energy of the host compound is larger than the excited triplet energy of the phosphorescent compound.   The white organic electroluminescence device according to claim 1, further comprising a hole blocking layer between the light emitting layer and the cathode and adjacent to the light emitting layer.   The white organic electroluminescence device according to claim 1, further comprising an electron blocking layer in a layer adjacent to the light emitting layer between the light emitting layer and the anode.   An image display element using the white organic electroluminescence element according to claim 1.   An illuminating device using the white organic electroluminescence element according to claim 1.

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