JP5765271B2 - Organic electroluminescence element, display device and lighting device - Google Patents

Description

  The present invention relates to an organic electroluminescence element, and more particularly to an organic electroluminescence element excellent in luminous efficiency and luminous lifetime, and a display device and an illumination device using the same.

  An organic electroluminescence element (hereinafter also referred to as an organic EL element) has a structure in which a light emitting layer containing a light emitting compound is sandwiched between a cathode and an anode, and by applying an electric field, holes injected from the anode and This is a light emitting device utilizing the emission of light (fluorescence / phosphorescence) when electrons injected from the cathode are recombined in the light emitting layer to generate excitons (excitons) and the excitons are deactivated. An organic EL element is an all-solid-state element composed of an organic material film having a thickness of only a submicron between electrodes, and can emit light at a voltage of several volts to several tens of volts. Therefore, it is expected to be used for next-generation flat display and lighting.

  In addition, organic EL elements that utilize phosphorescence can in principle achieve a luminous efficiency that is approximately four times that of previous fluorescence emission. Research and development of electrode layers and electrodes are conducted all over the world. In particular, as one of the measures to prevent global warming, application to lighting fixtures that consume a large amount of energy has begun to be studied, and performance improvement and cost reduction are aimed at practical application of white light-emitting panels that can replace conventional lighting fixtures. Attempts have been thriving.

  As a method for producing these organic EL elements (organic compound layers), there are a vacuum deposition method, a wet process (coating method), etc., but a vacuum process is not required, and continuous production is simple and the production speed can be increased. In recent years, a manufacturing method in a wet process (spin coating method, casting method, ink jet method, spray method, printing method, slot type coater method) has attracted attention.

In general, examples of the coating type organic EL element include a coating type polymer organic EL element using a polymer material as a constituent material of the light emitting layer (see, for example, Patent Document 1).
However, in the coating type polymer organic EL device, there are concerns in terms of performance and production stability because it is difficult to purify the material and it is difficult to control the molecular weight distribution. ing.

  Therefore, in recent years, a coating-type low molecular organic EL element using a low molecular material as a light emitting layer material has attracted attention. A low-molecular organic EL element formed by coating is disclosed (for example, see Patent Document 2), and a low-molecular organic EL element having good color purity and excellent emission efficiency and lifetime is provided. The type of low-molecular organic EL element does not have sufficient performance for use in lighting or display applications.

  In this regard, the present inventor examined the cause, and as one of the causes, it was found that the film produced by the coating method (hereinafter abbreviated as “coating film”) is “low in density”. It was. That is, when the density is lowered, the charge transport property is lowered, which causes a decrease in the recombination probability of electrons and holes and a higher voltage during driving, resulting in a lower emission efficiency and a shorter life. In addition, when the density is low, impurities (for example, residual solvent or ions) from the adjacent layer to the light emitting layer migrate at the time of driving, causing a light emitting defect in a specific light emitting material, resulting in a problem that the emission color is shifted.

Furthermore, it has also been found that “dispersibility” of host molecules and dopant molecules is another cause of the deterioration of the performance of the coating-type low-molecular organic EL device. There are prior literatures describing coating film formation methods that improve the dispersibility of such molecules.
For example, a method for improving the dispersibility of molecules by increasing the solubility in an organic solvent by introducing a substituent having a specific structure into the mother skeleton of the light emitting material is disclosed (for example, (See Patent Document 3).
However, this method can improve the dispersibility of molecules, but has not yet improved the density of the coating film.

JP-A-6-33048 JP 2006-190759 A JP 2011-195462 A

In such a situation, the present inventor has conducted further studies and can solve the problems caused by the density of the coating film and the dispersibility of the molecules if the host compound is selected by paying attention to the molecular aspect ratio. I found.
Therefore, the main object of the present invention is an organic EL device having a film (light emitting layer) having a high density and excellent molecular dispersibility, which can improve the light emission efficiency and the light emission life and can stabilize the light emission color. Another object of the present invention is to provide a display device and a lighting device using the organic EL element.

In order to solve the above problems, according to the present invention,
An organic electroluminescence device having at least one light emitting layer between an anode and a cathode,
The light emitting layer contains one or more phosphorescent dopant compounds and a plurality of host compounds,
Among the plurality of types of host compounds, at least two types of host compounds are represented by the general formula (1), the molecular aspect ratio of the one host compound is 1.7 or more, and the molecular aspect of the other host compound An organic electroluminescence device characterized in that the ratio is less than 1.7 is provided.

In the general formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″. “R ′” and “R ″” each represent a hydrogen atom or a substituent. “A ₁ ” and “A ₂ ” each represent an aromatic ring or a hydrogen atom. “N1” and “n2” each represents an integer of 0 to 4.

  According to the present invention, it is possible to improve the light emission efficiency and the light emission lifetime and stabilize the light emission color.

It is a schematic sectional drawing which shows an example of a structure of an organic EL element.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

<< Organic EL structure >>
As shown in FIG. 1, an organic electroluminescence element 100 (hereinafter also referred to as an organic EL element) according to a preferred embodiment of the present invention has a flexible support substrate 1. An anode 2 is formed on the flexible support substrate 1, an organic functional layer 20 is formed on the anode 2, and a cathode 8 is formed on the organic functional layer 20.
The organic functional layer 20 refers to each layer constituting the organic EL element 100 provided between the anode 2 and the cathode 8.
The organic functional layer 20 includes, for example, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and in addition, a hole block layer, an electron block layer, and the like. May be included.
The anode 2, the organic functional layer 20, and the cathode 8 on the flexible support substrate 1 are sealed with a flexible sealing member 10 through a sealing adhesive 9.

In addition, these layer structures (refer FIG. 1) of the organic EL element 100 show the preferable specific example, and this invention is not limited to these.
For example, the organic EL device 100 according to the present invention may have a layer structure of (i) to (viii).
(I) Flexible support substrate / anode / light emitting layer / electron transport layer / cathode / thermal conductive layer / sealing adhesive / sealing member (ii) flexible support substrate / anode / hole transport layer / light emission Layer / electron transport layer / cathode / heat conducting layer / sealing adhesive / sealing member (iii) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode / Heat conduction layer / adhesive for sealing / sealing member (iv) flexible support substrate / anode / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat conduction Layer / adhesive for sealing / sealing member (v) flexible support substrate / anode / anode buffer layer / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode buffer layer / cathode / heat Conductive layer / adhesive for sealing / sealing member (vi) glass support / anode / hole injection layer / light emitting layer / electron injection layer / cathode / sealing member (v i) Glass support / anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode / sealing member (viii) Glass support / anode / hole injection layer / hole transport layer / light emission Layer / electron transport layer / electron injection layer / cathode / sealing member

<< Organic functional layer 20 of organic EL element >>
Subsequently, the detail of the organic functional layer which comprises the organic EL element of this invention is demonstrated.
(1) Injection layer: hole injection layer 3, electron injection layer 7
In the organic EL device of the present invention, the injection layer can be provided as necessary. The injection layer includes an electron injection layer and a hole injection layer, and may be present between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer as described above.
The injection layer referred to in the present invention is a layer provided between the electrode and the organic functional layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and its industrialization front line (November 30, 1998, NT. 2) Chapter 2 “Electrode Materials” (pages 123 to 166) of the second edition of “S. Co., Ltd.”, and includes a hole injection layer and an electron injection layer. The details of the hole injection layer are described, for example, in JP-A-9-45479, JP-A-9-260062, and JP-A-8-288069. Injection materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives. , Polymers containing silazane derivatives, aniline copolymers, polyarylalkane derivatives, or conductive polymers, preferably polythiophene derivatives, polyaniline derivatives, polypyrrole derivatives, more preferably It is a thiophene derivative.
Details of the electron injection layer are described in, for example, JP-A-6-325871, JP-A-9-17574, and JP-A-10-74586, and specifically, strontium, aluminum and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide. In the present invention, the buffer layer (injection layer) is desirably a very thin film, and potassium fluoride and sodium fluoride are preferable. The film thickness is about 0.1 nm to 5 μm, preferably 0.1 to 100 nm, more preferably 0.5 to 10 nm, and most preferably 0.5 to 4 nm.

(2) Hole transport layer 4
As the hole transport material constituting the hole transport layer, the same compounds as those applied in the hole injection layer can be used, and further, porphyrin compounds, aromatic tertiary amine compounds, and styryl. It is preferable to use an amine 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-4-30 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type ( MTDATA) and the like.
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. JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004), JP-A-11-251067, J. MoI. Huang et. al. It is also possible to use a hole transport material that has a so-called p-type semiconducting property as described in the literature (Applied Physics Letters 80 (2002), p. 139), JP 2003-519432 A. it can.
The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Hereinafter, although the preferable specific example ((1)-(75)) of the compound used for the positive hole transport material of the organic EL element of this invention is given, this invention is not limited to these.

In addition, n described in the above exemplary compounds represents the degree of polymerization and represents an integer having a weight average molecular weight in the range of 50,000 to 200,000. If the weight average molecular weight is less than this range, there is a concern of mixing with other layers during film formation due to the high solubility in the solvent. Even if a film can be formed, the light emission efficiency does not increase at a low molecular weight. When the weight average molecular weight is larger than this range, problems arise due to difficulty in synthesis and purification. Since the molecular weight distribution increases and the residual amount of impurities also increases, the light emission efficiency, voltage, and life of the organic EL element deteriorate.
These polymer compounds are disclosed in Makromol. Chem. , Pages 193, 909 (1992) and the like.

(3) Electron transport layer 6
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 as a single layer or a plurality of layers.
Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the cathode side with respect to the light emitting layer is injected from the cathode. As long as it has a function of transmitting electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, fluorene derivatives, carbazole derivatives, azacarbazole Examples thereof include metal complexes such as derivatives, oxadiazole derivatives, triazole derivatives, silole derivatives, pyridine derivatives, pyrimidine derivatives, and 8-quinolinol derivatives.
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 transporting material.
Among these, a carbazole derivative, an azacarbazole derivative, a pyridine derivative, and the like are preferable in the present invention, and an azacarbazole derivative is more preferable.
The electron transport layer can be formed by thinning the electron transport material by a known method such as a spin coating method, a casting method, a printing method including an ink jet method, an LB method, and the like, preferably The electron transport material can be formed by a wet process using a coating solution containing a fluorinated alcohol solvent.
Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

Alternatively, an electron transport layer with high n property doped with impurities as a guest material can be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.
The electron transport layer in the present invention may contain an organic alkali metal salt. There are no particular restrictions on the type of organic substance, but carbonate, formate, acetate, propionic acid, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, Succinate, benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate, tosylate, benzenesulfonate Preferably, formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, benzoate More preferably, alkali metal salts of aliphatic carboxylic acids such as formate, acetate, propionate and butyrate are preferable, and the number of carbon atoms of the aliphatic carboxylic acid is preferably 4 or less. Most preferred is acetate.
The type of alkali metal of the alkali metal salt of the organic substance is not particularly limited, and examples thereof include Na, K, and Cs, preferably K, Cs, and more preferably Cs. Examples of the alkali metal salt of the organic substance include a combination of the organic substance and the alkali metal, preferably, Li carbonate, Na carbonate, K carbonate, C carbonate, Li formate, K formate, Na formate, C formate, Li acetate, acetic acid. K, Na acetate, Cs acetate, Li propionate, Na propionate, K propionate, K propionate, Li oxalate, Na oxalate, K oxalate, Cs, Li malonate, Na malonate, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Li, benzoic acid Na, benzoic acid K, benzoic acid Cs, more preferably Li acetate, acetic acid K, Na acetate, Acetic acid Cs, most preferably acetic acid Cs.
The content of these dope materials is preferably 1.5 to 35% by mass, more preferably 3 to 25% by mass, and most preferably 5 to 15% by mass with respect to the electron transport layer to be added.

(4) Light emitting layer 5
The light emitting layer constituting the organic EL device of the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is the light emitting layer. It may be in the layer or the interface between the light emitting layer and the adjacent layer.
The light emitting layer according to the present invention is not particularly limited in its configuration as long as the contained light emitting material satisfies the above requirements.
Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. You may have a nonluminous intermediate | middle layer between each light emitting layer.
The total thickness of the light emitting layers in the present invention is preferably in the range of 15 to 100 nm, and more preferably 15 to 50 nm because a lower driving voltage can be obtained. In addition, the sum total of the film thickness of the light emitting layer as used in this invention is a film thickness also including the said intermediate | middle layer, when a nonluminous intermediate | middle layer exists between light emitting layers.
The film thickness of each light emitting layer is preferably adjusted to a range of 5 to 50 nm. In addition, each light emitting layer may emit light of each color of blue, green, and red, and there is no particular limitation on the relationship between the thickness of each light emitting layer.
In the present invention, a plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.
In the present invention, the structure of the light-emitting layer preferably contains a host compound and a light-emitting material (also referred to as a light-emitting dopant compound) and emits light from the light-emitting material.

(4.1) Host compound As the host compound contained in the light emitting layer of the organic EL device of the present invention, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.

The light emitting layer includes a plurality of types of host compounds.
At least two of the plurality of types of host compounds are represented by the following general formula (1), and one of the host compounds (first host compound) has a molecular aspect ratio of 1.7 or more and 2.5 or less. The other host compound (second host compound) has a molecular aspect ratio of 1.0 or more and less than 1.7, preferably 1.0 or more and 1.6 or less.
When an organic EL element (light-emitting layer) is composed of only a host compound having a molecular aspect ratio of 1.7 or more, the density increases due to stacking of molecules (stacking of molecules), but the molecules aggregate and Therefore, it is difficult to improve luminous efficiency and lifetime.
On the other hand, when an organic EL device (light emitting layer) is composed only of a host compound having a molecular aspect ratio of less than 1.7, intermolecular aggregation in the device thin film is suppressed, and the dispersibility of the host and dopant compound in the thin film is promoted. However, since the intermolecular interaction is weak, the density is low and the voltage is increased. In such a case, it is difficult to improve the light emission efficiency and the light emission lifetime.

  As a result of intensive studies to achieve the object of obtaining a high-density film while maintaining molecular dispersibility, the present inventors have found that the first host compound having the aspect ratio in the light emitting layer and the first host compound It was discovered that a high-density film can be obtained while maintaining molecular dispersibility by mixing with two host compounds, and the present invention has been achieved.

Here, the “molecular aspect ratio” is defined by the ratio (L / D) of the length (L) of the cylinder with the smallest diameter inscribed by the molecule and the diameter (D).
For the aspect ratio described in the present invention, Gaussian 03 (Gaussian 03, Revision D02, MJ Frisch, et al, Gaussian, Inc., Wallingford CT, 2004.), which is software for molecular orbital calculation manufactured by Gaussian, USA. Using B3LYP / 6-31G * as a keyword, the structure of the target molecular structure is optimized. Furthermore, Tencube / WM (Senda, "Development of molecular computing support system Winmostar", Idemitsu Technical Report, 49, 1, 106-111 (2006)) is used to calculate the aspect ratio from the optimized structure. be able to.

  As the first host compound and the second host compound, a compound represented by the general formula (1) is preferably used.

In the general formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″.
“R ′” and “R ″” each represent a hydrogen atom or a substituent.
“A ₁ ” and “A ₂ ” each represent an aromatic ring or a hydrogen atom.
“N1” and “n2” each represents an integer of 0 to 4.

  In X in the general formula (1), the substituents represented by R ′ and R ″ are alkyl groups (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, Hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.), alkynyl group ( For example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group , Anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl Group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4- Triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl Group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom) Quinoxalinyl group, pyridazinyl group, Lyazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, Hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, Methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenylthio group) O group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxy) Carbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl) Aminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethyl group) Bonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy) Group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propyl) Carbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, Decylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group) Octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentyl) Ureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido Group), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.) , Alkylsulfonyl groups (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl groups or heteroarylsulfonyl groups (for example, phenylsulfonyl group, Naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentyl) Amino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg. , Fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group) Group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. A plurality of these substituents may be bonded to each other to form a ring.

  Among them, X is preferably NR ′ or O, and R ′ is an aromatic hydrocarbon group (also referred to as aromatic carbocyclic group, aryl group, etc., for example, phenyl group, p-chlorophenyl group, mesityl group, A tolyl group, a xylyl group, a naphthyl group, an anthryl group, an azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group, an indenyl group, a pyrenyl group, a biphenylyl group, or an aromatic heterocyclic group (for example, a furyl group, a thienyl group, a pyridyl group) Group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group and the like are particularly preferable.

  The above aromatic hydrocarbon group and aromatic heterocyclic group each may have a substituent represented by R ′ or R ″ in X of the general formula (1).

In the general formula (1), examples of the aromatic ring represented by A ₁ and A ₂ include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. The aromatic ring may be a single ring or a condensed ring, and may be unsubstituted or may have a substituent represented by R ′ or R ″ in X of the general formula (1).

In the general formula (1), examples of the aromatic hydrocarbon ring represented by A ₁ and A ₂ include a benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, and naphthacene ring. , Triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring , Pyrene ring, pyranthrene ring, anthraanthrene ring and the like.
These rings may further have substituents each represented by R ′ and R ″ in X of the partial structure represented by the general formula (1).

In the partial structure represented by the general formula (1), examples of the aromatic heterocycle represented by A ₁ and A ₂ include a furan ring, a dibenzofuran ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, and a pyridazine. Ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, Quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is a nitrogen atom) Substituted ring It includes shown) or the like.

  These rings may further have substituents represented by R ′ and R ″ in the general formula (1).

Among the above, in the general formula (1), the aromatic ring represented by A ₁ and A ₂ is preferably a carbazole ring, carboline ring, dibenzofuran ring, or benzene ring, and more preferably used. , A carbazole ring, a carboline ring, and a benzene ring, more preferably a benzene ring having a substituent, and particularly preferably a benzene ring having a carbazolyl group.

In the general formula (1), each of the aromatic rings represented by A ₁ and A ₂ is preferably a condensed ring having 3 or more rings, and an aromatic hydrocarbon condensed ring in which 3 or more rings are condensed. Specifically, naphthacene ring, anthracene ring, tetracene ring, pentacene ring, hexacene ring, phenanthrene ring, pyrene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, Coronene ring, benzocoronene ring, hexabenzocoronene ring, fluorene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene ring, naphthocoronene ring , Ovalene ring, Ansura Tren ring and the like. In addition, these rings may further have the above substituent.

  Specific examples of the aromatic heterocycle condensed with three or more rings include an acridine ring, a benzoquinoline ring, a carbazole ring, a carboline ring, a phenazine ring, a phenanthridine ring, a phenanthroline ring, a carboline ring, a cyclazine ring, Kindin ring, tepenidine ring, quinindrin ring, triphenodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is a nitrogen atom Phenanthroline ring, dibenzofuran ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, benzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, A Tiger thiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, such as thio fan Tren ring (naphthaldehyde thiophene ring), and the like. In addition, these rings may further have a substituent.

  In the general formula (1), n1 and n2 each represents an integer of 0 to 4, but “n1 + n2” is preferably 0 to 2, and in particular when X is O or S, 1-2. It is preferable that

  In the present invention, a host compound having both a dibenzofuran ring and a carbazole ring is particularly preferable.

  Specific examples (a-1 to a-45) of the host compound represented by the general formula (1) are shown below, but are not limited thereto.

(4.2) Luminescent material (luminescent dopant)
As the light-emitting material (light-emitting dopant) according to the present invention, a fluorescent compound or a phosphorescent light-emitting material (also referred to as a phosphorescent compound or a phosphorescent compound) can be used. Is preferred. The light emitting layer contains one or more kinds of such light emitting dopants.
In the present invention, the phosphorescent material is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield of 25 ° C. The phosphorescence quantum yield is preferably 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectra II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. The phosphorescence quantum yield in a solution can be measured using various solvents, but when using a phosphorescent material in the present invention, the above phosphorescence quantum yield (0.01 or more) is achieved in any solvent. It only has to be done.
There are two types of light emission principles of phosphorescent materials. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is converted into the phosphorescent material. The energy transfer type that obtains light emission from the phosphorescent light emitting material by moving it, and the other is that the phosphorescent light emitting material becomes a carrier trap, and carrier recombination occurs on the phosphorescent light emitting material, and light emission from the phosphorescent light emitting material However, in any case, the energy of the excited triplet state of the phosphorescent material is lower than the energy of the excited triplet state of the host compound.
The phosphorescent light-emitting material can be appropriately selected from known materials used for the light-emitting layer of the organic EL element, but is preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferably, an iridium complex, an osmium complex, a platinum complex, or a rare earth complex, and most preferably an iridium complex.
The phosphorescent material according to the present embodiment includes at least one blue phosphorescent material, preferably at least one blue phosphorescent material, and at least one having an excitation triplet energy lower than that of the blue phosphorescent material. One phosphorescent material.

  The phosphorescent dopant is preferably represented by the general formula (2).

In the general formula (2), “R ₁ ” represents a substituent.
“Z” represents a nonmetallic atom group necessary to form a 5- to 7-membered ring.
“N1” represents an integer of 0 to 5.
“B _{1 to} B ₅ ” represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom.
“M ₁ ” represents a group 8 to group 10 metal in the periodic table.
“X ₁ ” and “X ₂ ” represent a carbon atom, a nitrogen atom, or an oxygen atom, and “L ₁ ” represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ .
“M1” represents an integer of 1 to 3, “m2” represents an integer of 0 to 2, and “m1 + m2” is 2 or 3.

  The phosphorescent compound represented by the general formula (2) according to the present invention has a HOMO of −5.15 to −3.50 eV, a LUMO of −1.25 to +1.00 eV, and preferably a HOMO of −4. .80 to -3.50 eV, and LUMO is -0.80 to +1.00 eV.

In the phosphorescent compound represented by the general formula (2), examples of the substituent represented by R ₁ include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, Pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.), Alkynyl group (for example, ethynyl group, propargyl group, etc.), aromatic hydrocarbon ring group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group , Naphthyl, anthryl, azulenyl, acenaphthenyl, fluorenyl, phenanthryl, in Denyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (for example, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1, 2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, A quinolyl group, a benzofuryl group, a dibenzofuryl group, a benzothienyl group, a dibenzothienyl group, an indolyl group, a carbazolyl group, a carbolinyl group, a diazacarbazolyl group (one of the carbon atoms constituting the carboline ring of the carbolinyl group is a nitrogen atom) ), Quinoxalinyl group, Ridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyl) Oxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (Eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group ( For example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, Phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group) , Dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, aceto Til group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group ( For example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonyl) Amino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcal Nylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexyl) Aminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido) Group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyri Sulfinyl group (eg, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group) Group), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (for example, phenyl) Sulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino) Group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc., cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, Triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). Of these substituents, preferred are an alkyl group and an aryl group.

  Z represents a nonmetallic atom group necessary for forming a 5- to 7-membered ring. Examples of the 5- to 7-membered ring formed by Z include a benzene ring, naphthalene ring, pyridine ring, pyrimidine ring, pyrrole ring, thiophene ring, pyrazole ring, imidazole ring, oxazole ring, and thiazole ring. Of these, a benzene ring is preferred.

B ₁ .about.B ₅ represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, at least one nitrogen atom. The aromatic nitrogen-containing heterocycle formed by these five atoms is preferably a monocycle. Examples include pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, oxadiazole ring, and thiadiazole ring. Among these, a pyrazole ring and an imidazole ring are preferable, and an imidazole ring in which B ₂ and B ₅ are nitrogen atoms is particularly preferable. These rings may be further substituted with the above substituents. Preferred as the substituent are an alkyl group and an aryl group, and more preferably an aryl group.

L ₁ represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . Specific examples of the bidentate ligand represented by X ₁ -L ₁ -X ₂ include, for example, substituted or unsubstituted phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabol, picolinic acid And acetylacetone. These groups may be further substituted with the above substituents.

m1 represents an integer of 1 to 3, m2 represents an integer of 0 to 2, and m1 + m2 is 2 or 3. Especially, the case where m2 is 0 is preferable. The metal represented by M _1, but 8-10 transition metal elements of the Periodic Table of the Elements (also referred to simply as a transition metal) is used, inter alia iridium, platinum are preferred, more preferably iridium.

In addition, when the nitrogen-containing heterocycle formed by B _{1 to} B ₅ is an imidazole ring, the general formula (2) is more preferably represented by the general formula (3).

In the general formula (3), “R ₁ ”, “R ₂ ”, and “R ₃ ” represent a substituent.
“Z” represents a nonmetallic atom group necessary to form a 5- to 7-membered ring.
“N1” represents an integer of 0 to 5.
“M ₁ ” represents a group 8 to group 10 metal in the periodic table.
“X ₁ ” and “X ₂ ” represent a carbon atom, a nitrogen atom, or an oxygen atom, and “L ₁ ” represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ .
“M1” represents an integer of 1 to 3, “m2” represents an integer of 0 to 2, and “m1 + m2” is 2 or 3.

In the general formula (3), the substituents represented by R ₁ , R ₂ and R ₃ have the same meaning as the substituents represented by R ₁ in the general formula (2).
In the general formula (3), Z, M ₁ , X ₁ and X ₂ , L _{1 and the} like are also synonymous with those in the general formula (2), and m1 and m2 are also in the general formula (2). It is synonymous.

Further, the group represented by R ₂ in the general formula (3) is preferably an aromatic hydrocarbon ring group (aromatic carbocyclic group), more preferably a substituted aryl group, and the substituted aryl group is represented by the general formula (4). ) Is preferred.

In the general formula (4), “R ₄ ” represents a substituent having a steric parameter value (Es value) of −0.5 or less, “R ₅ ” represents a substituent, and “n5” is an integer of 0 to 4. Represents.
In the general formula (4), “*” represents a bonding position.

  Although the specific compound (D-1 to D-153) of the phosphorescent compound represented by General formula (2) is illustrated below, this invention is not limited to these.

<< Formation and characteristics of each layer of organic functional layer (especially light emitting layer) >>
In the organic EL device of the present invention, it is sufficient that at least one light emitting layer as a constituent layer is formed by a coating method, and the method for forming the other layers is not particularly limited to the coating method, and is necessary. Accordingly, the film can be formed using a vapor deposition method or the like.

In the method for producing an organic EL device of the present invention, a coating method (also referred to as a coating film forming method) is used as a method for forming a light emitting layer.
As a method for forming the light emitting layer, there are a spin coat method, a cast method, an ink jet method, a spray method, a printing method, a slot type coater method and the like.
From the standpoint that a homogeneous film is easily obtained and pinholes are not easily generated, the light emitting layer is preferably formed by a coating method such as a spin coating method, an ink jet method, a spray method, a printing method, or a slot coater method. Of these, the slot coater method is preferably used.

  Of course, it is preferable to apply the above-described coating method (coating film forming method) also to the constituent layers other than the light emitting layer of the organic EL device of the present invention.

After the coating film formation, the coating solution is dried.
As a drying method after coating film formation, spin drying, hot air drying, far-infrared drying, vacuum drying, reduced pressure drying, or the like can be applied.

<< Anode 2 >>
As the anode constituting the organic EL device, an electrode material made of a metal, an alloy, an electrically conductive compound or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as 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, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a desired shape pattern may be formed by a photolithography method, or when pattern accuracy is not so high (about 100 μm or more) A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be 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 in the range of 10 to 1000 nm, preferably in the range of 10 to 200 nm.

<< Cathode 8 >>
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material 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, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Magnesium / 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 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted 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.
Moreover, after producing the metal with a film thickness of 1 to 20 nm on the cathode, a transparent or translucent cathode can be produced by forming the conductive transparent material mentioned in the description of the anode thereon. By applying this, an organic EL element in which both the anode and the cathode are transmissive can be produced.

<Supporting substrate 1>
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. May be opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. Since the effect of suppressing high-temperature storage stability and chromaticity variation appears greatly in a flexible substrate than a rigid substrate, a particularly preferable support substrate has flexibility that can give flexibility to an organic EL element. Resin film.
Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both may be formed. Water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and more preferably oxygen permeability measured by a method according to JIS K 7126-1987. The film is preferably a high barrier film having a degree of 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less and a water vapor transmission rate of 10 ⁻³ g / (m ² · 24 h) or less. More preferably, the degree is 10 ⁻⁵ g / (m ² · 24 h) or less.
As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of factors that cause deterioration of the organic EL element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. Can do. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and organic material layers. Although there is no restriction | limiting in particular about the lamination order of an inorganic layer and an organic functional layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the molecular beam epitaxy method, the cluster ion beam method, the ion plating method, the plasma polymerization method, the atmospheric pressure plasma. A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.
In the organic EL device of the present invention, the external extraction efficiency of light emission at room temperature is preferably 1% or more, more preferably 5% 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.

<< Sealing (sealing adhesive 9, sealing member 10) >>
As a sealing means applicable to the organic EL element of the present invention, for example, a method of adhering a sealing member, an electrode, and a support substrate with an adhesive can be mentioned.
As a sealing member, it should just be arrange | positioned so that the display area | region of an organic EL element may be covered, and concave plate shape or flat plate shape may be sufficient. Further, transparency and electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicone, germanium, and tantalum.

In the present invention, a polymer film and a metal film can be preferably used because the element can be thinned. Furthermore, the polymer film has an oxygen permeability measured by a method according to JIS K 7126-1987 of 1 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less, and conforms to JIS K 7129-1992. The water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by the above method is preferably 1 × 10 ⁻³ g / (m ² · 24 h) or less.
For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

Specific examples of the adhesive include photo-curing and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. Further, a desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

  It is also preferable that the electrode and the organic functional layer are coated on the outside of the electrode facing the support substrate with the organic functional layer interposed therebetween, and an inorganic or organic layer is formed in contact with the support substrate to form a sealing film. Can be. In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster-ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In order to form a gas phase and a liquid phase in the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, an inert gas such as fluorinated hydrocarbon or silicon oil is used. It is preferable to inject a liquid. A vacuum is also possible. Moreover, a hygroscopic compound can also be enclosed inside.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate and the like), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.

  Sealing includes casing type sealing (can sealing) and close contact type sealing (solid sealing), but solid sealing is preferable from the viewpoint of thinning. Moreover, when producing a flexible organic EL element, since sealing is also required for the sealing member, solid sealing is preferable.

Below, the preferable aspect in the case of performing solid sealing is demonstrated.
As the sealing adhesive according to the present invention, a thermosetting adhesive, an ultraviolet curable resin, or the like can be used, but preferably a thermosetting adhesive such as an epoxy resin, an acrylic resin, or a silicone resin, more preferably moisture resistant. It is an epoxy thermosetting adhesive resin that is excellent in water resistance and water resistance and has little shrinkage during curing.
The water content of the sealing adhesive according to the present invention is preferably 300 ppm or less, more preferably 0.01 to 200 ppm, and most preferably 0.01 to 100 ppm.
The moisture content referred to in the present invention may be measured by any method. For example, a volumetric moisture meter (Karl Fischer), an infrared moisture meter, a microwave transmission moisture meter, a heat-dry weight method, GC / MS , IR, DSC (differential scanning calorimeter), TDS (temperature programmed desorption analysis). Further, using a precision moisture meter AVM-3000 (Omnitech) or the like, moisture can be measured from a pressure increase caused by evaporation of moisture, and moisture content of a film or a solid film can be measured.
In the present invention, the moisture content of the sealing adhesive can be adjusted by, for example, placing it in a nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, and changing the time. Further, it can be dried in a vacuum state of 100 Pa or less while changing the time. Further, the sealing adhesive can be dried only with an adhesive, but can also be placed in advance on the sealing member and dried.
When close sealing (solid sealing) is performed, as the sealing member, for example, a 50 μm thick PET (polyethylene terephthalate) laminated with an aluminum foil (30 μm thick) is used. Using this as a sealing member, it is uniformly applied to the aluminum surface using a dispenser, a sealing adhesive is placed in advance, the resin substrate 1 and the sealing member 5 are aligned, and both are pressure-bonded ( 0.1-3 MPa) and a temperature of 80-180 ° C. for tight adhesion / bonding (adhesion) for tight sealing (solid sealing).
The heating or pressure bonding time varies depending on the type, amount, and area of the adhesive, but temporary bonding is performed at a pressure of 0.1 to 3 MPa, and the thermosetting time is within a range of 5 seconds to 10 minutes at a temperature of 80 to 180 ° C. Just choose.
The use of a heated crimping roll is preferred because it allows simultaneous crimping (temporary bonding) and heating, and eliminates internal voids at the same time.
As a method for forming the adhesive layer, a coating method such as roll coating, spin coating, screen printing, or spray coating, or a printing method can be used depending on the material.

As described above, solid sealing is a form in which there is no space between the sealing member and the organic EL element substrate and the resin is covered with a cured resin.
Examples of the sealing member include metals such as stainless steel, aluminum and magnesium alloys, polyethylene terephthalate, polycarbonate, polystyrene, nylon, plastics such as polyvinyl chloride, and composites thereof, glass, and the like. In the case of a resin film, a laminate of gas barrier layers such as aluminum, aluminum oxide, silicon oxide, and silicon nitride can be used as in the case of a resin substrate.
The gas barrier layer can be formed by sputtering, vapor deposition or the like on both surfaces or one surface of the sealing member before molding the sealing member, or may be formed on both surfaces or one surface of the sealing member after sealing by a similar method. . Also in this case, the oxygen permeability is 1 × 10 ⁻³ ml / (m ² · 24 h · atm) or less, and the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is 1 ×. It is preferably 10 ⁻³ g / (m ² · 24 h) or less.
The sealing member may be a film laminated with a metal foil such as aluminum. As a method for laminating the polymer film on one side of the metal foil, a generally used laminating machine can be used. As the adhesive, polyurethane-based, polyester-based, epoxy-based, acrylic-based adhesives and the like can be used. You may use a hardening | curing agent together as needed. A hot melt lamination method, an extrusion lamination method and a coextrusion lamination method can also be used, but a dry lamination method is preferred.
In addition, when the metal foil is formed by sputtering or vapor deposition and is formed from a fluid electrode material such as a conductive paste, it may be produced by a method of forming a metal foil on a polymer film as a base material. Good.

《Protective film, protective plate》
In order to increase the mechanical strength of the organic EL element, a protective film or a protective plate may be provided outside the sealing film on the side facing the support substrate with the organic functional layer interposed therebetween or on the outer side of the sealing film. In particular, when sealing is performed with a sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.
In the present invention, it is preferable to have a light extraction member between the flexible support substrate and the anode, or at any location on the light emission side from the flexible support substrate.
Examples of the light extraction member include a prism sheet, a lens sheet, and a diffusion sheet. Further, a diffraction grating or a diffusion structure introduced into an interface or any medium that causes total reflection can be used.
Usually, in an organic EL element that emits light from a substrate, a problem arises in that part of the light emitted from the light emitting layer undergoes total reflection at the interface between the substrate and air, resulting in loss of light. In order to solve this problem, prismatic or lens-like processing is applied to the surface of the substrate, or prism sheets, lens sheets, and diffusion sheets are affixed to the surface of the substrate, thereby suppressing total reflection and light extraction efficiency. To improve.
In order to increase the light extraction efficiency, a method of introducing a diffraction grating or a method of introducing a diffusion structure in an interface or any medium that causes total reflection is known.

<< Method for Manufacturing Organic EL Element 100 >>
As an example of the method for producing an organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a desired electrode material, for example, a thin film made of an anode material is formed on a suitable substrate by a thin film forming 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 hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an organic functional layer (organic compound thin film) of an electron injection layer, which are organic EL element materials, are formed thereon.
The processing steps in the case of forming the organic functional layer by a coating method mainly include (i) a step of applying and laminating a coating liquid constituting the organic functional layer on the anode of the support substrate; And a step of drying the coating liquid after lamination.
The light emitting layer forming method (coating film forming method) is as described above.

In the step (i), as a method for forming each layer, as described above, a vapor deposition method, a wet process (for example, spin coating method, casting method, die coating method, blade coating method, roll coating method, ink jet method, printing method, spray coating). Method, curtain coating method, LB method (Langmuir Brodgett method and the like can be used), and at least the light emitting layer of the present invention is preferably formed by a wet process.
In the formation of the organic functional layer other than the light emitting layer, it is preferable to use a wet process in the present invention from the viewpoint that a homogeneous film is easily obtained and pinholes are difficult to be generated, among others, a spin coating method, a casting method, Film formation by a coating method such as a die coating method, a blade coating method, a roll coating method, or an ink jet method is preferable.
Examples of the liquid medium for dissolving or dispersing the organic EL material according to the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, and mesitylene. Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethylsulfoxide (DMSO) can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.
In addition, the preparation step for dissolving or dispersing the organic EL material according to the present invention and the coating process until coating on the base material are preferably performed under an inert gas atmosphere. Since the film can be formed without degrading the performance of the organic EL element even if it is not carried out in step 1, it may not necessarily be carried out in an inert gas atmosphere. In this case, the manufacturing cost can be suppressed, which is more preferable.

In the step (ii), the coated and laminated organic functional layer is dried.
The term “drying” as used herein refers to a reduction to 0.2% or less when the solvent content of the film immediately after coating is 100%.
As a means for drying, those generally used can be used, and examples thereof include reduced pressure or pressure drying, heat drying, air drying, IR drying, and electromagnetic wave drying. Of these, heat drying is preferable, the temperature is equal to or higher than the boiling point of the solvent having the lowest boiling point in the organic functional layer coating solvent, and the temperature is lower than (Tg + 20) ° C. of the material having the lowest Tg among the Tg of the organic functional layer material. Most preferably, it is held at In the present invention, more specifically, it is preferable to hold and dry at 80 ° C. or higher and 150 ° C. or lower, and more preferable to hold and dry at 100 ° C. or higher and 130 ° C. or lower.
The atmosphere when drying the coating liquid after coating / lamination is preferably an atmosphere having a volume concentration of a gas other than the inert gas of 200 ppm or less, but it is not necessarily in an inert gas atmosphere as in the liquid preparation coating process. It may not be necessary. In this case, the manufacturing cost can be suppressed, which is more preferable.
The inert gas is preferably a rare gas such as nitrogen gas and argon gas, and most preferably nitrogen gas in terms of production cost.

  The coating / laminating and drying steps of these layers may be single wafer manufacturing or line manufacturing. Further, the drying process may be performed while being conveyed on the line, but from the viewpoint of productivity, it may be deposited or rolled in a non-contact manner in a roll form.

After these layers are dried, 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 film thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm. By providing, a desired organic EL element can be obtained.
After the heat treatment, the organic EL element can be produced by adhering the close-sealing or sealing member to the electrode and the support substrate with an adhesive.

<Application>
The organic EL element of the present invention can be used as a display device such as a display device or a display, or various light emission sources (illumination devices).
Examples of 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, and light sources for optical sensors. Furthermore, it can be used in a wide range of applications such as general household appliances that require a display device, but it can be used effectively as a backlight for a liquid crystal display device combined with a color filter, and as a light source for illumination. it can.
In the organic EL element of the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like as needed during film formation. In the case of patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire layer of the element may be patterned. In the fabrication of the element, a conventionally known method is used. Can do.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Production of organic EL element >>
(1) Production of Example Sample A (1.1) Production of Gas Barrier Flexible Film First of polyethylene naphthalate film (Teijin DuPont film, hereinafter abbreviated as PEN) as the flexible film. An inorganic gas barrier film made of SiOx is continuously formed on the flexible film by using an atmospheric pressure plasma discharge treatment apparatus having a configuration described in JP-A-2004-68143 on the entire surface on the electrode forming side. A gas barrier flexible film having an oxygen permeability of 0.001 ml / m ² / day or less and a water vapor permeability of 0.001 g / m ² / day or less was formed.

(1.2) Formation of first electrode layer A 120 nm thick ITO (Indium Tin Oxide) film is formed on the prepared gas barrier flexible film by sputtering and patterned by photolithography. An electrode layer (anode) was formed.
The pattern was such that the light emission area was 50 mm square.

(1.3) Formation of hole injection layer The patterned ITO substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. On this substrate, a solution of poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (abbreviated as PEDOT / PSS, manufactured by Bayer, Baytron P Al 4083) diluted to 70% with pure water at 3000 rpm for 30 seconds. After film formation by a spin coating method, the film was dried at 200 ° C. for 1 hour to provide a hole injection layer having a thickness of 30 nm.

(1.4) Formation of hole transport layer This substrate was transferred to a nitrogen atmosphere using nitrogen gas (grade G1), and exemplary compound (60) (Mw = 80,000) as the hole transport material was transferred. A solution of 0.5% dissolved in chlorobenzene was formed by spin coating at 1500 rpm for 30 seconds, and then kept at 160 ° C. for 30 minutes to form a 30 nm-thick hole transport layer.

(1.5) Formation of Light-Emitting Layer Next, each light-emitting layer composition having the following composition was formed by spin coating at 1500 rpm for 30 seconds, and then held at 120 ° C. for 30 minutes to form a light-emitting layer having a thickness of 40 nm. did.
<Light emitting layer composition>
Host material ... Exemplified compound a-42: a-41 equimolar mixture 14.00 parts by mass Dopant material 1 ... Exemplified compound D-66 2.45 parts by mass Solvent species ... Toluene: isopropyl acetate = 1: 1 2,000 parts by mass During the application, drying air was applied to the coating solution while maintaining the environmental temperature at 40 ° C.

(1.6) Formation of Electron Transport Layer Subsequently, a solution obtained by dissolving 20 mg of the exemplified compound (Compound A), which is a compound represented by the general formula (A), in 4 ml of tetrafluoropropanol (TFPO) is 1500 rpm. After forming the film by spin coating in 30 seconds, the film was held at 120 ° C. for 30 minutes to form an electron transport layer having a thickness of 30 nm.

(1.7) Formation of electron injection layer and cathode Subsequently, the substrate was attached to a vacuum deposition apparatus without being exposed to the atmosphere. A molybdenum resistance heating boat containing sodium fluoride and potassium fluoride is attached to a vacuum deposition apparatus, and the vacuum chamber is depressurized to 4 × 10 ⁻⁵ Pa. Sodium fluoride was deposited at 0.02 nm / second to form a 1 nm thin film on the electron transport layer, and then potassium fluoride was similarly deposited at 0.02 nm / second to form a film on sodium fluoride. An electron injection layer having a thickness of 1.5 nm was formed.
Subsequently, aluminum was deposited to form a cathode having a thickness of 100 nm.

(1.8) Sealing and Production of Organic EL Element Subsequently, a sealing member was bonded using a commercially available roll laminating apparatus to produce Example Sample 1 (organic EL element).
Specifically, as a sealing member, a flexible aluminum foil (made by Toyo Aluminum Co., Ltd.) having a thickness of 30 μm, a polyethylene terephthalate (PET) film (12 μm thickness) and an adhesive for dry lamination (two-component reaction type urethane) (Adhesive layer thickness 1.5 μm) was used.
As a sealing adhesive, a thermosetting adhesive was uniformly applied to the aluminum surface with a thickness of 20 μm along the adhesive surface (shiny surface) of the aluminum foil using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Furthermore, it moved to nitrogen atmosphere with a dew point temperature of −80 ° C. or lower and an oxygen concentration of 0.8 ppm, dried for 12 hours or longer, and adjusted the moisture content of the sealing adhesive to 100 ppm or lower.
As the thermosetting adhesive, an epoxy adhesive mixed with the following (A) to (C) was used.
(A) Bisphenol A diglycidyl ether (DGEBA)
(B) Dicyandiamide (DICY)
(C) Epoxy adduct curing accelerator

  As described above, the sealing substrate is closely attached and arranged so as to cover the joint portion between the extraction electrode and the electrode lead so as to be in the form shown in FIG. Example sample A (organic EL element) was produced by tightly sealing at a temperature of 120 ° C., a pressure of 0.5 MPa, and an apparatus speed of 0.3 m / min.

(2) Production of Example Samples B to C and Comparative Example Sample D The host material of the light emitting layer composition was changed to the composition shown in Table 1.
Other than that was the same as Example Sample A.

<< Evaluation of organic EL elements >>
About Example sample AC and the comparative example sample D, each evaluation of following (1)-(3) was performed.

(1) Measurement of emission luminance and driving voltage For each sample, the emission luminance of each sample is measured at room temperature (about 23 to 25 ° C.) using a spectral radiance meter CS-2000 (manufactured by Konica Minolta Sensing). Then, the light emission luminance (current is constant) and the driving voltage were obtained. Table 2 shows the obtained results. In Table 2, the light emission luminance and driving voltage of sample D (comparative example) are set to “100”, and the light emission luminance and driving voltage of samples A to C are shown as relative values.

(2) Evaluation of continuous drive stability (lifetime) Each sample is wound around a cylinder with a radius of 5 cm, and then continuously driven in a state where each sample is bent, and the luminance is measured using the spectral radiance meter CS-2000. The time (LT50) during which the measured luminance was reduced by half was determined. The driving condition was set to a current value of 4000 cd / m ² at the start of continuous driving.
A relative value with the LT50 of Sample D (Comparative Example) set to “100” was determined, and this was used as a measure of continuous drive stability. The evaluation results are shown in Table 2. In Table 2, it shows that it is excellent in continuous drive stability (long life), so that a numerical value is large.

(3) Evaluation of color stability after driving The CIE chromaticity coordinates before and after the half-life evaluation were measured, and the distances before and after the life evaluation on the x and y coordinates were measured. A relative value with the distance of Sample D (Comparative Example) as “100” was determined and used as a measure of continuous drive stability. The evaluation results are shown in Table 2. In Table 2, the smaller the value, the better the color stability after driving.

(4) Summary As shown in Table 2, from the comparison of Example Samples A to C and Comparative Example Sample D, Example Samples A to C have good results in each evaluation, and in particular Example Samples B to C It was even better.
From the above, in order to improve the light emission efficiency and the light emission lifetime and stabilize the light emission color, a host compound having a molecular aspect ratio of 1.7 or more (a compound for obtaining a density improving effect by stacking) and a molecular aspect ratio of 1 It is useful to mix a host compound of less than 7 (a compound for obtaining a molecular dispersion effect), and it is particularly useful to use a compound having a molecular aspect ratio of 1.6 or less as the latter host compound. It can be seen that it is.

<< Production of organic EL element >>
(1) Production of Example Sample 1 The light emitting layer composition of Example Sample A according to [Example 1] was changed to the following composition to produce a white light emitting type sample.
Other than that was the same as Example Sample A above.
<Light emitting layer composition>
Host material ... Exemplified compound a-42: a-41 equimolar mixture 13.95 parts by mass Dopant material 1 ... Exemplified compound D-66 2.45 parts by mass Dopant material 2 ... Exemplified compound D-67 0.025 parts by mass Dopant material 3 ... Exemplified Compound D-80 0.025 part by mass Solvent type ... Toluene: Isopropyl acetate = 1: 1 2,000 parts by mass

(2) Production of Example Samples 2 to 10 and Comparative Samples 11 to 14 The dopant material 1 and the host material of the light emitting layer composition were changed to the compositions shown in Table 3.
Other than that, it was the same as the above-mentioned Example Sample 1.

<< Evaluation of organic EL elements >>
(1) Evaluation content The organic EL device produced as described above was evaluated in the same manner as in [Example 1], and the results are shown in Table 4. In Table 4, the result of each sample was expressed as a relative value with Sample 11 (Comparative Example) as “100”.

(2) Summary As shown in Table 4, from comparison between Example Samples 1 to 10 and Comparative Example Samples 11 to 14, Example Samples 1 to 10 have good results in each evaluation, and Example Samples 5 to 6 Was even better.
From the above, even in the case of a white light emitting organic EL device using three kinds of dopant materials, a host compound having a molecular aspect ratio of 1.7 or more is required to improve the light emission efficiency and the light emission lifetime and stabilize the light emission color. It is useful to mix (a compound for obtaining a density enhancement effect by stacking) and a host compound (a compound for obtaining a molecular dispersion effect) having a molecular aspect ratio of less than 1.7. It can be seen that it is useful to use a host compound having a molecular aspect ratio of 1.6 or less.

DESCRIPTION OF SYMBOLS 1 Flexible support substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Sealing adhesive 10 Flexible sealing member 20 Organic functional layer 100 Organic EL element

Claims (10)

An organic electroluminescence device having at least one light emitting layer between an anode and a cathode,
The light emitting layer contains one or more phosphorescent dopant compounds and a plurality of host compounds,
Among the plurality of types of host compounds, at least two types of host compounds are represented by the general formula (1), the molecular aspect ratio of the one host compound is 1.7 or more, and the molecular aspect of the other host compound An organic electroluminescence device having a ratio of less than 1.7.

[In the general formula (1), “X” represents NR ′, O, S, CR′R ″ or SiR′R ″. “R ′” and “R ″” each represent a hydrogen atom or a substituent. “A ₁ ” and “A ₂ ” each represent an aromatic ring or a hydrogen atom. “N1” and “n2” each represents an integer of 0 to 4. ] The organic electroluminescent device according to claim 1,
The light emitting layer contains two types of host compounds represented by the general formula (1),
An organic electroluminescence device, wherein a molecular aspect ratio of the one host compound is 1.7 or more and a molecular aspect ratio of the other host compound is 1.6 or less. The organic electroluminescent device according to claim 1,
The light emitting layer contains two types of host compounds represented by the general formula (1),
The organic aspect of the present invention is characterized in that the molecular aspect ratio of the one host compound is 1.7 or more and 2.5 or less, and the molecular aspect ratio of the other host compound is 1.0 or more and 1.6 or less. element. In the organic electroluminescent element as described in any one of Claims 1-3,
The organic light-emitting device, wherein the light-emitting layer contains at least two phosphorescent dopant compounds. In the organic electroluminescent element as described in any one of Claims 1-4,
The light emitting layer contains at least one phosphorescent dopant compound, and the phosphorescent dopant compound is represented by the general formula (2).

[In General Formula (2), “R ₁ ” represents a substituent. “Z” represents a nonmetallic atom group necessary to form a 5- to 7-membered ring. “N1” represents an integer of 0 to 5. “B _{1 to} B ₅ ” represents a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and at least one represents a nitrogen atom. “M ₁ ” represents a group 8 to group 10 metal in the periodic table. “X ₁ ” and “X ₂ ” represent a carbon atom, a nitrogen atom, or an oxygen atom, and “L ₁ ” represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . “M1” represents an integer of 1 to 3, “m2” represents an integer of 0 to 2, and “m1 + m2” is 2 or 3. ] In the organic electroluminescent element according to claim 5,
Said general formula (2) is represented by general formula (3), The organic electroluminescent element characterized by the above-mentioned.

[In General Formula (3), “R ₁ ”, “R ₂ ”, and “R ₃ ” represent a substituent. “Z” represents a nonmetallic atom group necessary to form a 5- to 7-membered ring. “N1” represents an integer of 0 to 5. “M ₁ ” represents a group 8 to group 10 metal in the periodic table. “X ₁ ” and “X ₂ ” represent a carbon atom, a nitrogen atom, or an oxygen atom, and “L ₁ ” represents an atomic group that forms a bidentate ligand together with X ₁ and X ₂ . “M1” represents an integer of 1 to 3, “m2” represents an integer of 0 to 2, and “m1 + m2” is 2 or 3. ] The organic electroluminescence device according to claim 6,
In the general formula (3), the substituent represented by R ₂ is represented by the general formula (4).

[In General Formula (4), “R ₄ ” represents a substituent having a steric parameter value (Es value) of −0.5 or less, “R ₅ ” represents a substituent, and “n5” represents 0-4. An integer is represented, and “*” indicates a binding position. ] In the organic electroluminescent element according to any one of claims 1 to 7,
An organic electroluminescence device, wherein the light emitting layer is formed by a wet process.   A display device using the organic electroluminescence element according to claim 1.   The illuminating device using the organic electroluminescent element as described in any one of Claims 1-8.

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