JP4581355B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescence element used for a planar light source and display. More specifically, the present invention relates to an organic electroluminescence device having high brightness, high efficiency, long life, and high heat resistance.

  When electrons injected from the cathode and holes injected from the anode are recombined in the organic light emitting body sandwiched between these two electrodes, excitons are generated. Organic electroluminescence (EL) devices that utilize light emission obtained when the excitons are deactivated to the ground state are promising for use as solid-state display devices, and have been actively researched and developed in recent years. Yes.

This study was conducted by Eastman Kodak's C.I. W. Tang et al., Appl. Phys. Lett. 51, 913, published in 1987, which originated from an EL element with an organic thin film laminated. In this report, a metal chelate complex is used for the light emitting layer and an amine compound is used for the hole injection layer. Thus, green light emission with a luminance of several thousand (cd / m ² ) at a DC voltage of 6 to 10 V and a maximum light emission efficiency of 1.5 (lm / W) is obtained (see Non-Patent Document 1). It can be said that the organic EL elements currently being developed by various research institutes basically follow the configuration of Eastman Kodak Company.

  At present, as an attempt to improve the light emission efficiency of the organic EL element, it has been proposed to use phosphorescence instead of fluorescence. If the excited singlet state and the excited triplet state of the organic phosphorescent substance are used in the light emitting layer of the organic EL element, it is expected that high light emission efficiency is achieved. When electrons and holes recombine in the organic EL element, it is considered that excited singlet states and excited triplet states having different spin multiplicity are generated at a ratio of 1: 3. When using fluorescence which is light emission from an excited singlet state, only 25% of excitons can be used, and the light emission efficiency is lowered. On the other hand, by using phosphorescence, that is, light emission from an excited triplet state, it is expected that the light emission efficiency is improved by 3 to 4 times compared to an organic EL element using conventional fluorescence.

As an example, an organic EL device using a phenylpyridine organometallic complex of iridium, which is a phosphorescent light-emitting substance, has been reported (Appl. Phys. Lett., Vol. 75, p. 4, 1999). According to this, high efficiency of current efficiency (26 cd / A) and power efficiency 19 (lm / W) is obtained at a driving voltage of 4.3 V and a luminance of 100 (cd / m ² ) (see Non-Patent Document 2). ).

  However, in the conventional organic phosphorescent light emitting device, for example, a device having a structure such as an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron injection layer / cathode, a light emitting layer host material In many cases, the following compound [A] is used. However, since this material has very high crystallinity and low stability in a thin film state, it has a problem of short life and low heat resistance. Further, in the hole injection layer and / or hole transport layer, the following compound [B] (TPD) or the following compound [C] (α-NPD) is often used, but the glass transition temperature of these materials is In this case, TPD is as low as about 63 ° C. and α-NPD is as low as about 96 ° C., which causes a decrease in heat resistance of the organic phosphorescent light emitting device.

Appl. Phys. Lett. 51, 913, 1987 Appl. Phys. Lett. 75, 4 pages, 1999

  An object of the present invention is to provide an organic electroluminescence device having high luminance and luminous efficiency, long life and high heat resistance.

As a result of intensive studies to solve the above problems, the present inventors have arrived at the present invention. That is, the present invention is an organic electroluminescence device comprising a light emitting layer or a plurality of organic thin film layers including a light emitting layer between a pair of electrodes consisting of an anode and a cathode, wherein the light emitting layer is a phosphorescent material . relates to an organic electroluminescence device comprising a compound represented by the following general formula [1].
General formula [1]

[Wherein, R ¹ to R ¹⁸ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted alkoxyl group, a substituted or unsubstituted alkylthio group, or a cyano group. Substituted or unsubstituted amino group, hydroxyl group, mercapto group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aliphatic complex Represents a cyclic group, a substituted or unsubstituted aromatic heterocyclic group. Here, at least one of R ⁹ to R ¹³ and at least one of R ¹⁴ to R ¹⁸ is a substituted or unsubstituted amino group. However, the case where R ¹¹ and R ¹⁶ simultaneously become a substituted or unsubstituted N-carbazolyl group is excluded. ]

  Since the organic electroluminescence device of the present invention has a longer life than conventional devices, it can be applied to flat panel displays such as wall-mounted televisions, light sources such as copiers and printers, light sources of liquid crystal displays, display plates, and indicator lights. Applications are conceivable, and because of its high heat resistance, it can also be used for in-vehicle applications.

Hereinafter, the present invention will be described in detail. In the compound represented by the general formula [1] in the present invention, R ¹ to R ¹⁸ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted alkoxyl group, Substituted or unsubstituted alkylthio group, cyano group, substituted or unsubstituted amino group, hydroxyl group, mercapto group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aromatic hydrocarbon Represents a group, a substituted or unsubstituted aliphatic heterocyclic group, and a substituted or unsubstituted aromatic heterocyclic group. Here, at least one of R ⁹ to R ¹³ and at least one of R ¹⁴ to R ¹⁸ is a substituted or unsubstituted amino group. However, the case where R ¹¹ and R ¹⁶ simultaneously become a substituted or unsubstituted N-carbazolyl group is excluded.

  Examples of the halogen atom include fluorine, chlorine, bromine and iodine.

  The aliphatic hydrocarbon group refers to an aliphatic hydrocarbon group having 1 to 18 carbon atoms, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, and a cycloalkyl group.

  Therefore, as the alkyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, hexyl group, heptyl group, octyl group, C1-C18 alkyl groups, such as a decyl group, a dodecyl group, a pentadecyl group, and an octadecyl group, are mentioned.

  Examples of the alkenyl group include vinyl group, 1-propenyl group, 2-propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-octenyl group, 1-decenyl group, 1 -An alkenyl group having 2 to 18 carbon atoms such as an octadecenyl group.

  Examples of the alkynyl group include ethynyl group, 1-propynyl group, 2-propynyl group, 1-butynyl group, 2-butynyl group, 3-butynyl group, 1-octynyl group, 1-decynyl group and 1-octadecynyl group. Examples thereof include alkynyl groups having 2 to 18 carbon atoms.

  In addition, the cycloalkyl group has a carbon number such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclooctadecyl group, 2-bornyl group, 2-isobornyl group, 1-adamantyl group. Examples thereof include 3 to 18 cycloalkyl groups.

  The alkoxyl group includes a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a tert-butoxy group, an octyloxy group, a tert-octyloxy group, a 2-bornyloxy group, a 2-isobornyloxy group, and a 1-adamantyl group. C1-C18 alkoxyl groups, such as an oxy group, are mention | raise | lifted.

  Examples of the alkylthio group include C1-C18 alkylthio groups such as a methylthio group, an ethylthio group, a tert-butylthio group, a hexylthio group, and an octylthio group.

  Examples of the aryloxy group include aryloxy groups having 6 to 30 carbon atoms such as a phenoxy group, a 4-tert-butylphenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, and a 9-anthryloxy group. .

  Examples of the arylthio group include arylthio groups having 6 to 30 carbon atoms such as a phenylthio group, a 2-methylphenylthio group, and a 4-tert-butylphenylthio group.

  Examples of the aromatic hydrocarbon group include monovalent monocyclic, condensed ring, and ring-aggregated aromatic hydrocarbon groups having 6 to 30 carbon atoms. Here, as the monocyclic aromatic hydrocarbon group having 6 to 30 carbon atoms, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 2,4-xylyl group, p-cumenyl group, mesityl And monovalent aromatic hydrocarbon groups having 6 to 30 carbon atoms such as groups.

  The condensed ring aromatic hydrocarbon group includes 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 5-anthryl group, 1-phenanthryl group, 9-phenanthryl group, 1-acenaphthyl group. Group, 2-azurenyl group, 1-pyrenyl group, 2-triphenylyl group, 1-pyrenyl group, 2-pyrenyl group, 1-perylenyl group, 2-perylenyl group, 3-perenylenyl group, 2-trephenylenyl group, 2-indenyl Group, a condensed ring hydrocarbon group having 10 to 30 carbon atoms such as 1-acenaphthylenyl group, 2-naphthacenyl group and 2-pentacenyl group.

  Moreover, as a ring assembly aromatic hydrocarbon group, it is C12-30, such as o-biphenylyl group, m-biphenylyl group, p-biphenylyl group, terphenylyl group, 7- (2-naphthyl) -2-naphthyl group. Examples thereof include a ring assembly hydrocarbon group.

  In addition, as the monovalent aliphatic heterocyclic group, a monovalent fatty acid having 3 to 18 carbon atoms such as a 3-isochromanyl group, a 7-chromanyl group, a 3-coumarinyl group, a piperidino group, a morpholino group, and a 2-morpholino group. Group heterocyclic group.

  Examples of the monovalent aromatic heterocyclic group include 2-furyl group, 3-furyl group, 2-thienyl group, 3-thienyl group, 2-benzofuryl group, 2-benzothienyl group, 2-pyridyl group, 3 Examples thereof include monovalent aromatic heterocyclic groups having 3 to 30 carbon atoms such as -pyridyl group, 4-pyridyl group, 2-quinolyl group, and 5-isoquinolyl group.

  These substituents may be further substituted with other substituents, and these substituents may be bonded to each other to form a ring. Moreover, the said substituent is an example and is not limited to these.

Here, at least one of R ⁹ to R ¹³ and at least one of R ¹⁴ to R ¹⁸ is a substituted or unsubstituted amino group, and examples of the substituent substituted on the amino group include R intended as a substituent group constituting ¹ to R ¹⁸ it can be mentioned. The substituent substituted with this amino group may be further substituted with another substituent, or the substituents may be bonded to each other to form a ring.

  Hereinafter, typical examples of the compound represented by the general formula [1] of the present invention are shown in Table 1, but the present invention is not limited thereto.

  By the way, the organic EL element is composed of an element in which a single layer or a multilayer organic layer is formed between an anode and a cathode. Here, the single layer type organic EL element is composed only of a light emitting layer between an anode and a cathode. The element which becomes. On the other hand, the multilayer organic EL element facilitates injection of holes and electrons into the light emitting layer in addition to the light emitting layer, and facilitates recombination of holes and electrons in the light emitting layer. For the purpose of this, it refers to a layer in which a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, and the like are laminated. Therefore, typical element configurations of the multilayer organic EL element include (1) anode / hole injection layer / light emitting layer / cathode, and (2) anode / hole injection layer / hole transport layer / light emitting layer / cathode. (3) Anode / hole injection layer / light emitting layer / electron injection layer / cathode, (4) Anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode, (5) Anode / positive Hole injection layer / light emitting layer / hole blocking layer / electron injection layer / cathode, (6) anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron injection layer / cathode, (7) An element structure in which a multilayer structure of anode / light emitting layer / hole blocking layer / electron injection layer / cathode, (8) anode / light emitting layer / electron injection layer / cathode, etc., is considered.

  In the light emitting layer in the organic EL device of the present invention, in addition to the light emitting material, not only other light emitting materials and doping materials but also combinations of two or more of the hole injection materials and electron injection materials described above are combined. Can also be used. Further, the hole injection layer, the light emitting layer, and the electron injection layer may each be formed with a layer configuration of two or more layers.

  Among organic electroluminescent elements, organic phosphorescent light emitting elements characterized by including a phosphorescent light emitting material are devised in material selection and layer configuration so that excited triplet state energy can be used for light emission. . In the present invention, the “organic phosphorescent light emitting device” means not only a case where a light emitting material or a doping material directly emits light from an excited triplet state, but also a recombination of charges injected from both electrodes. In addition, all devices having a structure designed to have a mechanism and a process for effectively using the excited triplet state in the device for light emission are included.

The compounds of the general formula [1], as the organic thin film layer forming material for an organic phosphorescent device, since the ability to function as efficiently light emission can be obtained in the light-emitting layer is high, used as the material for forming the light-emitting layer Is done .

  When the compound of the general formula [1] is used in the light emitting layer, the abundance ratio with the phosphorescent light emitting material or the doping material is not particularly limited, but preferably the compound of the general formula [1] is present in an abundance ratio of 50% or more. It is good to use as a certain light emitting layer host material.

As one preferred embodiment of the present invention, when the compound of the general formula [1] is used in the light emitting layer, at least one of R ⁹ to R ¹³ and at least one of R ¹⁴ to R ¹⁸ are the following: There is a general formula [2]. R ¹⁹ to R ²⁶ are respectively synonymous with R ¹ to R ¹⁸ described above. However, unless the R ¹¹ and R ¹⁶ is formula [2] at the same time.
General formula [2]

  Examples of phosphorescent materials or doping materials that can be used in the organic EL device of the present invention include organometallic complexes. The metal atom is usually a transition metal, and is preferably an element of the 5th or 6th period in the period, and from the 6th group to the 11th group in the group, and more preferably in the 8th to 10th group. Specific examples include iridium and platinum. Examples of the ligand include 2-phenylpyridine and 2- (2'-benzothienyl) pyridine, and the carbon atom on these ligands is directly bonded to the metal. Another example is a porphyrin or tetraazaporphyrin ring complex, and the central metal is platinum. Although the typical example of a phosphorescent luminescent material is specifically illustrated below, this invention is not limited to this representative example. In addition, this example is an example of a material for which it is known that light is emitted directly from the excited triplet state, and there is some other mechanism that can be effectively used for light emission without losing the triplet excitation energy in the device. In addition, more materials can be used as the light-emitting material or doping material, and the possibility of using existing organic fluorescent dyes, organic electroluminescent light-emitting materials, and doping materials for organic phosphorescent light-emitting devices is not denied. Absent.

  For the electron injection layer, an electron injection material that exhibits an excellent electron injection effect with respect to the light emitting layer and that can form an electron injection layer having excellent adhesion to the cathode interface and excellent thin film formability is used. Examples of such electron injection materials include metal complex compounds, nitrogen-containing five-membered ring derivatives, fluorenone derivatives, anthraquinodimethane derivatives, diphenoquinone derivatives, thiopyrandioxide derivatives, perylenetetracarboxylic acid derivatives, fluorenylidenemethane. Derivatives, anthrone derivatives, silole derivatives, calcium acetylacetonate, sodium acetate and the like. In addition, inorganic / organic composite materials doped with metal such as cesium in bathophenanthroline (Proceedings of the Society of Polymer Science, Vol. 50, No. 4, 660, published in 2001) and the 50th Applied Physics Related Lecture Conference Proceedings, No. Examples of electron injection materials include BCP, TPP, T5MPyTZ, etc. published on page 3, 1402, 2003. Electrons can be transported by forming a thin film necessary for device fabrication and injecting electrons from the cathode. If it is material, it will not specifically limit to these.

  Among the electron injection materials, particularly effective electron injection materials include metal complex compounds and nitrogen-containing five-membered ring derivatives. Among the electron injection materials that can be used in the present invention, preferable metal complex compounds include tris (8-hydroxyquinolinate) aluminum, tris (2-methyl-8-hydroxyquinolinato) aluminum, and tris (5-phenyl). -8-hydroxyquinolinato) aluminum, bis (8-hydroxyquinolinato) (1-naphtholato) aluminum, bis (8-hydroxyquinolinato) (2-naphtholato) aluminum, bis (8-hydroxyquinolinate) ) (Phenolate) aluminum, bis (8-hydroxyquinolinate) (4-cyano-1-naphtholate) aluminum, bis (4-methyl-8-hydroxyquinolinato) (1-naphtholato) aluminum, bis (5- Methyl-8-hydroxyquinolinate) (2-naphthler) ) Aluminum, bis (5-phenyl-8-hydroxyquinolinato) (phenolate) aluminum, bis (5-cyano-8-hydroxyquinolinato) (4-cyano-1-naphtholato) aluminum, bis (8-hydroxy) Quinolinate) chloroaluminum, aluminum complex compounds such as bis (8-hydroxyquinolinate) (o-cresolate) aluminum, tris (8-hydroxyquinolinato) gallium, tris (2-methyl-8-hydroxyquinoli) Nato) gallium, tris (2-methyl-5-phenyl-8-hydroxyquinolinato) gallium, bis (2-methyl-8-hydroxyquinolinato) (1-naphtholato) gallium, bis (2-methyl-8) -Hydroxyquinolinate) (2-naphtholate) gallium, bi (2-Methyl-8-hydroxyquinolinate) (phenolate) gallium, bis (2-methyl-8-hydroxyquinolinato) (4-cyano-1-naphtholato) gallium, bis (2,4-dimethyl-8) -Hydroxyquinolinato) (1-naphtholato) gallium, bis (2,5-dimethyl-8-hydroxyquinolinato) (2-naphtholato) gallium, bis (2-methyl-5-phenyl-8-hydroxyquinolinate) Nato) (phenolate) gallium, bis (2-methyl-5-cyano-8-hydroxyquinolinate) (4-cyano-1-naphtholato) gallium, bis (2-methyl-8-hydroxyquinolinato) chlorogallium Gallium complex compounds such as bis (2-methyl-8-hydroxyquinolinate) (o-cresolate) gallium In addition, 8-hydroxyquinolinate lithium, bis (8-hydroxyquinolinate) copper, bis (8-hydroxyquinolinate) manganese, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (8-hydroxyquinone) Nolinato) zinc and metal complex compounds such as bis (10-hydroxybenzo [h] quinolinato) zinc.

  Among the electron injection materials that can be used in the present invention, preferable nitrogen-containing five-membered ring derivatives include oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, and triazole derivatives. , 5-bis (1-phenyl) -1,3,4-oxazole, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5-bis (1-phenyl) -1, 3,4-oxadiazole, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) 1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1 , 3,4-oxadiazole, 1,4-bis [2- (5-phenyloxadiazolyl)] benzene, 1,4-bis [2- (5-phenyloxadiazolyl) -4-tert-butyl benzene], 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-thiadiazole, 2,5-bis (1-naphthyl) -1,3,4-thiadiazole, 1, 4-bis [2- (5-phenylthiadiazolyl)] benzene, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) -1,3,4-triazole, 2,5- Examples thereof include bis (1-naphthyl) -1,3,4-triazole, 1,4-bis [2- (5-phenyltriazolyl)] benzene and the like.

  The hole blocking layer has the ability to block holes that have passed through the light emitting layer from reaching the electron injection layer, and has the effect of preventing diffusion of excitons generated in the light emitting layer into the electron injection layer, and A compound having an excellent ability to form a thin film may be mentioned. Many of the electron injection materials can be used as hole blocking materials. For example, 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-triazole and 2,5- Azoles (nitrogen-containing five-membered rings) represented by bis (1-phenyl) -1,3,4-oxadiazole, phenanthroline derivatives represented by bathocuproine, bis (2-methyl-8-hydroxyquinolinate) ) (4-biphenyloxolate) aluminum, bis (2-methyl-8-hydroxyquinolinato) phenolate 6-membered nitrogen-containing rings such as metal complexes represented by gallium and metal complexes having these as ligands , Silacyclobutene (silole) derivatives and the like, but are not limited thereto.

  As the conductive material used for the anode of the organic EL device of the present invention, a material having a work function larger than 4 eV is suitable, and carbon, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum, Examples thereof include metals such as palladium and alloys thereof, metal oxides such as tin oxide and indium oxide used for ITO substrates and NESA substrates, and organic conductive resins such as polythiophene and polypyrrole.

  As the conductive material used for the cathode of the organic EL device of the present invention, a material having a work function smaller than 4 eV is suitable. Magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum And the alloys thereof, but are not limited thereto. Examples of the alloy include magnesium / silver, magnesium / indium, lithium / aluminum, and the like, but are not limited thereto. The ratio of the alloy is controlled by the temperature of the vapor deposition source, the atmosphere, the degree of vacuum, etc., and is selected to an appropriate ratio. As the cathode, an alkali metal such as lithium fluoride, magnesium fluoride, or lithium oxide, a fluoride of an alkaline earth metal, or an oxide is formed on the organic layer with a film thickness of 1 nm or less, and aluminum, silver, or the like is formed thereon. A metal having a relatively high conductivity may be formed. Moreover, these cathodes can be produced by methods known in the industry such as resistance heating, electron beam irradiation, sputtering, ion plating, and coating. The anode and cathode described above may be formed with a layer structure of two or more layers as necessary.

  In order to efficiently extract light emitted from the organic EL device of the present invention, it is desirable that the substrate material on the surface from which light is extracted is sufficiently transparent. Specifically, the transmittance of light emitted from the device in the light emission wavelength region is high. It is desirable that it is 50% or more, preferably 90% or more. These substrates have mechanical and thermal strength and are not particularly limited as long as they are transparent. For example, in addition to glass, transparent polymers such as polyethylene, polyethersulfone, and polypropylene are recommended.

  In addition, as a method for forming each organic thin film layer of the organic EL element of the present invention, dry deposition methods such as vacuum deposition, electron beam irradiation, sputtering, plasma, ion plating, or spin coating, dipping, flow coating, etc. Any of the wet film forming methods can be applied. The film thickness of each layer is not particularly limited, but if the film thickness is too thick, a large applied voltage is required to obtain a constant light output, resulting in low efficiency. Conversely, if the film thickness is too thin, pinholes, etc. And it becomes difficult to obtain sufficient light emission luminance even when an electric field is applied. Accordingly, the thickness of each layer is suitably in the range of 1 nm to 1 μm, but more preferably in the range of 10 nm to 0.2 μm.

  In order to improve the stability of the organic EL device of the present invention against temperature, humidity, atmosphere, etc., a protective layer may be provided on the surface of the device, or the entire device may be covered or sealed with a resin or the like. . In particular, when the entire element is covered or sealed, a photocurable resin that is cured by light is preferably used.

  As described above, since the organic electroluminescence element of the present invention has a long life, it can be applied to flat panel displays such as wall-mounted televisions, light sources such as copiers and printers, light sources of liquid crystal displays, display plates, and indicator lamps. In addition, since it has high heat resistance, it can be developed for in-vehicle use and the like, and its industrial value is very large.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following Example at all. In this example, all mixing ratios indicate weight ratios unless otherwise specified. In the evaluation of the light emission characteristics of the organic EL element, the characteristics of the element having an electrode area of 2 mm × 2 mm were measured.

Comparative Example 2
On the washed glass plate with an ITO electrode, the compound [C] was vacuum-deposited to form a hole injection layer having a thickness of 40 nm. Next, the compound [A] and the compound [29] were co-evaporated at a composition ratio of compound [A]: compound [29] = 94: 6 (weight ratio) to obtain a light emitting layer having a thickness of 20 nm. Further, bis (2-methyl-8-hydroxyquinolinate) (4-biphenyloxolate) aluminum (BAlq) was vacuum-deposited to form a hole blocking layer having a thickness of 6 nm, and then tris (8-hydroxyquinoate) was formed. Norinato) aluminum (Alq3) was vacuum-deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, an electrode having a thickness of 150 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic EL device. Each layer was deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. Green light emission was obtained from this device, and it was confirmed that light was emitted from the compound [29]. When this element was driven at a constant current at an initial luminance of 500 (cd / m ² ), the luminance half life was 680 hours.

Comparative Example 4
On the cleaned glass plate with an ITO electrode, copper phthalocyanine (CuPc) was vacuum-deposited to form a 20 nm-thick hole injection layer. Subsequently, the compound [C] was vacuum-deposited to form a 40 nm-thick hole transport layer. Further, the compound [A] and the compound [29] were co-evaporated at a composition ratio of compound [A]: compound [29] = 94: 6 (weight ratio) to obtain a light emitting layer having a thickness of 20 nm. Further, bis (2-methyl-8-hydroxyquinolinate) (4-biphenyloxolate) aluminum (BAlq) was vacuum-deposited to form a hole blocking layer having a thickness of 6 nm, and then tris (8-hydroxyquinoate) was formed. Norinato) aluminum (Alq3) was vacuum-deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, an electrode having a thickness of 150 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic EL device. Each layer was deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. Green light emission was obtained from this device, and it was confirmed that light was emitted from the compound [29]. When this element was driven at a constant current at an initial luminance of 500 (cd / m ² ), the luminance half life was 1250 hours.

Example 50
Compound [C] was vacuum-deposited on the cleaned glass plate with an ITO electrode to form a hole injection layer having a thickness of 40 nm. Next, using compound [1] as a light emitting layer host and compound [29] as a dopant, co-evaporation was performed at a composition ratio of compound [1]: compound [29] = 94: 6 (weight ratio), and light emission with a film thickness of 20 nm. A layer was obtained. Further, bis (2-methyl-8-hydroxyquinolinate) (4-biphenyloxolate) aluminum (BAlq) was vacuum-deposited to form a hole blocking layer having a thickness of 6 nm, and then tris (8-hydroxyquinoate) was formed. Norinato) aluminum (Alq3) was vacuum-deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, an electrode having a thickness of 150 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic EL device. Each layer was deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. Green light emission was obtained from this device, and it was confirmed that light was emitted from the compound [29]. When this element was driven at a constant current at an initial luminance of 500 (cd / m ² ), the luminance half life was 1020 hours.

Example 51, Examples 53 to 58, Example 60, Example 61
An organic EL device was produced in the same manner as in Example 50 except that the compound shown in Table 5 was used instead of the compound [ 1 ] as the light emitting layer host. Table 5 also shows the luminance half-life when these elements were driven at a constant current with an initial luminance of 500 cd / m ² . All of these elements had a luminance half life of 1000 hours or more when driven at a constant current at an initial luminance of 500 cd / m ² .

As is clear from the above results, Examples 50, 51, 53 to 58, 60, and 61 using the compound represented by the general formula [1] as the light emitting layer host. The device had a remarkably improved luminance half-life compared to the device of Comparative Example 2 using Compound [A] as the light emitting layer host.

Example 63
On the cleaned glass plate with an ITO electrode, copper phthalocyanine (CuPc) was vacuum-deposited to form a 20 nm-thick hole injection layer. Subsequently, the said compound [ 3 ] was vacuum-deposited and the 40-nm-thick hole transport layer was formed. Further, the compound [ 15 ] is used as the light emitting layer host, the compound [29] is used as the dopant, and the compound [ 15 ]: compound [29] = 94: 6 (weight ratio) is co-evaporated to emit light with a thickness of 20 nm. A layer was obtained. Further, bis (2-methyl-8-hydroxyquinolinate) (4-biphenyloxolate) aluminum (BAlq) was vacuum-deposited to form a hole blocking layer having a thickness of 6 nm, and then tris (8-hydroxyquinoate) was formed. Norinato) aluminum (Alq3) was vacuum-deposited to obtain an electron injection layer having a thickness of 30 nm. On top of this, an electrode having a thickness of 150 nm was formed from an alloy in which magnesium and silver were mixed at a ratio of 10: 1 (weight ratio) to obtain an organic EL device. Each layer was deposited in a vacuum of 10 ⁻⁶ Torr at a substrate temperature of room temperature. Green light emission was obtained from this device, and it was confirmed that light was emitted from the compound [29]. The device was stored at a temperature of 120 ° C. for 500 hours, and then driven at a current density of 2.5 (mA / cm ² ), the luminance was 72 % of the initial luminance.

Example 64, Example 69, Example 71, Example 72
The compound as the hole transport layer [3], except using the compounds shown in Table 6 instead of the compound [15] as a light emitting layer host, to produce an organic EL device in the same manner as in Example 63. Table 6 shows the ratio of the luminance to the initial luminance when the device was stored at a temperature of 120 ° C. for 500 hours and then driven at a current density of 2.5 (mA / cm ² ). All elements maintained 70% or more with respect to the initial luminance.

Comparative Example 5
When the device of Comparative Example 4 was stored at a temperature of 120 ° C. for 500 hours and then driven at a current density of 2.5 (mA / cm ² ), no light was emitted.

As is clear from the above results, the devices of Examples 63 to 69, Example 71, and Example 72 using the compound represented by the general formula [1] as the hole transport layer and the light emitting layer host were: The heat resistance of the device was remarkably improved as compared with the device of Comparative Example 4 using Compound [C] as the hole transport layer and Compound [A] as the light emitting layer host.

  As is clear from the examples described above, the organic EL device of the present invention can achieve a long life and high heat resistance.

Claims (1)

An organic electroluminescence device comprising a light emitting layer or a plurality of organic thin film layers including a light emitting layer between a pair of electrodes consisting of an anode and a cathode, wherein the light emitting layer comprises a phosphorescent material and the following general formula [1 ] The organic electroluminescent element containing the compound represented by this.
General formula [1]

[Wherein R ¹ to R ¹⁸ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted alkoxyl group, a substituted or unsubstituted alkylthio group, or a cyano group. Substituted or unsubstituted amino group, hydroxyl group, mercapto group, substituted or unsubstituted aryloxy group, substituted or unsubstituted arylthio group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aliphatic complex Represents a cyclic group, a substituted or unsubstituted aromatic heterocyclic group. Here, at least one of R ⁹ to R ¹³ and at least one of R ¹⁴ to R ¹⁸ is a substituted or unsubstituted amino group. However, the case where R ¹¹ and R ¹⁶ simultaneously become a substituted or unsubstituted N-carbazolyl group is excluded. ]