JP2005093159A - Organic electroluminescent element, display device, and lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroluminescent element and a display device, aiming at high luminance and long lifetime, especially in blue light emission. <P>SOLUTION: The organic electroluminescent element has a luminescent layer containing a host compound and a phosphorescent compound. Some one of the layers constituting the element contains a compound expressed in Formula (1). (In the formula, Ar denotes a 5-membered aromatic ring containing at least one nitrogen atom, Ar<SB>1</SB>, Ar<SB>2</SB>, Ar<SB>3</SB>, Ar<SB>4</SB>, and Ar<SB>5</SB>denote either an aryl group or a heteroaryl group, m denotes an integer of 0 or larger, and R denotes either a hydrogen atom or its substituent, respectively). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescence element, a display device, and a lighting device.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also referred to as organic EL elements). Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and excitons (excitons) by injecting electrons and holes into the light emitting layer and recombining them. Is a device that emits light using the emission of light (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a mold, it has a wide viewing angle, has high visibility, and is a thin-film complete solid-state device, and therefore has attracted attention from the viewpoints of space saving, portability, and the like.

  For the development of organic EL elements for practical use in the future, organic EL elements that emit light efficiently and with high luminance with lower power consumption are desired. For example, stilbene derivatives, distyrylarylene derivatives, or tristyrylarylene derivatives In addition, a technology (for example, see Patent Document 1) for doping a trace amount of a phosphor to improve emission luminance and extending the lifetime of the device is also used, and an 8-hydroxyquinoline aluminum complex is used as a host compound. A device having an organic light-emitting layer doped with a phosphor (see, for example, Patent Document 2) further having an organic light-emitting layer doped with a quinacridone dye as an 8-hydroxyquinoline aluminum complex as a host compound (See, for example, Patent Document 3).

  In the technique disclosed in the above document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

  However, since the University of Princeton reported on organic EL devices using phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature (for example, Non-Patent Documents). 2, see Patent Document 4).

  When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and is attracting attention.

  The 10th International Works on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu) reports on several phosphorescent compounds. For example, Ikai et al. Uses a hole transporting compound as a host of a phosphorescent compound. In addition, M.M. E. Thompson et al. Use various electron transport materials doped with a novel iridium complex as a host of a phosphorescent compound. Furthermore, Tsutsui et al. Have obtained high emission luminance by introducing a hole blocking layer (exciton blocking layer). As the hole blocking layer, other examples of using certain aluminum complexes by Pioneer, and Appl. Phys. Lett. 79, 156 (2001), Ikai et al. Achieved high-efficiency light emission by using a fluorine-substituted compound as a hole blocking layer (exciton blocking layer).

  In addition, examples in which a biscarbazole derivative is used as a host in a light emitting layer of a phosphorescent organic EL device and a specific 5-coordinate metal complex is used in a hole blocking layer (Patent Document 4), bis or tris There is an example in which a carbazole derivative is used for a hole blocking layer of an organic EL element (Patent Document 5).

  When blue to blue-green phosphorescent compounds are used as dopants, there is an example in which a carbazole derivative such as CBP is used as a host compound, but the external extraction quantum efficiency is 6%, which is an insufficient result. (For example, refer nonpatent literature 3.), The room for improvement remains. On the other hand, there is a report (Non-patent Document 4, Patent Document 6) that the efficiency is 7 to 10% when a hexaphenylbenzene derivative is used in a blue phosphorescent organic EL device. However, the present situation has not yet been obtained about a configuration that sufficiently balances the luminance and lifetime characteristics of the phosphorescent organic EL element.

At present, there is no single light-emitting material that emits white light, so that a plurality of light-emitting colors are simultaneously emitted by a plurality of light-emitting materials to obtain white light emission by color mixing. Combinations of multiple emission colors include those containing three emission maximum wavelengths of the three primary colors of blue, green and red, and two emission maximums utilizing the complementary colors such as blue and yellow, blue green and orange Although the thing containing a wavelength etc. can be considered, since the blue is utilized anyway, the present condition is that the element of white light emission with high efficiency is not discovered also about white.
Japanese Patent No. 3093796 Japanese Unexamined Patent Publication No. 63-264692 JP-A-3-255190 Japanese Patent Laid-Open No. 2002-8860 JP 2003-31371 A JP 2003-27048 A M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) 62nd Japan Society of Applied Physics Academic Lecture Proceedings 12-a-M8 Proceedings of the 50th Joint Conference on Applied Physics 28p-A-6

  An object of the present invention is to provide an organic electroluminescence element and a display device that exhibit high emission luminance and have a long lifetime. In particular, in blue light emission, the purpose is to achieve both the light emission luminance and the light emission lifetime of the device.

The above object of the present invention has been achieved by the following constitutions.
(Claim 1)
An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (1) An organic electroluminescence device characterized.

(In the general formula (1), Ar represents a five-membered aromatic ring containing at least one nitrogen atom, and Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ represents an aryl group or a heteroaryl group. M represents an integer of 0 or more, and R represents a hydrogen atom or a substituent.)
(Claim 2)
In the said General formula (1), Ar represents the aromatic condensed ring containing a 5-membered ring, and contains an at least 1 nitrogen atom, The organic electroluminescent element of Claim 1 characterized by the above-mentioned.
(Claim 3)
An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (2) An organic electroluminescence device characterized.

(In General Formula (2), n of R _{11 to} R ₁₉ represent an aryl group or a heteroaryl group, (9-n) represents a hydrogen atom or a substituent, and at least one represents hydrogen. Represents an atom, where n is an integer from 5 to 8.
(Claim 4)
An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (3) An organic electroluminescence device characterized.

(In the general formula (3), R _{21 to} R ₂₅ represent an aryl group or a heteroaryl group.)
(Claim 5)
An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein the light emitting layer contains the compound represented by the general formula (1), (2) or (3). An organic electroluminescence device characterized by comprising:
(Claim 6)
An organic electroluminescent device having a host compound, a light emitting layer containing a phosphorescent compound, and a hole blocking layer, wherein the compound represented by the general formula (1), (2) or (3) is And an organic electroluminescence device characterized by being used for a hole blocking layer.
(Claim 7)
The organic electroluminescent device according to claim 1, wherein the phosphorescent compound is osmium, iridium, rhodium, or a platinum complex compound.
(Claim 8)
The display apparatus which has an organic electroluminescent element of any one of Claims 1-7.
(Claim 9)
An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any one of the layers constituting the device is represented by the general formula (1), (2) or (3). And a white light-emitting organic electroluminescent device comprising a plurality of phosphorescent compounds.
(Claim 10)
An illuminating device comprising the white light-emitting organic electroluminescent element according to claim 9.

  According to the present invention, an organic electroluminescence element having high luminous efficiency and a long lifetime can be obtained, and an organic electroluminescence element having a high efficiency and a long lifetime can be obtained particularly in blue light emission. Thereby, high luminance white light emission is obtained.

  Next, the best mode for carrying out the present invention will be described, but the present invention is not limited thereto.

  The present invention will be described in detail. As a result of intensive studies, the inventors have used the compounds represented by the general formulas (1) to (3) in an organic EL element, thereby exhibiting high emission luminance and a long emission lifetime. It was also found that a display device and a lighting device having the element can be provided.

  In an organic electroluminescent device having a light-emitting layer containing a phosphorescent dopant and a fluorescent host compound that utilize the excited triplet of a phosphorescent dopant, any one of the layers constituting the device has the following general formula ( By containing the compound represented by 1), a high emission luminance and a long emission lifetime can be obtained.

  A carbazole derivative is a typical light-emitting host used in the past, but CBP (4,4′-bis (1-carbazolyl) biphenyl), which is a typical example of a conventional carbazole derivative when used in blue, is used. However, since the phosphorescence wavelength is longer than that of the blue dopant, sufficient efficiency cannot be obtained. Therefore, as a result of intensive studies, the inventors of the present invention have introduced a steric structure by introducing five or more aryl groups or heteroaryl groups in an aromatic ring-containing compound containing at least one nitrogen atom. It has been found that the phosphorescence wavelength can be shortened due to the bulkiness and the efficiency can be increased by suppressing the generation of the exciplex. Moreover, although the lifetime is also improved, this is presumed to be an effect due to the introduction of 5 or more aryl groups or heteroaryl groups.

  In addition to being used as the light emitting host, the compound of the present invention is excellent as an electron transport material, and particularly exhibits excellent properties when used in a hole blocking layer as a hole blocking material among electron transport materials. .

  The compound of the present invention will be described in more detail.

  In the general formula (1), Ar represents a five-membered aromatic ring containing at least one nitrogen atom, and specific examples include a pyrrole ring, an indole ring, and a carbazole ring.

Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ and Ar _{5 each} represents an aryl group or a heteroaryl group. m represents an integer of 0 or more, and R represents a hydrogen atom or a substituent.

Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ and Ar ₅ each represents an aryl group or a heteroaryl group. Specifically, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, mesityl group, phenanthryl group, biphenyl group, pyridyl group, pyrazyl group, pyrimidyl group, quinolyl group, quinazolyl group, acridyl group, triazyl group, etc. Is mentioned. Preferably, a phenyl group, a naphthyl group, and a pyridyl group are mentioned.
The aryl group or heteroaryl group represented by Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ may have a substituent. Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, t-butyl group), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), trifluoromethyl group. , Pentafluorophenyl group, cyano group, alkylsulfonyl group (methylsulfonyl group etc.), halogen atom (fluorine atom etc.), aryl group (eg phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, mesityl group etc.) ), A heteroaryl group, an alkoxy group (for example, a methoxy group), and the like.

  In the general formula (1) of the present invention, R represents a hydrogen atom or a substituent, and is preferably a hydrogen atom.

  When R represents a substituent, examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a hydroxyethyl group, a methoxymethyl group, a t-butyl group, etc.), a cycloalkyl group (for example, a cyclopentyl group, Cyclohexyl group etc.), aralkyl group (eg benzyl group, 2-phenethyl group etc.), aryl group (eg phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, mesityl group, pentafluorophenyl group etc.), alkoxy Groups (for example, ethoxy group, isopropoxy group, butoxy group, etc.), aryloxy groups (for example, phenoxy group, etc.), cyano groups, hydroxyl groups, alkenyl groups (for example, vinyl group, etc.), halogen atoms (fluorine atoms, etc.), trifluoro A methyl group etc. are mentioned. These groups may be further substituted.

  When R represents a substituent, it is preferably a trifluoromethyl group, a halogen atom, an alkyl group, an alkoxy group, or an aryl group.

  m is an integer of 0 or more. When m = 1, R is preferably a hydrogen atom. When m ≧ 2, it is preferable that at least one of R is a hydrogen atom.

  In the general formula (1), Ar represents a five-membered aromatic ring containing at least one nitrogen atom, but Ar is an aromatic condensed ring containing a five-membered ring and contains at least one nitrogen atom. Specifically, nitrogen-containing aromatic condensed rings such as an indole ring and a carbazole ring are exemplified.

In General Formula (2), n of R _{11 to} R ₁₉ represent an aryl group or a heteroaryl group, (9-n) represents a hydrogen atom or a substituent, and at least one represents a hydrogen atom. Represents. n is an integer of 5 or more and 8 or less.

When R _{11 to} R ₁₉ represent a substituent, they are specifically as defined for R. A trifluoromethyl group, a halogen atom, an alkyl group, an alkoxy group, or an aryl group is preferable.

In the general formula (3), R _{21 to} R ₂₅ each represents an aryl group or a heteroaryl group. As the aryl group and heteroaryl group represented by R _{21 to} R ₂₅ , specifically, the groups mentioned as Ar1 to Ar5 are represented.

  In the general formulas (2) and (3), the substituents constituting R19 and R25 each preferably have 11 or less carbon atoms.

  In general formulas (2) and (3), general formula (3) is preferred.

  Specific examples of the compound represented by the general formula (1), (2) or (3) are shown below, but are not limited thereto.

  The compounds represented by the general formula (1), (2) or (3) according to the present invention can be produced by a conventionally known method. A typical synthesis example is illustrated below.

(Synthesis example)
Production of Compound (4) 10 g of carbazole was dissolved in 300 ml of acetic acid, and 13 ml of bromine was added dropwise while keeping the reaction solution at 0 ° C. When the dropping was completed, the mixture was heated to 80 ° C. and stirred for 7 hours. Thereafter, the crystals were collected by filtration. Subsequently, it recrystallized with toluene, and 3.2 g of TBC (1,3.6,8-tetrabromocarbazole) was obtained. Using 3.2 g of TBC and a palladium catalyst, potassium carbonate was used as a base in a tetrahydrofuran solvent and reacted with phenylboronic acid, followed by heating and stirring for 12 hours. After completion of the reaction, water was added to extract the organic layer. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by column chromatography and recrystallized from ethyl acetate to obtain 2.2 g of TPC. 2.2 g of TPC was dissolved in 100 ml of dimethylformamide, and the mixture was heated and stirred at 150 ° C. for 17 hours with 0.5 g of copper, 1.4 g of potassium carbonate, and 1.0 g of iodobenzene. After completion of the reaction, water was added to extract the organic layer. After drying with magnesium sulfate, the solvent was distilled off under reduced pressure, and the residue was purified by column chromatography and recrystallized from ethyl acetate to obtain 0.4 g of Compound (4). It was confirmed to be the compound (4) by NMR spectrum and mass spectrum.

<< Host Compound >>: Main Component in Light-Emitting Layer The host compound according to the present invention will be described.

  Here, the “host compound” means a compound having the largest mixing ratio (mass) in the light emitting layer composed of two or more kinds of compounds, and other compounds are referred to as “dopant compounds”. . For example, if the light emitting layer is composed of two types of compound a and compound b and the mixing ratio is a: b = 10: 90, compound A is a dopant compound and compound B is a host compound. Further, if the light emitting layer is composed of three types of compound a, compound b, and compound c and the mixing ratio is a: b: c = 5: 10: 85, compound a and compound b are dopant compounds, Compound c is a host compound.

  As the host compound according to the present invention, a compound represented by the general formula (1), (2) or (3), a conventionally known fluorescent compound, a fluorescent compound described later, and the like can be used.

<< Phosphorescent Compound >>: A kind of dopant compound in the light emitting layer The phosphorescent compound used as the dopant compound according to the present invention will be described.

  A “phosphorescent compound” is a compound in which light emission from an excited triplet is observed, and is a compound having a phosphorescence quantum yield of 0.001 or more at 25 ° C. The phosphorescence quantum yield is preferably 0.01 or more, more preferably 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, it is preferable that the phosphorescence quantum yield according to the present invention achieves the above phosphorescence quantum yield in any solvent.

  The phosphorescent compound according to the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table, more preferably iridium, rhodium, ruthenium, osmium or a platinum complex compound. More preferably, it is an osmium, iridium, rhodium or platinum complex compound, and among these, the iridium complex compound is most preferably used.

  In the organic EL device of the present invention having a light emitting layer each containing a phosphorescent compound as a host compound and a dopant compound, any one of the layers constituting the organic EL device has the general formula (1), (2) or It is preferable that the compound represented by (3) has a light emission maximum wavelength of 500 nm or less.

  The lowest excited triplet energy level of the host material used in the present invention is higher than the lowest excited triplet energy level of the light emitting material, and is 1.05 to 1.38 times the lowest excited triplet energy level of the light emitting material. It is preferable that The lowest excited triplet energy level of the host material is preferably 68 kcal / mol (284.9 kJ / mol) to 90 kcal / mol (377.1 kJ / mol).

  In the organic EL device of the present invention, the lowest excited triplet energy level of the organic material contained in the layer adjacent to the light emitting layer is higher than the lowest excited triplet energy level of the material constituting the light emitting layer. It is preferably 1.05 to 1.38 times the lowest excited triplet energy level of the constituent material. In the organic EL device of the present invention, the lowest excited triplet energy level of the organic material contained in the layer adjacent to the light emitting layer is 68 kcal / mol (284.9 kJ / mol) to 90 kcal / mol (377.1 kJ / mol). It is preferable that

  Specific examples of the phosphorescent compound according to the present invention are shown below, but the present invention is not limited thereto. These compounds are described in, for example, Inorg. Chem. 40, 1704-1711, and the like.

  In addition to the above, the compounds described in the following published patent publications can also be used. WO 00/70655, JP 2002-280178, 2001-181616, 2002-280179, 2001-181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671 2001-345183, 2002-324679, WO 02/15645, JP 2002-332291, 2002-50484, 2002-332292, 2002-83684, JP 2002-540572, JP 2002-117978, 2002-338588, 2002-170684, 2002-352960, WO 01/93642, 2002-50483, 2002-1000047, 2002-1736 4, 2002-359082, 2002-175842, 2002-363552, 2002-184582, 2003-7469, JP2002-525808, JP2003-7471, JP2002-525833, JP2003-31366. 2002-226495, 2002-234894, 2002-2335076, 2002-241751, 2002-3179979, 2001-319780, 2002-62824, 2002-1000047, 2002-203679, 2002-343572. , 2002-203678, etc.

《Fluorescent compound》
The fluorescent compound used in the present invention will be described.

  In the present invention, in addition to the host compound and the phosphorescent compound, at least one fluorescent compound may be contained. In this case, electroluminescence as an organic EL element can be emitted from the fluorescent compound by energy transfer from the host compound or phosphorescent compound. Preferred as the fluorescent compound is one having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, and more preferably 30% or more.

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

  The fluorescence quantum yield here can also be measured by the method described in page 362 (1992 version, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.

  The phosphorescent compound has a phosphorescence quantum yield of not less than 0.001 at 25 ° C. and lower than the lowest excited triplet energy of the host, that is, a longer wavelength. It has a phosphor maximum wavelength. The maximum phosphorescence wavelength of phosphorescent compounds is not particularly limited. In principle, the emission wavelength obtained by selecting the central metal, ligand, ligand substituent, etc. can be changed. Can be made.

  The color emitted by the phosphorescent compound and fluorescent compound used in the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the luminance meter CS-1000 (manufactured by Minolta) is applied to the CIE chromaticity coordinates.

<< Layer structure of organic EL element >>
The layer structure of the organic EL element according to the present invention will be described.

  The organic EL device of the present invention has a structure in which at least one light emitting layer is sandwiched between a pair of electrodes (anode, cathode). Here, in a broad sense, the light emitting layer is a layer that emits light when a current is passed through an electrode composed of a cathode and an anode. Specifically, when a current is passed through an electrode composed of a cathode and an anode, This refers to a layer containing a compound that emits light.

  The organic EL device of the present invention has a hole transport layer, an electron transport layer, an anode buffer layer, a cathode buffer layer, and the like in addition to the light emitting layer as required, and has a structure sandwiched between a cathode and an anode. Specifically, the following structures are exemplified.

(I) Anode / light emitting layer / cathode (ii) Anode / hole transport layer / light emitting layer / cathode (iii) Anode / light emitting layer / electron transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / electron Transport layer / cathode (v) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode (vi) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode Buffer layer / cathode (vii) anode / anode buffer layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode (viii) anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking Layer / electron transport layer / cathode buffer layer / cathode << light emitting layer >>
The light emitting layer according to the present invention will be described.

  In the present invention, the light emitting layer is preferably formed using the compound represented by the general formula (1), (2) or (3) as a host compound. That is, the compound represented by the general formula (1), (2) or (3) according to the present invention is used as a host compound in combination with the phosphorescent compound (dopant).

  As a method for forming the light emitting layer, for example, a thin film can be formed by a known method such as a vapor deposition method, a spin coating method, a casting method, or an LB method. In the present invention, a molecular deposition film is particularly preferable. Here, the molecular deposited film is a thin film formed by deposition from the vapor phase state of the compound, or a film formed by solidification from the molten state or liquid phase state of the compound. In general, a molecular deposited film can be distinguished from a thin film (molecular accumulated film) formed by the LB method by a difference in aggregated structure and higher order structure and a functional difference resulting therefrom.

  In addition, as described in JP-A-57-51781, this light-emitting layer is prepared by dissolving the above compound as a light-emitting material together with a binder such as a resin into a solvent, followed by spin coating. It can obtain by apply | coating by etc. and forming a thin film.

(Film thickness of the light emitting layer)
There is no restriction | limiting in particular about the film thickness of the light emitting layer formed in this way, Although it can select suitably according to a condition, It is preferable to adjust film thickness in the range of 5 nm-5 micrometers.

  Next, other layers constituting the organic EL element in combination with the light emitting layer, such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, will be described.

<< Hole injection layer, hole transport layer, electron injection layer, electron transport layer >>
The hole injection layer and hole transport layer used in the present invention have a function of transmitting holes injected from the anode to the light emitting layer, and the hole injection layer and hole transport layer serve as the anode and the light emitting layer. Therefore, many holes are injected into the light emitting layer with a lower electric field, and electrons injected from the cathode, the electron injection layer, or the electron transport layer into the light emitting layer are positively connected to the light emitting layer. Due to the barrier of electrons present at the interface of the hole injection layer or the hole transport layer, an element having excellent light emitting performance such as accumulation at the interface in the light emitting layer and improvement in light emission efficiency is obtained.

《Hole injection material, hole transport material》
The material of the hole injection layer and hole transport layer (hereinafter referred to as hole injection material and hole transport material) has the property of transmitting holes injected from the anode to the light emitting layer. If it is a thing, there will be no restriction | limiting in particular, In a photoconductive material, what is conventionally used as a charge injection transport material of a hole, and the well-known thing used for the hole injection layer of a EL element, a hole transport layer are used. Any one can be selected and used.

  The hole injection material and the hole transport material have any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Examples of the hole injection material and hole transport material include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazoles. Derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, or conductive polymer oligomers, particularly thiophene oligomers. As the hole injecting material and the hole transporting material, those described above can be used, and porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds, particularly aromatic tertiary amine compounds can be used. preferable.

  Representative examples of the aromatic tertiary amine compound and styrylamine compound 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; Bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p- Tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadri N; N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenyl Amino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and 2 described in US Pat. No. 5,061,569. Having four condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD), JP-A-4-3 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 08688 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.

  Alternatively, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material. The hole injection layer and the hole transport layer are formed by thinning the hole injection material and the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. Can be formed.

(Hole injection layer thickness, hole transport layer thickness)
Although there is no restriction | limiting in particular about the film thickness of a positive hole injection layer and a positive hole transport layer, It is preferable to adjust to the range about 5 nm-5 micrometers. The hole injection layer and hole transport layer may have a single layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

<< Electron transport layer, electron transport material >>
The electron transport layer according to the present invention is only required to have a function of transmitting electrons injected from the cathode to the light emitting layer, and as the material thereof, any one of conventionally known compounds can be selected and used. Can do.

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

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

  Or metal complexes of 8-quinolinol derivatives, such as tris (8-quinolinol) aluminum (Alq3), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an electron transport material.

  In addition, metal-free or metal phthalocyanine, and those having the terminal substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Alternatively, the distyrylpyrazine derivative exemplified as the material for the light-emitting layer can also be used as an electron transport material, and, like the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by forming the above compound by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.

(Film thickness of electron transport layer)
Although the film thickness of an electron carrying layer does not have a restriction | limiting in particular, It is preferable to adjust to the range of 5 nm-5 micrometers. This electron transport layer may have a single layer structure composed of one or two or more of these electron transport materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

  Further, in the present invention, the fluorescent compound is not limited to the light emitting layer, and the hole transport layer adjacent to the light emitting layer, or the fluorescent compound serving as a host compound of the phosphorescent compound in the electron transport layer; At least one fluorescent compound having a fluorescent maximum wavelength may be contained in the same region, whereby the luminous efficiency of the EL element can be further increased. Fluorescent compounds contained in these hole transport layer and electron transport layer have the same fluorescence maximum wavelength as 330-440 nm, more preferably 360-410 nm, as in the light-emitting layer. A compound is used.

  In the present invention, when the organic EL device has a hole blocking (hole blocking) layer, the compound represented by the general formula (1), (2) or (3) according to the present invention is adjacent to the light emitting layer. Thus, it can be used as a hole blocking layer as described above. The hole blocking layer is an electron transporting layer in a broad sense, and is provided adjacent to the light emitting layer. The hole blocking layer has a function of transporting electrons and has an extremely small ability to transport holes. It is a layer made of (hole blocking material). By blocking holes while transporting electrons, the recombination probability of electrons and holes can be improved.

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

  The resin film is not particularly limited, and specifically, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose. Cellulose esters such as acetate phthalate and cellulose nitrate or their derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, polyether sulfone , Polysulfones, Polyetherketoneimide, Polyamide, Fluororesin, Niro , Polymethylmethacrylate, acrylic or polyarylates, norbornene (or cycloolefin) resins such as Arton (trade name: manufactured by JSR) or Apel (trade name: manufactured by Mitsui Chemicals), organic-inorganic hybrid resin Etc. Examples of the organic-inorganic hybrid resin include those obtained by combining an organic resin and an inorganic polymer (for example, silica, alumina, titania, zirconia, etc.) obtained by a sol-gel reaction.

  An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film.

  Specific examples of the coating include a silica layer formed by a sol-gel method, an organic layer formed by polymer application, etc. (for example, an organic material film having a polymerizable group is subjected to post-treatment by means such as ultraviolet irradiation or heating). A DLC film, a metal oxide film, a metal nitride film, or the like. The metal oxide film, metal oxide constituting the metal nitride film, and metal nitride include metal oxides such as silicon oxide, titanium oxide, and aluminum oxide, metal nitrides such as silicon nitride, silicon oxynitride, and oxynitride Examples thereof include metal oxynitrides such as titanium.

The water vapor permeability of the resin film having an inorganic or organic coating or a hybrid coating of both on the surface is preferably a high barrier film of 0.01 g / m ² · day · atm or less.

  Next, a suitable example for producing an organic EL element will be described. As an example, a method for manufacturing an EL element composed of the anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm. An anode is produced. Next, a thin film comprising a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer, which is a device material, is formed thereon.

  Further, a buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or hole injection layer and between the cathode and the light emitting layer or electron injection layer.

  The buffer layer is a layer provided between the electrode and the organic layer in order to lower the driving voltage and improve the luminous efficiency. “The organic EL element and its forefront of industrialization (published by NTS Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes an anode buffer layer and a cathode buffer layer.

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

  The details of the cathode buffer layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, specifically, metals represented by strontium, aluminum and the like. Examples include a buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, an oxide buffer layer typified by aluminum oxide and lithium oxide, and the like.

  The buffer layer is preferably a very thin film, and depending on the material, the film thickness is preferably in the range of 0.1 to 100 nm.

  Furthermore, in addition to the basic constituent layer, a layer having other functions may be laminated as necessary. The hole blocking layer (for example, JP-A-11-204258, JP-A-11-204359) And a functional layer such as “Organic EL device and its industrialization front line (published on November 30, 1998, NTS, Inc.)” on page 237, etc. .

"electrode"
Next, the electrode of the organic EL element will be described. The electrode of the organic EL element consists of a cathode and an anode. As the anode in the organic EL element, 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.

  The anode may be formed by depositing a thin film of these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much (about 100 μm or more) May form a pattern through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, or the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 nm to 200 nm.

On the other hand, as the cathode, those using an electrode substance of a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound and a mixture thereof are preferably used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. An aluminum / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, and the like are preferable. The cathode can be produced by forming a thin film from these electrode materials by a method such as vapor deposition or sputtering. Alternatively, 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 1 μm, preferably 50 to 200 nm. In order to transmit light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission efficiency is improved, which is convenient.

<< Method for producing organic EL element >>
Next, a method for manufacturing an organic EL element will be described.

  As the thinning method, there are a spin coating method, a casting method, a vapor deposition method and the like as described above, but a vacuum vapor deposition method is preferable from the standpoint that a homogeneous film can be easily obtained and pinholes are hardly generated. When a vacuum deposition method is employed for thinning, the deposition conditions vary depending on the type of compound used, the target crystal structure of the molecular deposition film, the association structure, etc., but generally the boat heating temperature is 50 to 450 ° C., the degree of vacuum It is desirable to select appropriately within the range of 10 −6 to 10 −3 Pa, vapor deposition rate 0.01 nm / second to 50 nm / second, substrate temperature −50 ° C. to 300 ° C., and film thickness 5 nm to 5 μm.

  As described above, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm. After preparing the anode, after forming each layer thin film consisting of the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer / electron injection layer on the anode as described above, for the cathode A desired organic EL device can be obtained by forming a thin film made of a material so as to have a thickness of 1 μm or less, preferably 50 to 200 nm, by a method such as vapor deposition or sputtering, and providing a cathode. The organic EL device is preferably produced from the hole injection layer to the cathode in this manner consistently by a single evacuation. However, the production order is reversed so that the cathode, the electron injection layer, the light emitting layer, It is also possible to produce the hole injection layer and the anode in this order. In the case of applying a DC voltage to the organic EL device thus obtained, light emission can be observed by applying a voltage of about 5 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Or even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The applied AC waveform may be arbitrary.

<Display device>
The organic EL device of the present invention may be used as a kind of lamp such as an illumination or exposure light source, a projection device that projects an image, or a display device that directly recognizes a still image or a moving image. (Display) may be used. When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using two or more organic EL elements of the present invention having different emission colors.

  An example of a display device composed of the organic EL element of the present invention will be described below based on the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

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

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

  FIG. 2 is a schematic diagram of the display unit A.

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

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

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

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

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

  FIG. 3 is an equivalent circuit diagram of a drive circuit that constitutes a pixel.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

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

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

  That is, the light emission of the organic EL element 10 is performed by providing the switching transistor 11 and the drive transistor 12 which are active elements with respect to the organic EL elements 10 of the plurality of pixels, respectively. It is carried out. Such a light emitting method is called an active matrix method.

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

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

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

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

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.

  In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  The carbazole derivative compound according to the present invention can also be used for an organic electroluminescence device that emits substantially white light.

  At present, there is no organic EL element that emits white light with a single light emitting material. Therefore, a plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing. The combination of a plurality of emission colors may include three emission maximum wavelengths of three primary colors of blue, green, and blue, or two using a complementary color relationship such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

  In addition, a combination of light emitting materials for obtaining a plurality of luminescent colors is a combination of a plurality of phosphorescent or fluorescent light emitting materials, a light emitting material that emits fluorescent or phosphorescent light, and light from the light emitting material. Any combination with a dye material that emits light as excitation light may be used.

  For example, the carbazole derivative according to the present invention is used as a light emitting layer material as a light emitting host material, and a plurality of phosphorescent dopants as a phosphorescent dopant, that is, a complementary color relationship among the phosphorescent dopants. White light emission can be obtained by using a mixture of dopants. High luminous efficiency can be obtained by using the compounds represented by the general formulas (1) to (3) of the present invention as the luminescent host, which is preferable.

  In addition to being able to use a compound known so far as a host material in the light emitting layer, there is no particular limitation on the material when a hole transport layer is provided, but a layer that emits holes from the anode. In the conventional photoconductive materials, those conventionally used as charge injection materials for holes, and well-known materials used for hole transport layers of EL devices Any one can be selected and used.

  Even in the case of providing an electron transport layer, there is no particular limitation, and any known material can be selected and used as long as it has a function of transmitting electrons from the cathode electrode to the light emitting layer. Can do.

  The white organic electroluminescence element basically needs only to be mixed with a dopant whose light emission has a complementary color relationship, and a light emitting material can be obtained only by patterning the light emitting portion. Therefore, it is only necessary to coat with a mask only when forming a light-emitting layer, a hole transport layer, an electron transport layer, or the like. Since the other layers are common, patterning of the mask or the like is unnecessary, and formation is easy, and vapor deposition is performed on one surface. For example, an electrode film can be formed by a method, a casting method, a spin coating method, an ink jet method, a printing method, etc., and productivity is also improved. According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the elements themselves are luminescent white.

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

  The white light-emitting organic EL element can be used for display devices, displays, and various light-emitting light sources. However, the white light-emitting organic EL element can be used as a kind of lamp (illumination device) for home lighting, interior lighting, and exposure light source, and for a liquid crystal display device. It is also useful for a display device as a backlight.

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

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<< Production of Organic EL Element OLED1-1 >>
After patterning on a substrate (made by NH Techno Glass Co., Ltd .: NA-45) having a 150 nm ITO film formed on glass as an anode, the transparent support substrate provided with this ITO transparent electrode was ultrasonically cleaned with iso-propyl alcohol. Then, it was dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus, and α-NPD, CBP, Ir-12, BCP, and Alq ₃ were placed in a molybdenum resistance heating boat, and attached to the vacuum deposition apparatus.

Next, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, α-NPD was vapor-deposited on the transparent support substrate to a thickness of 50 nm to provide a hole injection / transport layer. Further, the heating boat containing CBP and the boat containing Ir-12 are energized independently to adjust the deposition rate of CBP and Ir-12 to be 100: 7, so that the film thickness is 30 nm. The light emitting layer was provided.

Subsequently, BCP was vapor-deposited to provide a 10 nm thick hole blocking layer. Furthermore, Alq ₃ was deposited to provide an electron transport layer having a thickness of 40 nm.

  Next, after the element formed up to the electron injection layer as described above is transferred to the second vacuum chamber in a vacuum state, a stainless steel rectangular perforated mask is disposed on the electron injection layer from the outside of the apparatus. Installed with remote control.

After depressurizing the second vacuum tank to 2 × 10 ⁻⁴ Pa, a cathode buffer layer having a film thickness of 0.5 nm was provided at a deposition rate of 0.01 to 0.02 nm / second by energizing a boat containing lithium fluoride. Next, a boat containing aluminum was energized, and a cathode having a film thickness of 150 nm was attached at a deposition rate of 1 to 2 nm / second. Furthermore, this organic EL element was transferred to a glove box under nitrogen atmosphere (a glove box substituted with high-purity nitrogen gas with a purity of 99.999% or more) without being brought into contact with the atmosphere, and a sealing structure as shown in FIG. 5 was obtained. Thus, an organic EL element OLED1-1 was produced. In addition, barium oxide 25 which is a water replenisher is made of Aldrich's high-purity barium oxide powder in a glass sealing can 24 using a fluororesin semi-permeable membrane (Microtex S-NTF8031Q made by Nitto Denko) with an adhesive. The pasted one was prepared and used in advance. An ultraviolet curable adhesive 27 was used for adhesion between the sealing can 24 and the organic EL element, and an element having a sealing structure was produced by adhering and sealing both by irradiating an ultraviolet lamp. In the figure, 21 is a glass substrate provided with a transparent electrode, 22 is an organic EL layer comprising the hole injection / transport layer, light emitting layer, electron transport layer, electron injection layer and the like, and 23 is a cathode.

<< Production of Organic EL Elements OLED1-2 to 1-13 >>
In the production of the organic EL element OLED1-1, organic EL elements OLED1-2 to 1-13 were produced in the same manner except that the CBP used for the production of the light emitting layer was changed to the compounds shown in Table 1. .

  Each of the obtained organic EL elements was evaluated as follows.

[Evaluation]
(Luminance brightness)
In organic EL element OLED1-1, the blue light emission from the phosphorescent compound which is a dopant of a light emitting layer was shown. The luminance of the organic EL element OLED1-1 was measured using a Minolta CS-1000 when a current of ^2.5 mA / cm ² was supplied in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and this value was taken as 100. Table 1 shows the ratio (relative value) of the emission luminance of each sample of the organic EL element.

(lifespan)
In addition, the brightness of each organic EL element sample when the time to reduce the brightness by half is 100 when the initial brightness is 100 cd / m ² in a temperature of 23 ° C. and a dry nitrogen gas atmosphere of the organic EL element OLED1-1. Table 1 shows the ratio (relative value) of the halving time.

  From Table 1, it can be seen that the compound of the present invention achieves both luminance and lifetime compared to the comparative compound.

  Further, the same effect can be obtained in the organic EL element produced in the same manner as the organic EL elements 1-1 to 1-13 except that Ir-12, which is a phosphorescent compound, is changed to Ir-1 or Ir-9. It was. In addition, green light emission was obtained from the element using Ir-1, and red light emission was obtained from the element using Ir-9.

Example 2
Organic EL elements OLED2-1 to 2-11 were produced in the same manner as in Example 1 except that BCP was replaced with the compounds shown in Table 2 in Example 1. The measurement of light emission luminance and light emission lifetime was also performed according to Example 1. At this time, all are represented by relative values of the respective samples of the organic EL element when the value of the OLED 2-1 is 100. The OLED 2-1 has the same configuration as the OLED 1-1.

  The results are shown in Table 2.

  From Table 2, it was found that the device using the material of the present invention has both emission luminance and emission lifetime compared to the comparative hole blocking material.

  Further, the same effect can be obtained in an organic EL device produced in the same manner as the organic EL devices 2-1 to 2-11 except that Ir-12, which is a phosphorescent compound, is changed to Ir-1 or Ir-9. It was. In addition, green light emission was obtained from the element using Ir-1, and red light emission was obtained from the element using Ir-9.

Example 3
<Production of full-color display device>
<Full-color display device (1)>
(Blue light emitting organic EL device)
The organic EL element 1-5 produced in Example 1 was used.

(Green light-emitting organic EL device)
In the organic EL element 1-5 produced in Example 1, the organic EL element 1-5G produced by the same method as the organic EL element 1-5 was used except that Ir-1 was used instead of Ir-12. It was.

(Red light emitting organic EL device)
In the organic EL element 1-5 produced in Example 1, the organic EL element 1-5R produced by the same method as the organic EL element 1-5 was used except that Ir-9 was used instead of Ir-12. It was.

  The red, green and blue light emitting organic EL elements are juxtaposed on the same substrate to produce an active matrix type full color display device having the form shown in FIG. 1, and FIG. 2 shows a display of the produced display device. Only the schematic diagram of part A is shown. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. In this way, a full color display device was produced by appropriately juxtaposing the red, green, and blue pixels.

  It was confirmed that by driving the full-color display device, it was possible to obtain a full-color moving image display with a high luminance and luminous efficiency and a long life.

Example 4
In the organic EL element 1-5 produced in Example 1, the organic EL element 1 was used except that Ir-12 and Ir-9 (Ir-12: Ir-9 = 1: 4) were used instead of Ir-12. Organic EL element 1-5W produced by the same method as -5 was produced.

  The non-light emitting surface of the organic EL element 1-14W was covered with a glass sealing can to obtain a lighting device. The illuminating device was able to be used as a thin illuminating device that emits white light with high emission luminance and luminous efficiency and a long lifetime. FIG. 6 is a schematic view of the lighting device, and FIG. 7 is a cross-sectional view of the lighting device. 6 and 7, reference numeral 110 denotes barium oxide (a high-purity barium oxide powder manufactured by Aldrich), which is a water-retaining agent attached to the glass sealing can 102. Using a curable adhesive, both were bonded and sealed by irradiating an ultraviolet lamp. In the figure, 108 is a glass substrate provided with a transparent electrode 107, 106 is an organic EL layer comprising the hole injection / transport layer, light emitting layer, electron transport layer, electron injection layer, etc. 105 is a cathode. Reference numerals 103 and 104 denote lead wires connected to the cathode and the anode, respectively.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. 4 is a schematic diagram of a display unit A. FIG. It is an equivalent circuit diagram of the drive circuit which comprises a pixel. It is a schematic diagram of the display apparatus by a passive matrix system. It is a schematic diagram of the sealing structure of organic EL element OLED1-1. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part 21 Glass substrate with a transparent electrode 22 Organic EL layer 23 Cathode 24 Glass sealing can 25 Barium oxide (water trapping agent)
27 UV curable adhesive

Claims (10)

An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (1) An organic electroluminescence device characterized.

(In the general formula (1), Ar represents a five-membered aromatic ring containing at least one nitrogen atom, and Ar ₁ , Ar ₂ , Ar ₃ , Ar ₄ , Ar ₅ represents an aryl group or a heteroaryl group. M represents an integer of 0 or more, and R represents a hydrogen atom or a substituent.) In the said General formula (1), Ar represents the aromatic condensed ring containing a 5-membered ring, and contains an at least 1 nitrogen atom, The organic electroluminescent element of Claim 1 characterized by the above-mentioned. An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (2) An organic electroluminescence device characterized.

(In General Formula (2), n of R _{11 to} R ₁₉ represent an aryl group or a heteroaryl group, (9-n) represents a hydrogen atom or a substituent, and at least one represents hydrogen. Represents an atom, where n is an integer from 5 to 8. An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any layer constituting the device contains a compound represented by the following general formula (3) An organic electroluminescence device characterized.

(In the general formula (3), R _{21 to} R ₂₅ represent an aryl group or a heteroaryl group.) An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein the light emitting layer contains the compound represented by the general formula (1), (2) or (3). An organic electroluminescence device characterized by comprising: An organic electroluminescent device having a host compound, a light emitting layer containing a phosphorescent compound, and a hole blocking layer, wherein the compound represented by the general formula (1), (2) or (3) is And an organic electroluminescence device characterized by being used for a hole blocking layer. The organic electroluminescent device according to claim 1, wherein the phosphorescent compound is osmium, iridium, rhodium, or a platinum complex compound. The display apparatus which has an organic electroluminescent element of any one of Claims 1-7. An organic electroluminescent device having a light-emitting layer containing a host compound and a phosphorescent compound, wherein any one of the layers constituting the device is represented by the general formula (1), (2) or (3). And a white light-emitting organic electroluminescent device comprising a plurality of phosphorescent compounds. An illuminating device comprising the white-light-emitting organic electroluminescence element according to claim 9.

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