JP2012167058A - 1,8-aryl-substituted naphthalene derivative exhibiting excimer characteristic, and organic el element obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a 1,8-aryl-substituted naphthalene derivative exhibiting excimer characteristics and an organic EL element using the same.SOLUTION: The organic EL element is obtained by using the 1,8-aryl-substituted naphthalene derivative exhibiting excimer characteristics represented by general formula (1). In the formula, R-Rare each a group independently selected from the group consisting of hydrogen, deuterium, a 1C-4C linear or branched alkyl group, an alkoxy group or an alkylamino group each having a 1C-4C linear or branched alkyl moiety, fluorine and an acetoxy group; and Ar is any one of a pyrenyl group, a 4-(9-N-carbazolyl)phenyl group and a 4-[10-(9-phenyl)anthranyl]phenyl group.

Description

  The present invention relates to a 1,8-aryl substituted naphthalene derivative having excimer characteristics and an organic EL device using the same.

Among the 1,8-aryl substituted naphthalene derivatives according to the present invention, compounds having a pyrenyl group are known (Non-Patent Document 1), but no organic EL measurement examples are described, and the excimer characteristics of this compound are utilized. Thus, there is no description or suggestion about manufacturing an organic EL element.
Patent Document 1 describes an organic EL measurement example of a similar compound in which the 1,8-position of naphthalene is substituted with a π-conjugated site, but the emission spectrum is unknown and there is no description regarding excimer characteristics. Furthermore, there is no description regarding a 1,8-aryl substituted naphthalene derivative having the same structure as that used in the present invention.

JP 2004-14219 A

P. Wahl, C.I. Krieger, D.M. Schweitzer, H.C. A. Staab, Chem. Ber. 117, 260-276 (1984)

  An object of the present invention is to provide a 1,8-aryl-substituted naphthalene derivative having excimer characteristics and an organic EL (electroluminescence) device using the same.

The above problems are solved by the following inventions 1) to 4).
1) An organic EL device using a 1,8-aryl-substituted naphthalene derivative having excimer characteristics represented by the following general formula (1).
Wherein R ^{1 to} R ⁵ are hydrogen, deuterium, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms, or alkylamino A group independently selected from the group consisting of a group, fluorine and an acetoxy group, wherein Ar is a pyrenyl group represented by the following formula, 4- (9-N-carbazolyl) phenyl group, 4- [10- ( 9-phenyl) anthranyl] phenyl group, R ^{6 to} R ¹⁴ are hydrogen, deuterium, fluorine, a linear or branched alkyl group having 1 to 4 carbon atoms, and the alkyl moiety is a straight chain having 1 to 4 carbon atoms. are each independently a group selected from the group consisting of alkylamino group is a chain or branched alkyl group, R ¹⁵ to R ⁴³ are hydrogen, deuterium, fluorine, linear or branched aralkyl of 1 to 4 carbon atoms From the group consisting of Le group are each independently selected groups.)
2) The organic EL device according to 1), wherein the 1,8-aryl-substituted naphthalene derivative is used as a light-emitting material for a light-emitting layer.
3) The organic EL device according to 1), wherein the 1,8-aryl-substituted naphthalene derivative is used as a host material for a light emitting layer.
4) A 1,8-aryl substituted naphthalene derivative represented by the following general formula (1).
Wherein R ^{1 to} R ⁵ are hydrogen, deuterium, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms, or alkylamino A group independently selected from the group consisting of a group, fluorine and an acetoxy group, wherein Ar is a 4- (9-N-carbazolyl) phenyl group represented by the following formula, 4- [10- (9-phenyl); ) Anthranyl] phenyl group, and R ^{15 to} R ⁴³ are groups independently selected from the group consisting of hydrogen, deuterium, fluorine, and linear or branched alkyl groups having 1 to 4 carbon atoms. .)

  According to the present invention, a 1,8-aryl substituted naphthalene derivative having excimer characteristics and an organic EL device using the same can be provided.

¹ H-NMR full-region chart of (BPyN) of 1,8-bis (pyren-2-yl) naphthalene produced in Example 1. FIG. The enlarged chart of the aromatic site | part of ¹ H-NMR of BPyN produced in Example 1. FIG. 3 is a chart of EI-Mass spectrum of BPyN produced in Example 1. ^{1 is} a chart of the entire region of ¹ H-NMR of (BCzPN) of 1,8-bis [4- (carbazol-9-N-yl) phenyl] naphthalene prepared in Example 2. The chart of the aromatic site | part of ¹ H-NMR of BCzPN produced in Example 2. FIG. The chart of EI-Mass spectrum of BCzPN produced in Example 2. ^{1 is} a chart of the entire region of ¹ H-NMR of 1,8-bis [4- (9-phenylanthracen-10-yl) phenyl] naphthalene (BPAPN) prepared in Example 3. ^{1 is} a chart of aromatic sites of ¹ H-NMR of BPAPN produced in Example 3. FIG. 6 is a chart of the EI-Mass spectrum of BPAPN produced in Example 3. 2 is a DSC chart of BPyN produced in Example 1. 2 is a TGA chart of BPyN produced in Example 1. FIG. 6 is a DSC chart of BCzPN produced in Example 2. 5 is a TGA chart of BCzPN produced in Example 2. 6 is a DSC chart of BPAPN produced in Example 3. 6 is a TGA chart of BPAPN produced in Example 3. FIG. 3 is a chart showing HOMO values of BPyN produced in Example 1. 6 is a chart showing the HOMO value of BCzPN produced in Example 2. The figure which shows the measurement result of the ultraviolet-visible absorption (UV-vis) and photoluminescence (PL) in the toluene solution of BPyN produced in Example 1, and a thin film form. The figure which shows the measurement result of the ultraviolet-visible absorption (UV-vis) and photoluminescence (PL) in the methylene chloride solution of BCzPN produced in Example 2, and a thin film form. The figure which shows the measurement result of the ultraviolet-visible absorption (UV-vis) and photoluminescence (PL) in the THF solution of BPAPN produced in Example 3. FIG. The figure which shows the element structure of Examples 14-15. The figure which shows the current density-voltage characteristic of Examples 14-15. The figure which shows the luminance-voltage characteristic of Examples 14-15. The figure which shows the power efficiency-luminance characteristic of Examples 14-15. The figure which shows the current efficiency-luminance characteristic of Examples 14-15. The figure which shows the external quantum efficiency-luminance characteristic of Examples 14-15. FIG. 16 shows an EL spectrum of Example 14. FIG. 16 shows an EL spectrum of Example 15. The figure which shows the element structure of Examples 17-20. The figure which shows the current density-voltage characteristic of Examples 17-20. The figure which shows the luminance-voltage characteristic of Examples 17-20. The figure which shows the power efficiency-luminance characteristic of Examples 17-20. The figure which shows the current efficiency-luminance characteristic of Examples 17-20. The figure which shows the external quantum efficiency-brightness characteristic of Examples 17-20. The figure which shows EL spectrum of Examples 17-20. FIG. 25 shows an element structure of Example 21. FIG. 25 shows current density-voltage characteristics of Example 21. FIG. 25 shows luminance-voltage characteristics of Example 21. FIG. 25 shows power efficiency-luminance characteristics of Example 21. FIG. 25 shows current efficiency-luminance characteristics of Example 21. FIG. 25 shows external quantum efficiency-luminance characteristics of Example 21. FIG. 14 shows an EL spectrum of Example 21. FIG. 25 shows an element structure of Example 22. FIG. 25 shows current density-voltage characteristics of Example 22. FIG. 25 shows luminance-voltage characteristics of Example 22. FIG. 25 shows power efficiency-luminance characteristics of Example 22. FIG. 26 shows current efficiency-luminance characteristics of Example 22; FIG. 25 shows external quantum efficiency-luminance characteristics of Example 22. The figure which shows EL spectrum of Example 22. The figure which shows the structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention. The figure which shows the other structural example of the organic EL element of this invention.

Hereinafter, the present invention will be described in detail.
The π-conjugated molecule exhibits excimer emission that is greatly shifted in wavelength compared to the fluorescence emission exhibited by the isolated π-conjugated molecule due to stacking of π-conjugated planes.
Therefore, the present inventors considered that, when this excimer luminescence is used, a high fluorescence quantum yield can be expected because there is no overlap with the absorption spectrum due to a large long wavelength shift. In addition, since excimer luminescence shows a unique triplet state, it is expected that it can be expected as a highly efficient fluorescent material and host material by triplet-singlet conversion, and also as a phosphorescent host material. Moreover, if such excimer light emission was efficiently incorporated into an organic EL device, it was considered that further improvement in device characteristics could be expected.
As a result of intensive studies based on the above idea, a useful organic EL device can be obtained by using a 1,8-aryl-substituted naphthalene derivative having an excimer characteristic represented by the general formula (1) according to the present invention for a light emitting layer. It was found that it can be obtained.
The 1,8-aryl-substituted naphthalene derivative represented by the general formula (1) functions as a light emitting material when used alone, but when used as a host material, the light emitting material can efficiently emit light. It was confirmed. Furthermore, since it was easy to form an excimer, it was confirmed that fine processing of chromaticity was easy, and that when used for illumination or the like, color rendering could be improved. Therefore, the present invention is extremely useful industrially.

Examples of the linear or branched alkyl group having 1 to 4 carbon atoms of R ^{1 to} R ⁴³ in the compound of the general formula (1) include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, A tertiary butyl group can be exemplified.
Examples of the alkoxy group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a normal propoxy group, an isopropoxy group, a normal butoxy group, an isobutoxy group, and a tertiary butoxy group. Can be illustrated.
In addition, as the alkylamino group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms, a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a methylethylamino group, a normal propylamino group, Dinormal propylamino group, methyl normal propyl amino group, isopropyl amino group, diisopropyl amino group, methyl isopropyl amino group, normal butyl amino group, di normal butyl amino group, methyl normal butyl amino group, isobutyl amino group, diisobutyl amino group, Examples thereof include a methylisobutylamino group, a tertiary butylamino group, a ditertiary butylamino group, and a methyl tertiary butylamino group.

The compound of the general formula (1) can be prepared by the following reaction.
In the formula, R ^{1 to} R ⁵ are hydrogen, deuterium, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group or an alkylamino group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms. , A group independently selected from the group consisting of fluorine and acetoxy groups. Ar is any one of a pyrenyl group, a 4- (9-N-carbazolyl) phenyl group, and a 4- [10- (9-phenyl) anthranyl] phenyl group represented by the following formula, and R ^{6 to} R ¹⁴ are hydrogen. , Deuterium, fluorine, a linear or branched alkyl group having 1 to 4 carbon atoms, and an alkyl moiety independently selected from the group consisting of alkylamino groups that are linear or branched alkyl groups having 1 to 4 carbon atoms. R ^{15 to} R ⁴³ are groups independently selected from the group consisting of hydrogen, deuterium, fluorine, and a linear or branched alkyl group having 1 to 4 carbon atoms. )

The preparation method is a coupling reaction between a bromide and a borate ester. This is a reaction generally called Suzuki coupling, which is often used in organic synthesis reactions. The palladium catalyst used in the reaction is not particularly limited as long as it shows zero valence in the reaction system. Examples include tetrakis (triphenylphosphine) palladium (0) [Pd (PPh ₃ ) ₄ ], bis [1,2-bis (diphenylphosphino) ethane] palladium (0), bis (dibenzylideneacetone) palladium. (0), bis (tri-tert-butylphosphine) palladium (0), and the like. Tetrakis (triphenylphosphine) palladium (0) is preferable because of easy handling.
The base used for the reaction is not particularly limited, whether it is inorganic or organic. Examples of inorganic substances include carbonates such as sodium carbonate, potassium carbonate, and cesium carbonate; bicarbonates such as sodium bicarbonate and potassium bicarbonate; fluorides such as potassium fluoride and cesium fluoride; and organic substances such as sodium methylate. And alcoholate compounds such as sodium ethylate, and amine compounds such as triethylamine, diisopropylethylamine and tertiary butylamine. In view of ease of handling, potassium carbonate is preferred. When using an inorganic salt, it is preferable to use it as an aqueous solution in order to increase the dispersibility in the reaction system.
The reaction solvent is not particularly limited as long as it does not react with the palladium catalyst or the base used. For example, aromatic solvents such as toluene and xylene, ether solvents such as 1,4-dioxane and 1,2-dimethoxyethane can be used. In the case of an aromatic solvent, it may be used in combination with an alcohol solvent such as methanol or ethanol.

Specific examples of the compound of the general formula (1) are illustrated. In the exemplified compound, the methyl group can be replaced with another alkyl group such as an ethyl group or a propyl group.

The compound of the general formula (1) exhibits high excimer emission. Therefore, it can be used as a light emitting material. In any case, it is desirable to form a layer by vapor deposition or coating.
Moreover, the compound of the said General formula (1) shows light emission by excimer formation. It can also be used as a host material for a light emitting dopant. In any case, it is desirable to form a layer by vapor deposition or coating.
Moreover, when using the compound of the said General formula (1) for the luminescent material of an organic EL element, it can be used in combination with a suitable host material.

Next, the organic EL element of the present invention will be described.
The organic EL device of the present invention is a device in which a plurality of layers of organic compounds are laminated between an anode and a cathode, and contains the compound of the general formula (1) as a light emitting material of the light emitting layer.
The light emitting layer is composed of a light emitting material and a host material. Examples of the configuration of the multilayer organic EL device include an anode (for example, ITO) / hole transport layer / light emitting layer / electron transport layer / cathode, ITO / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode, ITO / hole transport layer / light emitting layer / hole block layer / electron transport layer / cathode, ITO / hole transport layer / light emitting layer / hole block layer / electron transport layer / electron injection layer / cathode, ITO / hole injection layer (hole Injecting layer) / hole transporting layer / light emitting layer / hole blocking layer / electron transporting layer / electron injecting layer / cathode and the like laminated. Moreover, you may have a sealing layer on a cathode as needed.
Each of the hole transport layer, the electron transport layer, and the light emitting layer preferably has a multilayer structure in which the functions are separated. In addition, the hole transport layer and the electron transport layer can be provided separately with a layer responsible for the injection function (hole injection layer and electron injection layer) and a layer responsible for the transport function (hole transport layer and electron transport layer).

Hereinafter, the constituent elements of the organic EL element of the present invention will be described by taking as an example an element structure composed of an anode / hole transport layer / light emitting layer / electron transport layer / cathode.
The organic EL element of the present invention is preferably supported on a substrate.
There is no restriction | limiting in particular about the raw material of a board | substrate, For example, what is conventionally used for the conventional organic EL element can be used, and what consists of glass, quartz glass, a transparent plastic, etc. can be used.

As the anode, an electrode material is preferably a single metal having a large work function (4 eV or more), an alloy of metals having a large work function (4 eV or more), a conductive substance, or a mixture thereof. Examples of such electrode materials include gold, silver, copper and other metals, ITO (indium-tin oxide), tin oxide (SnO ₂ ), zinc oxide (ZnO), and other conductive transparent materials, polypyrrole, polythiophene, etc. The conductive polymer material is mentioned. For the anode, these electrode materials can be formed by a method such as vapor deposition, sputtering, or coating. The sheet electrical resistance of the anode is preferably several hundred Ω / cm ² or less. The thickness of the anode depends on the material, but is generally about 5 to 1,000 nm, preferably 10 to 500 nm.

As the cathode, an electrode material is preferably a single metal having a low work function (4 eV or less), an alloy of metals having a low work function (4 eV or less), a conductive substance, or a mixture thereof. Examples of such electrode materials include lithium, lithium-indium alloy, sodium, sodium-potassium alloy, magnesium, magnesium-silver alloy, magnesium-indium alloy, aluminum, aluminum-lithium alloy, aluminum-magnesium alloy, and the like. It is done. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering.
The sheet electrical resistance of the cathode is preferably several hundred Ω / cm ² or less. The thickness of the cathode depends on the material, but is generally about 5 to 1,000 nm, preferably 10 to 500 nm.
In order to efficiently extract light emitted from the organic EL device of the present invention, at least one of the anode and the cathode is preferably transparent or translucent.

The hole transport layer is made of a hole transfer compound and has a function of transmitting holes injected from the anode to the light emitting layer. When a hole transfer compound is disposed between two electrodes to which an electric field is applied and holes are injected from the anode, a hole transfer material having a hole mobility of at least 10 ⁻⁶ cm ² / V · sec or more is preferable. The hole transfer material used for the hole transport layer of the organic EL device of the present invention is not particularly limited as long as it has the above-mentioned preferable performance. A photoconductive material that has been conventionally used as a hole charge injection material or a known material that is used for a hole transport layer of an organic EL element can be selected and used.

Examples of hole transfer materials include phthalocyanine derivatives such as copper phthalocyanine, N, N, N ′, N′-tetraphenyl-1,4-phenylenediamine, N, N′-di (m-tolyl) -N, N Triarylamine derivatives such as' -diphenyl-4,4-diaminophenyl (TPD), N, N'-di (1-naphthyl) -N, N'-diphenyl-4,4-diaminophenyl (α-NPD) , Polyphenylenediamine derivatives, polythiophene derivatives, and water-soluble PEDOT-PSS (polyethylenedioxathiophene-polystyrenesulfonic acid).
The hole transport layer may be composed of one or more of these other hole transport compounds, or may be a stack of hole transport layers composed of a compound different from the hole transport material. .

Examples of the hole injection material include PEDOT-PSS (polymer mixture) and DNTPD represented by the following chemical formula. N in the formula is the number of repeating units.
Examples of the hole transport material include TPD, DTASi, α-NPD, and TAPC represented by the following chemical formula.

The electron transport layer is made of an electron transport material and has a function of transmitting electrons injected from the cathode to the light emitting layer. When an electron transport material is arranged between two electrodes to which an electric field is applied and electrons are injected from the cathode, an electron transport material having an electron mobility of at least 10 ⁻⁶ cm ² / V · sec or more is preferable. The electron transport material is not particularly limited as long as it has the above-mentioned preferable performance. Any one of materials conventionally used as electron charge injection materials in photoconductive materials and known materials used for electron transport layers of organic EL elements can be selected and used.
Examples of electron transport materials include quinoline complexes such as tris (8-hydroxyquinolinolato) aluminum complex (Alq ₃ ), 1-N-phenyl-2- (p-biphenylyl) -5- (p-tert -Triazine derivatives such as butylphenyl) -1,3,5-triazine (TAZ), phenanthroline derivatives such as 1,4-di (1,10-phenanthroline-2-yl) benzene (DPB), lithium fluoride And alkali metal halides.
Following the Alq ₃ and TAZ formula.

In addition to the above, an electron transport material of a triazine derivative represented by the following chemical formula (TmPyPhTAZ, see Japanese Patent Application Laid-Open No. 2007-137829), an electron transport material of a bisphenol derivative (tetra-pPyPhBP, see Japanese Patent Application Laid-Open No. 2008-066322), etc. Can also be used.
The electron transport layer may be composed of one or more of the above electron transport materials, but may be a stack of electron transport layers composed of compounds different from these.

Examples of the electron injection material include lithium fluoride (LiF), 8-hydroxyquinolinolatolithium complex (Liq) represented by the following chemical formula, lithium complex of phenanthroline derivative (LiPB, see JP 2008-106015 A), A lithium complex of phenoxypyridine (LiPP, see JP 2008-195623 A) can be mentioned.

In the light emitting layer of the organic EL device of the present invention, the compound of the general formula (1) is used as the light emitting material, and any compound can be selected and used in combination with the compound of the general formula (1).
Examples of the light-emitting material used in combination include perylene derivatives, naphthacene derivatives, quinacridone derivatives, coumarin derivatives (eg, coumarin 1, coumarin 540, coumarin 545), pyran derivatives (eg, DCM-1, DCM-2, DCJTB, etc.), organometallic complexes [For example, fluorescent materials such as tris (8-hydroxyquinolinolato) aluminum complex (Alq ₃ ), tris (4-methyl-8-hydroxyquinolinolato) aluminum complex (Almq ₃ ), [2- (4,6 -Difluorophenyl) pyridyl-N, C2 '] iridium (III) picolylate (FIrpic), tris {1- [4- (trifluoromethyl) phenyl] -1H-pyrazolate-N, C2'} iridium (III) (Irtfmpppz _3), bis [2- (4 ', 6'-difluoro-phenylene ) Pyridinato -N, C2 '] iridium (III) tetrakis (1-pyrazolyl) borate (FIr6), and the like tris (2-phenylpyridinato) iridium (III) (phosphorescent material Irppy _3), etc.] .

The light emitting layer is generally formed of a host material and a light emitting material (dopant) [Appl. Phys. Lett. , 65 3610 (1989)], the compound of the general formula (1) can be used as a light emitting material without a host material. Examples of the case where a host material is used in combination include 2-tertiarybutyl-9,10-di (naphthalen-2-yl) anthracene (TBADN) and 2-methyl-9,10-di (naphthalene) represented by the following chemical formula: -2-yl) anthracene (MADN). Examples of using a phosphorescent material in combination with a dopant include 4,4′-di (N-carbazolyl) -1,1′-biphenyl (CBP) and 1,4-di (N-carbazolyl) represented by the following chemical formula: ) Benzene-2,2'-di [4 "-(N-carbazolyl) phenyl] -1,1'-biphenyl (4CzPBP).

The ratio of the compound of the general formula (1) is preferably 0.01 to 40% by weight, more preferably 0.1 to 20% by weight with respect to the host material.

In the organic EL device of the present invention, a hole injection layer composed of an organic conductor may be provided between the anode and the organic compound layer for the purpose of further improving the hole injection property. As the hole injection material used here, in addition to the compound of the general formula (1), phthalocyanine derivatives such as copper phthalocyanine, polyphenylenediamine derivatives, polythiophene derivatives, PEDOT-PSS (polyethylenedioxythiophene-polystyrenesulfonic acid), etc. Is mentioned.
The formation method of the hole injection layer and the hole transport layer of the organic EL device containing the compound of the general formula (1) is not particularly limited. For example, a dry film forming method (vacuum vapor deposition method, ionization vapor deposition method, etc.), wet type A film forming method (solvent coating method: spin coating method, casting method, ink jet method, etc.) can be used. The film formation of the electron transport layer is limited to dry film formation methods (vacuum vapor deposition method, ionization vapor deposition method, etc.) because the lower layer may be eluted when the wet film formation method is used. For the production of the element, the above film forming method may be used in combination.
When forming each layer such as a hole transport layer, a light emitting layer, and an electron transport layer by a vacuum deposition method, the vacuum deposition conditions are not particularly limited. Usually, under a vacuum of about 10 ⁻⁵ Torr or less, a boat temperature (deposition source temperature) of about 50 to 500 ° C., a substrate temperature of about −50 to 300 ° C., and 0.01 to 50 nm / sec. Vapor deposition is preferred. When forming each layer of a positive hole transport layer, a light emitting layer, and an electron carrying layer using a some compound, it is preferable to co-evaporate the boat which put the compound, respectively controlling temperature.

When forming the hole injection layer and the hole transport layer by a solvent coating method, the components constituting each layer are dissolved or dispersed in a solvent to obtain a coating solution. Solvents include hydrocarbon solvents (heptane, toluene, xylene, cyclohexane, etc.), ketone solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), halogen solvents (dichloromethane, chloroform, chlorobenzene, dichlorobenzene, etc.), ester solvents Solvents (ethyl acetate, butyl acetate, etc.), alcohol solvents (methanol, ethanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ether solvents (dibutyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, etc.) ), Aprotic solvents (N, N′-dimethylacetamide, dimethylsulfoxide, etc.), water and the like. The solvent may be used alone or in combination with a plurality of solvents.
The thickness of each layer such as a hole transport layer, a light emitting layer, and an electron transport layer is not particularly limited, but is usually set to 5 to 5,000 nm.

  The organic EL device of the present invention can be protected by providing a protective layer (sealing layer) for the purpose of blocking the contact of oxygen, moisture, etc., or encapsulating the device in an inert material. Examples of the inert substance include paraffin, silicon oil, and fluorocarbon. Examples of the material used for the protective layer include fluororesin, epoxy resin, silicone resin, polyester, polycarbonate, and photocurable resin.

50 to 57 show preferred configuration examples of the organic EL element of the present invention.
FIG. 50 shows a configuration in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. This is a separation of the functions of carrier transport and light emission, and the degree of freedom in material selection increases, so that the efficiency of light emission and the degree of freedom in light emission color increase.
FIG. 51 shows a structure in which an anode 2, a hole injection layer 7, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. In this case, the provision of the hole injection layer 7 increases the adhesion between the anode 2 and the hole transport layer 5, improves the injection of holes from the anode, and is effective in lowering the voltage of the light emitting element.
FIG. 52 shows a structure in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6, an electron injection layer 8 and a cathode 4 are sequentially provided on a substrate 1. In this case, injection of electrons from the cathode 4 is improved, which is effective for lowering the voltage of the light emitting element.
FIG. 53 shows a structure in which an anode 2, a hole injection layer 7, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6, an electron injection layer 8 and a cathode 4 are sequentially provided on a substrate 1. In this case, hole injection from the anode 2 is improved and electron injection from the cathode 4 is improved, which is the most effective for low voltage driving.

54 to 57 are configuration examples in which the hole block layer 9 is inserted into the organic EL element.
The hole blocking layer has an effect of preventing holes injected from the anode or excitons generated by recombination in the light emitting layer 3 from escaping to the cathode 4, and is effective in improving the light emission efficiency of the organic EL element. . The hole blocking layer 9 can be inserted between the light emitting layer 3 and the cathode 4, between the light emitting layer 3 and the electron transport layer 6, or between the light emitting layer 3 and the electron injection layer 8. Preferred is between the light emitting layer 3 and the electron transport layer 6.
Each of the hole transport layer 5, the hole injection layer 7, the electron transport layer 6, the electron injection layer 8, the light emitting layer 3, and the hole block layer 9 may have a single layer structure or a multilayer structure.
50 to 57 are only basic element structures, and the structure of the organic EL element of the present invention is not limited to this.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1
Synthesis of 1,8-bis (pyren-2-yl) naphthalene (BPyN) BPyN was synthesized by a reaction represented by the following formula. In the synthesis, P.I. Wahl, C.I. Krieger, D.M. Schweitzer, H.C. A. Staab, Chem. Ber. 117, 260-276 (1984).

In a 50 mL three-necked flask, 0.50 g (1.75 mmol) of 1,8-dibromonaphthalene, 1.72 g (5.25 mmol) of pyrene-2-boronic acid pinacol ester, tetrakistriphenylphosphine palladium [Pd (PPh ₃ ) ₄ ] 0.2 g (0.175 mmol), 2.0 M-K ₂ CO ₃ 10 mL aqueous solution, and toluene 100 mL were reacted at 85 ° C. for 24 hours in a nitrogen atmosphere. Purification by silica gel column chromatography (hexane) gave the target compound as pale yellow crystals (2.43 g, yield 65%).
The target product was confirmed by ¹ H-NMR and EI-Mass spectrum. FIG. 1 shows an overall chart of ¹ H-NMR, FIG. 2 shows an enlarged chart of aromatic sites, and FIG. 3 shows an EI-Mass spectrum chart.
¹ H-NMR (400 MHz, CDCl ₃ ): δ 7.26 (d, J = 9.2 Hz, 4H, Py-H5, 9), 7.29 (d, J = 8.72 Hz, 4H, Py-H4) 10), 7.52-7.54 (m, 8H, Py-H1, 3, 6, 8), 7.58-7.62 (m, 2H, Py-H7), 7.66-7.67. (Dd, 4H), 8.10-8.13 (dd, 2H). EI-MS: m / z: calcd. For C ₄₂ H ₂₄ [M ⁺ ] 528.6 Found. 529.

Example 2
Synthesis of 1,8-bis [4- (carbazol-9-N-yl) phenyl] naphthalene (BCzPN)
In a 50 mL three-necked flask, 0.058 g (0.181 mmol) of 1,8-dibromonaphthalene, 0.200 g (0.542 mmol) of 4- (carbazol-9-N-yl) phenylboronic acid pinacol ester, 10 mL of toluene, 5 mL of ethanol Then, 5 mL of 2.0 M K ₂ CO ₃ was added and nitrogen bubbling was performed for 1 hour. Next, 0.042 g (0.036 mmol) of Pd (PPh ₃ ) ₄ was added and stirred at 85 ° C. under a nitrogen stream. After 24 hours, consumption of 1,8-dibromonaphthalene (Rf: 0.38) was confirmed by thin layer chromatography (developing solvent hexane), and then the reaction mixture was returned to room temperature. Next, the organic layer was extracted with toluene, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered and the solvent was distilled off under reduced pressure. Next, hexane was added to recover an insoluble solid. Subsequently, it was separated and purified by silica gel column chromatography (developing solvent toluene) to obtain 0.020 g (yield 18%) of a white solid.
The obtained white solid was confirmed to be BCzPN by EI-Mass spectrum, ¹ H-NMR, and elemental analysis. FIG. 4 shows a chart of the entire ¹ H-NMR, FIG. 5 shows an enlarged chart of aromatic sites, and FIG. 6 shows a chart of EI-Mass spectrum. The results of elemental analysis are shown in Table 1.

Example 3
Synthesis of 1,8-bis [4- (9-phenylanthracen-10-yl) phenyl] naphthalene (BPAPN)
1,8-dibromonaphthalene (100 mg, 0.35 mmol), 9-phenylanthracene-10-boronic acid pinacol ester (472 mg, 1.05 mmol), tris (dibenzylideneacetone) dipalladium [Pd ₂ (dba) ₃ ] ( 32.04 mg, 0.035 mmol), tricyclohexylphosphine (PCy ₃ ) (9.80 mg, 0.035 mmol), 1.35 M-K ₃ PO ₄ aqueous solution (4.0 mL), dioxane (10.0 mL) in a nitrogen atmosphere Reflux for 48 hours under. After cooling to room temperature, water and dichloromethane (200 mL) were added, the organic layer was washed with water, and then dried over anhydrous MgSO ₄ . After column chromatography purification using hexane: dichloromethane (1: 1), recrystallization from hexane gave pale yellow crystals (123 mg, yield 45.0%). The target product was confirmed by ¹ H-NMR and EI-Mass spectrum. FIG. 7 shows an entire chart of ¹ H-NMR, FIG. 8 shows an enlarged chart of aromatic sites, and FIG. 9 shows an EI-Mass spectrum chart.
¹ H-NMR (400 MHz, CDCl ₃ ) δ 8.07 (dd, J = 1.84, 1.84 Hz, 2H), 7.78 (s, 2H), 7.72-7.66 (m, 4H) , 7.59 to 7.51 (m, 8H), 7.46 (d, J = 7.8 Hz, 8H), 7.39 to 7.35 (m, 10H), 7.21 (s, 2H) , 6.62 (s, 2H), 5.85 (s, 2H) ppm. EI-MS: m / z: calcd. For C ₆₂ H ₄₀ [M ⁺ ] 784.98; Found. 785.0.

Example 4
Thermal analysis measurement of BPyN produced in Example 1 was performed. The thermal analysis measurement was carried out by differential scanning calorimetry [Differential-scanning-colorimetry (DSC)] and heat weight loss analysis [Thermogravimetry-analysis (TGA)]. DSC was performed by Perkin-Elmer-Diamond-DSC-Pyris, and TGA was performed by SEIKO-EXSTAR-6000-TG / DTA-6200 in a nitrogen atmosphere at a temperature increase of 10 ° C. min ⁻¹ . The DSC chart is shown in FIG. 10, and the TGA chart is shown in FIG.
From the DSC results, the one corresponding to the melting point was found around 326 ° C., and from the TGA results, it was found that the 5% decomposition start temperature was around 409 ° C.

Example 5
The thermal analysis measurement of BCzPN produced in Example 2 was performed. Thermal analysis measurement was performed by DSC and TGA. The measuring apparatus and measuring method are the same as those in Example 4.
From the DSC results, the one corresponding to the melting point was found around 306 ° C., and from the TGA results, it was found that the 5% decomposition start temperature was around 417 ° C. The DSC chart is shown in FIG. 12, and the TGA chart is shown in FIG.

Example 6
Thermal analysis measurement of BPAPN produced in Example 3 was performed. Thermal analysis measurement was performed by DSC and TGA. The measuring apparatus and measuring method are the same as those in Example 4.
From the DSC results, the one corresponding to the melting point was found around 343 ° C., and from the TGA results, it was found that the 5% decomposition start temperature was around 477 ° C. FIG. 14 shows a DSC chart and FIG. 15 shows a TGA chart.

Example 7
The HOMO value of BPyN produced in Example 1 was determined by atmospheric photoelectron yield spectroscopy. The apparatus used for the measurement is AC-3 manufactured by Riken Keiki Co., Ltd. The resulting chart is shown in FIG.
From FIG. 16, it was found that the value of HOMO was 5.98 eV.

Example 8
The HOMO value of BCzPN produced in Example 2 was determined by photoelectron yield spectroscopy in the atmosphere. The apparatus used for the measurement is AC-3 manufactured by Riken Keiki Co., Ltd. The resulting chart is shown in FIG. From FIG. 17, it was found that the value of HOMO was 5.81 eV.

Example 9
Ultraviolet-visible absorption (UV-vis) and photoluminescence (PL) in a toluene solution (1.0 × 10 ⁻⁵ M) of BPyN prepared in Example 1 and in a thin film state were measured.
Ultraviolet-visible absorption and PL spectrum measurements were performed with a Shimadzu-UV-3150-UV-vis-NIR spectrophotometer and a FLUROMAX-4 (Jobin-Yvon-Spex) fluorescence spectrometer. The measurement results are shown in FIG.
In the annotation of FIG. 18, “UV (solution)” is an ultraviolet-visible absorption spectrum in a toluene solution, “UV (film)” is an ultraviolet-visible absorption spectrum in a thin film state, and “PL (solution)” is A PL spectrum in a solution, “PL (film)” is a PL spectrum in a thin film state, and “PL (pyrene)” is a PL spectrum in a solution of a pyrene monomer.
The ultraviolet-visible absorption spectrum showed a vibration structure characteristic of pyrene monomer at 300 to 350 nm (λmax = 335 nm), while the fluorescence spectrum did not show a vibration structure peculiar to pyrene monomer. The maximum emission wavelength is shifted to a wavelength longer by 486 nm than the emission of pyrene monomer, and this emission is derived from pyrene excimer. Absorption in the thin film showed a broad band at 250 to 450 nm, and the wavelength shifted by about 10 nm compared to the solution. The maximum emission wavelength in the fluorescence spectrum was 492 nm, and the emission of pyrene excimer was similar to that of a dilute solution.

Example 10
The measurement of UV-visible absorption (UV-vis) and photoluminescence (PL) in the methylene chloride solution (1.0 × 10 ⁻⁵ M) of BCzPN prepared in Example 2 and in the form of a thin film is the same as in Example 6. The measurement was performed using a measuring instrument. The measurement results are shown in FIG.
In the annotation of FIG. 19, “UV (solution)” indicates an ultraviolet-visible absorption spectrum in dichloromethane, and “UV (film)” indicates an ultraviolet-visible absorption spectrum in a thin film form. “PL (solution)” indicates a PL spectrum in dichloromethane, and “PL (film)” indicates a PL spectrum in a thin film form. “PL (9-phenylcarbazole)” indicates a PL spectrum in a 9-phenylcarbazole solution.
As can be seen from FIG. 19, the maximum emission wavelength is shifted to 404 nm longer than the emission of 347 nm of 9-phenylcarbazole, and this emission is derived from the excimer of phenylcarbazole.

Example 11
The same measurement equipment as in Example 6 was used to measure UV-visible absorption (UV-vis) and photoluminescence (PL) in a THF solution of BPAPN prepared in Example 3 (1.0 × 10 ⁻⁵ M). I went. The measurement results are shown in FIG.
In the annotation of FIG. 20, “UV (solution)” indicates an ultraviolet-visible absorption spectrum in THF. “PL (solution)” indicates a PL spectrum in THF. “PL (9,10-diphenylanthracene)} indicates a PL spectrum in a 9,10-diphenylanthracene solution.
As can be seen from FIG. 20, the absorption derived from the vibration structure of the diphenylanthracene skeleton was shown at 300 to 400 nm. In the fluorescence spectrum, the vibration structure disappeared and a peak shifted by 17 nm longer wavelength than that of 9,10-diphenylanthracene was shown at 427 nm.

Examples 12-13
A film obtained by doping BPyN prepared in Example 1 into PMMA (polymethylmethacrylic acid) (Example 12) and MADN represented by the following formula [2-methyl-9,10-bisnaphthalen-2-yl) anthracene] A film doped with (Example 13) was prepared, and the fluorescence quantum yield of BPyN was measured. The measuring device used was an integrating sphere manufactured by Hamamatsu Photonics. The dope concentrations were 1 wt%, 3 wt%, and 5 wt%. The results in the PMMA thin film are shown in Table 2, and the results in the MADN co-deposited film are shown in Table 3.

Examples 14-15
An organic EL device using BPyN produced in Example 1 as a non-doped light emitting layer was produced. The element structure is shown in FIG. The element configuration is as follows, and each uses a glass substrate.
Example 14: ITO (anode) / α-NPD (hole transport layer, 40 nm) / BPyN (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 1 nm) / Al (cathode, 80nm)
Example 15: ITO (anode) / TAPC (hole transport layer, 40 nm) / BPyN (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 20 nm) / LiF (electron injection layer, 1 nm) / Al (cathode, 80 nm)
For the electron transport layer, BmPyPB [3,3 ", 5,5" -tetra (pyridin-3-yl) 1,1 ', 3', 1 "-terphenyl] represented by the following formula was used.
FIG. 22 shows the current density-voltage characteristics of each element, FIG. 23 shows the brightness-voltage characteristics, FIG. 24 shows the power efficiency-luminance characteristics, FIG. 25 shows the current efficiency-luminance characteristics, and FIG. 25 shows the external quantum efficiency-luminance characteristics. 26 shows the EL spectrum of Example 14, and FIG. 28 shows the EL spectrum of Example 15.
Table 4 shows the voltage, power efficiency, current efficiency, and external quantum efficiency at 100 cd / m ² and 1000 cd / m ² of each element.

Example 16, Comparative Example 1
Using BPyN produced in Example 1 as a host material, a thin film doped with 1 wt%, 3 wt% and 5 wt% of a green fluorescent dopant C545T represented by the following formula was produced, and the fluorescence quantum yield was measured. For comparison, a thin film was prepared using MADN [2-methyl-9,10-bisnaphthalen-2-yl) anthracene] as the host material. Table 5 shows the measurement results.
The BPyN host showed higher PLQE (fluorescence quantum yield) than the MADN host. In particular, a high superiority was shown in the heavily doped region at 5 wt%.

Examples 17-20
An organic EL device having a light emitting layer doped with green fluorescent dopant C545T using BPyN produced in Example 1 as a host material was produced. Materials with different dope concentrations and film thicknesses (Examples 17 to 20) were produced as follows. Their device structures are shown in FIG. The element configuration is as follows, and each uses a glass substrate.
Example 17: ITO (anode) / α-NPD (hole transport layer, 40 nm) / BPyN: 1 wt% C545T (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 1 nm) / Al (cathode, 80 nm)
Example 18: ITO (anode) / α-NPD (hole transport layer, 40 nm) / BPyN: 3 wt% C545T (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 1 nm) / Al (cathode, 80 nm)
Example 19: ITO (anode) / α-NPD (hole transport layer, 40 nm) / BPyN: 5 wt% C545T (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 1 nm) / Al (cathode, 80 nm)
Example 20: ITO (anode) / TAPC (hole transport layer, 40 nm) / BPyN: 5 wt% C545T (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 1 nm) / Al ( Cathode, 80nm)
FIG. 30 shows the current density-voltage characteristics of each element, FIG. 31 shows the brightness-voltage characteristics, FIG. 32 shows the power efficiency-luminance characteristics, FIG. 33 shows the current efficiency-luminance characteristics, and FIG. 33 shows the external quantum efficiency-luminance characteristics. FIG. 34 shows the EL spectrum in FIG.
Table 6 shows the voltage, power efficiency, current efficiency, and external quantum efficiency at 100 cd / m ² and 1000 cd / m ² of each element.
In Example 20 using TAPC as the HTL, the external quantum efficiency exceeds 6%, and it can be seen that the monomolecular excimer molecule BPyN shows extremely high utility as a host material. Most of the known green fluorescent host materials have a 9,10-diphenylanthracene skeleton, and BPyN is a novel non-anthracene host material.

Examples 21-23
An organic EL element using BCzPN produced in Example 2 as a light emitting material for a light emitting layer was produced. Their element structures are shown in FIG. The element configuration is as follows, and each uses a glass substrate.
Example 21: ITO (anode) / TAPC (hole transport layer, 40 nm) / BCzPN (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 0.5 nm) / Al (cathode, 80nm)
Example 22: ITO (anode) / TAPC (hole transport layer, 40 nm) / BCzPN (light emitting layer, 10 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 0.5 nm) / Al (cathode, 80nm)
Example 23: ITO (anode) / TAPC (hole transport layer, 45 nm) / BCzPN (light emitting layer, 5 nm) / BmPyPB (electron transport layer, 45 nm) / LiF (electron injection layer, 0.5 nm) / Al (cathode, 80nm)
37 shows current density-voltage characteristics in each element, brightness-voltage characteristics in FIG. 38, power efficiency-luminance characteristics in FIG. 39, current efficiency-luminance characteristics in FIG. 40, and external quantum efficiency-luminance characteristics. FIG. 41 shows the EL spectrum in FIG.
Table 7 shows the voltage, power efficiency, current efficiency, external quantum efficiency, and chromaticity coordinate value (CIE) at 1 cd / m ² and 100 cd / m ² of each element.

Example 21 showed the maximum emission wavelength at 412 nm, and Example 22 and Example 23 showed the maximum emission wavelength at 402 nm. In Example 22, the CIE value (0.170, 0.045) showed deep blue light emission. From these results, it can be seen that the single-molecule excimer molecule BCzPN exhibits high utility as a blue organic EL material.

Example 24
Blue fluorescent light-emitting material 4,4′-bis {[4-di (p-tolyl) aminophenyl] β-ethenyl} -1,1′-biphenyl represented by the following formula using BCzPN produced in Example 2 as a host material An organic EL element having a light emitting layer doped with 6 wt% of (DPAVBi) was produced. The element structure is shown in FIG.
The element configuration is as follows, and each uses a glass substrate.
Example 24: ITO (anode) / TAPC (hole transport layer, 40 nm) / BCzPN: 6 wt% DPAVBi (light emitting layer, 20 nm) / BmPyPB (electron transport layer, 40 nm) / LiF (electron injection layer, 0.5 nm) / Al (cathode, 80 nm)
FIG. 44 shows current density-voltage characteristics of this element, FIG. 45 shows luminance-voltage characteristics, FIG. 46 shows power efficiency-luminance characteristics, FIG. 47 shows current efficiency-luminance characteristics, and FIG. 47 shows external quantum efficiency-luminance characteristics. 48 shows the EL spectrum in FIG.
Table 8 shows the voltage, power efficiency, current efficiency, and external quantum efficiency at 1 cd / m ² , 100 cd / m ^2, and 1000 cd / m ² .

  The organic EL device of the present invention can be usually used as a direct current drive device. When a DC voltage is applied, light emission is usually observed when about 1.5 to 20 V is applied with the positive polarity of the anode and the negative polarity of the cathode. The organic EL element of the present invention can also be used as an AC drive element. When an AC voltage is applied, light is emitted when the anode is in a positive state and the cathode is in a negative state. The organic EL element of the present invention includes, for example, a flat light emitter such as an electrophotographic photosensitive member and a flat panel display, a copying machine, a printer, a backlight of a liquid crystal display, a light source such as an instrument, various light emitting elements, various display devices, various signs, It can be used for various sensors and various accessories.

1 Substrate 2 Anode (ITO)
DESCRIPTION OF SYMBOLS 3 Light emitting layer 4 Cathode 5 Hole transport layer 6 Electron transport layer 7 Hole injection layer 8 Electron injection layer 9 Hole block layer

Claims (4)

An organic EL device using a 1,8-aryl-substituted naphthalene derivative having excimer characteristics represented by the following general formula (1).
Wherein R ^{1 to} R ⁵ are hydrogen, deuterium, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms, or alkylamino A group independently selected from the group consisting of a group, fluorine and an acetoxy group, wherein Ar is a pyrenyl group represented by the following formula, 4- (9-N-carbazolyl) phenyl group, 4- [10- ( 9-phenyl) anthranyl] phenyl group, R ^{6 to} R ¹⁴ are hydrogen, deuterium, fluorine, a linear or branched alkyl group having 1 to 4 carbon atoms, and the alkyl moiety is a straight chain having 1 to 4 carbon atoms. are each independently a group selected from the group consisting of alkylamino group is a chain or branched alkyl group, R ¹⁵ to R ⁴³ are hydrogen, deuterium, fluorine, linear or branched aralkyl of 1 to 4 carbon atoms From the group consisting of Le group are each independently selected groups.)
  2. The organic EL device according to claim 1, wherein the 1,8-aryl substituted naphthalene derivative is used as a light emitting material of a light emitting layer.   The organic EL device according to claim 1, wherein the 1,8-aryl-substituted naphthalene derivative is used as a host material of a light emitting layer. 1,8-aryl substituted naphthalene derivative represented by the following general formula (1).

Wherein R ^{1 to} R ⁵ are hydrogen, deuterium, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group in which the alkyl portion is a linear or branched alkyl group having 1 to 4 carbon atoms, or alkylamino A group independently selected from the group consisting of a group, fluorine and an acetoxy group, wherein Ar is a 4- (9-N-carbazolyl) phenyl group represented by the following formula, 4- [10- (9-phenyl); ) Anthranyl] phenyl group, and R ^{15 to} R ⁴³ are groups independently selected from the group consisting of hydrogen, deuterium, fluorine, and linear or branched alkyl groups having 1 to 4 carbon atoms. .)