`
`(19) Japan Patent Office (JP)
`
`(12) Japanese Unexamined Patent
`Application Publication (A)
`
`
`(11) Japanese Unexamined Patent
`Application Publication Number
`2000-53956
`(P2000-53956A)
`(43) Publication date February 22, 2000 (2000.2.22)
`Theme codes (reference)
` FI
` C09K 11/06 650 3K007
` H05B 33/14 B
`
`
`
`
`Request for examination Not yet requested Number of claims 4 OL (Total of 13 pages)
`
`(51) Int. Cl.7
` C09K 11/06
` H05B 33/14
`
`
`
`
`
`
`Identification codes
`650
`
`(21) Application number
`
`(22) Date of application
`
`
`Japanese Patent Application
`H10-225504
`August 10, 1998 (1998.8.10)
`
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`
`
`
`
`
`
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`
`
`(71) Applicant
`
`(72) Inventor
`
`(72) Inventor
`
`F terms
`(reference)
`
`000222118
`Toyo Ink Co., Ltd.
`3-13 Kyobashi 2-chome, Chuo-ku, Tokyo
`MICHIKO TAMANO
`℅ Toyo Ink Co., Ltd.
`3-13 Kyobashi 2-chome, Chuo-ku, Tokyo
`SHUNICHI ONIKUBO
`℅ Toyo Ink Co., Ltd.
`3-13 Kyobashi 2-chome, Chuo-ku, Tokyo
`3K007 AB00 AB02 AB03 AB06 CA01
`
`
`CB01 DA00 DA01 DB03 EB00
`
`
`FA01
`
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`
`(54) (TITLE OF THE INVENTION) Luminescent material for organic electroluminescent element and organic
`electroluminescent element using the same
`
`(57) (ABSTRACT)
`(PROBLEM) Provide an organic EL element that has high
`luminous intensity and is very stable during repeat use.
`(MEANS FOR SOLVING) Luminescent material for organic
`electroluminescent element indicated by general formula
`[1].
`General formula [1]
`(CHEMICAL FORMULA 1)
`
`alkoxy group, substituted or unsubstituted allyloxy group,
`substituted or unsubstituted alkylthio group, substituted or
`unsubstituted allylthio group, substituted or unsubstituted
`allyl group (but 2 or more of R1-R6 indicate –NR7R8.).]
`
`
`
`
`
`
`[Where R1-R6 each independently stand for –NR7R8 (R7
`and R8 indicate a substituted or unsubstituted alkyl group or
`substituted or unsubstituted allyl group and R7 and R8 may
`be a single unit.), hydrogen atom, halogen atom, substituted
`or unsubstituted alkyl group, substituted or unsubstituted
`
`
`
`RHEMK-1005.001
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(2)
`
`(SCOPE OF PATENT CLAIMS)
`organic
`for
`1)
`Luminescent material
`(CLAIM
`electroluminescent element indicated by general formula
`[1] below.
`General formula [1]
`(CHEMICAL FORMULA 1)
`
`
`[Where R1-R6 each independently stand for –NR7R8 (R7
`and R8 indicate a substituted or unsubstituted alkyl group or
`substituted or unsubstituted allyl group and R7 and R8 may
`be a single unit.), hydrogen atom, halogen atom, substituted
`or unsubstituted alkyl group, substituted or unsubstituted
`alkoxy group, substituted or unsubstituted allyloxy group,
`substituted or unsubstituted alkylthio group, substituted or
`unsubstituted allylthio group, substituted or unsubstituted
`allyl group (but 2 or more of R1-R6 indicate –NR7R8.).]
`(CLAIM 2) Luminescent material set forth in claim 1,
`wherein at least R3 and R6 in general formula [1] or at least
`R1 and R4 are –NR7R8.
`(CLAIM
`organic
`for
`3)
`Luminescent material
`electroluminescent element comprised of host material and
`compound indicated by the aforesaid general formula [1].
`(CLAIM 4) Organic electroluminescent element having a
`plurality of organic compound thin films including a
`luminescent layer formed between a pair of electrodes,
`wherein
`the
`luminescent
`layer
`is
`an
`organic
`electroluminescent element consisting of a layer containing
`the luminescent material for organic electroluminescent
`element set forth in any one of claims 1-3.
`(DETAILED DESCRIPTION OF THE INVENTION)
`(0001)
`(FIELD OF INDUSTRIAL APPLICATION) This invention relates
`to a luminescent material for organic electroluminescent
`(EL) element used in a flat surface light source or for
`display, and a high-intensity luminescent element.
`(0002)
`(PRIOR ART) EL elements using organic substances have
`been deemed promising for applications in inexpensive
`solid-state luminescent-type large-area full-color display
`elements, and many have been developed. Typically, an EL
`element is comprised of a luminescent layer and a pair of
`counter electrodes on either
`side of
`said
`layer.
`Luminescence is a phenomenon that is produced when an
`electric field is applied between both electrodes, causing
`electrons to be injected from the cathode side and a positive
`hole to be injected from the anode side. These electrons
`then recombine with the positive hole in the luminescent
`layer, emitting light as energy when the energy level
`returns from the conduction band to the valence band.
`(0003) In comparison with inorganic EL elements, prior-art
`organic EL elements had high driving voltage and low
`luminous intensity and luminous efficiency. Furthermore,
`they were not suited to practical use as they underwent
`significant property degradation. In recent years, the
`announcement of an organic EL element comprised of a
`
`
`
`laminated thin film containing organic compound having
`high fluorescent quantum efficiency that is able to emit
`light at low voltages of 10V or less has attracted
`considerable attention (see Applied Physics Letters, Vol. 51,
`page 913, 1987). This method has produced high-intensity
`green emission using a metal chelate complex as the
`luminescent layer and an amine-based compound as the
`positive hole injection layer, having attained intensity of
`several 1000cd/m2 at DC voltage of 6-7V and a maximum
`luminous efficiency of 1.51m/W, which is close to
`practicable performance.
`(0004) However, although the luminous strength of organic
`EL elements has by now been increased through structural
`improvements, luminous intensity remains inadequate.
`Furthermore, a significant problem with these is that they
`are not stable over repeat use. The reason for this is that
`metal chelate complexes such as, for example, tris(8-
`hydroxyquinolinate) aluminum complex, are chemically
`unstable in the presence of electroluminescence, and have
`poor adhesion to the cathode, causing them to degrade
`significantly after several hours of illumination. For the
`above reasons, there has been demand for the development
`of a durable luminescent material that has superior
`luminous performance to aid in the development of an
`organic EL element that has good luminous intensity and
`luminous efficiency and is stable over repeat use.
`(0005)
`(PROBLEM TO BE SOLVED BY THE INVENTION) This invention
`has as its objective to provide an organic EL element that
`has strong luminous intensity and is stable over repeat use.
`The inventors discovered this invention upon conducting
`painstaking researched and learning that an organic EL
`element using the luminescent material for organic EL
`element indicated in general formula [1] as the luminescent
`layer has high luminous intensity and luminous efficiency
`and is stable over repeat use.
`(0006)
`(MEANS OF SOLVING THE PROBLEM) This invention relates to
`the luminescent material for organic electroluminescent
`element indicated by general formula [1] below.
`General formula [1]
`(0007)
`(CHEMICAL FORMULA 2)
`
`
`(0008)
`[Where R1-R6 each independently stand for –NR7R8 (R7
`and R8 indicate a substituted or unsubstituted alkyl group or
`substituted or unsubstituted allyl group and R7 and R8 may
`be a single unit.), hydrogen atom, halogen atom, substituted
`or unsubstituted alkyl group, substituted or unsubstituted
`alkoxy group, substituted or unsubstituted allyloxy group,
`substituted or unsubstituted alkylthio group, substituted or
`unsubstituted allylthio group, substituted or unsubstituted
`
`RHEMK-1005.002
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(3)
`
`group, 4-cyclohexylbiphenyl group[,] terphenyl group, 3,5-
`dichlorophenyl group, naphthyl group, 5-methylnaphthyl
`group, anthryl group or pyrenyl group, and furthermore the
`aromatic carbon atoms in the allyl group may be substituted
`by a nitrogen atom, oxygen atom and/or sulfur atom.
`Examples of allyl groups of this kind include a furanyl
`group, thiophenyl group, pyrrole group, pyranyl group,
`thiopyranyl group, pyridinyl group,
`thiazolyl group,
`imidazolyl group, pyrimidinyl group, pyridinyl group,
`triazinyl group, indolinyl group, quinolyl group or purinyl
`group.
`(0013) Examples of a substituted or unsubstituted allyloxy
`group include a phenoxy group, p-nitrophenoxy group, p-
`tert-butylphenoxy
`group,
`3-fluorophenoxy
`group,
`pentafluorophenyl group or 3-trifluoromethylphenoxy
`group, while examples of an allylthio group include a
`phenylthio
`group,
`p-nitrophenylthio
`group,
`p-tert-
`butylphenylthio
`group,
`3-fluorophenylthio
`group,
`pentafluorophenylthio
`group
`or
`3-
`trifluoromethylphenylthio group.
`(0014) Examples of the alkylamino group in –NR7R8 of the
`compound expressed by general formula [1] in this
`invention (where R7 and R8 indicate a substituted or
`unsubstituted alkyl group or substituted or unsubstituted
`allyl group) include a dimethylamino group, diethylamino
`group,
`dipropylamino
`group,
`dibutylamino
`group,
`benzylamino group or dibenzylamino group, while
`examples
`of
`the
`allylamino
`group
`include
`a
`phenylmethylamino
`group,
`diphenylamino
`group,
`ditrylamino
`group,
`dibiphenylamino
`group,
`di(4-
`methylbiphenyl)amino group, di(3-methylphenyl)amino
`group,
`di(4-methylphenyl)amino
`group,
`naphthylphenylamino
`group
`or
`bis[4-(α,α’-
`dimethylbenzyl)phenyl]amino group.
`(0015) Furthermore, R7 and R8 may be integrated to form a
`saturated or unsaturated ring such as a morpholine ring,
`piperazine ring, piperidine ring, benzopiperazine ring,
`acridine ring, phenazine ring, pyrenyl ring, carbazole ring,
`benzopyranyl ring, xanthene ring, thiazolyl ring, thiazine
`ring or phanothiazine ring.
`(0016) Among these compounds, compounds of the kind
`expressed by general formula [1] having a substituted
`group containing an allyl group increase the glass transition
`point and melting point, improving resistance to Joule heat
`(thermostability) produced within
`the organic
`layer,
`between organic layers or between the organic layer and
`the metal electrode layer during electroluminescence, for
`which reason it exhibits high luminous intensity when used
`as luminescent material in an organic EL element, which is
`also advantageous when performing
`illumination for
`extended periods of time. The compound in this invention
`
`allyl group (but 2 or more of R1-R6 indicate –NR7R8.).]
`(0009) Furthermore, this invention relates to the aforesaid
`luminescent material wherein at least R3 and R6 in general
`formula [1] or at least R1 and R4 are –NR7R8. Furthermore,
`this invention relates to a luminescent material for organic
`electroluminescent element comprised of host material and
`compound indicated by the aforesaid general formula [1].
`Furthermore,
`this
`invention
`relates
`to an organic
`electroluminescent element having a plurality of organic
`compound thin films including a luminescent layer formed
`between a pair of electrodes, wherein the luminescent layer
`is an organic electroluminescent element consisting of a
`layer containing the aforesaid luminescent material for
`organic electroluminescent element.
`(0010)
`(EMBODIMENTS OF THE INVENTION) R1-R6 in the compound
`indicated by general formula [1] of this invention each
`independently stand for –NR7R8 (R7 and R8 indicate a
`substituted or unsubstituted alkyl group or substituted or
`unsubstituted allyl group and R7 and R8 may be a single
`unit.), hydrogen atom, halogen atom, substituted or
`unsubstituted alkyl group, substituted or unsubstituted
`alkoxy group, substituted or unsubstituted allyloxy group,
`substituted or unsubstituted alkylthio group, substituted or
`unsubstituted allylthio group, substituted or unsubstituted
`allyl group. However, 2 or more of R1-R6 indicate –NR7R8.
`Furthermore, it is desirable that at least R3 and R6 or R1 and
`R4 are –NR7R8.
`include fluorine,
`these
`(0011) Specific examples of
`chlorine, bromine and iodine as halogen atoms, and an
`unsubstituted alkyl group with 1-20 carbons such as a
`methyl group, ethyl group, propyl group, butyl group, sec-
`butyl group, tert-butyl group, pentyl group, hexyl group,
`heptyl group, octyl group or stearyl group or a substituted
`alkyl group with 1-20 carbons such as a 2-phenylisopropyl
`group, trichloromethyl group, trifluoromethyl group, benzyl
`group, α-phenoxybenzyl, α,α-dimethylbenzyl group, α,α-
`methylphenylbenzyl group, α,α-ditrifluoromethylbenzyl
`group, triphenylmethyl group or α-benzyloxybenzyl group
`as a substituted or unsubstituted alkyl group. Additionally,
`adjoining alkyl groups may be fused to form a cycloalkyl
`ring.
`(0012) Examples of substituted or unsubstituted alkoxyl
`groups include unsubstituted alkoxyl groups with 1-20
`carbons such as a methoxy group, ethoxy group, propoxy
`group, n-butoxy group, t-butoxy group, n-octyloxy group or
`t-octyloxy group and substituted alkoxy groups with 1-20
`carbons such as a 1,1,1-tetrafluoroethoxy group, phenoxy
`group, benzyloxy group or octylphenoxy group, while
`examples of substituted or unsubstituted alkylthio groups
`include a methylthio group, ethylthio group, tert-butylthio
`group,
`hexylthio
`group,
`octylthio
`group
`or
`trifluoromethylthio group, examples of substituted or
`unsubstituted
`allyl groups
`include
`substituted or
`unsubstituted allyl groups with 6-18 aromatic carbons such
`as a phenyl group, 2-methylphenyl group, 3-methylphenyl
`group, 4-methylphenyl group, 4-ethylphenyl group,
`biphenyl group, 4-methylbiphenyl group, 4-ethylbiphenyl
`
`
`
`RHEMK-1005.003
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(4)
`
`(0020)
`
`Compound
`
`Chemical structure
`
`is not limited to these substituted groups.
`(0017) In this invention, the compound indicated by
`general formula [1] can be synthesized by, for example, a
`method of the kind described below. The aromatic amine
`compound indicated by general formula [1] can be
`synthesized
`by
`reacting
`dibromoquinoxaline
`or
`diiodoquinoxaline and aromatic diamine compound in
`nitrobenzene solvent together with a catalyst such as
`potassium carbonate or copper for 50 hours at 200°C.
`Alternately, diaminoquinoxaline and halogen-substituted
`allyl derivative can similarly be synthesized by reacting in
`1,3-dimethyl-2-imidazolidinone using potassium carbonate
`or copper catalyst. It is acceptable to use sodium carbonate,
`sodium hydroxide or
`the
`like
`instead of potassium
`carbonate. Examples of catalysts include copper powder,
`cuprous chloride, tin, stannous chloride, etc. Examples of
`solvents
`include
`N,N-dimethylformamide,
`dimethylsulfoxide, etc.
`(0018) Representative examples of the compound indicated
`by general formula [1] will be indicated specifically in
`Table 1, although these examples are not exclusive.
`(0019)
`(TABLE 1)
`
`Compound
`
`Chemical structure
`
`(0021)
`
`
`
`
`
`
`
`RHEMK-1005.004
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(5)
`
`Compound
`
`Chemical structure
`
`(0022)
`
`
`
`
`
`RHEMK-1005.005
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(6)
`
`Compound
`
`Chemical structure
`
`(0023)
`
`
`
`
`
`RHEMK-1005.006
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(7)
`
`Compound
`
`Chemical structure
`
`(0024)
`
`
`
`
`
`RHEMK-1005.007
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(8)
`
`Compound
`
`Chemical structure
`
`Compound
`
`Chemical structure
`
`(0025)
`
`
`
`
`(0026) An organic EL element is an element having one or
`more layers of organic compound thin film formed between
`the anode and the cathode. In the case of a single-layer type,
`a luminescent layer is provided between the anode and the
`cathode. The
`luminescent
`layer contains
`luminescent
`material, and may also contain positive hole injection
`material or electron injection material for the purpose of
`transporting a positive hole injected from the anode or
`electrons injected from the cathode to the luminescent
`material. A multi-layer type is an organic EL element
`having a multi-layer
`laminate
`structure
`such as
`(anode/positive
`hole
`injection
`layer/luminescent
`layer/cathode), (anode/luminescent layer/electron injection
`layer/cathode),
`(anode/positive
`hole
`injection
`layer/luminescent layer/electron injection layer/cathode).
`The compound indicated by general formula [1] in this
`invention has excellent electroluminescent property
`because it is a compound that exhibits strong fluorescence
`in the solid state, for which reason it can be used within the
`luminescent layer as a luminescent material. Furthermore,
`by doping the compound in general formula [1] into the
`luminescent layer in an proportion optimal for doping
`material in the luminescent layer, it is possible to achieve
`high luminous efficiency and select the optimal luminous
`wavelength. Here,
`the positive hole
`injection
`layer,
`luminescent layer or electron injection layer may each be
`formed into two or more layers.
`(0027) Using the compound in general formula [1] as
`doping material (guest material) in the host material of the
`luminescent layer also makes it possible to obtain an
`organic EL element with high luminous intensity. The
`
`
`
`RHEMK-1005.008
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(9)
`
`compound in general formula [1] should desirably be
`contained within the luminescent layer in a proportion
`relative to the host material within a range of 0.001 wt% to
`50 wt%; in particular, a range of 0.01 wt% to 10 wt% is
`effective.
`(0028) Host materials that can be used together with the
`compound in general formula [1] include quinoline metal
`complex, oxadiazole, benzothiazole metal complex,
`benzooxazole metal complex, benzoimidazole metal
`complex, triazole, imidazole, oxazole, oxadiazole, stilbene,
`butadiene, benzidine-type triphenylamine, styrylamine-type
`triphenylamine, diamine-type triphenylamine fluorenone,
`diaminoanthracene-type
`triphenylamine,
`diaminophenanthrine-type
`triphenylamine,
`anthraquinodimethane,
`diphenoquinone,
`thiadiazole,
`tetrazole, perylenetetracarboxylic acid,
`flared Oreni
`alkylidene methane, anthraquinodimethane, triphenylene,
`anthrone, etc., and derivatives thereof, as well as polymer
`materials
`such
`as
`polyvinylcarbazole,
`polysilane,
`conductive polymer, etc.
`(0029) It is also possible to change the illumination color
`using another doping material together with general
`formula [1]. Doping materials that can be used together
`with general formula [1] include anthracene, naphthalene,
`phenanthrene, pyrene,
`tetracene, coronene, chrysene,
`fluorescein, perylene, phthaloperylene, naphthaloperylene,
`perinone,
`phthaloperinone,
`naphthaloperinone,
`diphenylbutadiene,
`tetraphenylbutadiene,
`coumarin,
`oxadiazole,
`aldazine,
`bis-benzoxazoline,
`bis-styryl,
`pyrazine, cyclopentadiene, quinoline metal complex,
`aminoquinoline metal complex, imine, diphenylethylene,
`vinylanthracene, diaminocarbazole, pyran,
`thiopyran,
`polymethyl, merocyanine,
`imidazole chelated oxinoid
`compound, quinacridone, rubrene, etc., and derivatives
`thereof, but are not limited to these.
`(0030) If necessary, positive hole injection material and
`electron injection material may be used in the luminescent
`layer in addition to luminescent material and doping
`material.
`(0031) The organic EL element is able to prevent decline in
`intensity and life arising from quenching due to its multi-
`layer structure. Furthermore, if necessary, it is also possible
`to combine two or more types of luminescent material,
`doping material, or positive hole injection material or
`electron injection material that performs carrier injection.
`Furthermore, the positive hole injection layer, luminescent
`layer and electron injection layer may each be formed from
`a layer structure with two or more layers, and an element
`structure in which the positive hole or electron is efficiently
`injected from the electrode and transported into the layer is
`selected.
`(0032) The conductive material used in the anode of the
`organic EL element should ideally have a work function
`greater than 4eV, with carbon, aluminum, vanadium, iron,
`cobalt, nickel, tungsten, silver, gold, platinum, palladium,
`etc., or alloys thereof, tin oxides called ITO substrate or
`NESA substrate, oxide metal such as indium oxide, or
`organic conductive resin such as polythiophene or
`polypyrrole, etc. being capable of being used for this
`purpose. The conductive material used in the cathode
`should ideally have a work function smaller than 4eV, with
`
`magnesium, calcium, tin, lead, titanium, yttrium, lithium,
`ruthenium, manganese, etc., or alloys thereof, being
`capable of being used for this purpose. Magnesium/silver,
`magnesium/indium, lithium/aluminum, etc. can be cited as
`representative examples of alloys, but the alloys are not
`restricted to these. The ratio of the alloy is controlled by
`heating temperature, atmosphere and degree of vacuum,
`and can be appropriately selected. The anode and cathode
`may, if necessary, be formed into a layer structure with two
`or more layers.
`(0033) In order to effectively illuminate the organic EL
`element, it is desirable for at least one to have adequate
`transparency
`in
`the
`luminous wavelength
`region.
`Furthermore, it is also desirable for the substrate to be
`transparent. Using the aforesaid conductive material, the
`transparent electrode is set in such a way as to attain a
`designated transparency by a method such as deposition or
`sputtering. The electrode for the luminescent surface should
`desirably be made to have a light transmittance of 10% or
`greater. There is no restriction on the substrate as long as it
`has mechanical and thermal strength and is transparent, but
`to cite examples that can be used, a glass substrate or
`transparent resin such as polyethylene sheet, polyether
`sulphone sheet, polypropylene sheet, etc., may be used.
`(0034) Formation of each layer of the organic EL element
`in this invention can be performed by any dry deposition
`method such as vacuum deposition or sputtering or wet
`deposition method such as spin coating or dipping. There is
`no particular restriction on the film thickness, but each
`layer must be set to an appropriate film thickness. If the
`film thickness is excessive, it will be necessary to apply
`large voltage to obtain fixed light output, which will impair
`efficiency. If the film thickness is inadequate, pinholes and
`the like will occur, rendering it impossible to obtain
`adequate luminous intensity even when an electric field is
`applied. Although typically a thickness of within the range
`of 5nm to 10μm is suitable, a thickness within the range of
`10nm to 0.2μm is even more suitable.
`(0035) In the case of a wet deposition method, the thin film
`is formed by dissolving or dispersing the material from
`which each layer is to be formed in an appropriate solvent
`such as chloroform, tetrahydrofurane, dioxane, etc., but any
`of these solvents is acceptable. Furthermore, irrespective of
`the thin film, it is acceptable towards the aim of improving
`formability to use any appropriate resin or additive to
`prevent the formation of pinoles in the film, etc. Examples
`of this kind of resin that can be cited include insulating
`resins such as polystyrene, polycarbonate, polyarylate,
`polyester,
`polyamide,
`polyurethane,
`polysulfone,
`polymethylmethacrylate, polymethylacrylate, cellulose, etc.,
`photoconductive resins such as poly-N-vinylcarbazole,
`polysilane,
`etc.,
`and
`conductive
`resins
`such
`as
`polythiophene, polypyrrole, etc. Examples of additives that
`can be cited include antioxidant, UV absorber, plasticizer,
`etc.
`(0036) Compounds that can be used for the positive hole
`injection material should have the ability to inject a positive
`hole, should have excellent positive hole injection effect
`against the luminescent layer or luminescent material,
`should prevent transfer of excitons produced in the
`luminescent layer to the electron injection layer or electron
`injection material, and should have good
`thin film
`
`
`
`RHEMK-1005.009
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(10)
`
`formation ability. Specifically, this includes phthalocyanine
`compounds, naphthalocyanine compounds, porphyrin
`compounds, oxadiazole, triazole, imidazole, imidazolone,
`imidazole
`thion,
`pyrazoline,
`pyrazolone,
`tetrahydroimidazole, oxazole, oxadiazole, hydrazone,
`acylhydrazone,
`polyarylalcane,
`stilbene,
`butadiene,
`benzidine-type
`triphenylamine,
`styrylamine-type
`triphenylamine, diamine-type
`triphenylamine, etc., or
`derivatives thereof, as well as polymer materials such as
`polyvinylcarbazole, polysilane, conductive polymer, etc.,
`but are not limited to these.
`(0037) Among the positive hole injection materials that can
`be used in the organic EL element in this invention, an even
`more effective positive hole injection material is an
`aromatic
`tertiary amine derivative or phthalocyanine
`derivative. Specifically,
`this
`includes
`triphenylamine,
`tritolylamine,
`tolyldiphenylamine, N,N’-diphenyl-N,N’-
`di(3-methylphenyl)-1,1’-biphenyl-4,4’-diamine,
`N,N,N’,N’-tetra(4-methylphenyl)-1,1’-biphenyl-4,4’-
`diamine, N,N,N’,N’-tetra(4-methylphenyl)-1,1’-biphenyl-
`4,4’-diamine,
`N,N’-diphenyl-N,N’-dinaphthyl-1,1’-
`biphenyl-4,4’-diamine, N,N’-di(methylphenyl)-N,N’-di(4-
`n-butylphenyl)-phenanthrene-9,10-diamine,
`1,1-bis[N,N-
`di(tolylamino)phenyl]cyclohexane, etc., or an oligomer or
`polymer, etc., of the same having an aromatic tertiary
`amine
`framework, but are not
`limited
`to
`these.
`Phthalocyanine (Pc) derivatives include phthalocyanine
`derivatives and naphthalocyanine derivatives such as H2Pc,
`CuPc, CoPc, NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc,
`ClGaPc, ClInPc, ClSnPc, Cl2SiPc, (HO)AlPc, (HO)GaPc,
`VOPc, TiOPc, MoOPc, GaPc-O-GaPc, etc., but are not
`limited to these.
`(0038) Compounds that can be used for the electron
`injection material should have the ability to inject electrons,
`should have excellent electron injection effect against the
`luminescent layer or luminescent material, should prevent
`transfer of excitons produced in the luminescent layer to
`the positive hole injection layer or positive hole injection
`material, and should have good thin film formation ability.
`For example, these include quinoline metal complex,
`oxadiazole, benzothiazole metal complex, benzooxazole
`metal complex, benzoimidazole metal complex, fluorenone,
`anthraquinodimethane, diphenoquinone, thiopyran dioxide,
`oxadiazole, thiadiazole, tetrazole, perylenetetracarboxylic
`acid, flared Oreni alkylidene methane,
`
`anthraquinodimethane, anthrone, etc., or derivatives thereof,
`but are not limited to these. Furthermore, an electron-
`accepting substance can be added to the positive hole
`injection material and an electron-donating substance can
`be added to the electron injection material to increase
`intensity.
`(0039) In the organic EL element in this invention, an even
`more effective electron injection material is metal complex
`compound
`or
`nitrogenous
`pentacyclic
`derivative.
`Specifically, metal complex compounds include lithium 8-
`hydroxyquinolinate, zinc bis(8-hydroxyquinolinate), copper
`bis(8-hydroxyquinolinate),
`manganese
`bis(8-
`hydroxyquinolinate), aluminum tris(8-hydroxyquinolinate),
`aluminum
`tris(2-methyl-8-hydroxyquinolinate), gallium
`tris(8-hydroxyquinolinate),
`beryllium
`bis(10-
`hydroxybenzo[h]quinolinate),
`zinc
`bis(10-
`hydroxybenzo[h]quinolinate), chlorogallium bis(2-methyl-
`8-quinolinate),
`gallium
`bis(2-methyl-8-quinolinate)(o-
`cresolate),
`aluminum
`bis(2-methyl-8-quinolinate)(1-
`naphtholate),
`gallium
`bis(2-methyl-8-quinolinate)(2-
`naphtholate), etc., but are not limited to these. Oxazole,
`thiazole, oxadiazole, thiadiazole or triazole derivatives are
`desirable as the nitrogenous pentacyclic derivative.
`(0040) Specifically, this includes 2,5-bis(1-phenyl)-1,3,4-
`oxazole, dimethyl POPOP, 2,5-bis(1-phenyl)-1,3,4-thiazole,
`2,5-bis(1-phenyl)-1,3,4-oxadiazole, 2-(4’-tert-butylphenyl)-
`5-(4”-biphenyl)1,3,4-oxadiazole, 2,5-bis(1-naphthyl)-1,3,4-
`oxadiazole, 1,4-bis[2-(5-phenyloxadiazole)]benzene, 1,4-
`bis[2-(5-phenyloxadiazole)]-2-tert-butylbenzene, 2-(4’-tert-
`butylphenyl)-5-(4”-biphenyl)-1,3,4-thiadiazole, 2,5-bis(1-
`naphthyl)-1,3,4-thiadiazole,
`1,4-bis[2-(5-
`phenylthiadiazole)]benzene, 2-(4’-tert-butylphenyl)-5-(4”-
`biphenyl)-1,3,4-triazole, 2,5-bis(1-naphthyl)-1,3,4-triazole,
`1,4-bis[2-(5-phenyltriazole)]benzene, etc., but is not limited
`to these.
`(0041) In this organic EL element, it is acceptable for at
`least one type of luminescent material, doping material,
`positive hole injection material and electron injection
`material to be contained within the same luminescent layer
`in addition to the compound in general formula [1].
`Furthermore, it is also possible to protect the element as a
`whole by providing a protective layer on the surface of the
`element or by means of silicone oil, resin or the like
`towards the aim of improving the stability of the organic
`
`
`
`RHEMK-1005.010
`
`

`

`Japanese Unexamined Patent Application Publication 2000-53956 (P2000-53956A)
`(11)
`
`EL element obtained from this invention with regards to
`temperature, humidity, atmosphere, etc.
`(0042) By using the compound in this invention in the
`luminescent layer of an organic EL element and combining
`it with a designated positive hole injection layer or electron
`injection layer in the manner set forth above, it was
`possible
`to ameliorate
`the organic EL element’s
`characteristics such as luminous efficiency, maximum
`luminous intensity, etc. Furthermore, this element was very
`stable in terms of heat and current, and provided a
`luminous intensity suitable for practical use at a low
`driving voltage, and was able to significantly reduce the
`amount of deterioration, which was a major problem with
`the prior art.
`(0043) Conceivable applications of the organic EL element
`in this invention include flat-panel displays such as wall-
`mount televisions or the like, light sources for photocopiers,
`printers or the like in the form of a flat surface light source,
`light sources for liquid crystal displays, calculators or the
`like, and indicators, beacon lights and the like, which gives
`it considerable industrial value.
`(0044) The material in this invention can be used in the
`field of organic EL elements, electrophotographic
`photoreceptors, photoelectric conversion elements, solar
`cells, image sensors, etc.
`(0045)
`(EMBODIMENT EXAMPLES) This invention will be described
`in more detail below based on embodiment examples. Note
`that “parts” in the description indicates parts by weight.
`Synthesis method for compound (2)
`7.2 parts 5,8-dibromoquinoxaline, 16.2 parts p,p’-
`ditolylamine, 12 parts potassium carbonate and 0.5 parts
`copper powder were added to 50 parts 1,3-dimethyl-2-
`imidazolidinone and stirred for 50 hours while heating at
`200°C. Subsequently, this was diluted with 500 parts water.
`Extraction was performed with ethyl acetate, concentration
`was performed, and purification was performed by column
`chromatography using silica gel, producing 12 parts white
`fluorescent powder. Molecular weight analysis by FD-MS
`confirmed that it was compound (2).
`(0046) Synthesis method for compound (3)
`6.0 parts 5,8-dibromoquinoxaline, 12.2 parts 1-naphthyl-
`phenylamine, 8 parts potassium carbonate and 0.5 parts
`copper powder were added to 50 parts 1,3-dimethyl-2-
`imidazolidinone and stirred for 50 hours while heating at
`200°C. Subsequently, this was diluted with 500 parts water.
`Extraction was performed with ethyl acetate, concentration
`was performed, and purification was performed by column
`chromatography using silica gel, producing 13 parts white
`fluorescent powder. Molecular weight analysis by FD-MS
`confirmed that it was compound (3).
`(0047) Synthesis method for compound (16)
`8 parts 2,6-dibromoquinoxaline, 35 parts di(4-(1,1-
`dimethyl-1-phenyl)methylphenyl)amine,
`10
`parts
`potassium carbonate and 0.5 parts copper powder were
`added to 30 parts 1,3-dimethyl-2- imidazolidinone and
`stirred for 50 hours while heating at 200°C. Subsequently,
`this was diluted with 500 parts water. Extraction was
`performed with ethyl acetate, concentration was performed,
`and purification was performed by column chromatography
`using silica gel, producing 15 parts white fluorescent
`powder. Molecular weight analysis by FD-MS confirmed
`
`
`
`that it was compound (16). Embodiment example