Classifications

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  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
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  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
  • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
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  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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  • H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
  • H10K85/622—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene containing four rings, e.g. pyrene
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  • H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
  • H10K85/626—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene containing more than one polycyclic condensed aromatic rings, e.g. bis-anthracene
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  • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
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  • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
  • H10K85/633—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine comprising polycyclic condensed aromatic hydrocarbons as substituents on the nitrogen atom
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  • C09K2211/00—Chemical nature of organic luminescent or tenebrescent compounds
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  • C09K2211/00—Chemical nature of organic luminescent or tenebrescent compounds
  • C09K2211/10—Non-macromolecular compounds
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  • C09K2211/1014—Carbocyclic compounds bridged by heteroatoms, e.g. N, P, Si or B
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  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K2102/00—Constructional details relating to the organic devices covered by this subclass
  • H10K2102/10—Transparent electrodes, e.g. using graphene
  • H10K2102/101—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO]
  • H10K2102/103—Transparent electrodes, e.g. using graphene comprising transparent conductive oxides [TCO] comprising indium oxides, e.g. ITO
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  • H10K85/615—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
  • H10K85/624—Polycyclic condensed aromatic hydrocarbons, e.g. anthracene containing six or more rings
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/917—Electroluminescent

Definitions

• the present invention relates to an organic electroluminescent device (hereinafter sometimes referred to as an organic EL device). More specifically, the present invention relates to an organic electroluminescent device suitably used for a consumer or industrial display device (display) or a light source of a printer head.
• organic EL device organic electroluminescent device
• the present invention relates to an organic electroluminescent device suitably used for a consumer or industrial display device (display) or a light source of a printer head.
• an organic electroluminescent device having an inorganic semiconductor thin film layer together with an organic light emitting layer between electrodes in order to facilitate the injection of electrons and the like has been disclosed in, for example, Japanese Patent Application Laid-Open No. 2-139893. It is disclosed in Japanese Unexamined Patent Application Publication No. Hei 2-196464 and Japanese Unexamined Patent Application Publication No. Hei 2-196475.
• the organic electroluminescent device disclosed in this publication includes an inorganic semiconductor material such as carbon, germanium, silicon, tin, silicon carbide, boron nitride, boron phosphide, and gallium nitride on the anode. An organic light emitting layer and a cathode are further formed thereon.
• Japanese Patent Application Laid-Open Nos. Hei 10-88120 and 2000-150-161 disclose a hole injection layer / light emitting layer / electron injection.
• An electroluminescent device having a layer structure is disclosed. More specifically, a hole-transporting amine-based material is used as a light-emitting material, and tris (8-hydroxyquinolinato) aluminum ( Alq), bis (2-methyl-8-hydroxyquinolinate) (P-cyanophenol) gallium, and the like were used.
• the inorganic semiconductor thin film layer is provided.
• the mobility of electrons injected from the cathode was relatively reduced, thereby lowering the luminous efficiency.
• the inorganic semiconductor thin film is provided by providing the inorganic semiconductor thin film layer. Recombination in the vicinity of the layer and quenching easily, or the recombination property was reduced, and the organic emission of the organic electroluminescent element was There was a problem that the light emission luminance in the light layer was reduced.
• the inventors of the present invention diligently studied the above problem, and found that an inorganic compound layer was provided between an organic light emitting layer and a cathode layer, and a specific aromatic amine compound was used for the organic light emitting layer.
• the first invention provides a reducing dopant-containing layer between the organic light emitting layer and the cathode layer, and the use of a specific aromatic amine compound in the organic light emitting layer (second invention).
• a specific electron injection layer is provided between the organic light emitting layer and the cathode layer, and a specific aromatic amine compound is used in the organic light emitting layer (third invention). It has been found that even when a voltage (for example, DC 10 V) is applied, high emission luminance can be obtained, and that the half-life can be significantly extended.
• a voltage for example, DC 10 V
• an object of the present invention is to provide an organic electroluminescent device having a high emission luminance and a remarkably long half-life even when the driving voltage is low. Disclosure of the invention
• An organic electroluminescent device including at least an anode layer, an organic light emitting layer, and a cathode layer, and an inorganic compound layer provided between the organic light emitting layer and the cathode layer (the structure of the first invention);
• An organic electroluminescent device including at least an anode layer, an organic light emitting layer, and a cathode layer, and further including a reducing dopant-containing layer between the organic light emitting layer and the cathode layer.
• Each organic light emitting layer contains an aromatic amine compound represented by the following general formula (1), an aromatic amine compound represented by the following general formula (2), or one of the aromatic amine compounds.
• An organic electroluminescent device characterized by the above features is provided, and the above-described problems can be solved.
• an anode layer, an organic light emitting layer, and an anode layer are included, and an energy gap is provided between the organic light emitting layer and the cathode layer.
• an organic electroluminescent device (constitution of the third invention), which is provided with an electron injection layer containing a hydrocarbon compound having 2.7 eV or more and having a hydrocarbon compound having an anthracene nucleus or a fluoranthene nucleus
• the organic light emitting layer contains an aromatic amine compound represented by the following general formula (3) and / or an aromatic amine compound represented by the following general formula (4).
• an organic electroluminescent device characterized by containing, as a light emitting material, an aromatic amine compound containing three or more condensed aromatic rings.
• the symbol A, and the substituents Ar 1 and Ar 2 are each independently a substituted or unsubstituted aromatic group having 6 to 60 carbon atoms, and An aromatic group not containing a styryl group or an alkenyl group, and at least one of the symbol A and the substituents Ar 1 and Ar 2 is a substituted or unsubstituted fused aromatic ring having three or more rings.
• the condensed number P is an integer of 1 to 6.
• the symbol B and the substituents Ar 3 , Ar 4 , Ar 5 and Ar 6 are each independently a substituted or unsubstituted aromatic group having 6 to 60 carbon atoms.
• An aromatic group not containing a styryl group and an alkenyl group; and at least one of the symbol B and the substituents Ar 3 , Ar 4 , Ar 5 and Ar 6 Is a group containing three or more substituted or unsubstituted condensed aromatic rings, and the condensed numbers Q and r are integers of 1 to 6.
• the symbol A and the substituents Ar 7 and Ar 8 are each independently a substituted or unsubstituted aromatic group having 6 to 60 carbon atoms. And at least one of the substituents Ar 7 and Ar 8 is a group containing a substituted or unsubstituted three or more condensed aromatic ring, and the condensed number p is an integer of 1 to 6. . ]
• Each of 12 may be the same or different, and preferably has 6 to 40 carbon atoms. Also preferably, A and B each include a substituted or unsubstituted fused aromatic ring of three or more rings.
• FIG. 1 is a cross-sectional view of the organic electroluminescent device according to the first embodiment.
• FIG. 2 is a cross-sectional view of the organic electroluminescent device according to the second embodiment.
• FIG. 3 is a cross-sectional view of the organic electroluminescent device according to the third embodiment.
• FIG. 1 is a cross-sectional view of an organic electroluminescent device 100, which has a structure in which an anode layer 10, an organic light emitting layer 12, an inorganic compound layer 14, and a cathode layer 16 are sequentially laminated on a substrate (not shown). It shows that you are doing.
• the organic light emitting layer 12 and the inorganic compound layer 14, which are characteristic portions of the first embodiment, will be mainly described. Therefore, other components, for example, the configurations and manufacturing methods of the anode layer 10 and the cathode layer 16 will be briefly described, and those not mentioned will be generally known in the field of organic electroluminescent devices. It can adopt a composition and a manufacturing method.
• Organic light emitting layer The aromatic amine compound represented by the above general formula (1) and general formula (2) is used for the organic light emitting layer.
• the reason for this is that, by containing an aromatic amine compound containing three or more condensed aromatic rings as described above, when an inorganic compound layer is provided, excellent emission luminance can be obtained at a low voltage of about 10 V. It is.
• the aromatic amine compounds represented by the general formulas (1) and (2) are characterized in that they do not contain a substituent containing a styryl group and an alkenyl group. The reason for this is that by not including such a substituent, the half life of the organic electroluminescent device can be further extended.
• Ar 1 and Ar 2 are the same, and in general formula (2), Ar 3 and Ar 5 are the same and Ar 4 and Ar 6 are the same.
• the aromatic amine compound may have a symmetric structure. As a result, by containing an aromatic amine compound containing a fused aromatic ring of three or more rings substituted with an arylamino group having a symmetric structure, the half life can be significantly increased.
• Examples of the condensed aromatic ring contained in the aromatic amine compounds represented by the general formulas (1) and (2) include pyrene, perylene, anthracene, fluoranthene, chrysene, rubicene, tetracene, and pentacene.
• Bone such as sen, tetrabenzophenanthrene, tetrabenzoanthracene, tetrabenzofluorene, benzoperylene, dibenzopyrene, dibenzochrysene, dibenzoperylene, benzotetracene, decacyclene, acenaphthofluoranthene, and dibenzofluoranthene And three or more condensed aromatic rings containing a specific site.
• more preferred condensed aromatic rings include pyrene, perylene, anthracene, fluoranthene, chrysene, rubicene, tetracene, penducene, tetrabenzophenanthrene, tetrabenzoanthracene, tetrabenzofluorene, Examples include benzoperylene, dibenzopyrene, dibenzochrysene, dibenzoperylene, benzotetracene, decacyclene, acenaphthofluoranthene, and dibenzofluoranthene skeleton. It is also preferable that the aromatic amine compounds represented by the general formulas (1) and (2) have a substituent.
• the aromatic amine compounds have a cyano group, a halogen group, a straight-chain, branched or cyclic group.
• substituents include halogen groups such as fluorine atom and chlorine atom; methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl Group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, cyclohexyl group, n-heptyl group, cyclohexylmethyl group, n-octyl group, tert-octyl group, 21 A linear, branched or cyclic alkyl group having 1 to 8 carbon atoms such as ethylhexyl group; methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, Isoptoxy, n-pentyloxy, isopentyloxy
• aromatic amine compounds represented by the general formulas (1) and (2) preferred examples include the following specific examples.
• the aromatic amine compounds represented by the following formulas (5) to (14) are abbreviated as compounds 1 to 10 in the examples. H5
• the electron mobility of the organic light emitting material in the organic light-emitting layer it is preferable to 1 X 10- 7 cm 2 ZV ⁇ s or more. This is because the electron mobility, l X 1 0_ 7 cm 2 / V - becomes a value less than s, Ri became difficult high-speed response in the organic electroluminescent device, because the emission luminance may be lowered is there.
• the electron mobility of the organic luminescent material 1. more preferably within a range of 1 X 1 0- 7 ⁇ 2X 1 0_ 6 cm 2 ZV ⁇ s, 1. 2 X 1 0- 7 ⁇ 1. is more preferably within a range of 0 X 10- 6 cmW ⁇ s.
• the electron mobility is smaller than the hole mobility of the organic light emitting material in the organic light emitting layer. The reason for this is that if the reverse is true, the organic light-emitting materials that can be used for the organic light-emitting layer may be excessively limited, and the light emission luminance may be reduced.
• the electron mobility of the organic light-emitting material be larger than 1/1000 of the hole mobility. The reason for this is that if the electron mobility becomes excessively small, it becomes difficult to recombine with holes near the center of the organic light emitting layer, and the light emission luminance may also decrease.
• luminescent dopants or fluorescent dopants examples include benzothiazole-based, benzimidazole-based, and benzoxazole-based fluorescent whitening agents, styrylbenzene-based compounds, and 8-quinolinol derivatives as ligands. And the like.
• a compound other than the aromatic amine compounds represented by the general formulas (1) and (2) which is a compound other than the aromatic amine compounds represented by formulas (1) and (2), is added to the organic light emitting layer. Is also preferred.
• Examples of such a luminescent aromatic amine compound or fluorescent aromatic amine compound include 2,7-bis (diphenylamino) naphthalene and 2,7-bis [4 ′-(di-p-tolylamino) phenyl] naphne. Evening Len.
• the method for forming the organic light emitting layer is not particularly limited, and for example, a known method such as an evaporation method, a spin coating method, a casting method, and an LB method can be applied.
• the organic light emitting layer can also be formed by dissolving a binder such as a resin and an organic light emitting material in a solvent to form a solution, and then thinning the solution by spin coating or the like.
• the thickness of the organic light emitting layer formed in this manner is not particularly limited and can be appropriately selected depending on the situation. For example, the thickness is preferably in the range of 5 nm to 5 / m. .
• the thickness of the organic light emitting layer is less than 5 nm, the light emission luminance and durability may decrease.On the other hand, when the thickness of the organic light emitting layer exceeds 5 zzm, the value of the applied voltage becomes high. This is because it may be.
• the thickness of the organic light emitting layer is more preferably set to a value in the range of 10 nm to 3 m, and further preferably to a value in the range of 20 nm to 1 m.
• an organic electroluminescent element having excellent electron injectability and durability from a cathode can be obtained.
• an organic electroluminescent element which has a remarkably long life, high strength, and high luminance even when driven at a low voltage. it can. It is preferable to use an insulator material or a semiconductor material as the inorganic compound forming the inorganic compound layer.
• an insulator material it is preferable to use at least one metal compound selected from the group consisting of an alkali metal chalcogenide, an alkaline earth metal chalcogenide, an alkali metal halide and an alkaline earth metal octogenide. preferable.
• alkali metal chalcogenide include, L i 2 0, L i 0, Na 2 S, N a 2 S e and N A_ ⁇ .
• Al Chikarari earth metal chalcogenides Is, for example, Ca0, Ba0, Sr ⁇ , Be ⁇ , BaS, and CaSe.
• Preferred examples of the alkali metal halide include LiF, NaF, KF, LiCl, KCl, and NaCl.
• Preferable halides of alkaline earth metals for example, CaF 2, BaF 2, S rF 2, Mg F 2 and B e F 2 such fluoride include Ha port Gen compound other than the fluorides.
• semiconductor materials constituting the inorganic compound layer include Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, 313 and 11 And oxides, nitrides, oxynitrides and the like containing at least one element.
• the inorganic compound constituting the inorganic compound layer is more preferably a microcrystalline or amorphous insulating material. The reason for this is that if the inorganic compound layer is composed of these insulating materials, a more uniform thin film is formed, so that pixel defects such as dark spots can be reduced.
• microcrystalline or amorphous insulating material examples include the above-mentioned alkali metal chalcogenide, alkaline earth metal chalcogenide, and alkali metal halo. Genides and alkaline earth metal haptic compounds.
• a conductive compound in an amount of 1 to 20% by weight based on the total amount of the inorganic compound layer.
• the electron affinity of the inorganic compound layer in the first embodiment is preferably set to a value in the range of 1.8 to 3.6 eV.
• the reason for this is that if the value of the electron affinity is less than 1.8 eV, the electron injection property is reduced, which may lead to an increase in driving voltage and a decrease in luminous efficiency. When the value exceeds 3.6 eV, a complex force S having low luminous efficiency may easily be generated.
• the electron affinity of the inorganic compound layer is more preferably set to a value in the range of 1.9 to 3. O eV, and further preferably to a value in the range of 2.0 to 2.5 eV. .
• the difference in electron affinity between the inorganic compound layer and the organic light emitting layer is preferably set to a value of 1.2 eV or less, more preferably 0.5 eV or less.
• the reason for this is that the smaller the difference in the electron affinity, the easier the electron injection from the electron injection layer to the organic light emitting layer, and an organic electroluminescent device that can respond at high speed.
• the energy gap (band gap energy) of the inorganic compound layer in the first embodiment is preferably set to a value of 2.7 eV or more, and more preferably to a value of 3.O eV or more.
• the structure of the inorganic compound layer is not particularly limited, and may be, for example, a single-layer structure, a double-layer structure, or a three-layer structure.
• the thickness of the inorganic compound layer is not particularly limited, but is preferably, for example, in the range of 0.1 nm to 1,000 nm.
• the reason for this is that if the thickness of the inorganic compound layer is less than 0.1 nm, the electron injection property may decrease, or the mechanical strength may decrease. If the thickness exceeds 1,000 nm, the resistance becomes high, and high-speed response of the organic electroluminescent device may become difficult, or it may take a long time to form a film.
• the thickness of the inorganic compound layer is more preferably set to a value within the range of 0.5 to 100 nm, and even more preferably set to a value within the range of 1 to 50 nm.
• the method of forming the inorganic compound layer is not particularly limited as long as it can be formed as a thin film layer having a uniform thickness.
• Examples of the method include a vapor deposition method, a spin coating method, a casting method, and an LB method. A known method such as a method can be applied.
• Electrode As the anode layer, it is preferable to use a metal, an alloy, an electrically conductive compound or a mixture thereof having a large work function (for example, 4.O eV or more). Specifically, one kind of indium tin oxide (ITO), indium copper, tin, zinc oxide, gold, platinum, palladium and the like can be used alone or in combination of two or more kinds.
• ITO indium tin oxide
• ITO indium copper, tin, zinc oxide, gold, platinum, palladium and the like
• the thickness of the anode layer is not particularly limited, but is preferably in the range of 10 to 1,000 nm, and more preferably in the range of 10 to 200 nm. More preferred.
• the anode layer is substantially transparent, and more specifically, has a light transmittance of 10% or more so that light emitted from the organic light emitting layer can be effectively extracted to the outside.
• a metal, an alloy, a conductive compound, or a mixture thereof having a small work function for example, less than 4. O eV.
• the thickness of the cathode layer is not particularly limited, but is preferably in the range of 10 to: ⁇ , a value in the range of 100 nm, and a value in the range of 10 to 200 nm. Is more preferred.
• the cathode layer is also substantially transparent, and more specifically, has a light transmittance of 10% or more, so that light emitted from the organic light emitting layer can be effectively extracted to the outside. It is preferred that
• the hole injection / transport layer between the anode layer and the organic light emitting layer.
• the reason for this is that by providing such a hole injecting and transporting layer, the function of smoothly injecting holes can be exhibited, but the injected holes can be efficiently transported. Therefore, by providing the hole injection / transport layer, injection of holes and transfer to the organic light emitting layer are facilitated, and high-speed response of the organic electroluminescent device becomes possible.
• the hole injection / transport layer is preferably formed of an organic material or an inorganic material.
• organic materials include, for example, phthalocyanine compounds, diamine compounds, diamine-containing oligomers and thiophene-containing oligomers.
• Preferable inorganic materials include, for example, amorphous silicon (a-Si), a-SiC, microcrystalline silicon (iC-Si), C-SiC, II-VI compound, III-I Group V compounds, amorphous carbon, crystalline carbon and diamond can be mentioned.
• a sealing layer for preventing moisture and oxygen from entering the organic electroluminescent element is preferably provided so as to cover the entire organic electroluminescent element.
• Preferred materials for the sealing layer include a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer; a copolymer having a cyclic structure in the main chain. Coalescing; polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorinated trifluoroethylene, polydichlorodifluoroethylene or trichloroethylene and dichlorodifluoroethylene.
• metals such as N i; Mg_ ⁇ , S I_ ⁇ , S i 0 2, GeO, N i 0, C aO, B aO, F e 2 0, Y 2 0 3, T i 0 metal oxides such as 2; MgF 2, L i F , a 1 F 3, C a F 2 metal fluorides such as; Pafuruoroaru cans, PA full O b amine, per full O Ropo Rie Liquid fluorinated carbon such as one ter; and a composition in which an adsorbent for adsorbing moisture and oxygen is dispersed in the liquid fluorinated carbon.
• FIG. 2 is a cross-sectional view of an organic electroluminescent device 102 according to the second embodiment, which has a structure in which an anode layer 10, an organic light-emitting layer 12, a reducing dopant-containing layer 22, and a cathode layer 16 are sequentially stacked.
• anode layer 10 an organic light-emitting layer 10
• a reducing dopant-containing layer 22 a cathode layer 16 are sequentially stacked.
• Such a reducing dopant-containing layer (sometimes referred to as an interface layer) has a function of enhancing electron injection properties. Therefore, by providing the reducing dopant-containing layer, injection of electrons and transfer to the organic light-emitting layer are facilitated, and high-speed response of the organic electroluminescent device becomes possible.
• the reductive dopant-containing layer which is a characteristic portion of the second embodiment, will be mainly described.
• the organic light-emitting layer and other components are the same as those of the first embodiment. A similar configuration can be adopted.
• the reducing dopant is not particularly limited as long as it has a reducing property to the aromatic ring compound, and specific examples thereof include alkali metals, alkaline earth metals, rare earth metals, and alkali metals. At least one selected from the group consisting of oxides, alkali metal halides, alkaline earth metal oxides, alkaline earth metal halides, rare earth metal oxides, and rare earth metal haptic halides Preferably, it is one substance.
• alkali metals include, for example, Li (lithium, work function: 2.93 eV), Na (sodium, work function: 2.36 eV), K (potassium, work function: 2.3 eV), Rb (rubidium, work function: 2.16 eV) and Cs (cesium, work function: 1.95 eV).
• Li lithium, work function: 2.93 eV
• Na sodium, work function: 2.36 eV
• K potassium, work function: 2.3 eV
• Rb rubidium, work function: 2.16 eV
• Cs cesium, work function: 1.95 eV
• Preferred alkaline earth metals include, for example, Ca (calcium, work function: 2.9 eV), Mg (magnesium, work function: 3.66 eV), Ba (barium, work function: 2.52) eV), and Sr (strontium, work function: 2.0 to 2.5 eV).
• Ca calcium, work function: 2.9 eV
• Mg magnesium, work function: 3.66 eV
• Ba barium, work function: 2.52) eV
• Sr sinrontium, work function: 2.0 to 2.5 eV.
• the value of the work function of strontium is described in Fujitsu Zubov Semiconductor Device (N. Y. Wylo, 1969, p. 366).
• Preferred rare earth metals include, for example, Yb (ytterbium, work function: 2.6 eV)> Eu (europium, work function: 2.5 eV), Gd (gadmium, work function: 3). l eV) and En (erbium, work function: 2.5 eV).
• alkali metal oxides for example, L i F, L i 2 ⁇ , L I_ ⁇ , NaF, and N A_ ⁇ the like.
• the preferable alkali earth metal oxides e.g., CaO, BaO, S and rO, BeO, Mg_ ⁇ , and B a x S r Bok x ⁇ (0 ⁇ x ⁇ 1) mixed with these and, (0 ⁇ x ⁇ l).
• Preferred alkali metal halides include, for example, fluorides such as LiF, NaF and KF, as well as LiCl, KCl and NaCl.
• Preferable halides of alkaline earth metals for example, fluorides such as CaF 2, BaF 2, S rF 2, M g F 2 and B e F 2, and halides other than fluorides.
• a metal complex in which an aromatic compound is coordinated with an alkali metal can also be mentioned.
• a metal complex include a compound represented by the following general formula (15).
• aromatic compound contained in the metal complex represented by the general formula (15) for example, anthracene, naphthylene, diphenylanthracene, terfene , Quarterphenyl, Kinkphenyl, Sexifiphenyl, Quinolinol, Benzoquinolinol, Acridinol, Hydroxyphenyloxazole, Hydroxyphenylthiazole, Hydroxydiaryloxazole, Hydroxyphenylthiaziazole, Hydroxyphenylviridine , Hydroxyphenyl benzoimidazole, hydroxybenzotriazole, hydroxyfluporan, piperidyl, phenanthroline, phthalocyanine, porphyrin and derivatives thereof.
• the aromatic compound When the aromatic compound is a hydroxy compound, it coordinates in the general formula (15) in such a manner that A + and H (proton) of a hydroxyl group exchange.
• the amount of the reducing dopant to be added is 0.01% by weight or more when the entire material constituting the reducing dopant-containing layer is 100% by weight.
• the amount of the reducing dopant added is set to a value of 0.2% by weight or more from the viewpoint of better balance between the emission luminance and the life.
• the reducing dopant may be used alone and arranged at the interface between the cathode layer and the organic light emitting layer.
• the mixing ratio of the reducing dopant and the aromatic ring compound is 1:20 to 20:20. It is preferable that the value be within the range of 1 (molar ratio).
• the reason for this is that if the mixing ratio is outside these ranges, the emission brightness of the organic EL device may be reduced or the life may be shortened.
• the mixing ratio between the aromatic ring compound and the reducing dopant is set to a value within the range of 1:10 to 10: 1 (molar ratio), and within the range of 1: 5 to 5: 1. Is more preferable.
• the reducing dopant-containing layer is not limited to a single-layer structure, and for example, preferably has a two-layer structure or a multilayer structure having more layers.
• the thickness of the reducing dopant-containing layer is not particularly limited. For example, when a mixture of a reducing dopant and an aromatic ring compound is used, the thickness is in the range of 0.1 to 15 nm. It is preferably a value, more preferably a value in the range of 0.1 to 8 nm.
• the thickness of the reducing dopant-containing layer is preferably set to a value in the range of 0.05 to 3 nm, and 0.1 to 1 nm. More preferably, the value is within the range.
• reducing dopant-containing layer uniformly or non-uniformly to form a discontinuous reducing dopant-containing layer in an island shape, or to have a uniform or non-uniform thickness. It is also preferable to form a continuous reducing dopant-containing layer.
• the reducing dopant-containing layer for example, an aromatic ring compound, a luminescent material, and an electron injection material that form an interface region are simultaneously deposited while depositing a reducing dopant by a resistance heating deposition method. Further, it is preferable to disperse the reducing compound in these materials.
• FIG. 3 is a cross-sectional view of an organic electroluminescent device 104 according to the third embodiment, in which an anode layer 10, an organic light-emitting layer 12, an electron injection layer 24, and a cathode layer 16 are sequentially laminated. It has a structure.
• the electron injection layer contains a hydrocarbon compound having an energy gap of 2.7 eV or more and has an anthracene nucleus or a fluoranthene nucleus, and the organic light emitting layer has a general formula (3) ), An aromatic amine compound represented by the general formula (4), or one of the aromatic amine compounds.
• the aromatic amine compound represented by the formula (4) is a compound which may contain a styryl group and an alkenyl group in the aromatic amine compounds represented by the formulas (1) and (2) described above.
• the description and examples of the aromatic amine compounds represented by the general formulas (1) and (2) are described in the general formulas (3) and (4). It is also applicable to the aromatic amine compounds represented.
• the electron injection layer and the organic light emitting layer which are characteristic portions of the third embodiment, will be mainly described.
• Other components are the same as those of the first embodiment and the second embodiment. A similar configuration can be adopted.
• Electron injection layer For the electron injection layer, a hydrocarbon compound having an energy gap of 2.7 eV or more and having an anthracene nucleus or a fluoranthene nucleus is used. The reason for this is that when the energy gap of the hydrocarbon compound is less than 2.7 eV, the hydrocarbon compound itself emits light, so that the luminous efficiency of the organic electroluminescent device may decrease.
• hydrocarbon compounds having an anthracene nucleus or a fluoranthene nucleus have excellent electron mobility and enhance the light emission efficiency of the organic electroluminescent device.
• Suitable examples of such a hydrocarbon compound having an anthracene nucleus include a compound represented by the following general formula (16).
• 1 ⁇ to 11 () are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon number.
• Ar 13 and Ar 14 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms; 20 alkyl groups, substituted or unsubstituted alkoxy groups having 1 to 20 carbon atoms, substituted or unsubstituted
• hydrocarbon compound having a fluoranthene nucleus a compound represented by the following general formula (17) can be preferably mentioned.
• the thickness of the electron injection layer is not particularly limited, but is preferably in the range of 1 to 50 nm, more preferably in the range of 2 to 30 nm, More preferably, the value is in the range of 3 to 25 nm. The reason is that if the thickness of the electron injection layer is less than lnm, the electron injection On the other hand, the effect of improvement may not be exhibited. On the other hand, if the thickness of the electron injection layer exceeds 50 nm, the light emission luminance of the organic EL element may be reduced or the half life may be shortened.
• the aromatic amine compound represented by the general formula (3) and the general formula (4) is used for the organic light emitting layer.
• the reason for this is that by containing an aromatic amine compound containing three or more condensed aromatic rings, when an electron injection layer is provided, excellent emission luminance can be obtained at a low voltage of about 10 V. is there.
• the type, the electron mobility, the additive, the forming method, and the film thickness of the organic light emitting layer in the third embodiment can be the same as those in the first embodiment.
• ITZ indium tin oxide
• a transparent electrode-coated glass substrate while mounted on a substrate holder one in the vapor deposition chamber of a vacuum deposition apparatus, the vacuum degree in the vacuum chamber, the pressure was reduced to 1 X 10_ 3 P a, at deposition conditions follows On the anode layer, a hole injection layer, an organic light emitting layer, an inorganic compound layer, and an anode layer were sequentially laminated to produce an organic electroluminescent device.
• Hole injection layer 4,4'-bis- (N, N-di-m-tolylamino) 1-4 "-1
• Inorganic compound layer L i F
• the light emission luminance is the 540 c dZcm 2, it was confirmed that emission color is orange.
• Examples 2 to 6 compounds 5 (Example 2), compound 6 (Example 3), compound 9 (Example 4), and compound 10 were used as the luminescent materials instead of compound 8 of Example 1.
• An organic electroluminescent device was produced in the same manner as in Example 1 except that (Example 5) and Compound 1 (Example 6) were used. Then, evaluation was performed by applying a DC voltage of 5.5 V or 6 V between the cathode layer and the anode layer.
• the emission color was three hundred and ten to seven hundred and twenty c DZM 2, half life 2, 100-3, was 700 hours.
• Table 1 shows the obtained results.
• Comparative Examples 1 to 3 a 20-nm-thick electron transport layer made of tris (8-hydroxyxynolinato) aluminum (Aid) was provided instead of the inorganic compound of Example 1, and a light-emitting material was used.
• An organic electroluminescent device was produced in the same manner as in Example 1, except that Compound 1 was used in Comparative Example 1, Compound 6 was used in Comparative Example 2, and Compound 4 was used in Comparative Example 3. Then, a DC voltage of 5.5 V was applied between the cathode layer and the anode layer for evaluation.
• Example 7 a compound 1 was used as the light emitting material instead of the compound 8 of Example 1, and instead of the inorganic compound layer, a mixture of compound 1 and metal lithium (Li) as a reducing dopant (Li) was used.
• An organic electroluminescent device was manufactured in the same manner as in Example 1, except that an interface layer (reducing dopant-containing layer) having a mixing molar ratio of 1: 1) and a thickness of 2 Onm was provided. Then, a DC voltage of 5.5 V was applied between the cathode layer and the anode layer for evaluation.
• Example 8 compound 1 was used as the light emitting material instead of compound 8 of Example 1, and instead of the inorganic compound layer, the following formula was used as a reducing dopant in the interface region.
• Compound 11 a lithium metal complex represented by (18)
• Example 9 instead of the reducing dopant of Example 8, mono (2,2,6,6-tetramethyl-3,5-heptanedionato) lithium complex (referred to as Li (dpm)) was used.
• An organic electroluminescent device was fabricated in the same manner as in Example 8, except that an interface layer (reducing dopant-containing layer) having a thickness of l nm was provided. Then, evaluation was performed by applying a DC voltage of 6.5 V between the cathode layer and the anode layer.
• Example 10 instead of the reducing dopant of Example 8, the light-emitting material was a mixture of Compound 1 and Li (dm) as the reducing dopant (mixed mole ratio of 1: 1).
• An organic electroluminescent device was produced in the same manner as in Example 8, except that an interface layer (reducing dopant-containing layer) having a thickness of 5 nm was provided. Then, a DC voltage of 6.5 V was applied between the cathode layer and the anode layer for evaluation.
• Example 11 instead of the inorganic compound layer of Example 1, a phenylanthracene compound represented by the following formula (19) (compound 12, having an energy gap of 3.0 eV), An organic electroluminescent device was fabricated in the same manner as in Example 1, except that a 2 Onm-thick electron injection layer composed of a mixture with a metallic lithium (Li) as a dopant (mixing molar ratio 1: 1) was provided. did. Then, evaluation was performed by applying a DC voltage of 6.5 V between the cathode layer and the anode layer.
• a 2 Onm-thick electron injection layer composed of a mixture with a metallic lithium (Li) as a dopant (mixing molar ratio 1: 1) was provided. did. Then, evaluation was performed by applying a DC voltage of 6.5 V between the cathode layer and the anode layer.
• Example 12 Compound 1 was used as the light-emitting material instead of Compound 8 of Example 1, and instead of the inorganic compound layer, a fluoranthene-based compound represented by the following formula (20) (referred to as Compound 13; Except for providing a 20-nm-thick electron injection layer consisting of a mixture of energy gap 2.8 eV) and lithium metal (Li) as a reducing dopant (mixing molar ratio 1: 1). An organic electroluminescent device was produced in the same manner as in 1. Then, evaluation was performed by applying a DC voltage of 6.5 V between the cathode layer and the anode layer.
• a fluoranthene-based compound represented by the following formula (20) referred to as Compound 13; Except for providing a 20-nm-thick electron injection layer consisting of a mixture of energy gap 2.8 eV) and lithium metal (Li) as a reducing dopant (mixing molar ratio 1: 1).
• An organic electroluminescent device was produced
• the aromatic material containing three or more fused aromatic rings is used as the light emitting material.
• an amine compound By using an amine compound, electrons and holes can be effectively recombined in the organic light emitting layer.
• the driving voltage is low, high light emission luminance, for example, 500 cd Zm 2
• the driving voltage can be similarly reduced even if the driving voltage is low.
• the third invention by using a specific hydrocarbon compound for the electron injection layer and using an aromatic amine compound containing three or more condensed aromatic rings for the organic light emitting layer, Even if the driving voltage is low, high emission luminance can be obtained, and an organic electroluminescent device having an extremely long half-life can be provided.

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