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WO2011096465A1 - Nouvel élément électroluminescent organique à rendement lumineux amélioré - Google Patents

Nouvel élément électroluminescent organique à rendement lumineux amélioré Download PDF

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WO2011096465A1
WO2011096465A1 PCT/JP2011/052221 JP2011052221W WO2011096465A1 WO 2011096465 A1 WO2011096465 A1 WO 2011096465A1 JP 2011052221 W JP2011052221 W JP 2011052221W WO 2011096465 A1 WO2011096465 A1 WO 2011096465A1
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organic
produced
doping concentration
comparative example
light emitting
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Japanese (ja)
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大前吉則
西松雅之
啓 下村
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ケミプロ化成株式会社
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
    • C09K11/06—Luminescent, e.g. electroluminescent, chemiluminescent materials containing organic luminescent materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K50/00—Organic light-emitting devices
    • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
    • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/10—Triplet emission
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K2101/00—Properties of the organic materials covered by group H10K85/00
    • H10K2101/80—Composition varying spatially, e.g. having a spatial gradient
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
    • H10K85/342—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising iridium

Definitions

  • the present invention relates to a novel organic EL element.
  • An organic electroluminescence element (hereinafter referred to as an organic EL element) emits light when excitation energy generated by recombination of holes and electrons injected from an electrode is relaxed to a ground state through a light emission process.
  • an organic EL element emits light when excitation energy generated by recombination of holes and electrons injected from an electrode is relaxed to a ground state through a light emission process.
  • Non-patent Document 1 Adachi et al. Also reported in a paper published in 1988 that a three-layer organic EL device with a light-emitting layer sandwiched between an electron transport layer and a hole transport layer, which is the basic form of organic EL devices currently in wide use.
  • non-patent document 1 As a material used for the light-emitting layer of the organic EL element, non-patent document 1 emits yellow-green light by using a chelate complex such as tris (8-quinolinolato) aluminum complex, and patent document 1 uses orange and a coumarin derivative. It is reported that blue light emission can be obtained by using a styryl compound in Patent Document 2 and blue light emission and blue light emission by using a terylene derivative in Patent Document 3.
  • the material used for the light emitting layer is changed (for example, Patent Documents 4 to 13), the material used for other organic layers (for example, Patent Documents 14 to 19), and the organic EL element structure is changed.
  • Research for example, Patent Documents 20 to 25
  • the material used for the light emitting layer for example, in Patent Documents 4 to 9, etc., the light emitting layer is a mixed layer composed of two layers of a host and a dopant, and the material used for the dopant of the light emitting layer is a complex compound such as iridium or platinum. It has been reported that the luminous efficiency has been improved by using luminescence from a triplet excited state.
  • Patent Document 10 As a change of the material used for the light emitting layer, as a material used for the host of the light emitting layer, in Patent Document 10, a quinoxaline derivative which is a bipolar material having both a hole transporting property and an electron transporting property in the host, and Ir as a dopant.
  • an amine derivative is used as a host
  • an Ir complex is used as a dopant
  • a fluorene compound is used as a host
  • Al complex or a rubrene compound is used as a dopant
  • a fluorene compound is used as a host. It has been reported that the luminous efficiency was improved by using an arylamine compound and an Ir complex, respectively.
  • Patent Document 14 discloses a tetraaryldiamine derivative having relatively low molecular structure symmetry
  • Patent Document 15 discloses tetraphenylbenzidine.
  • Patent Document 16 reports that the luminous efficiency was improved by using a benzidine compound as a compound.
  • Patent Document 17 discloses a phenanthroline compound
  • Patent Document 18 includes a compound having 3,4'-bipyridyl
  • Patent Document 19 Reported that luminous efficiency was improved by using benzofluorene compounds respectively.
  • Patent Documents 20 to 21 report that the luminous efficiency has been improved by providing a new organic layer as a hole blocking layer between the light emitting layer and the electron transporting layer. .
  • Patent Document 20 reports that the light emission efficiency is improved by using a triazine derivative.
  • Patent Documents 22 to 25 and the like use a multi-photon structure in which a charge generation layer is provided on an electron transport layer, a hole injection layer and a hole transport layer are provided on the charge generation layer, and the element structure is repeated. It has been reported that the luminous efficiency has been improved.
  • Patent Documents 4 to 9, etc. a technique using a complex compound in the light emitting layer, Patent Documents 10-13, etc. Improvement of the host material of the light emitting layer, improvement of the material used for the hole transport layer in Patent Documents 14 to 16 and the like, improvement of the electron transport layer in Patent Documents 17 to 19 and the like, improvement of the organic EL element structure in Patent Documents 20 to 25 and the like Various improvements have been made, but the luminous efficiency has not yet been satisfactory. Therefore, an object of the present invention is to solve the above-described problems, and is to provide a novel organic EL element that is more efficient than the conventional one.
  • the organic EL device of the present invention is a device in which a multilayer organic compound is laminated between an anode and a cathode.
  • At least one of the organic films is a light emitting layer, and the light emitting layer includes a host using an aromatic compound or a complex compound and a dopant using the complex compound, and the doping concentration in the light emitting layer is within the layer.
  • a gradient is provided.
  • an organic electroluminescence element including one or more organic films between two electrodes arranged to face each other
  • at least one of the organic films is a host
  • the compound contains a light emitting layer composed of an aromatic compound or a complex compound) and a dopant (the compound is a complex compound), and is a part by weight of the complex compound which is a dopant with respect to 100 parts by weight of the total weight of the host and the dopant.
  • the present invention relates to a characteristic organic EL element.
  • the light emitting layer has a doping concentration distributed within the range of 0 to 100% by weight, and the portion adjacent to one electrode remains at the maximum concentration.
  • a portion adjacent to the substrate has a minimum concentration.
  • the third of the present invention relates to the organic EL device according to claim 1 or 2, wherein the compound used for the host of the light emitting layer is an aromatic compound.
  • the central metal of the complex compound used as the dopant of the light emitting layer is a metal selected from the group consisting of Ru, Rh, Pd, Ir, Pt, and Au.
  • the present invention relates to an organic EL element. 5th of this invention is related with the organic EL element of Claim 4 whose complex compound used for the dopant of the said light emitting layer is an Ir complex.
  • a method for forming the organic EL element there are a dry film forming method (for example, a vacuum deposition method, an ionization vapor deposition method, etc.) and a wet film forming method [a solution coating method (for example, a spin coating method, a casting method, an ink jet method, etc.)]
  • a technique for doping for example, co-evaporation in which two or more evaporation sources are simultaneously heated is used, and after adjusting the evaporation rate of each evaporation source so that the dope concentration becomes an arbitrary dope concentration, the evaporation is performed.
  • a method of starting deposition and keeping the deposition rate constant until the deposition is completed, or adjusting a solution composed of two or more compounds so as to have an arbitrary dope concentration, and applying the solution by a solution coating method There are methods. Regarding the gradient of the doping concentration, the portion adjacent to one electrode is set to the maximum concentration, the portion adjacent to the other electrode is set to the minimum concentration, and the ratio of the maximum concentration to the minimum concentration is preferably 20: 1 to 1. 1: 0, more preferably 10: 1 to 1.5: 1, most preferably 5: 1 to 2: 1.
  • the maximum concentration side and the minimum concentration side may be either the anode side or the cathode side.
  • the method of providing the concentration gradient uses co-evaporation, starts the deposition after adjusting the deposition rate of each deposition source so that the dope concentration at the start of deposition becomes an arbitrary dope concentration, and at the end of the deposition an arbitrary dope concentration So that the deposition rate is reduced until the deposition is completed, and the remaining deposition rate is increased, or a solution with a different dope concentration (two so as to obtain an arbitrary dope concentration).
  • Examples of the configuration of the organic EL element include, for example, ITO (anode) / hole transport layer (hole transport layer) / light emitting layer / electron transport layer / cathode, ITO / hole injection layer (hole injection layer) / hole transport layer.
  • 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 (hole block layer) / electron transport Layer / cathode, ITO / hole injection layer / 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, Examples thereof include those laminated in a multilayer structure such as ITO / hole injection layer / hole transport layer / light emitting layer / hole block layer / electron transport layer / electron injection layer / cathode.
  • a charge generation layer is provided on the electron transport layer, a hole injection layer or a hole transport layer is provided on the charge generation layer, and the above-described device configuration is repeated (for example, Patent Documents 22 to 25), or a sealing layer may be provided on the cathode.
  • a hole blocking layer can be inserted between the light emitting layer and the electron transporting layer.
  • the hole blocking layer has a preferable property of functioning to balance the holes and electrons injected into the device.
  • the hole block compound used for the hole block layer in the organic EL device of the present invention is not particularly limited as long as it has the above preferred properties.
  • a photoconductive material that has been conventionally used as a hole blocking material or a known material that is used for a hole blocking layer of an organic EL element can be selected and used.
  • the block material include 4,7-diphenyl-1,10-phenanthroline (BPhen), 2,5-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and Patent Document 21.
  • BPhen 4,7-diphenyl-1,10-phenanthroline
  • BCP 2,5-dimethyl-4,7-diphenyl-1,10-phenanthroline
  • Patent Document 21 Patent Document 21.
  • a compound or the like can be used. These compounds are
  • Each layer of the hole transport layer, the electron transport layer, and the light emitting layer may have a single layer structure or a multilayer structure.
  • the hole transport layer and the electron transport layer can be separately provided 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). .
  • the organic EL element of the present invention only needs to have a gradient in the doping concentration of the light emitting layer, and is not limited to the above-described configuration example, and can have various configurations.
  • the organic EL device of the present invention is preferably supported on a substrate.
  • the substrate material is not particularly limited and may be any material that can support the organic EL element.
  • a material made of metal such as glass, quartz glass, plastic, and stainless steel can be used.
  • anode of the organic EL device of the present invention a simple metal having a work function larger than that of the electrode material used for the cathode, an alloy of metals having a large work function, a conductive material having a work function larger than that of the electrode material used for the cathode, and the like. It is preferable to use a mixture of the above as an electrode material.
  • electrode materials include, for example, metals such as gold, silver, and copper, conductive transparent materials such as ITO (indium-tin oxide), tin oxide (SnO 2 ), and zinc oxide (ZnO), polypyrrole, Examples thereof include conductive polymer materials such as polythiophene.
  • these electrode materials can be formed on the substrate by a method such as vapor deposition, sputtering, or coating.
  • the sheet electrical resistance of the anode is preferably several hundred ⁇ / cm 2 or less.
  • the film thickness of the anode depends on the material, it is generally about 5 to 1,000 nm, preferably 10 to 500 nm.
  • the cathode As the cathode, a single metal having a work function smaller than that of the electrode material used for the anode, an alloy of metals having a work function smaller than that of the electrode material used for the anode, or a conductive substance having a work function smaller than that of the electrode material used for the anode, and the like. It is preferable to use a mixture of the above as an electrode material.
  • 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, Examples thereof include an aluminum-cesium alloy.
  • 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 ⁇ / cm 2 or less.
  • the film thickness of the cathode depends on the material, it is generally about 5 to 1,000 nm, preferably 10 to 500 nm.
  • at least one of the anode and the cathode is preferably transparent or translucent.
  • the hole transport layer of the organic EL device of the present invention is composed of a hole transport compound (hole transport material), and is not particularly limited as long as it has a function of transmitting holes injected from the anode to the light emitting layer. No.
  • a hole transfer compound is disposed between two electrodes and holes are injected from the anode
  • a hole transfer material having a hole transport degree of at least 10 ⁇ 6 cm 2 / V ⁇ sec or more is preferable as a material used for the hole transport layer.
  • 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 for use in a hole transport layer. it can.
  • the hole transport material examples include phthalocyanine derivatives such as copper phthalocyanine, N, N, N ′, N′-tetraphenyl-1,4-phenylenediamine, N, N′-di (m-tolyl) -N, Triarylamine derivatives such as N′-diphenyl-4,4′-diaminobiphenyl (TPD), polyphenylenediamine derivatives, polythiophene derivatives, water-soluble PEDOT-PSS (polyethylenedioxathiophene-polystyrenesulfonic acid), and Patent Document 15
  • phthalocyanine derivatives such as copper phthalocyanine, N, N, N ′, N′-tetraphenyl-1,4-phenylenediamine, N, N′-di (m-tolyl) -N
  • Triarylamine derivatives such as N′-diphenyl-4,4′-diaminobiphenyl (TPD), poly
  • the hole (hole) transport layer may be a laminate of a hole transport layer made of a compound different from these other hole transport materials.
  • a hole injection layer for example, PEDOT: PSS (polymer mixture) represented by the following chemical formula or N 4 , N 4 '-bis- [4- (di-m-tolyl-amino ) -Phenyl] -N 4 , N 4 '-diphenyl-biphenyl-4,4'-diamine can be used.
  • compounds described in Patent Documents 15 to 17 can be used as the hole injection layer.
  • TPD represented by the following chemical formula, 1,1-bis ⁇ 4- [N, N′-di (p-tolyl) aminophenyl] ⁇ cyclohexane (TAPC), and N, N′-di (1-naphthyl) -N, N′-diphenyl-4,4-diaminophenyl ( ⁇ -NPD) and the like can be used.
  • the light emitting layer of the organic EL device of the present invention is formed from a host and a dopant.
  • a host 2-tertiarybutyl-9,10-di-naphthalen-2-yl-anthracene (TBADN), tris- (4-carbazol-9-yl-phenyl) -amine (TCTA) represented by the following chemical formula, mCP, dmCBP, UGH2, 4,4'-di (N-carbazolyl) -1,1'-biphenyl (CBP), 2,2'-bis (4-carbazolylphenyl) biphenyl (see [Chemical Formula 24])
  • TAADN 2-tertiarybutyl-9,10-di-naphthalen-2-yl-anthracene
  • TCTA tris- (4-carbazol-9-yl-phenyl) -amine
  • mCP 2-tertiarybutyl-9,10-di-naphthalen
  • the dopant is 0 to 100% by weight, preferably 0 to 40% by weight, more preferably 0.1 to 20% by weight, based on the total weight of the host and the dopant.
  • the dopants include conventionally known Ir (Btp) 2 acac, Ir (piq) 3 , FIrpic, Ir (ppy) 3 , Ir (ppy) 2 acac, FIr6, Ir (piq) 2 acac ( 22]) and the compounds described in Patent Documents 4 to 9 can be used.
  • examples of the central metal atom of the dopant include Ru, Rh, Pd, Ir, Pt, Au and the like having a strong phosphorescence function, and various chemical species shown in the following chemical formulas as ligands. Selected to form a complex.
  • the electron transport layer of the organic EL device of the present invention is only required to be composed of an electron transfer compound (electron transport material), and is conventionally used as a charge injection material for electrons in organic photoconductive materials or organic EL devices. Any one of known materials used for the electron transport layer can be selected and used for the electron transport layer.
  • electron transport material an electron transfer compound
  • Any one of known materials used for the electron transport layer can be selected and used for the electron transport layer.
  • Examples of the electron transport material include tri (8-quinolinolato) aluminum (III) [Alq 3 ], 3-biphenyl-4-yl-5- (4-tert-butyl-phenyl) -4- Phenyl-4H- (1,2,4) triazole [TAZ] and compounds described in Patent Documents 17 to 19 can be used.
  • the electron transport layer may be a stack of electron transport layers made of a compound different from these other electron transfer materials. Examples of the electron transport material include Alq 3 and TAZ shown in the following chemical formula.
  • the organic EL device of the present invention when an electron injection layer is provided, it is preferable to use at least one metal compound selected from alkali metal halides, alkaline earth metal halides and the like.
  • alkali metal halide lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, lithium chloride, or the like can be used.
  • alkaline earth metal halide magnesium fluoride, calcium fluoride, barium fluoride, strontium fluoride, or the like can be used.
  • the formation method of the organic EL element using the compound of the present invention is not particularly limited.
  • a dry film forming method for example, a vacuum deposition method, an ionization vapor deposition method, etc.
  • a wet film forming method [a solution coating method (for example, a spin coating method, a casting method, an ink jet method, etc.)] can be used.
  • a dry film forming method is used.
  • the above-described film formation method may be used in combination for manufacturing the element.
  • each layer such as a hole injection layer, a hole transport layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer by a solvent coating method
  • the components constituting each layer are dissolved or dispersed in a solvent to form a coating solution To do.
  • each layer such as a hole injection layer, a hole transport layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer is not particularly limited, but is usually 5 to 5000 nm.
  • the organic EL device of the present invention can be protected by providing a protective layer (sealing layer) for the purpose of blocking contact with oxygen, moisture or the like, or by enclosing the device in an inert substance.
  • a protective layer for the purpose of blocking contact with oxygen, moisture or the like
  • an inert substance include paraffin, silicon oil, and fluorocarbon.
  • fluorine resin, epoxy resin, silicone resin, polyester, polycarbonate, photo-curing resin, or the like can be used as a material used for the protective layer.
  • the organic EL element of the present invention can be usually used as a direct current drive element. When a DC voltage is applied, light emission is observed when a voltage of 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 device of the present invention can also be used as an AC drive device. 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 can be used not only for display screens of televisions, mobile phones, music players, etc., but also for lighting applications.
  • 19 to 32 show preferred examples of the organic EL device of the present invention.
  • FIG. 19 is a cross-sectional view showing an example of the organic EL element of the present invention.
  • FIG. 19 shows a structure in which an anode 2, a light emitting layer 3 and a cathode 4 are sequentially provided on a substrate 1.
  • FIG. 20 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 20 shows a configuration in which an anode 2, a hole transport layer 5, a light emitting layer 3, and a cathode 4 are sequentially provided on a substrate 1.
  • FIG. 21 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 21 shows a configuration in which an anode 2, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1.
  • FIG. 22 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 22 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.
  • FIG. 23 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 23 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.
  • FIG. 24 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 24 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.
  • FIG. 25 is a cross-sectional view showing another example of the organic EL element of the present invention.
  • FIG. 25 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.
  • 26 to 32 are cross-sectional views of the organic EL device of the present invention in which the hole block layer 9 is inserted into the device.
  • the hole blocking layer 9 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 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. More preferred is between the light emitting layer 3 and the electron transport layer 6.
  • each of the hole injection layer 7, the hole transport layer 5, the light emitting layer 3, the electron transport layer 6, the electron injection layer 8 and the hole block layer 9 has a single layer structure or a multilayer structure. May be.
  • the anode 2 is provided on the substrate 1, but the substrate 1 may be on the cathode 4 side.
  • 19 to 32 are only basic element configurations. If necessary, a charge generation layer may be provided to form a multiphoton structure (for example, described in Patent Documents 22 to 25). Moreover, the structure of the organic EL element of this invention is not limited to these.
  • Examples of the electron injection material used for the electron injection layer include the compounds according to Japanese Patent Application No. 2006-292032 (Japanese Patent Laid-Open No. 2008-106015) of the present applicant, for example, the following compound group.
  • the structure of the organic EL element of the present invention is a structure that emits light with high efficiency by providing a gradient in the doping concentration in the light emitting layer, as shown in the examples.
  • the same compound as the compound used in the comparative example is used and the average value of the doping concentration of the entire light emitting layer is the same, the example emits light with high efficiency.
  • the element structure of the present invention even if the average value of the doping concentration of the light emitting layer is the same using the same compound, energy is used more efficiently than before by providing a gradient in the doping concentration. It is possible to produce a great effect on power saving.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 1, Example 2, and Comparative Example 1 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 1, Example 2, and Comparative Example 1 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 1, Example 2, and Comparative Example 1 are shown.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 3, Example 4, and Comparative Example 2 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 3, Example 4, and Comparative Example 2 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 3, Example 4, and Comparative Example 2 are shown.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 5, Example 6, and Comparative Example 3 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 5, Example 6, and Comparative Example 3 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 5, Example 6, and Comparative Example 3 are shown.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 7, Example 8, and Comparative Example 4 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 7, Example 8, and Comparative Example 4 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 7, Example 8, and Comparative Example 4 are shown.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 9, Example 10, and Comparative Example 5 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 9, Example 10, and Comparative Example 5 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 9, Example 10, and Comparative Example 5 are shown.
  • the current density-luminous efficiency characteristics of the organic EL elements of Example 11, Example 12, and Comparative Example 6 are shown.
  • the current density-current efficiency characteristics of the organic EL elements of Example 11, Example 12, and Comparative Example 6 are shown.
  • the current density-external quantum efficiency characteristics of the organic EL elements of Example 11, Example 12, and Comparative Example 6 are shown. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention. It is sectional drawing which shows an example of the organic EL element in this invention.
  • Example 1 (Production of organic EL device) After scrub cleaning a glass substrate with an ITO transparent electrode of 25 mm x 25 mm size (AGC Asahi Glass) with isopropanol and Bencotton (nonwoven wiper), Semico Clean (organic alkaline cleaning solution manufactured by Furuuchi Chemical), pure Ultrasonic cleaning was performed in the order of water, acetone, and isopropanol. After ultrasonic cleaning, boiling cleaning with isopropanol was performed, UV-O 3 cleaning was performed, and the substrate was set on a substrate holder provided in the vapor deposition apparatus, and the pressure was reduced to about 10 ⁇ 4 Pa.
  • ITO transparent electrode 25 mm x 25 mm size
  • Bencotton nonwoven wiper
  • Semico Clean organic alkaline cleaning solution manufactured by Furuuchi Chemical
  • the UV-O 3 cleaning is a combination of ozone generation due to the reaction between light having an extremely short wavelength (185 nm) and oxygen and the chemical bond dissociation effect of light having an extremely short wavelength (254 nm). It is a cleaning method that removes organic contaminants on the substrate that could not be removed by cleaning alone.
  • a hole transport layer (HTL) N, N′-di (1-naphthyl) N, N′-diphenyl-4,4′-diaminobiphenyl ( ⁇ -NPD) represented by the following formula was deposited to a thickness of 50 nm. did.
  • CBP 4,4′-di (N-carbazolyl) -1,1′-biphenyl (CBP) represented by the following formula is used as a host material, and bis (1-phenyl-isoquinolinolato) acetylacetonatoiridium is used as a dopant.
  • CBP 4,4′-di (N-carbazolyl) -1,1′-biphenyl
  • the concentration gradient is set such that the doping concentration at the start of vapor deposition is 15 wt%, the vapor deposition rate of the dopant is decreased immediately after the vapor deposition is started, and the vapor deposition rate of the host is increased, and the thickness of the issue layer becomes 30 nm.
  • the deposition was completed, and the deposition rate of the dopant and host was adjusted so that the doping concentration at that time was 5 wt% (electron transport layer interface) and the doping concentration of the entire light emitting layer was 10 wt%. .
  • the change in the doping concentration from the start of vapor deposition to the end of vapor deposition does not change continuously or stepwise, but there are discontinuous portions having a high doping concentration and thin portions in the light emitting layer.
  • 1,4-bis (1,10-phenanthrolin-3-yl) benzene was deposited to a thickness of 40 nm as an electron transport layer (ETL).
  • ETL electron transport layer
  • lithium fluoride was vapor-deposited as an electron injection layer to a thickness of 1 nm
  • aluminum was vapor-deposited as a cathode to a thickness of 100 nm to produce an organic EL device.
  • This organic EL element was sealed with a glass cap under a nitrogen atmosphere to block contact with the atmosphere.
  • a UV curable epoxy resin was used for adhesion between the glass cap and the organic EL element.
  • a voltage of 5 V was applied to the organic EL element, red light emission from Ir (piq) 2 acac was obtained with a luminance of 474 cd / m 2 .
  • the direct current at this time was 0.15 mA.
  • Example 2 In Example 1, the dope concentration at the start of vapor deposition of the light emitting layer was 15 wt%, the dopant vapor deposition rate was reduced from the start of vapor deposition to the end of vapor deposition, the vapor deposition rate of the host was increased, and the dope concentration at the end of vapor deposition was 5 wt%. Instead, the doping concentration at the start of deposition was 5 wt%, the doping concentration at the end of deposition was 15 wt%, the dopant deposition rate was increased from the start of deposition to the end of deposition, and the host deposition rate was reduced. According to the operation of 1, an organic EL device was produced.
  • Comparative Example 1 In Examples 1 and 2, instead of providing a gradient in the doping concentration of the light emitting layer, the organic EL element was changed according to the operation described in Examples 1 and 2 except that no gradient was provided in the doping concentration of the light emitting layer. Produced. When a voltage of 5 V was applied to the organic EL element, red light emission from Ir (piq) 2 acac was obtained with a luminance of 102 cd / m 2 . The direct current at this time was 0.07 mA.
  • FIG. 1 to 3 show the initial characteristics of the organic EL elements produced in Example 1, Example 2 and Comparative Example 1.
  • FIG. FIG. 1 is a diagram showing the relationship between luminous efficiency and current density of an organic EL element.
  • FIG. 2 is a diagram showing a relationship between current efficiency and current density of the organic EL element.
  • FIG. 3 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 2 As shown in FIG. 1, regarding the luminous efficiency of the organic EL devices produced in Example 1, Example 2 and Comparative Example 1, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 and Example 1 was used. It can be seen that the device manufactured in Example 2 is higher in efficiency than the device manufactured in Comparative Example 1, and the device having a gradient in the doping concentration is higher in efficiency than the device having no gradient in the doping concentration.
  • Example 1 for the current efficiency of the organic EL device produced in Example 2 and Comparative Example 1, a current density of from 0.1 mA / cm 2 until 50 mA / cm 2, Example 1, It can be seen that the element produced in Example 2 is more efficient than the element produced in Comparative Example 1, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 2 As shown in FIG. 3, regarding the external quantum efficiency of the organic EL devices produced in Example 1, Example 2, and Comparative Example 1, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 , and Example 1 It can be seen that the device manufactured in Example 2 is higher in efficiency than the device manufactured in Comparative Example 1, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Table 1 is a table summarizing initial characteristics of the organic EL element obtained from FIGS. 1 to 3 at a luminance of 100 cd / m 2 .
  • the “HTL interface” in the table is the part where the light emitting layer and the HTL are in contact
  • the “ETL interface” is the part where the light emitting layer and the ETL are in contact.
  • the voltage when the luminance is 100 cd / m 2 is 4.02 V for the organic EL element produced in Example 1, and 4.23 V for the organic EL element produced in Example 2.
  • the organic EL element produced in Comparative Example 1 is 4.99V.
  • the current density at that time is 0.70 mA / cm 2 for the organic EL element produced in Example 1, 1.05 mA / cm 2 for the organic EL element produced in Example 2 , and Comparative Example 1 It is 1.66 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time is 11.15 Lm / W for the organic EL element produced in Example 1, 7.09 Lm / W for the organic EL element produced in Example 2, and in Comparative Example 1 It is 3.79 Lm / W about the produced organic EL element.
  • the current efficiency at that time was 14.28 cd / A for the organic EL element produced in Example 1, and 9.55 cd / A for the organic EL element produced in Example 2, which was produced in Comparative Example 1.
  • the organic EL element thus obtained is 6.02 cd / A.
  • the external quantum efficiency at that time was 18.92% for the organic EL element produced in Example 1, and 13.09% for the organic EL element produced in Example 2, and was produced in Comparative Example 1.
  • the organic EL element is 8.97%.
  • the organic EL device in which the doping concentration at the hole transport layer interface prepared in Example 1 is higher than the doping concentration at the electron transport layer interface, and the doping concentration at the hole transport layer interface is lower than the doping concentration at the electron transport layer interface.
  • the organic EL device fabricated in Example 2 has a voltage and current density lower than those of Comparative Example 1 in which no gradient is provided in the doping concentration, and the luminous efficiency is 1.9 to 3.0 times higher.
  • the external quantum efficiency improved by 1.6 to 2.4 times, and the external quantum efficiency by 1.5 to 2.1 times.
  • Table 2 summarizes the initial characteristics of the organic EL element obtained from FIGS. 1 to 3 at a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 5.66 V for the organic EL element produced in Example 1, and 5.84 V for the organic EL element produced in Example 2.
  • the organic EL element produced in Comparative Example 1 is 6.75V.
  • the current density at this time, for the organic EL devices fabricated in Example 1 was 8.95mA / cm 2
  • for the organic EL device produced in Example 2 was 11.07mA / cm 2
  • Comparative Example 1 The organic EL element produced in the above is 17.76 mA / cm 2 .
  • the luminous efficiency at that time was 6.23 Lm / W for the organic EL element produced in Example 1, and 4.87 Lm / W for the organic EL element produced in Example 2.
  • the produced organic EL element is 2.62 Lm / W.
  • the current efficiency at that time was 11.20 cd / A for the organic EL element produced in Example 1, and 9.05 cd / A for the organic EL element produced in Example 2, which was produced in Comparative Example 1.
  • the organic EL element thus obtained is 5.63 cd / A.
  • the external quantum efficiency at that time was 14.84% for the organic EL element produced in Example 1, and 12.40% for the organic EL element produced in Example 2, and was produced in Comparative Example 1.
  • the organic EL element is 8.40%.
  • the organic EL device in which the doping concentration at the hole transport layer interface prepared in Example 1 is higher than the doping concentration at the electron transport layer interface, and the doping concentration at the hole transport layer interface is lower than the doping concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 2 has a voltage and current density lower than those of Comparative Example 1 in which no gradient is provided in the doping concentration, and the luminous efficiency is 1.9 to 2.4 times higher.
  • the external quantum efficiency improved by 1.6 to 2.0 times and the external quantum efficiency by 1.5 to 1.8 times.
  • Example 3 In Example 1, instead of adjusting the deposition rate so that the doping concentration at the start of vapor deposition of the light emitting layer is 15 wt%, the doping concentration at the end of vapor deposition is 5 wt%, and the average doping concentration of the entire light emitting layer is 10 wt%. In addition, except that the doping concentration at the start of deposition was 20 wt%, the doping concentration at the end of deposition was 10 wt%, and the deposition rate was adjusted so that the average doping concentration of the entire light emitting layer was 15 wt%. An organic EL element was produced according to the operation.
  • Example 4 In Example 3, the dope concentration at the start of vapor deposition of the light emitting layer was 20 wt%, the dopant deposition rate was reduced from the start of vapor deposition to the end of vapor deposition, the host vapor deposition rate was increased, and the dope concentration at the end of vapor deposition was 10 wt%.
  • the doping concentration at the start of deposition was 10 wt%
  • the doping concentration at the end of deposition was 20 wt%
  • the deposition rate of the dopant was increased from the start of deposition to the end of deposition
  • the deposition rate of the host was decreased. According to the operation of 3, an organic EL device was prepared.
  • FIG. 4 to 6 show the initial characteristics of the organic EL devices produced in Example 3, Example 4, and Comparative Example 2.
  • FIG. 4 is a diagram showing the relationship between the luminous efficiency and the current density of the organic EL element.
  • FIG. 5 is a diagram showing the relationship between the current efficiency and the current density of the organic EL element.
  • FIG. 6 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 4 As shown in FIG. 4, regarding the luminous efficiency of the organic EL devices produced in Example 3, Example 4 and Comparative Example 2, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 and Example 3 was used. It can be seen that the device manufactured in Example 4 is higher in efficiency than the device manufactured in Comparative Example 2, and the device having a gradient in the doping concentration has a higher efficiency than the device having no gradient in the doping concentration.
  • Example 3 for the current efficiency of the organic EL device produced in Example 4 and Comparative Example 2, a current density of from 0.1 mA / cm 2 until 50 mA / cm 2, Example 3, It can be seen that the element produced in Example 4 is higher in efficiency than the element produced in Comparative Example 2, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 4 As shown in FIG. 6, regarding the external quantum efficiency of the organic EL devices produced in Example 3, Example 4, and Comparative Example 2, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 , and Example 3 It can be seen that the device manufactured in Example 4 is higher in efficiency than the device manufactured in Comparative Example 2, and the device having a gradient in the doping concentration has a higher efficiency than the device having no gradient in the doping concentration.
  • Table 3 is a table summarizing initial characteristics of the organic EL element obtained from FIGS. 4 to 6 at a luminance of 100 cd / m 2 .
  • the voltage when the luminance is 100 cd / m 2 is 3.81 V for the organic EL element produced in Example 3, and 3.66 V for the organic EL element produced in Example 4.
  • the voltage is 3.85V.
  • the current density at this time, for the organic EL device produced in Example 3 was 0.72 mA / cm 2
  • for the organic EL device produced in Example 4 was 1.01mA / cm 2
  • Comparative Example 2 It is 1.42 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time was 11.44 Lm / W for the organic EL element produced in Example 3, 8.52 Lm / W for the organic EL element produced in Example 4, and in Comparative Example 2 It is 5.75 Lm / W about the produced organic EL element.
  • the current efficiency at that time is 13.86 cd / A for the organic EL element produced in Example 3, and 9.92 cd / A for the organic EL element produced in Example 4, and is produced in Comparative Example 2.
  • the organic EL element thus produced is 7.05 cd / A.
  • the external quantum efficiency at that time was 19.22% for the organic EL device produced in Example 3, and 12.64% for the organic EL device produced in Example 4, and was produced in Comparative Example 2.
  • the organic EL element is 10.29%.
  • the organic EL device in which the doping concentration at the hole transport layer interface prepared in Example 3 is higher than the doping concentration at the electron transport layer interface, and the doping concentration at the hole transport layer interface is lower than the doping concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 4 has a current density lower than that of Comparative Example 2 in which no gradient is provided in the doping concentration, and the luminous efficiency is 1.4 to 2.0 times higher.
  • the external quantum efficiency was improved by about 1.2 to 1.9 times from 1.5 to 2.0 times.
  • Table 4 summarizes the initial characteristics of the organic EL element obtained from FIGS. 4 to 6 at a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 5.16 V for the organic EL element produced in Example 3, and 5.26 V for the organic EL element produced in Example 4.
  • the voltage is 5.42V.
  • the current density at this time, for the organic EL device produced in Example 3 was 7.96mA / cm 2
  • for the organic EL device produced in Example 4 was 10.11mA / cm 2
  • Comparative Example 2 It is 13.93 mA / cm ⁇ 2 > also about the organic EL element produced by this.
  • the luminous efficiency at that time was 7.66 Lm / W for the organic EL element produced in Example 3, and 5.92 Lm / W for the organic EL element produced in Example 4.
  • the produced organic EL element is 4.16 Lm / W.
  • the current efficiency at that time is 12.58 cd / A for the organic EL element produced in Example 3, 9.89 cd / A for the organic EL element produced in Example 4, and is produced in Comparative Example 2. It is 7.18 cd / A for the organic EL element.
  • the external quantum efficiency at that time was 17.44% for the organic EL element produced in Example 3, and 12.60% for the organic EL element produced in Example 4, and was produced in Comparative Example 2.
  • the organic EL element is 10.48%.
  • the organic EL device in which the doping concentration at the hole transport layer interface prepared in Example 3 is higher than the doping concentration at the electron transport layer interface, and the doping concentration at the hole transport layer interface is lower than the doping concentration at the electron transport layer interface.
  • the organic EL device fabricated in Example 4 has a voltage and current density lower than that of Comparative Example 2 in which no gradient is provided in the doping concentration, and the luminous efficiency is 1.4 to 1.8 times higher.
  • the external quantum efficiency improved by 1.4 to 1.8 times, and the external quantum efficiency by about 1.2 to 1.7 times.
  • Example 5 In Example 1, instead of adjusting the deposition rate so that the doping concentration at the start of vapor deposition of the light emitting layer was 15 wt%, the doping concentration at the end of vapor deposition was 5 wt%, and the doping concentration of the entire light emitting layer was 10 wt%. According to the operation of Example 1, except that the doping concentration at the start of deposition was 100 wt%, the doping concentration at the end of deposition was 0 wt%, and the deposition rate was adjusted so that the doping concentration of the entire light emitting layer was 20 wt%. An EL element was produced.
  • Example 6 In Example 5, the dope concentration at the start of vapor deposition of the light emitting layer was 100 wt%, the dopant deposition rate was decreased from the start of vapor deposition to the end of vapor deposition, the vapor deposition rate of the host was increased, and the dope concentration at the end of vapor deposition was set to 0 wt%.
  • the doping concentration at the start of deposition was 0 wt%
  • the doping concentration at the end of deposition was 100 wt%
  • the deposition rate of the dopant was increased from the start of deposition to the end of deposition
  • the deposition rate of the host was decreased. According to the operation of 5, an organic EL device was produced.
  • FIG. 7 to 9 show initial characteristics of the organic EL devices produced in Example 5, Example 6, and Comparative Example 3.
  • FIG. 7 is a diagram showing the relationship between the luminous efficiency and the current density of the organic EL element.
  • FIG. 8 is a diagram showing the relationship between the current efficiency and the current density of the organic EL element.
  • FIG. 9 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 7 As shown in FIG. 7, regarding the luminous efficiency of the organic EL elements produced in Example 5, Example 6 and Comparative Example 3, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 and Example 5 was used. It can be seen that the element produced in Example 6 is higher in efficiency than the element produced in Comparative Example 3, and the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 5 for the current efficiency of the organic EL devices fabricated in Example 6 and Comparative Example 3, a current density of from 0.1 mA / cm 2 until 50 mA / cm 2, Example 5, It can be seen that the element produced in Example 6 is more efficient than the element produced in Comparative Example 3, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 9 the external quantum efficiencies of the organic EL devices produced in Example 5, Example 6, and Comparative Example 3 are also shown in Example 5 with a current density from 0.1 mA / cm 2 to 50 mA / cm 2. It can be seen that the element produced in Example 6 is higher in efficiency than the element produced in Comparative Example 3, and the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Table 5 summarizes the initial characteristics of the organic EL elements obtained from FIGS. 7 to 9 with a luminance of 100 cd / m 2 .
  • the voltage when the luminance is 100 cd / m 2 is 3.28 V for the organic EL element produced in Example 5, and 3.39 V for the organic EL element produced in Example 6.
  • the voltage is 3.46V.
  • the current density at this time, for the organic EL device produced in Example 5 was 0.92mA / cm 2
  • for the organic EL devices fabricated in Example 6 was 1.21mA / cm 2
  • Comparative Example 3 It is 1.42 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time is 10.38 Lm / W for the organic EL element produced in Example 5, 7.66 Lm / W for the organic EL element produced in Example 6, and in Comparative Example 3 About the produced organic EL element, it is 6.41 Lm / W.
  • the current efficiency at that time was 10.82 cd / A for the organic EL element produced in Example 5, and 8.27 cd / A for the organic EL element produced in Example 6, and produced in Comparative Example 3.
  • the organic EL element thus produced is 7.06 cd / A.
  • the external quantum efficiency at that time was 15.75% for the organic EL element produced in Example 5, and 12.03% for the organic EL element produced in Example 6, and was produced in Comparative Example 3.
  • the organic EL element is 10.28%.
  • the organic EL device in which the dope concentration at the hole transport layer interface produced in Example 5 is higher than the dope concentration at the electron transport layer interface, and the dope concentration at the hole transport layer interface is lower than the dope concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 6 has a current density lower than that of Comparative Example 3 in which the doping concentration is not gradient, and the luminous efficiency is 1.2 to 1.6 times higher. Improved by 1.2 to 1.5 times and external quantum efficiency by about 1.2 to 1.5 times.
  • Table 6 summarizes the initial characteristics of the organic EL element obtained from FIGS. 7 to 9 with a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 4.57 V for the organic EL element produced in Example 5, and 4.78 V for the organic EL element produced in Example 6.
  • the organic EL element produced in Comparative Example 3 is 4.93V.
  • the current density at this time, for the organic EL device produced in Example 5 was 9.16mA / cm 2
  • for the organic EL devices fabricated in Example 6 was 11.99mA / cm 2
  • Comparative Example 3 The organic EL element produced in the above is 14.49 mA / cm 2 .
  • the luminous efficiency at that time is 7.51 Lm / W for the organic EL element produced in Example 5, 5.49 Lm / W for the organic EL element produced in Example 6, and About the produced organic EL element, it is 4.40 Lm / W.
  • the current efficiency at that time was 10.91 cd / A for the organic EL element produced in Example 5, and 8.34 cd / A for the organic EL element produced in Example 6, and produced in Comparative Example 3.
  • the organic EL element thus produced is 6.91 cd / A.
  • the external quantum efficiency at that time was 15.89% for the organic EL element produced in Example 5, and 12.14% for the organic EL element produced in Example 6, and was produced in Comparative Example 3.
  • the organic EL element is 10.06%.
  • the organic EL device in which the dope concentration at the hole transport layer interface produced in Example 5 is higher than the dope concentration at the electron transport layer interface, and the dope concentration at the hole transport layer interface is lower than the dope concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 6 has a current density lower than that of Comparative Example 3 in which the doping concentration is not gradient, and the luminous efficiency is 1.2 to 1.7 times.
  • the external quantum efficiency was improved by 1.2 to 1.6 times from 1.2 to 1.6 times.
  • Example 7 In Example 1, instead of using CBP as the host material as the light emitting layer and Ir (piq) 2 acac as the dopant, 2,2′-bis (4-carbazolylphenyl) biphenyl represented by the following formula is used as the host material.
  • An organic EL device was produced according to the procedure of Example 1 except that bis [2- (4,6-difluorophenyl) pyridinate-N, C ′] iridium (III) picolate (FIrpic) was used as the dopant. When a voltage of 10 V was applied to the organic EL element, light blue light emission from FIrpic was obtained with a luminance of 110 cd / m 2 . The direct current at this time was 0.10 mA.
  • Example 8 In Example 7, the dope concentration at the start of vapor deposition of the light emitting layer was 15 wt%, the dopant deposition rate was reduced from the start of vapor deposition to the end of vapor deposition, the host vapor deposition rate was increased, and the dope concentration at the end of vapor deposition was 5 wt%. Instead, the doping concentration at the start of deposition was 5 wt%, the doping concentration at the end of deposition was 15 wt%, the dopant deposition rate was increased from the start of deposition to the end of deposition, and the host deposition rate was reduced. According to the operation of No. 7, an organic EL device was prepared.
  • Comparative Example 4 In Examples 7 and 8, instead of providing a gradient in the doping concentration of the light emitting layer, an organic EL element was prepared according to the operations described in Examples 7 and 8 except that no gradient was provided in the doping concentration of the light emitting layer. Produced. When a voltage of 10 V was applied to the organic EL element, light blue light emission from FIrpic was obtained with a luminance of 346 cd / m 2 . The direct current at this time was 0.44 mA.
  • FIG. 10 to 12 show initial characteristics of the organic EL devices produced in Example 7, Example 8, and Comparative Example 4.
  • FIG. 10 is a diagram showing the relationship between the luminous efficiency and the current density of the organic EL element.
  • FIG. 11 is a diagram showing the relationship between the current efficiency and the current density of the organic EL element.
  • FIG. 12 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 7 As shown in FIG. 10, regarding the luminous efficiency of the organic EL elements produced in Example 7, Example 8, and Comparative Example 4, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 , and Example 7 It can be seen that the element produced in Example 8 is higher in efficiency than the element produced in Comparative Example 4, and the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration. .
  • Example 7 for the current efficiency of the organic EL device produced in Example 8 and Comparative Example 4, the current density is from 0.1 mA / cm 2 until 50 mA / cm 2, Example 7, It can be seen that the element produced in Example 8 is more efficient than the element produced in Comparative Example 4, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • the external quantum efficiencies of the organic EL devices produced in Example 7, Example 8, and Comparative Example 4 are as follows: the current density is from 0.1 mA / cm 2 to 50 mA / cm 2. It can be seen that the element produced in Example 8 is higher in efficiency than the element produced in Comparative Example 4, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Table 7 is a table summarizing initial characteristics of the organic EL element obtained from FIGS. 10 to 12 at a luminance of 100 cd / m 2 .
  • the voltage when the luminance was 100 cd / m 2 was 9.83 V for the organic EL element produced in Example 7, and 8.16 V for the organic EL element produced in Example 8.
  • the organic EL device produced in Comparative Example 4 it is 8.76V.
  • the current density at this time, for the organic EL device produced in Example 7 was 2.09mA / cm 2
  • for the organic EL device produced in Example 8 was 2.10mA / cm 2
  • Comparative Example 4 It is 3.41 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time was 1.53 Lm / W for the organic EL element produced in Example 7, and 1.83 Lm / W for the organic EL element produced in Example 8, About the produced organic EL element, it is 1.05 Lm / W.
  • the current efficiency at that time was 4.77 cd / A for the organic EL element produced in Example 7, and 4.75 cd / A for the organic EL element produced in Example 8, which was produced in Comparative Example 4. It is 2.93 cd / A about the organic EL element made.
  • the external quantum efficiency at that time was 2.87% for the organic EL element produced in Example 7, 2.86% for the organic EL element produced in Example 8, and was produced in Comparative Example 4.
  • the organic EL element is 1.45%.
  • the voltage of the device of Example 7 exceeded that of the device of Comparative Example 4 in which no gradient was provided in the doping concentration.
  • the luminous efficiency was improved by about 1.5 to 1.7 times
  • the current efficiency was improved by about 1.6 times
  • Table 8 is a table summarizing initial characteristics of the organic EL element obtained from FIGS. 10 to 12 at a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 12.67 V for the organic EL element produced in Example 7, and 11.33 V for the organic EL element produced in Example 8.
  • the voltage is 11.29V.
  • the current density at this time, for the organic EL device produced in Example 7 was 17.27mA / cm 2
  • for the organic EL device produced in Example 8 was 17.69mA / cm 2
  • Comparative Example 4 The organic EL element produced in the above is 29.45 mA / cm 2 .
  • the luminous efficiency at that time was 1.44 Lm / W for the organic EL element produced in Example 7, 1.57 Lm / W for the organic EL element produced in Example 8, and About the produced organic EL element, it is 0.94 Lm / W.
  • the current efficiency at that time is 5.79 cd / A for the organic EL element produced in Example 7, and 5.65 cd / A for the organic EL element produced in Example 8, and is produced in Comparative Example 4.
  • the organic EL element thus produced is 3.39 cd / A.
  • the external quantum efficiency at that time was 3.43% for the organic EL device produced in Example 7, and 3.35% for the organic EL device produced in Example 8, and was produced in Comparative Example 4.
  • the organic EL element is 1.67%.
  • Example 8 and Dope in which the doping concentration at the hole transport layer interface is lower than the doping concentration at the electron transport layer interface
  • the organic EL element of Comparative Example 4 having no gradient in concentration was the lowest, but Comparative Example 4 was the highest in terms of current density. Therefore, the organic EL elements of Examples 7 and 8 having a gradient in the luminous efficiency in the luminous efficiency are about 1.5 to 1.7 times as compared with the element of Comparative Example 4 having no gradient. Improved. In terms of current efficiency, an element having a gradient in the doping concentration was improved by about 1.7 times as compared with an element having no gradient. Also in the external quantum efficiency, an element having a gradient in the doping concentration was improved by about 2.0 to 2.1 times compared with an element having no gradient.
  • Example 9 (Production of organic EL device) In Example 7, instead of adjusting the deposition rate so that the doping concentration at the start of vapor deposition of the light emitting layer is 15 wt%, the doping concentration at the end of vapor deposition is 5 wt%, and the average doping concentration of the entire light emitting layer is 10 wt%. In Example 7, except that the doping concentration at the start of deposition was 20 wt%, the doping concentration at the end of deposition was 10 wt%, and the deposition rate was adjusted so that the average doping concentration of the entire light emitting layer was 15 wt%.
  • An organic EL element was produced according to the operation. When a voltage of 10 V was applied to the organic EL element, light blue light emission from FIrpic was obtained with a luminance of 594 cd / m 2 . The direct current at this time was 0.36 mA.
  • Example 10 In Example 9, the dope concentration at the start of vapor deposition of the light emitting layer was 20 wt%, the dopant deposition rate was reduced from the start of vapor deposition to the end of vapor deposition, the host vapor deposition rate was increased, and the dope concentration at the end of vapor deposition was 10 wt%. Instead of Example, except that the doping concentration at the start of deposition was 10 wt%, the doping concentration at the end of deposition was 20 wt%, the deposition rate of the dopant was increased from the start of deposition to the end of deposition, and the deposition rate of the host was decreased. According to the operation in 9, an organic EL device was prepared.
  • Comparative Example 5 In Examples 9 and 10, instead of providing a gradient in the doping concentration of the light emitting layer, the organic EL element was prepared according to the operations described in Examples 9 and 10 except that no gradient was provided in the doping concentration of the light emitting layer. Produced. When a voltage of 10 V was applied to this organic EL element, light blue light emission from FIrpic was obtained with a luminance of 151 cd / m 2 . The direct current at this time was 0.21 mA.
  • FIG. 13 to 15 show initial characteristics of the organic EL elements produced in Example 9, Example 10, and Comparative Example 5.
  • FIG. 13 is a diagram showing the relationship between the luminous efficiency and the current density of the organic EL element.
  • FIG. 14 is a diagram showing the relationship between current efficiency and current density of the organic EL element.
  • FIG. 15 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 10 As shown in FIG. 13, regarding the luminous efficiency of the organic EL devices produced in Example 9, Example 10 and Comparative Example 5, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 and Example 9 was used. It can be seen that the device manufactured in Example 10 is higher in efficiency than the device manufactured in Comparative Example 5, and the device having a gradient in the doping concentration has a higher efficiency than the device having no gradient in the doping concentration.
  • Example 9 As shown in FIG. 14, regarding the current efficiency of the organic EL elements produced in Example 9, Example 10 and Comparative Example 5, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 , and Example 9, It can be seen that the element produced in Example 10 is more efficient than the element produced in Comparative Example 5, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 10 As shown in FIG. 15, regarding the external quantum efficiency of the organic EL devices produced in Example 9, Example 10, and Comparative Example 5, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 , and Example 9 It can be seen that the element produced in Example 10 is more efficient than the element produced in Comparative Example 5, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration. .
  • Table 9 is a table summarizing the initial characteristics of the luminance of 100 cd / m 2 of the organic EL elements obtained from FIGS.
  • the voltage when the luminance is 100 cd / m 2 is 8.25 V for the organic EL element produced in Example 9, and 7.86 V for the organic EL element produced in Example 10.
  • the organic EL device produced in Comparative Example 5 it is 9.56V.
  • the current density at this time, for the organic EL device produced in Example 9 was 1.83mA / cm 2
  • for the organic EL device produced in Example 10 was 1.76mA / cm 2
  • Comparative Example 5 It is 3.65 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time is 2.08 Lm / W for the organic EL element produced in Example 9, 2.27 Lm / W for the organic EL element produced in Example 10, and in Comparative Example 5 About the produced organic EL element, it is 0.90 Lm / W.
  • the current efficiency at that time is 5.46 cd / A for the organic EL element produced in Example 9, and 5.68 cd / A for the organic EL element produced in Example 10, and is produced in Comparative Example 5.
  • the organic EL element thus obtained is 2.74 cd / A.
  • the external quantum efficiency at that time was 3.18% for the organic EL element produced in Example 9, 2.70% for the organic EL element produced in Example 10, and was produced in Comparative Example 5.
  • the organic EL element is 1.28%.
  • the organic EL devices produced in Example 9 and Example 10 in which the doping concentration is provided with a gradient are lower in voltage and current density than the device in Comparative Example 5 in which the gradient is not provided.
  • the sensitivity was improved by 2.3 to 2.5 times
  • the current efficiency was improved by about 2.0 to 2.1 times
  • the external quantum efficiency was improved by about 2.1 to 2.5 times.
  • Table 10 is a table summarizing initial characteristics of the organic EL element obtained from FIGS. 13 to 15 at a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 10.63 V for the organic EL element produced in Example 9, and 10.21 V for the organic EL element produced in Example 10.
  • the voltage is 12.31V.
  • the current density at this time, for the organic EL device produced in Example 9 was 14.68mA / cm 2
  • for the organic EL device produced in Example 10 was 14.54mA / cm 2
  • Comparative Example 5 It is 28.25 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time is 2.01 Lm / W for the organic EL device produced in Example 9, 2.12 Lm / W for the organic EL device produced in Example 10, and in Comparative Example 5 About the produced organic EL element, it is 0.90 Lm / W.
  • the current efficiency at that time was 6.81 cd / A for the organic EL element produced in Example 9, and 6.88 cd / A for the organic EL element produced in Example 10, and was produced in Comparative Example 5. It is 3.54 cd / A for the organic EL element.
  • the external quantum efficiency at that time was 3.97% for the organic EL device produced in Example 9, and 3.28% for the organic EL device produced in Example 10, and was produced in Comparative Example 5.
  • the organic EL element is 1.65%.
  • the organic EL devices produced in Example 9 and Example 10 in which the doping concentration is provided with a gradient are lower in voltage and current density than the device in Comparative Example 5 in which the gradient is not provided.
  • the sensitivity was improved by 2.2 to 2.4 times
  • the current efficiency was improved by about 1.9 times
  • the external quantum efficiency was improved by about 2.0 to 2.4 times.
  • Example 11 In Example 7, instead of adjusting the deposition rate so that the dope concentration at the start of vapor deposition of the light emitting layer was 15 wt%, the dope concentration at the end of vapor deposition was 5 wt%, and the dope concentration of the entire light emitting layer was 10 wt%. According to the operation of Example 7, except that the doping concentration at the start of deposition was 100 wt%, the doping concentration at the end of deposition was 0 wt%, and the deposition rate was adjusted so that the doping concentration of the entire light emitting layer was 20 wt%. An EL element was produced. When a voltage of 10 V was applied to the organic EL element, light blue light emission from FIrpic was obtained with a luminance of 110 cd / m 2 . The direct current at this time was 0.10 mA.
  • Example 12 In Example 11, the doping concentration at the start of vapor deposition of the light emitting layer was 100 wt%, the deposition rate of the dopant was decreased from the start of deposition to the end of deposition, the deposition rate of the host was increased, and the dope concentration at the end of deposition was set to 0 wt%. Instead of Example, except that the doping concentration at the start of deposition was 0 wt%, the doping concentration at the end of deposition was 100 wt%, the deposition rate of the dopant was increased from the start of deposition to the end of deposition, and the deposition rate of the host was decreased. According to the operation of 11, an organic EL element was produced. When a voltage of 10 V was applied to this organic EL element, light blue light emission from FIrpic was obtained with a luminance of 115 cd / m 2 . The direct current at this time was 0.10 mA.
  • FIG. 16 to 18 show initial characteristics of the organic EL elements produced in Example 11, Example 12, and Comparative Example 6.
  • FIG. 16 is a diagram showing the relationship between the luminous efficiency and the current density of the organic EL element.
  • FIG. 17 is a diagram showing the relationship between the current efficiency and the current density of the organic EL element.
  • FIG. 18 is a diagram showing the relationship between the external quantum efficiency of the organic EL element and the current density.
  • Example 12 As shown in FIG. 16, regarding the luminous efficiency of the organic EL elements produced in Example 11, Example 12, and Comparative Example 6, the current density was from 0.1 mA / cm 2 to 50 mA / cm 2 and Example 11 was used. It can be seen that the element produced in Example 12 is higher in efficiency than the element produced in Comparative Example 6, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 11 for the current efficiency of the organic EL device produced in Example 12 and Comparative Example 6, a current density of from 0.1 mA / cm 2 until 50 mA / cm 2, Example 11, It can be seen that the element produced in Example 12 is more efficient than the element produced in Comparative Example 6, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Example 12 As shown in FIG. 18, the external quantum efficiencies of the organic EL devices produced in Example 11, Example 12, and Comparative Example 6 were also different from Example 11 in that the current density was from 0.1 mA / cm 2 to 50 mA / cm 2. It can be seen that the element produced in Example 12 is higher in efficiency than the element produced in Comparative Example 6, and that the element having a gradient in the doping concentration has a higher efficiency than the element having no gradient in the doping concentration.
  • Table 11 is a table summarizing the initial characteristics of the luminance of 100 cd / m 2 of the organic EL elements obtained from FIG. 16 to FIG.
  • the voltage when the luminance was 100 cd / m 2 was 9.86 V for the organic EL element produced in Example 11, and 9.81 V for the organic EL element produced in Example 12.
  • the voltage is 10.65V.
  • the current density at this time, for the organic EL device produced in Example 11 was 2.31mA / cm 2
  • for the organic EL device produced in Example 12 was 2.21mA / cm 2
  • Comparative Example 6 It is 4.03 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time is 1.38 Lm / W for the organic EL element produced in Example 11, 1.45 Lm / W for the organic EL element produced in Example 12, and in Comparative Example 6 About the produced organic EL element, it is 0.73 Lm / W.
  • the current efficiency at that time is 4.34 cd / A for the organic EL element fabricated in Example 11, 4.51 cd / A for the organic EL element fabricated in Example 12, and is fabricated in Comparative Example 6.
  • the organic EL element thus obtained is 2.48 cd / A.
  • the external quantum efficiency at that time was 2.02% for the organic EL element produced in Example 11, and 2.11% for the organic EL element produced in Example 12, and was produced in Comparative Example 6.
  • the organic EL element is 1.16%.
  • the organic EL device in which the dope concentration at the hole transport layer interface produced in Example 11 is higher than the dope concentration at the electron transport layer interface, and the dope concentration at the hole transport layer interface is lower than the dope concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 12 has a current density lower than that of Comparative Example 6 in which no gradient is provided in the doping concentration, the luminous efficiency is 1.9 to 2.0 times, and the current efficiency is The external quantum efficiency was improved by 1.7 to 1.8 times from 1.7 to 1.8 times.
  • Table 12 summarizes the initial characteristics of the organic EL elements obtained from FIGS. 16 to 18 at a luminance of 1000 cd / m 2 .
  • the voltage when the luminance is 1000 cd / m 2 is 14.76 V for the organic EL element produced in Example 11, and 14.61 V for the organic EL element produced in Example 12.
  • the voltage is 17.64V.
  • the current density at this time, for the organic EL device produced in Example 11 was 23.50mA / cm 2
  • for the organic EL device produced in Example 12 was 22.31mA / cm 2
  • Comparative Example 6 It is 52.42 mA / cm ⁇ 2 > about the organic EL element produced by this.
  • the luminous efficiency at that time was 0.91 Lm / W for the organic EL element produced in Example 11, 0.96 Lm / W for the organic EL element produced in Example 12, and About the produced organic EL element, it is 0.34 Lm / W.
  • the current efficiency at that time is 4.26 cd / A for the organic EL element produced in Example 11, and 4.48 cd / A for the organic EL element produced in Example 12, and is produced in Comparative Example 6. It is 1.91 cd / A about the organic EL element made.
  • the external quantum efficiency at that time was 1.99% for the organic EL element produced in Example 11, 2.10% for the organic EL element produced in Example 12, and was produced in Comparative Example 6.
  • the organic EL element is 0.90%.
  • the organic EL device in which the dope concentration at the hole transport layer interface produced in Example 11 is higher than the dope concentration at the electron transport layer interface, and the dope concentration at the hole transport layer interface is lower than the dope concentration at the electron transport layer interface.
  • the organic EL device manufactured in Example 12 has a current density lower than that of Comparative Example 6 in which no gradient is provided in the doping concentration, the luminous efficiency is 2.7 to 2.8 times, and the current efficiency is The external quantum efficiency was improved by 2.2 to 2.3 times, and by 2.2 to 2.3 times.
  • Table 13 shows the luminance and direct current of the organic EL elements obtained from Examples 1 to 12 and Comparative Examples 1 to 6 when the same voltage is applied to the group of organic EL elements having the same dope concentration.
  • Table 14 is a table that summarizes Tables 1, 3, 5, 7, 9, and 11, and Table 15 is a table that summarizes Tables 2, 4, 6, 8, 10, and 12.
  • the example does not necessarily outperform the comparative example in terms of luminance and direct current under the same voltage. However, as shown in Tables 14 and 15, when the efficiency is compared, the example exceeds the comparative example. As is clear from this, the organic EL element of the present invention can emit light with higher efficiency than the conventional organic EL element by the configuration of the present invention.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
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  • Electroluminescent Light Sources (AREA)

Abstract

L'invention porte sur un nouvel élément électroluminescent organique (élément EL organique). L'élément EL organique comprend deux électrodes agencées pour se faire face et un ou plusieurs films organiques intercalés entre elles, et est caractérisé en ce qu'au moins un des films organiques comprend une couche luminescente comprenant un hôte (qui est un composé aromatique ou un composé complexe) et un dopant (qui est un composé complexe) et en ce que la quantité du composé complexe dopant, en termes de parties en poids pour 100 parties en poids de la quantité totale de l'hôte et du dopant (appelée concentration en dopant dans ce qui suit), n'est pas uniforme dans toute la couche et la couche présente un gradient de concentration en dopant tel que la concentration en dopant est maximale dans une partie proche d'une électrode et est minimale dans une partie proche de l'autre électrode.
PCT/JP2011/052221 2010-02-04 2011-02-03 Nouvel élément électroluminescent organique à rendement lumineux amélioré WO2011096465A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004006102A (ja) * 2002-05-31 2004-01-08 Canon Inc エレクトロルミネッセンス素子
JP2005100767A (ja) * 2003-09-24 2005-04-14 Fuji Photo Film Co Ltd 有機電界発光素子
WO2008035595A1 (fr) * 2006-09-19 2008-03-27 Konica Minolta Holdings, Inc. Dispositifs électroluminescents organiques
JP2009071188A (ja) * 2007-09-14 2009-04-02 Fujifilm Corp 有機電界発光素子

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004006102A (ja) * 2002-05-31 2004-01-08 Canon Inc エレクトロルミネッセンス素子
JP2005100767A (ja) * 2003-09-24 2005-04-14 Fuji Photo Film Co Ltd 有機電界発光素子
WO2008035595A1 (fr) * 2006-09-19 2008-03-27 Konica Minolta Holdings, Inc. Dispositifs électroluminescents organiques
JP2009071188A (ja) * 2007-09-14 2009-04-02 Fujifilm Corp 有機電界発光素子

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