JP2010092741A - Organic electroluminescent element - Google Patents

Abstract

Provided is an organic electroluminescence device that can emit light with high brightness and high efficiency, and that can increase driving voltage, cause an undesirable increase in voltage, and suppress light emission in regions other than the intended light emitting region. To do.
In an organic electroluminescent device A according to the present invention, a plurality of light emitting layers 4 each having an organic light emitting layer are laminated via an intermediate layer 3 between an anode 1 and a cathode 2. The intermediate layer 3 includes a conductive layer 3a containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and a hole injecting layer 3b containing a hole injecting metal oxide. The hole injecting layer 3b and the conductive layer 3a are laminated in order from the cathode 2 side, and the thickness of the conductive layer 3a is 10 nm or less.
[Selection] Figure 1

Description

  The present invention relates to an organic electroluminescence element used for an illumination light source, a backlight for a liquid crystal display, a flat panel display, and the like. Specifically, the present invention relates to an organic electroluminescence element that includes a plurality of organic light emitting layers and emits light with high brightness and high efficiency. .

  As an example of an organic light-emitting device called an organic electroluminescence device, a transparent electrode (anode 1), a hole transport layer, an organic light-emitting layer, an electron injection layer, and an electrode (cathode 2) are sequentially laminated on one surface of a transparent substrate. The thing which was done is mentioned. When a voltage is applied between the anode 1 and the cathode 2 of the organic electroluminescence element A, electrons injected into the organic light emitting layer through the electron injection layer and injected into the organic light emitting layer through the hole transport layer. The holes recombine in the organic light emitting layer to emit light, and this light is emitted to the outside through the transparent electrode and the transparent substrate.

  The organic electroluminescence element A has features such as self-emission, relatively high-efficiency emission characteristics, and capable of emitting light in various colors, and emits light from a display device such as a flat panel display. It is expected to be used as a body or as a light source, for example, a backlight for a liquid crystal display or illumination, and a part thereof has already been put into practical use.

  However, the organic electroluminescent element A has a problem that the luminance and the lifetime are in a trade-off relationship, and the lifetime is shortened when the luminance is increased to obtain a clearer image or bright illumination light. .

  In order to solve this problem, in recent years, an organic light emitting device having a plurality of organic light emitting layers between the anode 1 and the cathode 2 and electrically connecting each organic light emitting layer has been proposed (for example, Patent Document 1). 5).

  FIG. 4 shows an example of the structure of such an organic electroluminescence element A. In the illustrated example, a plurality of light emitting layers 4a and 4b including an organic light emitting layer are provided between an anode 1 and a cathode 2 provided on one surface of a transparent substrate 5, and between adjacent light emitting layers 4a and 4b. The intermediate layer 3 is interposed between the two. The anode 1 is formed as a light transmissive electrode, and the cathode 2 is formed as a light reflective electrode. In FIG. 4, illustration of the electron injection layer and the hole transport layer provided on both sides of the organic light emitting layer in the light emitting layers 4a and 4b is omitted.

  In this example, the plurality of light emitting layers 4a and 4b are electrically connected via the intermediate layer 3, whereby the light emitting layers 4a and 4b are connected in series, and a voltage is applied between the anode 1 and the cathode 2. When applied, the organic light emitting layers in the light emitting layers 4a and 4b emit light simultaneously. For this reason, from the organic electroluminescent element A, the light which the light from the organic light emitting layer in each light emitting layer 4a, 4b adds is radiate | emitted, and the light-emission brightness with respect to the amount of electricity supply improves rather than the conventional organic electroluminescent element A To do. This avoids the brightness-lifetime tradeoff in the organic electroluminescent element A as described above.

Commonly known configurations of the intermediate layer 3 include, for example, (1) BCP: Cs / V ₂ O ₅ , (2) BCP: Cs / NPD: V ₂ O ₅ , (3) In-situ reaction product of Li complex and Al, (4) Alq: Li / ITO / hole transport material, (5) metal-organic mixed layer, (6) oxide containing alkali metal and alkaline earth metal, etc. (":" Represents a mixture of two materials, and "/" represents a stack of preceding and following compositions).

  However, if the intermediate layer 3 for partitioning a plurality of organic light emitting layers is provided as in the above prior art, an increase in driving voltage and an undesirable increase in voltage may occur.

  For example, in the system shown in the above (2), there is a problem of voltage increase due to a side reaction occurring between two layers. That is, it has been reported that Lewis acid molecules react with electron transport materials, and alkali metals react with hole transport materials as Lewis bases, and these reactions cause an increase in driving voltage (reference: polymer). Society of Organic EL Research Meeting December 9, 2005 Multi-photon organic EL lighting).

  Further, in the system shown in (3) above, there is a problem that the organic ligand component of the Li complex used for obtaining the in-situ reaction product may adversely affect the device characteristics.

  In the system shown in (4), the hole injection property from the ITO as the intermediate layer 3 to the hole transport material is not always good, and there is a problem in terms of drive voltage and device characteristics. Furthermore, since the specific resistance of ITO is small, there is a problem that electric charges are transmitted through the ITO to a region where it is not desired to emit light, and light emission may occur in a region other than the intended light emitting region.

  In the system shown in (5) above, since the intermediate layer 3 is formed by mixing a metal containing a metal compound such as a metal oxide and an organic substance, the thermal stability of the intermediate layer 3 is lowered, and particularly a large current is generated. There was a problem that the stability of the intermediate layer 3 with respect to heat generation when energized was inferior.

  Further, the system shown in the above (6) has a problem that the function as the intermediate layer 3 of the metal oxide containing an alkali metal or an alkaline earth metal is not always sufficient.

  Patent Document 3 describes a method of forming the intermediate layer 3 by adding an additive to one kind of matrix so that its concentration does not become zero at any position in the film. Even in this case, it is impossible to solve all of the above problems.

Therefore, in producing an organic electroluminescent device A having a plurality of organic light emitting layers stacked via the intermediate layer 3, it is desired to realize the intermediate layer 3 that overcomes various problems. .
Japanese Patent Laid-Open No. 11-329748 JP 2003-272860 A JP 2005-135600 A JP 2006-332048 A JP 2006-173550 A

  The present invention has been made in view of the above points, can emit light with high luminance and high efficiency, and has an increase in driving voltage, occurrence of an undesirable voltage increase, and a region other than the intended light emitting region. An object of the present invention is to provide an organic electroluminescence device in which the light emission is suppressed.

  In the organic electroluminescent element A according to the present invention, a plurality of light emitting layers 4 each including an organic light emitting layer are laminated via an intermediate layer 3 between an anode 1 and a cathode 2.

In the first invention, the intermediate layer 3 includes a conductive layer 3a containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and a hole injecting layer 3b containing a hole injecting metal oxide. And the hole injecting layer 3b and the conductive layer 3a are laminated in order from the cathode 2 side, and the thickness of the conductive layer 3a is 10 nm or less.

  According to 1st invention, since the intermediate | middle layer 3 contains the conductive layer 3a with a low specific resistance, the drive voltage of the organic electroluminescent element A containing the said intermediate | middle layer 3 reduces. Further, since the function of the intermediate layer 3 is maintained by the conductive layer 3a and the thickness of the conductive layer 3a is 10 nm or less, the current conduction in the lateral direction in the conductive layer 3a is reduced to a level that can be ignored. Light emission in a region other than the light emitting region is suppressed. Moreover, the hole injection layer 3b reduces the charge injection barrier from the intermediate layer 3 to the adjacent light emitting layer 4 on the cathode 2 side, and as a result, the driving voltage is further reduced.

  In the first invention, the conductive layer preferably contains at least one selected from cerium, cesium, lithium, sodium, magnesium, potassium, rubidium, samarium, yttrium, and compounds of these metals.

  In this case, electron injection properties are imparted to the conductive layer 3a, and the charge injection barrier to the light emitting layer 4 adjacent to the intermediate layer 3 is further reduced. Moreover, the stability of the intermediate layer 3 is improved by forming the electron-injecting layer from an inorganic material having high morphological stability.

In the second invention, the intermediate layer 3 includes a conductive layer 3a containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and an electron injecting layer 3c containing an electron injecting metal oxide. The conductive layer 3a and the electron injecting layer 3c are stacked in this order from the cathode 2 side, and the thickness of the conductive layer 3a is 10 nm or less.

  According to the second invention, since the intermediate layer 3 includes the conductive layer 3a having a low specific resistance, the driving voltage of the organic electroluminescence element A including the intermediate layer 3 is reduced. Further, since the function of the intermediate layer 3 is maintained by the conductive layer 3a and the thickness of the conductive layer 3a is 10 nm or less, the current conduction in the lateral direction in the conductive layer 3a is reduced to a level that can be ignored. Light emission in a region other than the light emitting region is suppressed. Further, the electron injecting layer 3c reduces the charge injection barrier from the intermediate layer 3 to the adjacent light emitting layer 4 on the anode 1 side. As a result, the driving voltage is further reduced.

  In the second invention, the conductive layer preferably contains at least one selected from tungsten, molybdenum, rhenium, vanadium, ruthenium, aluminum, and a compound of these metals.

  In this case, hole injecting property is imparted to the conductive layer 3a, and the charge injection barrier to the light emitting layer 4 adjacent to the intermediate layer 3 is further reduced. Moreover, the stability of the intermediate layer 3 is improved by forming the hole-injecting layer from an inorganic material having high morphological stability.

  According to the present invention, the driving voltage of an organic electroluminescent device including a plurality of light emitting layers through an intermediate layer is reduced, light emission in a region other than the intended light emitting region is suppressed, and the organic electroluminescent device Long life can be achieved.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 shows an example of the structure of the organic electroluminescence element A. In the illustrated example, a light emitting layer 4 and an intermediate layer 3 including an organic light emitting layer are interposed between an electrode to be the anode 1 and an electrode to be the cathode 2. As the light-emitting layer 4, a plurality of light-emitting layers 4a and 4b are stacked in the electrode stacking direction, and the intermediate layer 3 is interposed between the light-emitting layers 4a and 4b adjacent to each other. Furthermore, one electrode (anode 1) is laminated on the surface of the transparent substrate 5. The anode 1 is formed as a light transmissive electrode, and the cathode 2 is formed as a light reflective electrode.

  In the present embodiment, the two light emitting layers 4 a and 4 b are provided as the light emitting layer 4, but a larger number of light emitting layers 4 may be laminated via the intermediate layer 3. The number of stacked light emitting layers 4 is not particularly limited. However, the increase in the number of layers increases the difficulty of designing optical and electrical elements. As in the general organic electroluminescence device A, the light emitting layers 4a and 4b include a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, etc. between the organic light emitting layer and the anode 1 or the cathode 2. These layers may be provided, but these layers are not shown in FIG.

In the first embodiment shown in FIG. 1A, the intermediate layer 3 includes a conductive layer 3a containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and a hole-injecting metal oxide. A hole injecting layer 3b is provided. The hole injecting layer 3b and the conductive layer 3a are laminated in this order from the cathode 2 side.

The conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less contained in the conductive layer 3a is not particularly limited as long as it is a material generally known as a conductive material, and is appropriately selected from metals, metal oxides, electrically conductive compounds, and the like. Selected. Specific examples of this conductor include metals such as Al, Cu, Ni, Ag, Au, and Ti, metal compounds such as CuI, ZnSe, ZnS, and CuSe, ITO (indium-tin oxide), SnO ₂ , ZnO, and IZO. Examples thereof include metal oxides such as (indium-zinc oxide), carbon compounds such as carbon nanotubes and fullerenes. Further, the conductor constituting the conductive layer 3a is not limited to one type. For example, the conductive layer 3a may be any one of the above, such as indium and tin, indium and zinc, aluminum and gallium, gallium and zinc, titanium and niobium, etc. It may be composed of a plurality of metals selected from metals, or a mixture of two or more conductors selected from these metals, metal oxides, metal compounds, and other conductors. May be. The oxidation number of the metal in the conductor constituting the conductive layer 3a, the mixing ratio of the plurality of conductors, and the like are appropriately set so that the film quality, thermal stability, and electrical characteristics of the conductive layer 3a are good. The The conductive layer 3a is formed, for example, by forming a conductor constituting the conductive layer 3a into a thin film by an appropriate method such as vacuum deposition, sputtering, or coating.

The thickness of the conductive layer 3a is 10 nm or less, preferably 5 nm or less. By forming the conductive layer 3a as a thin film in this way, the current conduction in the lateral direction of the conductive layer 3a (the direction orthogonal to the stacking direction of the organic electroluminescent element A) is reduced to a negligible level. Light emission in a region other than the light emitting region is suppressed. In particular, the value obtained by dividing the thickness (nm) of the conductive layer 3a by the specific resistance (Ωcm) at 23 ° C. of the conductive layer 3a is preferably 10 ⁴ (nm / Ωcm) or less. The lower limit of the thickness of the conductive layer 3 is not particularly limited, but is preferably 1 nm or more from the viewpoint of forming a stable continuous film.

  The hole-injecting metal oxide contained in the hole-injecting layer 3b is a metal oxide having a work function larger than the ionization potential of the organic compound in the adjacent light-emitting layer 4 and capable of prompt hole injection, Alternatively, any metal oxide that can inject holes by forming a charge transfer complex with an organic compound in the adjacent light emitting layer 4 may be used. Specifically, for example, molybdenum, rhenium, tungsten, vanadium, zinc, indium , Metal oxides containing any of tin, gallium, titanium, and aluminum. This metal oxide is not limited to a single oxide, and for example, indium and molybdenum, vanadium and zinc, aluminum and gallium, gallium and zinc, titanium and niobium, and the like containing two or more of the above metals. Multi-element oxides may also be used. The oxidation number of the metal in this layer, the mixing ratio of a plurality of metals, and the like are appropriately set so that the film quality, thermal stability, and electrical characteristics of this layer are good.

  The hole injecting layer 3b may be made of a conductor (metal oxide) that can form the conductive layer 3a as long as the layer exhibits hole injecting properties. Whether or not the hole injection property is exhibited can be determined by whether or not the drive voltage is reduced by providing the hole injection layer 3b.

In addition to the metal oxide, the hole injecting layer 3b may contain an organic compound or a non-conductive inorganic insulator. The inorganic insulator is not particularly limited as long as it can be formed by mixing with the metal oxide constituting the hole injecting layer 3b. For example, a metal fluoride such as lithium fluoride or magnesium fluoride; Metal halides such as metal chlorides typified by sodium and magnesium chloride; aluminum, cobalt, zirconium, titanium, vanadium, niobium, chromium, tantalum, tungsten, manganese, molybdenum, ruthenium, iron, nickel, copper, gallium, Examples thereof include oxides of various metals such as zinc (except those corresponding to hole-injecting metal oxides), nitrides, carbides, oxynitrides, and the like. Specific examples of the inorganic insulator include, for example, Al ₂ O ₃ , MgO, iron oxide, AlN, SiN, SiC, SiON, BN, SiO ₂ , SiO, and the like. The compound is used by appropriately selecting from a compound, a carbon compound and the like.

  These insulators are preferably selected from those having low absorption in the visible light region or having a low refractive index. In this case, the light absorptivity and refractive index of the hole injecting layer 3b are reduced, and as a result As a result, reflection and absorption inside the device are reduced. For this reason, the loss when the light generated in the light emitting layer 4 is emitted to the outside is reduced. In particular, any one of metal oxides, metal halides, metal nitrides, metal carbides, carbon compounds, and silicon compounds having no electrical conductivity is preferable from the viewpoints of heat resistance, stability, and optical properties.

The specific resistance at 23 ° C. of the hole injecting layer 3b is preferably in the range of 1 × 10 ⁵ Ωcm or less. Therefore, when the hole-injecting metal oxide and other substances are contained in the hole-injecting layer 3b, the mixing ratio is adjusted so that the specific resistance of the hole-injecting layer 3b is in the above range. It is preferable.

Moreover, in this embodiment, in addition to the above conductors having a size of 1 × 10 ⁵ Ωcm or less, the conductive layer 3a includes cerium, cesium, lithium, sodium, magnesium, potassium, rubidium, samarium, yttrium, as additives. Moreover, you may contain at least 1 type selected from the compound of these metals. When these materials are added to the conductive layer 3a, the electron injection property from the conductive layer 3a to the light emitting layer 4 adjacent to the conductivity is improved, and the carrier transport property of the intermediate layer 3 is further improved. The content of the material in the conductive layer 3a is not particularly limited as long as the specific resistance of the conductive layer 3a does not depart from the spirit of the present invention, but is preferably in the range of 0.1 to 20% by weight. .

In the second embodiment shown in FIG. 1B, the intermediate layer 3 includes a conductive layer 3a containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and an electron-injecting metal oxide. An electron injecting layer 3c is provided. The conductive layer 3a and the electron injecting layer 3c are laminated in this order from the cathode 2 side. The conductive layer 3a is formed, for example, in the same manner as the conductive layer 3a in the first embodiment.

  The electron injecting metal compound contained in the electron injecting layer 3c is a metal oxide having a work function smaller than the electron affinity of the organic compound in the adjacent light emitting layer 4 and capable of prompt electron injection, Alternatively, any metal oxide that can inject electrons by forming a charge transfer complex with an organic compound in the adjacent light emitting layer 4 may be used, and specific examples thereof include, but are not particularly limited to, for example, lithium, cesium, Examples include sodium, strontium, magnesium, calcium, yttrium, samarium, alkali metal, alkaline earth metal, rare earth metal oxides, iridium, nickel oxides, and the like. These metal compounds are used alone or in combination of two or more. The oxidation number of the metal in the metal oxide and the mixing ratio of the plurality of metals are arbitrarily set so that the film quality, thermal stability, and electrical characteristics of the electron injecting layer 3c are within preferable ranges.

  In addition, the electron injecting layer 3c may be made of a conductor (metal compound) that can form the conductive layer 3a as long as the layer exhibits electron permeability. Whether or not the electron injection property is exhibited can be determined by whether or not the drive voltage is reduced by providing the electron injection layer 3c.

The specific resistance at 23 ° C. of the electron injecting layer 3c is preferably in the range of 1 × 10 ⁵ Ωcm or less.

In the present embodiment, the conductive layer 3a is made of tungsten, molybdenum, rhenium, vanadium, ruthenium, aluminum, and compounds of these metals as additives in addition to the above conductor of 1 × 10 ⁵ Ωcm or less. You may contain at least 1 type selected from these. When these materials are added to the conductive layer 3a, the hole injection property from the conductive layer 3a to the light emitting layer 4 adjacent to the conductivity is improved, and the carrier transport property of the intermediate layer 3 is further improved. The content of the material in the conductive layer 3a is not particularly limited as long as the specific resistance of the conductive layer 3a does not depart from the spirit of the present invention, but is preferably in the range of 0.1 to 20% by weight. .

  In the first embodiment, the intermediate layer 3 is composed of the conductive layer 3a and the hole injecting layer 3b, and in the second embodiment, the intermediate layer 3 is composed of the conductive layer 3 and the electron injecting layer 3c. However, the intermediate layer 3 having a configuration in which the hole injecting layer 3b, the conductive layer 3a, and the electron injecting layer 3c are stacked in this order from the cathode 2 side may be formed. In this case, the hole injecting layer 3b reduces the charge injection barrier from the intermediate layer 3 to the adjacent light emitting layer 4 on the cathode 2 side, and the electron injecting layer 3c adjoins the intermediate layer 3 on the anode 1 side. The charge injection barrier to the light emitting layer is reduced, and as a result, the driving voltage of the organic electroluminescence element A is further reduced.

  A configuration other than the intermediate layer 3 in the organic electroluminescence element A will be described.

  The light emitting layer 4 may be provided with a layer containing a charge transfer complex adjacent to the intermediate layer 3 as necessary.

  For example, the light emitting layer 4 disposed on the cathode 2 side with respect to the intermediate layer 3 may be provided with a hole injection layer containing a hole injection charge transfer complex adjacent to the intermediate layer 3. This layer is composed of, for example, a system in which an organic material such as a hole transporting material or a material from which electrons are easily extracted and a material that accepts electrons from the organic material are added.

  As the hole transporting material, generally used triarylamine derivatives such as α-NPD (4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl), TPD (N, N′-bis) are used. (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine), 2-TNATA (4 ′, 4 ″ -tris [N, N- (2-naphthyl) phenylamino] triphenyl) In addition, examples of materials that easily extract electrons include aromatic derivatives such as biphenyl derivatives, anthracene derivatives, and naphthalene derivatives, aniline derivatives, and thiophene derivatives.

Examples of the material that accepts electrons from the organic material include metals, metal oxide semiconductors, inorganic acceptors, and organic acceptors. Examples of the metal include a metal having a high work function, for example, gold having a work function of 5 eV or more, and metals such as vanadium, molybdenum, rhenium, tungsten, and nickel. The metal oxide is not particularly limited, but for example, metal oxides of vanadium, molybdenum, rhenium, tungsten, nickel, zinc, tin, and niobium are preferable. Examples of the inorganic acceptor include iron chloride, iron bromide, copper iodide, bromine and iodine. Examples of the organic acceptor include fluorine-containing organic compounds and cyano group-containing organic compounds. Specifically, for example, F ₄ -TCNQ (tetrafluorotetracyanoquinodimethane), DDQ (dichlorodicyanoquinone), CF ₃ TCNQ (Trifluoromethyltetracyanoquinodimethane), 2-TCNQ, or derivatives thereof are exemplified, but derivatives containing a larger number of fluorine, cyano groups and the like in the molecule are also preferably used.

  The mixing ratio of the material that accepts electrons from the organic material to the organic material is appropriately set according to the type of the material, but is preferably in the range of 0.1 mol% to 80 mol%, more preferably 1 mol% to 50 mol%. Range.

The hole injection layer is made of an organic compound or an inorganic substance other than the components constituting the charge transfer complex, for example, a metal such as Al, Cu, Ni, Ag, Au, Ti, LiF, Li ₂ O, NaF, CsF. , SiO ₂ , SiO and other metal halides and metal oxides may be contained. By containing two or more components in this way, the stability of components that are not stable by themselves is improved, or the properties such as film quality and adhesion to adjacent layers are deteriorated by a single component. The characteristics can be improved, and the film formability can be improved.

On the other hand, the light emitting layer 4 disposed on the anode 1 side with respect to the intermediate layer 3 may be provided with an electron injection layer containing an electron injecting charge transfer complex adjacent to the intermediate layer 3. An electron injection charge transfer complex is generally known as a charge transfer complex system and is not particularly limited as long as it is a substance system that contributes to electron injection. For example, an electron transport material and a work of 3.7 eV or less The system which mixed the metal which has a function is mentioned. Examples of the electron transport material include organometallic complexes such as Alq ₃ and compounds having a heterocycle such as phenanthroline derivatives, pyridine derivatives, tetrazine derivatives, and oxadiazole derivatives. Examples of the metal having a work function of 3.7 eV or less include cerium, lithium, sodium, magnesium, potassium, rubidium, samarium, yttrium and the like. Examples of the charge transfer complex system include a system in which the electron transport material as described above is mixed with an organic material or an inorganic material having an energy level capable of donating electrons to the electron transport material. As an organic material or an inorganic material having an energy level capable of donating electrons to an electron transport material, for example, an organic material such as a ruthenium complex generally known as an organic donor, a metal having a work function of 3.7 eV or less, Examples thereof include metal oxide semiconductors containing metals.

  The electron injection layer may be formed of a layer made of a metal layer having a work function of 3.7 eV or less. Although it does not specifically limit as said metal, The metal chosen from the group of the alkali metal, alkaline-earth metal, and rare earth metal containing the above-mentioned example is mentioned.

The thickness of the layer containing these charge transfer complexes is not particularly limited, but is preferably in the range of 1 nm to 20 nm. The layer containing these charge transfer complexes may contain an organic compound or an inorganic substance other than the charge transfer complex as described above. Examples of the other organic compounds and inorganic substances include metals such as Al, Cu, Ni, Ag, Au and Ti, metal halides and metal oxides such as LiF, Li ₂ O, NaF, CsF, SiO ₂ and SiO. Etc. In this way, the layer containing the charge transfer complex contains two or more components, so that the stability of components that are not stable alone is improved, or the film quality and adhesion to adjacent layers are isolated with a single component. When the characteristics such as the above are deteriorated, the characteristics can be improved, and the film forming property can be improved.

  Moreover, as a material which comprises the organic light emitting layer in the light emitting layers 4a and 4b, the arbitrary materials known as a material for the organic electroluminescent elements A can be used. Examples of such materials include, but are not limited to, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclohexane Pentadiene, quinoline metal complex, tris (8-hydroxyquinolinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) aluminum complex, aminoquinoline metal complex, benzo Quinoline metal complex, tri- (p-terphenyl-4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone, rubrene, distyrylbenzene Conductor, distyryl arylene derivatives, distyrylamine derivatives, and various fluorescent pigments, etc., and derivatives thereof. A plurality of materials selected from the above materials may be used in combination. In addition to a material that emits fluorescence such as the above materials, a material system that emits light from a spin multiplet, for example, a phosphorescent material that emits phosphorescence, and a portion made of the material are included in a part of the molecule. Compounds and the like are also preferably used. The organic layer made of these materials is formed by a dry process such as vapor deposition or transfer, or by a wet process such as spin coating, spray coating, die coating, or gravure printing.

  Further, as other members constituting the organic electroluminescence element A, that is, the substrate 5, the anode 1, the cathode 2, and the like holding the stacked elements, the conventional structure can be applied as it is.

  That is, the substrate 5 needs to have light transmittance when light is emitted from the organic electroluminescence element A through the substrate 5. Such a light-transmitting substrate may be slightly colored in addition to being colorless and transparent, or may be in the form of frosted glass. As such a substrate, for example, a transparent glass plate such as soda lime glass or alkali-free glass, a resin such as polyester, polyolefin, polyamide, epoxy, or a plastic film or plastic produced by an arbitrary method from a fluorine resin, etc. A board etc. are mentioned. In addition, the substrate 5 may contain particles, powder, bubbles, etc. having a refractive index different from that of the base material constituting the substrate 5, and the surface is processed into an appropriate shape to provide a light diffusion effect. May be.

  Further, in the case where light is emitted from the organic electroluminescence element A without passing through the substrate 5, the substrate 5 does not necessarily need to have a light transmission property, as long as the light emission characteristics, life characteristics, etc. of the element are not impaired. Made of material. In particular, it is preferable to use the substrate 5 having high thermal conductivity in order to reduce a temperature rise due to heat generation of the element during energization.

The anode 1 is an electrode for injecting holes into the organic light emitting layer in the light emitting layer 4, and is formed of an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function. In particular, it is preferably formed of a material having a work function of 4 eV or more. Examples of the material of the anode 1 include metals such as gold; conductive metal oxides such as CuI, ITO (indium-tin oxide), SnO ₂ , ZnO, and IZO (indium-zinc oxide); PEDOT And conductive polymers such as polyaniline; conductive polymers doped with an arbitrary acceptor; and conductive light-transmitting materials such as carbon nanotubes. The anode 1 is formed, for example, by forming the electrode material as described above into a thin film on the surface of the substrate 5 by a method such as vacuum deposition, sputtering, or coating. In addition, when light emitted from the light emitting layer 4 is extracted through the anode 1, the light transmittance of the anode 1 is preferably 70% or more. The sheet resistance of the anode 1 is preferably several hundred Ω / □ or less, and particularly preferably 100 Ω / □ or less. The film thickness of the anode 1 is appropriately set according to the material constituting the anode 1 so that the characteristics such as light transmittance and sheet resistance of the anode 1 are as desired, but preferably 500 nm or less. Preferably, it is set in the range of 10 to 200 nm.

The cathode 2 is an electrode for injecting electrons into the organic light emitting layer in the light emitting layer 4, and is formed of an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a low work function. It is particularly preferable that the material is formed of a material having a work function of 5 eV or less. Examples of the electrode material of the cathode 2 include alkali metals, alkali metal halides, alkali metal oxides, alkaline earth metals and the like, and alloys thereof with other metals such as sodium and sodium-potassium alloys. , Lithium, magnesium, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / LiF mixture, and the like. Aluminum, Al / Al ₂ O ₃ mixture, etc. can also be used as the electrode material of the cathode 2. Alternatively, the cathode 2 may be formed by forming a base with an alkali metal oxide, an alkali metal halide, or a metal oxide, and laminating one or more conductive materials such as metal on the base. . Examples of such a laminated structure of the base and the cathode 2 include an alkali metal / Al laminated structure, an alkali metal halide / alkaline earth metal / Al laminated structure, and an alkali metal oxide / Al laminated structure. Etc. Alternatively, the cathode 2 may be formed of a transparent electrode material typified by ITO, IZO, etc., and light emitted from the organic electroluminescence element A may be extracted from the cathode 2 side. Further, an interface portion with the cathode 2 in the organic layer in contact with the cathode 2 may be doped with an alkali metal or alkaline earth metal such as lithium, sodium, cesium, or calcium. The cathode 2 is formed, for example, by forming an electrode material constituting the cathode 2 on a thin film by a method such as a vacuum evaporation method or a sputtering method. In addition, when light emitted from the light emitting layer 4 is extracted through the anode 1, the light transmittance of the cathode 2 is preferably 10% or less. Conversely, when light emitted from the light emitting layer 4 is extracted through the cathode 2 (including the case where light is extracted through both the anode 1 and the cathode 2), the light transmittance of the cathode 2 is 70. % Or more is preferable. The film thickness of the cathode 2 is appropriately set according to the material constituting the cathode 2 so that the characteristics such as light transmittance of the cathode 2 become a desired level, preferably 500 nm or less, more preferably 100 to 100 nm. It is set in the range of 200 nm.

  The element structure of the organic electroluminescence element A according to the present invention is not limited to the above-described form, and any structure can be adopted as long as it is not contrary to the gist of the present invention. For example, in FIG. 1, the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer in the light emitting layer 4 are omitted, but these configurations may be appropriately provided as necessary.

  The material constituting the hole transport layer is appropriately selected from, for example, a group of compounds having hole transport properties. Examples of this type of compound include arylamine compounds, amine compounds containing a carbazole group, amine compounds containing a fluorene derivative, and typical examples of these compounds include α-NPD (4,4′-bis [ N- (naphthyl) -N-phenyl-amino] biphenyl), TPD (N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine), 2-TNATA (4 ′, 4 ″ -tris [N, N- (2-naphthyl) phenylamino] triphenylamine), 4,4 ′, MTDATA (4 ″ -tris (N- (3-methylphenyl) N-phenylamino) ) Triphenylamine), CBP (4,4′-N, N′-dicarbazolebiphenyl), spiro-NPD, spiro-TPD, spiro-TAD, TNB, and the like. That. Moreover, not only the said material but the arbitrary generally known hole transport material may be used.

Moreover, the material which comprises an electron carrying layer is suitably selected, for example from the group of compounds which have electron transport property. Examples of this type of compound include metal complexes known as electron transport materials such as Alq ₃ (tris (quinolin-8-yloxy) aluminum), and heterocycles such as phenanthroline derivatives, pyridine derivatives, tetrazine derivatives, and oxadiazole derivatives. However, the present invention is not limited to this, and any generally known electron transporting material can be used.

  In the organic electroluminescent element A configured as described above, since the plurality of light emitting layers 4 are laminated, high luminance light emission is possible.

  Next, the present invention will be specifically described with reference to examples.

Example 1
A 0.7 mm thick glass substrate 5 having an ITO film (anode 1) having a thickness of 110 nm, a width of 5 mm, and a sheet resistance of about 12Ω / □ formed as shown in the pattern of FIG. 2 was prepared. The substrate 5 was subjected to ultrasonic cleaning with a detergent, ion-exchanged water, and acetone for 10 minutes each, then subjected to vapor cleaning with IPA (isopropyl alcohol), dried, and further subjected to UV / O ₃ treatment.

Next, this substrate 5 was set in a vacuum deposition apparatus, and 4,4′-bis [N- (naphthyl)-as a hole injection layer on the anode 1 under a reduced pressure atmosphere of 1 × 10 ⁻⁴ Pa or less. A co-evaporated body (molar ratio 1: 1) of N-phenyl-amino] biphenyl (α-NPD) and molybdenum oxide (MoO ₃ ) was deposited to a thickness of 30 nm. Next, α-NPD was vapor-deposited thereon with a thickness of 40 nm as a hole transport layer. Then, on the hole transport layer to form a layer by depositing rubrene 7 wt% both in Alq ₃ as an organic light-emitting layer with a thickness of 40 nm. It was then deposited to a thickness of 30nm to Alq ₃ alone as an electron transporting layer on the organic light-emitting layer. Subsequently, as an electron injection layer, an alloy film of Al and Li having a molar ratio of 1: 1 was formed to a thickness of 3 nm. This formed the light emitting layer 4a.

Next, Au, which is a conductor of 1 × 10 ⁵ Ωcm or less, is deposited to form a conductive layer 3a having a thickness of 3 nm. Subsequently, MoO ₃ is deposited by resistance heating vapor deposition to form a hole-injecting layer 3b having a thickness of 10 nm. Formed. Thereby, the intermediate layer 3 was formed.

Subsequently, α-NPD was vapor-deposited with a thickness of 50 nm as a hole transport layer on the intermediate layer 3, and a layer obtained by co-depositing 7% by mass of rubrene with Alq ₃ on the hole transport layer as an organic light-emitting layer was 40 nm. The film thickness was formed. Next, 30 nm of Alq ₃ alone was formed as an electron transport layer on the organic light emitting layer. Thereby, the light emitting layer 4b was formed.

  Next, after depositing LiF to a thickness of 0.5 nm, the cathode 2 was formed by depositing aluminum at a deposition rate of 0.4 nm / s to a width of 5 mm and a thickness of 100 nm as shown in the pattern of FIG.

  Thereby, the organic electroluminescent element A provided with the light emitting layer 4 of a double structure as shown in FIG. 2 was obtained.

(Example 2)
In forming the electron injection layer in the light emitting layer 4a, a 1 nm thick Na vapor deposition film was formed.

In forming the intermediate layer 3, first, ZnO, which is a conductor of 1 × 10 ⁵ Ωcm or less, is vapor-deposited to form a conductive layer 3 a having a thickness of 10 nm, and then WO ₃ is deposited by resistance heating vapor deposition. A 5 nm hole injecting layer 3b was formed.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Example 3)
In forming the conductive layer 3 a in the intermediate layer 3, ITO is EB evaporated and SiO is heated by resistance heating to form a conductive layer 3 a having a thickness of 10 nm (weight ratio of ITO to SiO: 8: 2, specific resistance 1 × 10 ³ Ωcm ) Was formed. Other than that was carried out similarly to Example 2, and obtained the organic electroluminescent element A. FIG.

Example 4
In forming the conductive layer 3 a in the intermediate layer 3, ITO is EB-deposited and Na is heated by resistance heating to form a conductive layer 3 a having a thickness of 10 nm (weight ratio of ITO: Na 95: 5, specific resistance 9 × 10 ⁻³ Ωcm) was formed. Other than that was carried out similarly to Example 2, and obtained the organic electroluminescent element A. FIG.

(Example 5)
In forming the light emitting layer 4a, no electron injection layer was provided.

In forming the intermediate layer 3, Li ₂ O, which is an electron injecting metal oxide, is first formed by resistance heating vapor deposition to form a 2 nm thick electron injecting layer 3 c, followed by 1 × 10 ^5. A conductive layer 3a having a thickness of 10 nm was formed by co-evaporating ITO and Al, which are conductors of Ωcm or less, at a mass ratio of 9: 1.

In forming the light emitting layer 4b, first, a 10 nm thick hole injection layer containing α-NPD and F ₄ -TCNQ in a molar ratio of 98: 2 is formed by resistance heating vapor deposition on the intermediate layer 3. Thereafter, a hole transport layer, an organic light emitting layer, and an electron transport layer were sequentially formed in the same manner as in Example 1.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Example 6)
In forming the light emitting layer 4a, no electron injection layer was provided.

Further, in forming the intermediate layer 3, first, an electron injecting layer 3c having a thickness of 2 nm was formed by forming a film of Na ₂ O, which is an electron injecting metal oxide, by resistance heating vapor deposition. Subsequently, a conductive layer 3a having a thickness of 10 nm was formed by co-evaporating ZnO and Al, which are conductors of 1 × 10 ⁵ Ωcm or less, at a mass ratio of 9: 1.

Further, in forming the light emitting layer 4b, first, a 10 nm thick hole injection layer containing α-NPD and F ₄ -TCNQ in a molar ratio of 98: 2 is formed by resistance heating vapor deposition, and is laminated on the intermediate layer 3. Thereafter, a hole transport layer, an organic light emitting layer, and an electron transport layer were sequentially formed in the same manner as in Example 1.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Example 7)
In forming the light emitting layer 4a, no electron injection layer was provided.

Further, in forming the intermediate layer 3, first, an electron injecting layer 3c having a thickness of 2 nm was formed by forming a film of Na ₂ O, which is an electron injecting metal oxide, by resistance heating vapor deposition. Subsequently, a conductive layer 3a having a thickness of 10 nm was formed by co-evaporating ZnO and Al, which are conductors of 1 × 10 ⁵ Ωcm or less, at a mass ratio of 9: 1. Subsequently, ZnO and Mo were co-evaporated at a mass ratio of 9: 1 to form a hole-injecting layer 3b having a thickness of 5 nm.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Example 8)
In Example 4, Cs was used instead of Na in forming the conductive layer 3a. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

Example 9
In Example 4, Rb was used instead of Na in forming the conductive layer 3a. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

(Example 10)
In Example 4, Li was used instead of Na in forming the conductive layer 3a. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

(Example 11)
In Example 4, K was used instead of Na in forming the conductive layer 3a. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

Example 12
In Example 4, Na was not used in forming the conductive layer 3a. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

(Example 13)
In Example 7, when forming the conductive layer 3a, instead of ZnO and Al, only ZnO which is a conductor of 1 × 10 ⁵ Ωcm or less was vapor-deposited to form a film having a thickness of 10 nm. The hole injecting layer 3b was not provided. Other than that was carried out similarly to Example 7, and obtained the organic electroluminescent element A. FIG.

(Example 14)
In Example 7, in forming the conductive layer 3a, instead of ZnO and Al, ZnO and Mo, which are conductors of 1 × 10 ⁵ Ωcm or less, were co-evaporated at a mass ratio of 9: 1 to a thickness of 10 nm. A film was formed. The hole injecting layer 3b was not provided. Other than that was carried out similarly to Example 7, and obtained the organic electroluminescent element A. FIG.

(Example 15)
In Example 7, in forming the conductive layer 3a, instead of ZnO and Al, ZnO and V, which are conductors of 1 × 10 ⁵ Ωcm or less, were co-evaporated at a mass ratio of 9: 1 to a thickness of 10 nm. A film was formed. The hole injecting layer 3b was not provided. Other than that was carried out similarly to Example 7, and obtained the organic electroluminescent element A. FIG.
)
(Example 16)
In Example 7, in forming the conductive layer 3a, instead of ZnO and Al, ZnO and W, which are conductors of 1 × 10 ⁵ Ωcm or less, were co-evaporated at a mass ratio of 9: 1 to a thickness of 10 nm. A film was formed. The hole injecting layer 3b was not provided. Other than that was carried out similarly to Example 7, and obtained the organic electroluminescent element A. FIG.

(Conventional example)
In the same manner as in Example 1, a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron transport layer were sequentially formed on the anode 1 of the glass substrate 5 provided with the ITO film (anode 1). An electron injection layer was not formed. Thereby, the light emitting layer 4 was formed.

  Next, without forming the intermediate layer 3, LiF was deposited on the electron transport layer by resistance heating vapor deposition to a thickness of 0.5 nm, and then aluminum was added at a thickness of 0.4 nm / nm as in the pattern of FIG. The cathode 2 was formed by vapor deposition to a width of 5 mm and a thickness of 100 nm at a vapor deposition rate of s.

  Thereby, the organic electroluminescent element A provided with only one light emitting layer 4 was obtained.

(Comparative Example 1)
In forming the intermediate layer 3, first, Au, which is a conductor of 1 × 10 ⁵ Ωcm or less, is vapor-deposited to form a conductive layer 3 a having a thickness of 20 nm, followed by resistance to MoO ₃ , which is a hole-injecting metal oxide. A hole injection layer 3b having a thickness of 10 nm was formed by heat evaporation.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 2)
In forming the intermediate layer 3, Au, which is a conductor of 1 × 10 ⁵ Ωcm or less, was vapor-deposited to form the intermediate layer 3 consisting only of the conductive layer 3a having a thickness of 2 nm.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 3)
In forming the intermediate layer 3, SiO having a high specific resistance of about 1 × 10 ¹⁰ Ωcm is deposited to form a layer having a thickness of 10 nm, followed by resistance heating of the hole-injecting metal oxide MoO _3. The hole injection layer 3b having a thickness of 10 nm was formed by vapor deposition.

  Other than that was carried out similarly to Example 2, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 4)
In forming the light emitting layer 4a, no electron injection layer was provided.

In forming the intermediate layer 3, Li ₂ O, which is an electron-injecting metal oxide, was formed by resistance heating vapor deposition to form the intermediate layer 3 consisting only of the electron-injecting layer 3 c having a thickness of 2 nm.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 5)
In forming the light emitting layer 4a, no electron injection layer was provided.

In forming the intermediate layer 3, ITO and Al, which are conductors of 1 × 10 ⁵ Ωcm or less, are co-evaporated at a mass ratio of 9: 1, and the intermediate layer 3 consisting only of the conductive layer 3 a having a thickness of 10 nm is formed. Formed.

  Other than that was carried out similarly to Example 1, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 6)
In Example 2, the thickness of the conductive layer 3a was formed to 30 nm. Other than that was carried out similarly to Example 2, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 7)
In Example 3, the thickness of the conductive layer 3a was formed to 40 nm. Other than that was carried out similarly to Example 3, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 8)
In Example 4, the thickness of the conductive layer 3a was formed to 20 nm. Other than that was carried out similarly to Example 4, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 9)
In Example 5, the thickness of the conductive layer 3a was formed to 20 nm. Other than that was carried out similarly to Example 5, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 10)
In Example 6, the thickness of the conductive layer 3a was formed to 20 nm. Other than that was carried out similarly to Example 6, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 11)
In Example 7, the thickness of the conductive layer 3a was formed to 20 nm. Other than that was carried out similarly to Example 7, and obtained the organic electroluminescent element A. FIG.

(Comparative Example 12)
In Comparative Example 1, the thickness of the conductive layer 3a was formed to 15 nm. Other than that was carried out similarly to the comparative example 1, and the organic electroluminescent element A was obtained.

(Evaluation test)
The organic electroluminescence element A obtained in each example, conventional example and comparative example was connected to a power source (source meter manufactured by Keithley Instruments Inc., model number 2400), and 15 mA / cm ² between the anode 1 and the cathode ^2. Then, the light emission luminance of the organic electroluminescent element A and the voltage (drive voltage) between the anode 1 and the cathode 2 were measured. The upper limit voltage for securing the constant current value was 20V. Moreover, Topcon Co., Ltd. "BM-9" was used for the brightness | luminance measurement. The results are shown in Table 1.

  As can be seen in Table 1, the organic electroluminescence elements A of Examples 1 to 16 have a drive voltage that is approximately twice that of Conventional Example 1, and a light emission luminance that is approximately twice that of Conventional Example 1, It was confirmed that the electrical connection between the two light emitting layers 4 due to the presence of the intermediate layer 3 was maintained well.

  Further, in Examples 4 and 8 to 11 in which Na, Cs, Rb, Li, and K were added as additives to the conductive layer 3a, the driving voltage was further reduced as compared with Example 12 that did not contain such additives. ing. In addition, in Examples 5 to 7 and 14 to 16 in which Al, Mo, V, and W were added as additives to the conductive layer 3a, the driving voltage was reduced, and in particular, examples having the same configuration except for the additives. Among Examples 13 to 16, in Examples 14 to 16 containing the additive, the driving voltage is further reduced as compared to Example 13 not containing the additive.

  On the other hand, in Comparative Examples 1 and 6-12, although the drive voltage was approximately twice that of Conventional Example 1, the light emission luminance was low. Further, in Examples 1 to 16, the light emitting layer 4 emitted light only in a region sandwiched between the cathode 2 and the anode 1 (region represented by a dark dotted line in FIG. 3), whereas in Comparative Examples 1 and 6 to 11 Then, light was emitted even in a region protruding from the region, and a region having a cross shape as a whole (region combined with a region represented by a dark stippling and a region represented by a thin stippling in FIG. 3) emitted light. Even in Comparative Example 12, light emission was observed in a region protruding from the region sandwiched between the cathode 2 and the anode 1 although it was somewhat suppressed as compared with Comparative Examples 1 and 6-11. That is, in Comparative Examples 1 and 6 to 12, light emission occurred in a region other than the intended light emitting region.

In Comparative Examples 2 to 5, even when the drive voltage reached 20 V, the energization current did not reach 15 mA / cm ² , and light emission of the light emitting layer 4 was not confirmed.

Among these, in Comparative Example 2, the energization current at a driving voltage of 20 V was about 10 mA / cm ² . This is presumed that a sufficient current did not flow even when a high voltage was applied because the hole injection barrier from the intermediate layer 3 was increased.

  In Comparative Examples 3 to 5, almost no energization occurred even though the driving voltage was 20V. This is because the conductivity of the intermediate layer 3 is low for the comparative example 3, the intermediate layer 3 does not include a conductive layer for the comparative example 4, and the intermediate layer 3 has the electron injecting property for the comparative example 5. It is presumed that no current was applied even when a high voltage was applied because the layer was not included.

(A) is 1st embodiment of this invention, (b) is a schematic sectional drawing which shows 2nd embodiment of this invention, respectively. BRIEF DESCRIPTION OF THE DRAWINGS The schematic structure of the organic electroluminescent element for a test produced in the Example is shown, (a) is a top view, (b) is B-B 'sectional drawing of (a). It is a top view which shows the area | region which light-emits at the time of electricity supply in the organic electroluminescent element of an Example and a comparative example. It is a schematic sectional drawing which shows an example of a prior art.

Explanation of symbols

A organic electroluminescence element 1 anode 2 cathode 3 intermediate layer 3a conductive layer 3b hole injection layer 3c electron injection layer 4 light emitting layer 4a light emitting layer 4b light emitting layer

Claims (4)

An organic electroluminescence device in which a plurality of light emitting layers including an organic light emitting layer are laminated via an intermediate layer between an anode and a cathode,
The intermediate layer includes a conductive layer containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C. and a hole injecting layer containing a hole injecting metal oxide, and in order from the cathode side A hole injecting layer and a conductive layer are laminated,
An organic electroluminescence element, wherein the conductive layer has a thickness of 10 nm or less.   2. The organic material according to claim 1, wherein the conductive layer contains at least one selected from cerium, cesium, lithium, sodium, magnesium, potassium, rubidium, samarium, yttrium, and a compound of these metals. Electroluminescence element. An organic electroluminescence device in which a plurality of light emitting layers including an organic light emitting layer are laminated via an intermediate layer between an anode and a cathode,
The intermediate layer includes a conductive layer containing a conductor having a specific resistance of 1 × 10 ⁵ Ωcm or less at 23 ° C., and an electron injecting layer containing an electron injecting metal oxide, and in order from the cathode side A conductive layer and an electron injecting layer are laminated,
An organic electroluminescence element, wherein the conductive layer has a thickness of 10 nm or less.   4. The organic electroluminescent device according to claim 3, wherein the conductive layer contains at least one selected from tungsten, molybdenum, rhenium, vanadium, ruthenium, aluminum, and a compound of these metals.

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