JP2005190998A - Light-emitting element and light-emitting device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element in which failure of the light-emitting element due to separation can be controlled and stable luminescence can be obtained with high-efficiency and for a long stretch of time by controlling the separation of layers constituting the light-emitting element. <P>SOLUTION: This light-emitting element sandwiches a plurality of layers between a pair of electrodes, and is characterized by that at least one layer of the plurality of layers is a layer containing a substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, and titanium oxide, or at least one layer of layers different from a light-emitting layer among the plurality of layers is a mixed region of one substance selected from bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide, and an organic compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light-emitting element including an anode, a cathode, and a layer containing an organic compound that can emit light by applying an electric field (hereinafter referred to as a “layer containing a light-emitting substance”). The present invention relates to a light-emitting element that can be achieved.

  Light-emitting elements (also referred to as organic or organic-inorganic hybrid electroluminescent elements) and solar cells are examples of photoelectronic devices using organic semiconductor materials as functional organic materials, and these are the electrical properties of organic semiconductor materials. It is a device that takes advantage of (carrier transportability) and optical physical properties (light absorption or light emission), and in particular, a light emitting element is making remarkable progress.

  A light-emitting element includes a layer containing a light-emitting substance between a pair of electrodes (an anode and a cathode), and the light-emitting mechanism includes holes injected from the anode when a voltage is applied between the electrodes. Electrons injected from the cathode are said to recombine at the emission center in the layer containing the luminescent material to form molecular excitons that emit energy and emit light when the molecular excitons return to the ground state. Yes. Note that singlet excitation and triplet excitation are known as excited states, and light emission is considered to be possible through either excited state.

  Conventionally, attempts have been made to increase the light emission efficiency or extend the life of the light emitting element, but there is a drawback that the light emission life is short although high luminance light emission can be obtained. These factors include, for example, poor bonding between the metal electrodes and the organic compound layer when they are stacked due to long-term conduction. For this reason, various studies have been made to increase the light emission efficiency of the light emitting element or to extend the lifetime.

  By the way, a light-emitting element using an alkali metal having a low work function is known as a light-emitting element having a high luminous efficiency (for example, Patent Document 1). However, although the light-emitting element using the alkali metal is efficient, the alkali metal is easily oxidized, so that it is necessary to pay close attention when handling the light-emitting element and it is difficult to use it for manufacturing the light-emitting element. There was a problem.

Japanese Patent Laid-Open No. 5-121172

  A light-emitting element is also known in which a thin-film insulating layer using an easy-to-handle metal fluoride or the like is inserted at the organic / cathode interface (see, for example, Non-Patent Document 1). However, although the efficiency is improved as compared with a light emitting device using an MgAg alloy known as a low work function cathode, the adhesion with an organic thin film is poor and it is difficult to obtain stable light emission for a long time. was there.

L. S. Hung, et al., Applied Physics Letters, Vol. 70, 152-154 (1997)

  Therefore, an object of the present invention is to provide a light-emitting element that can emit light efficiently and obtain stable light emission for a long time. In addition, a light-emitting element that can be applied to mass production using a material that does not require advanced techniques when manufacturing a light-emitting element is provided.

  As a result of intensive studies, the present inventor obtained efficient light emission and stable light emission for a long time in a light-emitting element containing bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide. I found that being achieved. Therefore, in the present invention, in a light-emitting element in which a plurality of layers are sandwiched between a pair of electrodes and mainly an organic compound is used as a light emitter, bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide is used. It has the layer which contains.

  Bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, and titanium oxide have good adhesion to a metal film, a metal oxide film, or the like that functions as an electrode of a light-emitting element. Furthermore, the adhesiveness with an organic compound is also good.

  Therefore, bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide and titanium oxide are selected between the electrode of the light emitting element and the organic compound, or between the plurality of layers sandwiched between the electrodes of the light emitting element. By using a light-emitting element having at least one layer containing the extracted substance, a light-emitting element with few defects due to separation between layers can be obtained.

  A specific structure of the light-emitting element of the present invention is a light-emitting element in which a plurality of layers are sandwiched between a pair of electrodes, and at least one of the plurality of layers includes bismuth oxide, cobalt oxide, chromium oxide, oxide A light-emitting element including a layer containing one substance selected from copper, nickel oxide, and titanium oxide.

  The specific structure of the light-emitting element of the present invention is a light-emitting element in which a plurality of layers are sandwiched between a pair of electrodes, and bismuth oxide, cobalt oxide, and chromium oxide are in contact with at least one of the electrodes. A light-emitting element including a layer containing one substance selected from copper oxide, nickel oxide, and titanium oxide is provided.

  In addition, as a result of intensive studies, the inventor of the present invention, in a light-emitting element using an organic compound as a light emitter, the organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide are formed in a layer different from the light-emitting layer. In a light emitting device having a region containing at least one compound selected from the group consisting of zinc oxide and titanium oxide, it is possible to efficiently emit light and to obtain stable light emission for a long time. I also found that. Therefore, in the present invention, in a light emitting device using an organic compound as a light emitter, a group consisting of an organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide in a layer different from the light emitting layer. A light-emitting element having a region containing at least any one compound selected from the above.

  In a light-emitting element using an organic compound as a light emitter, an organic compound having carrier (electron, hole) transportability or carrier injection property and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, oxidation A light emitting device comprising any compound selected from the group consisting of titanium.

  In addition, a hole transport region made of a hole transport material, a first mixed region containing both the hole transport material and the light emitting material, a light emitting region made of the light emitting material, and both an electron transport material and a light emitting material are included. In the light-emitting element having a structure connecting the second mixed region and the electron transport region made of an electron transport material, either the hole transport material or the electron transport material includes an organic compound, bismuth oxide, cobalt oxide, A light-emitting element that is any compound selected from the group consisting of copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide is characterized.

  In addition, it includes a hole transport region made of a hole transport material, a first mixed region including both the hole transport material and the first organic compound, and both the first organic compound and the second organic compound. A light-emitting region, a second mixed region including both the electron transport material and the first organic compound, and an electron transport region made of the electron transport material, and the second organic compound is In the light-emitting element that is a light-emitting body, either the hole transport material or the electron transport material is selected from the group consisting of an organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. It is characterized by a light emitting device which is any one of the above compounds.

  In particular, the mixed region described above is characterized by a light-emitting element containing 10 wt% or more of any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. .

  In addition, a hole injection region made of a hole injection material, a first mixed region containing both the hole injection material and the hole transport material, a hole transport region made of a hole transport material, and a hole transport material And a second mixed region including both the light emitting material, a light emitting region composed of the light emitting material, a third mixed region including both the light emitting material and the electron transport material, an electron transport region composed of the electron transport material, and an electron A fourth mixed region comprising both a transport material and a hole blocking material; a hole blocking region comprising a hole blocking material; a fifth mixed region comprising both a hole blocking material and an electron injecting material; and an electron In a light-emitting element having a structure connecting an electron injection region made of an injection material, any one of a hole injection material, a hole transport material, an electron transport material, and an electron injection material is an organic compound , Bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and wherein the light emitting element is any compound selected from the group consisting of titanium oxide.

  In addition, a hole injection region made of a hole injection material, a first mixed region containing both the hole injection material and the hole transport material, a hole transport region made of a hole transport material, and a hole transport material A second mixed region including both the first organic compound and the first organic compound; a light emitting region including both the first organic compound and the second organic compound; and a second mixed region including both the first organic compound and the electron transport material. A third mixed region, an electron transport region made of an electron transport material, a fourth mixed region made of both an electron transport material and a hole blocking material, a hole blocking region made of a hole blocking material, and a hole blocking property. In a light emitting device having a structure connecting a fifth mixed region including both a material and an electron injecting material and an electron injecting region made of an electron injecting material, and the second organic compound is a light emitter. , Hole injection material, hole transport material, electron transport material or electron injection material is composed of organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, titanium oxide A light-emitting element that is any compound selected from the group is characterized.

  In particular, a light-emitting element in which any of the above-described mixed regions contains 10 wt% or more of any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. Features.

  Note that the light-emitting element of the present invention thus obtained emits light efficiently, and stable light emission can be obtained over a long period of time. Therefore, a light-emitting device (image display device or light-emitting device) using this as a light-emitting element Device) can achieve a long service life. Therefore, the present invention includes a light emitting device using the light emitting element of the present invention.

  Note that the light emitting device in this specification refers to an image display device or a light emitting device using an electroluminescent element as a light emitting element. Also, a module in which a connector, for example, an anisotropic conductive film, a TAB (Tape Automated Bonding) tape or a TCP (Tape Carrier Package) is attached to an electroluminescent element, a module in which a printed wiring board is provided at the end of a TAB tape or TCP Alternatively, a module in which an IC (integrated circuit) is directly mounted on an electroluminescent element by a COG (Chip On Glass) method is included in the light emitting device.

  By implementing the present invention, it is possible to provide a light-emitting element that emits light efficiently and obtains stable light emission for a long time. In addition, it is possible to provide a light-emitting element that can be applied to mass production using a material that does not require advanced techniques when manufacturing the light-emitting element.

  Embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

(Embodiment 1)
The element structure of the light-emitting element of the present invention will be described with reference to FIG.

  The light-emitting element of the present invention has a structure in which a plurality of layers are sandwiched between a pair of electrodes. The plurality of layers include a layer made of a substance having a high carrier transporting property or a substance having a high carrier injecting property, a bismuth oxide, a cobalt oxide, an oxidation so that a light emitting region is formed at a site away from each electrode. A combination of layers containing a substance selected from chromium, copper oxide, nickel oxide or titanium oxide is laminated.

  Specifically, the light-emitting element of the present invention includes a first substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, and titanium oxide so as to be in contact with the first electrode 101. A second layer 103 made of a substance having a high electron-transport property so as to be in contact with the first layer 102, and a third layer containing a light-emitting substance so as to be in contact with the second layer 103 104, a fourth layer 105 made of a substance having a high hole transporting property is provided so as to be in contact with the third layer 104, and a fourth layer 105 made of a substance having a high hole injecting property is provided so as to be in contact with the fourth layer 105 The fifth layer 106 is provided, and the second electrode 107 is provided so as to be in contact with the fifth layer 106. Note that the first layer 102 is formed with such a thickness that a tunnel current flows between the first electrode 101 and the second layer 103. The first electrode 101 and the second electrode 107 function as a cathode and an anode, respectively.

Examples of the substance having a high electron transporting property include Alq ₃ , tris (4-methyl-8-quinolinolato) aluminum (hereinafter referred to as Almq ₃ ), bis (10-hydroxybenzo [h] -quinolinato) beryllium (hereinafter BeBq _2). Bis (2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (hereinafter referred to as BAlq) which is a metal complex having a quinoline skeleton or a benzoquinoline skeleton such as ) And the like. Further, bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (hereinafter referred to as Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (hereinafter referred to as Zn ( BTZ) ₂ ), tris- (2- (2′hydroxyphenyl) -1-phenyl-1H-benzimidazolate) aluminum (hereinafter referred to as Al (PBI) ₃ ), oxazole, thiazole, benz There is also a metal complex in which a metal is coordinated to an imidazole ligand. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (hereinafter referred to as PBD), 1,3-bis [ Oxadiazole derivatives such as 5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (hereinafter referred to as OXD-7), 3- (4-tert-butyl Phenyl) -4-phenyl-5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl)- Triazole derivatives such as 5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as p-EtTAZ), bathophenanthroline (hereinafter referred to as BPhen), bathocuproin (hereinafter referred to as “p-EtTAZ”) Phenanthroline derivatives such as BCP), 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris (1-phenyl-1H-benzimidazole (hereinafter referred to as TPBI), 1, 3,5-tris [4- (1-phenyl-1H-benzimidazol-2-yl) benzolyl] benzene (hereinafter referred to as TPBIBB), N-phenyl-2,4,5,7-tetrakis (1-phenyl) Benzimidazole derivatives such as -1H-benzimidazol-2-yl) -9-phenylcarbazole (hereinafter referred to as PBIC).

As the layer containing a light-emitting substance, for example, a highly luminescent substance such as N, N′-dimethylquinacridone (abbreviation: DMQd) or 2H-chromen-2-one (abbreviation: coumarin) and tris (8-quinolinolato) aluminum. A mixed layer formed by freely combining substances having high carrier transport properties such as (abbreviation: Alq ₃ ) and 9,10-di (2-naphthyl) anthracene (abbreviation: DNA) can be used. However, since Alq ₃ and DNA are highly luminescent substances, a layer using these substances alone may be a layer containing a luminescent substance.

  As a substance having a high hole-transport property, for example, 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: α-NPD), N, N′-bis (3 -Methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD) or 4,4 ', 4 "-tris (N, N-diphenyl- Aroma) such as amino) -triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (abbreviation: MTDATA) Group amine-based compounds (that is, having a benzene ring-nitrogen bond).

As a substance having a high hole-injecting property, a porphyrin-based compound is effective, and phthalocyanine (hereinafter referred to as H ₂ -Pc), copper phthalocyanine (hereinafter referred to as Cu-Pc), or the like can be used. Alternatively, a material obtained by chemically doping a conductive polymer compound, for example, polyethylene dioxythiophene (hereinafter referred to as PEDOT) doped with polystyrene sulfonic acid (hereinafter referred to as PSS) can be used.

  The first electrode 101 is preferably formed using a material having a low work function, for example, aluminum or aluminum containing lithium or magnesium. Further, the second electrode 107 is made of a material having a high work function, for example, indium tin oxide (ITO), ITO containing silicon oxide, metal oxide containing 2 to 20 wt% zinc oxide in indium oxide. Etc. are preferably used.

  In the light-emitting element of the present invention having the above structure, the first electrode 101 and the first layer 102 have good adhesion, and the adhesion between the first layer 102 and the second layer 103 is also good. Good.

  In the light-emitting element of the present invention as described above, a layer containing a substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide is provided between the electrode and the layer made of an organic compound. Thus, peeling due to poor adhesion between the electrode and the organic compound can be prevented, and as a result, stable light emission is possible.

  Note that in the light-emitting element described above, the first electrode 101 and the second electrode 107 may each be formed by any method such as a sputtering method or an evaporation method. The first to fifth layers 102 to 106 may be formed using any method such as an evaporation method or an inkjet method.

  Note that the above is one embodiment of the light-emitting element of the present invention, and the structure of the light-emitting element of the present invention is not limited thereto.

(Embodiment 2)
In this embodiment, a light-emitting element having a stacked structure different from that described in Embodiment 1 will be described with reference to FIGS.

  In the light-emitting element of this embodiment mode, the first layer 202 containing one substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide is in contact with the first electrode 201. A second layer 203 made of a substance having a high electron-transport property is provided so as to be in contact with the first layer 202, and a third layer 204 containing a light-emitting substance is provided so as to be in contact with the second layer 203. A fourth layer 205 made of a substance having a high hole-transport property is provided so as to be in contact with the third layer 204, and bismuth oxide, cobalt oxide, chromium oxide, copper oxide are provided so as to be in contact with the fourth layer 205, A fifth layer 206 containing one substance selected from nickel oxide or titanium oxide is provided, and a sixth layer 207 made of a substance having a high hole-injecting property is provided in contact with the fifth layer 206. 6th layer 2 In contact with 7 and has a second electrode 208 is provided structure. The first electrode 201 and the second electrode 208 function as a cathode and an anode, respectively. Note that the first layer 202 is formed with such a thickness that a tunnel current flows. As the substance having a high electron-transporting property, the substance having a high hole-transporting property, the substance having a high hole-injecting property, and the substance used for the electrode, the same materials as those described in Embodiment Mode 1 can be used.

  As described above, a plurality of layers containing one substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide may be provided. Further, it may be provided not only between the electrode and the layer made of an organic compound but also sandwiched by the layer made of the organic compound.

  Since the present invention has good adhesion with an organic compound, a layer containing one substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide or titanium oxide is provided between organic compounds with poor adhesion. By forming, it functions as an adhesive layer, and defects such as peeling in the light-emitting element can be suppressed. As a result, stable light emission can be obtained.

  Note that the above is one embodiment of the light-emitting element of the present invention, and the structure of the light-emitting element of the present invention is not limited thereto.

(Embodiment 3)
The element structure of the light-emitting element of the present invention is not particularly limited and may be appropriately selected depending on the purpose. Basically, a layer containing a light-emitting substance (holes) between a pair of electrodes (anode and cathode) Injection layer, hole transport layer, first mixed layer composed of hole transport material and light emitting material, light emitting layer, second mixed layer composed of light emitting material and electron transport material, hole blocking layer (hole blocking layer), For example, anode / hole injection layer / light emitting layer / electron transport layer / cathode, anode / hole injection layer / hole Transport layer / light emitting layer / electron transport layer / cathode, anode / hole injection layer / hole transport layer / light emission layer / electron transport layer / electron injection layer / cathode, anode / hole injection layer / hole transport layer / light emission Layer / hole blocking layer / electron transport layer / cathode, anode / hole injection layer / hole transport layer / light emitting layer / hole Stopping layer / electron transport layer / electron injection layer / cathode, anode / hole injection layer / first mixed layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode, anode / Hole injection layer / hole transport layer / light emitting layer / second mixed layer / electron transport layer / electron injection layer / cathode, anode / hole injection layer / first mixed layer / hole transport layer / light emitting layer / Second mixed layer / electron transport layer / electron injection layer / cathode, anode / hole injection layer / first mixed layer / hole transport layer / second mixed layer / light emitting layer / third mixed layer / Examples include a light emitting device having a configuration of an electron transport layer / fourth mixed layer / hole blocking layer / fifth mixed layer / electron injection layer / cathode. At this time, the hole transport layer, the hole injection layer, the electron transport layer, the electron injection layer, and the mixed layer described above from an organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. And any compound selected from the group consisting of: Note that the light-emitting element in the present invention may be stacked from either the anode or the cathode.

  For example, FIG. 6A is a diagram in which the light emitting elements are stacked from the anode, and FIG. 6B is a diagram in which the light emitting elements are stacked from the cathode. 6A, the anode 701 is stacked with a hole injection layer 702 / a hole transport layer 703 / a light emitting layer 704 / an electron transport layer 705 / an electron injection layer 706 / a cathode 707. Here, a p-channel TFT 708 is attached to the anode. 6B, the cathode 707 is stacked with an electron injection layer 706 / electron transport layer 705 / light-emitting layer 704 / hole transport layer 703 / hole injection layer 702 / anode 701. Here, an n-channel TFT 709 is attached to the cathode. In this embodiment, an example in which a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer are used as a layer containing a light-emitting substance sandwiched between an anode and a cathode is shown. It is not always necessary to form an auxiliary layer such as a hole blocking layer (hole blocking layer) or a mixed layer.

  The light-emitting element of the present invention is preferably supported by a substrate, and there is no particular limitation on the substrate, and those used in conventional light-emitting elements such as glass, quartz, metal, bulk semiconductor, and transparent plastic A material made of a flexible substrate or the like can be used.

  In addition, as the anode material of the light emitting element of the present invention, it is preferable to use a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a high work function (work function of 4.0 eV or more). Specific examples of the anode material include ITO (indium tin oxide), ITO containing silicon oxide, metal oxide in which 2 to 20 wt% zinc oxide (ZnO) is mixed with indium oxide, gold oxide, and the like. (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or A metal material nitride (TiN) or the like can be used.

  On the other hand, as the cathode material, it is preferable to use a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function (work function of 3.8 eV or less). Specific examples of the cathode material include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, aluminum-lithium alloys, magnesium. -Silver alloys or mixed metals thereof can be used.

  In addition, the anode material and cathode material which were mentioned above form an anode and a cathode, respectively, by forming a thin film by a vapor deposition method, sputtering method, etc. The film thickness is preferably 10 to 500 nm.

  Finally, a protective layer (barrier layer) made of an inorganic material such as SiN or an organic material such as polytetrafluoroethylene or styrene polymer is formed. The barrier layer may be transparent or opaque, and the inorganic material or organic material is formed by vapor deposition, sputtering, or the like.

  Further, a desiccant such as SrOx or SiOx is formed by an electron beam irradiation method, a vapor deposition method, a sputtering method, a sol-gel method or the like in order to prevent the organic layer and the electrode of the light emitting element from being oxidized and moisture.

  In the light-emitting element of the present invention, light generated by recombination of carriers in the layer containing a light-emitting substance is emitted from one or both of the anode and the cathode. That is, when light is emitted from the anode, the anode is formed of a light transmissive material, and when light is emitted from the cathode side, the cathode is formed of a light transmissive material.

  In addition, a known material can be used for the layer containing a light-emitting substance, and either a low molecular material or a high molecular material can be used. Note that the material for forming a layer containing a light-emitting substance includes not only an organic compound material but also a structure including an inorganic compound in part.

  Note that the layer containing a light emitting substance is a hole injection layer made of a hole injection material, a first mixed layer containing both a hole injection material and a hole transport material, a hole transport layer made of a hole transport material, Second mixed layer containing both hole transport material and luminescent material, luminescent layer made of luminescent material, third mixed layer containing both luminescent material and electron transport material, electron transport layer made of electron transport material, electron A fourth mixed layer containing both a transport material and an electron injecting material, a hole blocking layer made of a hole blocking material (hole blocking layer), a fifth mixed layer containing both a hole blocking material and an electron injecting material, It is formed by stacking a combination of electron injection layers made of electron injection materials. In the present invention, an organic compound and any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide may be used in a layer different from the light emitting layer. . In particular, it is preferably used for an electron transport layer or a hole transport layer. Moreover, it is preferable to use for an electron injection layer or a hole injection layer from a viewpoint of adhesiveness with an electrode.

  In the present invention, when an organic compound and any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide are used as an electron transport layer as an electron transport layer Alternatively, a light-emitting element can be formed by stacking a combination other than an electron transport layer on a layer containing a light-emitting substance formed between a pair of electrodes. In this case, the layer containing the light-emitting substance may include a hole injection layer, a hole transport layer, a light emitting layer, the above-described mixed layer, an electron injection layer, or a hole blocking layer in addition to the electron transport layer. And can be combined and laminated. Specific materials used in this case are shown below.

As the hole injecting material, a porphyrin-based compound is effective as long as it is an organic compound, and phthalocyanine (hereinafter referred to as H ₂ -Pc), copper phthalocyanine (hereinafter referred to as Cu-Pc), or the like is used. it can. In addition, there is a material in which a conductive polymer compound is chemically doped, and polyethylenedioxythiophene (hereinafter referred to as PEDOT) doped with polystyrene sulfonic acid (hereinafter referred to as PSS) can also be used. Further, a conductive inorganic compound such as molybdenum oxide (hereinafter referred to as MoOx), or a composite material of the conductive inorganic compound and a hole transport material described below can be used.

  As the hole transporting material, an aromatic amine-based compound (that is, a compound having a benzene ring-nitrogen bond) is suitable. Examples of widely used materials include N, N′-bis (3-methylphenyl) -N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (hereinafter referred to as TPD). 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (hereinafter referred to as α-NPD) or 4,4′-4 ′, 4 ′ '-Tris (N-carbazolyl) -triphenylamine (hereinafter referred to as TCTA), 4,4', 4 ''-tris (N, N-diphenyl-amino) -triphenylamine (hereinafter referred to as TDATA) , 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (hereinafter referred to as MTDATA) and the like. . Alternatively, a conductive inorganic compound such as MoOx or a composite material with the above organic compound can be used.

Examples of the light-emitting material include metal complexes such as tris (8-quinolinolato) aluminum (hereinafter referred to as Alq ₃ ). In addition to these, quinacridone, coumarin, rubrene, styryl dyes, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-phthaloperinone derivatives may be used alone. The light emitting layer may also serve as an electron injecting and transporting layer. In such a case, it is preferable to use Alq ₃ or the like.

  As the hole blocking material, BAlq, OXD-7, TAZ, p-EtTAZ, BPhen, BCP and the like described above can be used.

Examples of the electron transporting material include Alq ₃ , tris (4-methyl-8-quinolinolato) aluminum (hereinafter referred to as Almq ₃ ), bis (10-hydroxybenzo [h] -quinolinato) beryllium (hereinafter referred to as BeBq ₂ ). ) And the like, bis (2-methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (hereinafter referred to as BAlq) which is a mixed ligand complex, etc. Is preferred. Further, bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (hereinafter referred to as Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) -benzothiazolate] zinc (hereinafter referred to as Zn ( BTZ) ₂ ), tris- (2- (2′hydroxyphenyl) -1-phenyl-1H-benzimidazolate) aluminum (hereinafter referred to as Al (PBI) ₃ ), oxazole, thiazole, benz There is also a metal complex in which a metal is coordinated to an imidazole ligand.

  In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (hereinafter referred to as PBD), 1,3-bis [ Oxadiazole derivatives such as 5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (hereinafter referred to as OXD-7), 3- (4-tert-butyl Phenyl) -4-phenyl-5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl)- Triazole derivatives such as 5- (4-biphenylyl) -1,2,4-triazole (hereinafter referred to as p-EtTAZ), bathophenanthroline (hereinafter referred to as BPhen), bathocuproin (hereinafter referred to as “p-EtTAZ”) Phenanthroline derivatives such as BCP), 2,2 ′, 2 ″-(1,3,5-benzenetriyl) -tris (1-phenyl-1H-benzimidazole (hereinafter referred to as TPBI), 1, 3,5-tris [4- (1-phenyl-1H-benzimidazol-2-yl) benzolyl] benzene (hereinafter referred to as TPBIBB), N-phenyl-2,4,5,7-tetrakis (1-phenyl) A benzimidazole derivative such as -1H-benzimidazol-2-yl) -9-phenylcarbazole (hereinafter referred to as PBIC) can be used.

Further, a metal oxide or a metal halide may be used as an electron injection layer between the cathode and the layer containing a light-emitting substance. As specific examples of the electron injection layer, Li ₂ O, MgO, Al ₂ O ₃ can be used as the metal oxide, and LiF, MgF ₂ , SrF _2, etc. can be used as the metal halide.

  As described above, by using an organic compound and any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide in a layer different from the light emitting layer. In addition, it is possible to improve the bondability of the laminated interface inside the element. As a result, a light-emitting element capable of emitting light efficiently and obtaining stable light emission for a long time can be manufactured.

(Embodiment 4)
A plurality of the light-emitting elements described in Embodiments 1, 2, and 3 are formed over a substrate formed of glass, quartz, metal, bulk semiconductor, transparent plastic, flexible substrate, or the like, so that passive A light emitting device of a type can be manufactured. In addition to a substrate made of glass, quartz, transparent plastic, a flexible substrate, or the like, for example, as shown in FIG. 3, a light emitting element in contact with a thin film transistor (TFT) array may be manufactured. In FIG. 3, 10 is a substrate, 11 and 12 are TFTs, and 13 is a first electrode 14 and one selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide or titanium oxide. The light emitting body is different from one substance selected from bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide in a layer different from the light emitting layer or the layer containing at least one layer containing the material. The light-emitting element is composed of a layer 15 including at least one mixed region with an organic compound and the second electrode 16, and is electrically connected to the TFT 11 through a wiring 17. Thus, an active matrix light-emitting device in which driving of the light-emitting element is controlled by the TFT can be manufactured. Note that the structure of the TFT is not particularly limited. For example, a staggered type or an inverted staggered type may be used. Further, the crystallinity of the semiconductor layer constituting the TFT is not particularly limited, and may be crystalline or amorphous.

  In Example 1, a light-emitting element of the present invention will be specifically described with reference to FIG.

  First, the first electrode 301 of the light emitting element is formed over the substrate 300. Note that in this embodiment, the first electrode 301 functions as an anode. The material is ITO, which is a transparent conductive film, and is formed with a film thickness of 110 nm by a sputtering method.

  Next, a layer 302 containing a light-emitting substance is formed over the first electrode (anode) 301. Note that the layer 302 containing a light-emitting substance in this embodiment has a stacked structure including a hole injection layer 311, a hole transport layer 312, a light-emitting layer 313, an electron transport layer 314, and an electron injection layer 315.

  The substrate on which the first electrode 301 is formed is fixed to a substrate holder of a commercially available vacuum deposition apparatus with the surface on which the first electrode 101 is formed facing downward, and copper is attached to an evaporation source provided inside the vacuum deposition apparatus. Phthalocyanine (hereinafter referred to as Cu—Pc) is added, and a hole injection layer 311 is formed with a thickness of 20 nm by a vapor deposition method using a resistance heating method. Note that a known hole injecting material can be used as a material for forming the hole injecting layer 311.

  Next, the hole transport layer 312 is formed using a material having excellent hole transport properties. As a material for forming the hole transport layer 312, a known hole transport material can be used. In this example, α-NPD and MoOx are mixed at a weight ratio of 1: 1 by a similar method to 40 nm. The film thickness is formed.

Next, the light emitting layer 313 is formed. Note that holes and electrons recombine in the light-emitting layer 313 to emit light. In this embodiment, Alq ₃ is used as a material for forming the light emitting layer 313, and it is formed by a vapor deposition method with a film thickness of 30 nm.

Next, the electron transport layer 314 is formed. As a material for forming the electron transport layer 314, a known electron transport material can be used. In this embodiment, Alq ₃ and TiOx are used, and TiOx is 50 wt% in a film thickness of 20 nm. It is formed by vapor deposition.

  Next, the electron injection layer 315 is formed. As a material for forming the electron injection layer 315, a known electron injectable material can be used. In this embodiment, calcium fluoride (hereinafter referred to as CaF2) is used and a film thickness of 2 nm is formed by a vapor deposition method. Form.

  In this way, after forming the layer 302 containing a light-emitting substance formed by stacking the hole injection layer 311, the hole transport layer 312, the light emitting layer 313, the electron transport layer 314, and the electron injection layer 315, the cathode The second electrode 303 functioning as is formed by a sputtering method or an evaporation method. Note that in this embodiment, the second electrode 303 is formed by forming aluminum (150 nm) over the layer 302 containing a light-emitting substance by an evaporation method.

  Thus, the light emitting element of the present invention is formed.

  In this example, a light-emitting element of the present invention used for a light-emitting device will be described with reference to FIGS. 8A is a cross-sectional view in which light generated by carrier recombination in a layer containing a light-emitting substance is emitted from below in a light-emitting device having a light-emitting element, and FIG. FIG. 8C is a cross-sectional view in which light generated by carrier recombination in a layer containing a light-emitting substance is emitted from both above and below in the light-emitting device having the light-emitting device. FIG. It is sectional drawing made to radiate | emit. 8A, in a light-emitting element having a structure similar to that in FIG. 6A, an anode is formed using a transparent material and light is emitted from the anode side. Alternatively, in the case of a light-emitting element having a structure similar to that in FIG. 6B, the cathode is formed using a transmissive material and light is emitted from the cathode side. 8B, in the case of a light-emitting element having a structure similar to that in FIGS. 6A and 6B, both the anode and the cathode are formed of a transmissive material. Light is emitted from both electrode sides. 8C, in a light-emitting element having a structure similar to that in FIG. 6A, a cathode is formed using a transparent material and light is emitted from the cathode side. Alternatively, in the case of a light-emitting element having a structure similar to that in FIG. 6B, the anode is formed using a transparent material and light is emitted from the anode side.

  In this embodiment, a light-emitting device having the light-emitting element of the present invention in a pixel portion will be described with reference to FIG. 4A is a top view illustrating the light-emitting device, and FIG. 4B is a cross-sectional view taken along line A-A ′ in FIG. 4A. Reference numeral 601 indicated by a dotted line denotes a driving circuit portion (source side driving circuit), 602 denotes a pixel portion, and 603 denotes a driving circuit portion (gate side driving circuit). Reference numeral 604 denotes a sealing substrate, reference numeral 605 denotes a sealing agent, and an inner side 607 surrounded by the sealing agent 605 is a space.

  Reference numeral 608 denotes a wiring for transmitting signals input to the source side driver circuit 601 and the gate side driver circuit 603, and a video signal, a clock signal, and a start signal from an FPC (flexible printed circuit) 609 serving as an external input terminal. Receive a reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.

  Next, a cross-sectional structure is described with reference to FIG. A driver circuit portion and a pixel portion are formed over the substrate 610. Here, a source side driver circuit 601 which is a driver circuit portion and a pixel portion 602 are shown.

  Note that the source side driver circuit 601 is a CMOS circuit in which an n-channel TFT 623 and a p-channel TFT 624 are combined. The TFT forming the driving circuit may be formed by a known CMOS circuit, PMOS circuit or NMOS circuit. Further, in this embodiment, a driver integrated type in which a drive circuit is formed on a substrate is shown, but this is not always necessary, and it can be formed outside the substrate.

  The pixel portion 602 is formed by a plurality of pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof. Note that an insulator 614 is formed so as to cover an end portion of the first electrode 613. Here, a positive photosensitive acrylic resin film is used.

  In order to improve the film forming property, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 614. For example, when positive photosensitive acrylic is used as a material for the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface with a curvature radius (0.2 μm to 3 μm). Further, as the insulator 614, either a negative type that becomes insoluble in an etchant by photosensitive light or a positive type that becomes soluble in an etchant by light can be used. For example, both silicon oxide, silicon oxynitride, siloxane, and the like can be used.

  Over the first electrode 613, a layer 616 containing a light-emitting substance and a second electrode 617 are formed. Here, as a material used for the first electrode 613 functioning as an anode, a material having a high work function is preferably used. For example, an ITO (indium tin oxide) film, an ITSO (indium tin silicon oxide) film, an indium zinc oxide (IZO) film, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, or the like In addition, a stack of titanium nitride and a film containing aluminum as a main component, a three-layer structure including a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film can be used. Note that with a stacked structure, resistance as a wiring is low, good ohmic contact can be obtained, and a function as an anode can be obtained.

  The layer 616 containing a light-emitting substance is formed by an evaporation method using an evaporation mask or an inkjet method.

  The layer 616 containing a light-emitting substance includes bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide, or an organic compound and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and oxide. And any compound selected from the group consisting of titanium. When forming a layer containing bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, magnesium oxide, zinc oxide or titanium oxide, bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, oxidation Magnesium, zinc oxide, or titanium oxide may be formed of ultrafine powder using the above method, which is more effective for improving the bonding property between films at the time of lamination. In addition, materials used in combination with these bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide or titanium oxide, or organic compounds and bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, oxidation The material used in combination with any compound selected from the group consisting of titanium may be a low molecular material, a medium molecular material (including oligomers and dendrimers), or a high molecular material. In addition, as a material used for a layer containing a light-emitting substance, an organic compound is usually used in a single layer, a stacked layer, or a mixed layer. In the present invention, an inorganic compound is used as part of a film made of an organic compound. The configuration is also included.

Furthermore, as a material used for the second electrode (cathode) 617 formed over the layer 616 containing a light-emitting substance, a material having a low work function (Al, Ag, Li, Ca, or alloys thereof MgAg, MgIn, AlLi , CaF ₂ , or CaN) may be used. Note that in the case where light generated in the layer 616 containing a light-emitting substance is transmitted through the second electrode 617, a thin metal film and a transparent conductive film (ITO (ITO)) are used as the second electrode (cathode) 617. A stack of indium tin oxide alloy (ITSO), indium tin silicon oxide (ITSO), indium oxide zinc oxide alloy (In ₂ O ₃ —ZnO), zinc oxide (ZnO), or the like) is preferably used.

  Further, the sealing substrate 604 is bonded to the element substrate 610 with the sealant 605, whereby the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. Yes. Note that the space 607 includes a structure filled with a sealant 605 in addition to a case where the space 607 is filled with an inert gas (such as nitrogen or argon).

  Note that an epoxy resin is preferably used for the sealant 605. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), Mylar, polyester, acrylic, or the like can be used as a material for the sealing substrate 604.

  As described above, a light-emitting device having the light-emitting element of the present invention can be obtained.

  In this embodiment, various electric appliances completed using a light-emitting device having a light-emitting element according to the present invention will be described.

  As an electric appliance manufactured using a light-emitting device formed using the present invention, a television, a video camera, a digital camera, a goggle-type display (head-mounted display), a navigation system, a sound reproduction device (car audio, audio component) Etc.), notebook personal computers, game machines, portable information terminals (mobile computers, cellular phones, portable game machines, electronic books, etc.), and image playback devices (specifically digital video discs (DVD)) equipped with recording media For example, a device provided with a display device capable of reproducing the recording medium and displaying the image. A specific example of such an electric appliance is shown in FIG.

  Here, FIG. 5 shows a mobile phone, which includes a main body 2701, a housing 2702, a display unit 2703, an audio input unit 2704, an audio output unit 2705, operation keys 2706, an external connection port 2707, an antenna 2708, and the like. The display device 2703 is manufactured using the light-emitting device having the light-emitting element of the present invention.

  As described above, the applicable range of the light-emitting device having the light-emitting element of the present invention is extremely wide, and the light-emitting element used for the light-emitting device is formed using the light-emitting element of the present invention, so that the driving voltage is low and the lifetime is long. It has the feature of being. Therefore, by applying this light-emitting device to electric appliances in all fields, low power consumption and long life can be realized.

3A and 3B each illustrate an element structure of a light-emitting element of the present invention. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention. 3A and 3B each illustrate an active matrix light-emitting device to which the light-emitting element of the present invention is applied. 4A and 4B illustrate a light-emitting device to which the present invention is applied. The figure explaining the electric appliance to which this invention is applied. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention. 3A and 3B each illustrate an element structure of a light-emitting element of the present invention.

Claims (14)

A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
At least one layer among the plurality of layers is a layer containing one substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide, or titanium oxide. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
A layer containing one substance selected from bismuth oxide, cobalt oxide, chromium oxide, copper oxide, nickel oxide or titanium oxide is provided so as to be in contact with at least one of the electrodes among the plurality of layers. A light emitting device characterized. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
The plurality of layers include a first layer having an organic compound, a second layer having an organic compound, and bismuth oxide, cobalt oxide, chromium oxide, and oxidation between the first layer and the second layer. And a layer containing one substance selected from copper, nickel oxide, and titanium oxide. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
Bismuth oxide, cobalt oxide, chromium oxide, copper oxide formed with such a thickness that a tunnel current flows between the first electrode functioning as a cathode of the pair of electrodes and the layer having an organic compound, A light-emitting element having a layer containing one substance selected from nickel oxide or titanium oxide. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
An organic compound and at least one compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide and titanium oxide in a layer different from the light emitting layer among the plurality of layers. A light emitting element having a containing region. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
At least one of the plurality of layers contains at least one organic compound and at least one compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting element which is a hole transport region. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
At least one of the plurality of layers contains an organic compound and at least one compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting element which is a transport region. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
The plurality of layers include a hole transport region made of a hole transport material, a first mixed region containing both the hole transport material and the light emitting material, a light emitting region made of the light emitting material, an electron transport material, and A second mixed region containing both of the light emitting material, and an electron transport region comprising the electron transport material,
Either the hole transport material or the electron transport material is an organic compound and any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting element comprising: A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
The plurality of layers include a hole transport region made of a hole transport material, a first mixed region including both the hole transport material and the first organic compound, the first organic compound, and the second layer. A light emitting region including both of the organic compound, a second mixed region including both the electron transport material and the first organic compound, and an electron transport region composed of the electron transport material,
The second organic compound is a phosphor;
Either the hole transport material or the electron transport material is an organic compound and any compound selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting element comprising: The first mixed region or the second mixed region is selected from the group consisting of bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting element containing any one compound in an amount of 10 wt% or more. A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
The plurality of layers include a hole injection region made of a hole injection material, a first mixed region containing both the hole injection material and the hole transport material, and a hole transport region made of the hole transport material. A second mixed region containing both the hole transport material and the light emitting material, a light emitting region made of the light emitting material, a third mixed region containing both the light emitting material and the electron transport material, and the electrons An electron transport region made of a transport material; a fourth mixed region made of both the electron transport material and the hole blocking material; a hole blocking region made of the hole blocking material; the hole blocking material and an electron injection. A fifth mixed region containing both materials, and an electron injection region made of the electron injection material,
The hole injection material, the hole transport material, the electron transport material, or the electron injection material includes an organic compound, bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light emitting device comprising any one compound selected from the group consisting of: A pair of electrodes, and a plurality of layers sandwiched between the pair of electrodes,
The plurality of layers include a hole injection region made of a hole injection material, a first mixed region containing both the hole injection material and the hole transport material, and a hole transport region made of the hole transport material. A second mixed region containing both the hole transport material and the first organic compound, a light emitting region containing both the first organic compound and the second organic compound, and the first organic compound And a third mixed region including both the electron transporting material, an electron transporting region composed of the electron transporting material, a fourth mixed region composed of both the electron transporting material and the hole blocking material, and the hole blocking property. A hole blocking region made of a material, a fifth mixed region containing both the hole blocking material and the electron injection material, and an electron injection region made of the electron injection material,
The second organic compound is a phosphor;
The hole injection material, the hole transport material, the electron transport material, or the electron injection material includes an organic compound, bismuth oxide, cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light emitting device comprising any one compound selected from the group consisting of: 13. The bismuth oxide according to claim 11 or claim 12, wherein any one of the first mixed region, the second mixed region, the third mixed region, the fourth mixed region, or the fifth mixed region. A light emitting device comprising 10 wt% or more of any compound selected from the group consisting of cobalt oxide, copper oxide, magnesium oxide, nickel oxide, zinc oxide, and titanium oxide. A light-emitting device comprising the light-emitting element according to claim 1.

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