JP2010050281A - Light-emitting element, display device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element that is reducible in drive voltage while having superior stability and durability (life) at high temperature, and to provide a display device and electronic equipment including the light-emitting element. <P>SOLUTION: The light-emitting element 1 has an positive electrode 3, a negative electrode 9, a light-emitting layer 6 provided between the positive electrode 3 and negative electrode 9 and containing a light-emitting material, a hole transport layer 5 provided between the positive electrode 3 and light-emitting layer 6 and made of a hole transport material having a function of transporting a hole, and a carrier generating layer 4 provided between the positive electrode 3 and hole transport layer 5 while bonded to the hole transport layer 5, and generating the hole and an electron, wherein the carrier generating layer 4 contains a carrier generating material having a function of generating the hole and electron by coming into contact with the hole transport layer 5, as a main material, and is added with an inert material which is electrochemically inactive. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting element, a display device, and an electronic device.

  An organic electroluminescence element (so-called organic EL element) is a light emitting element having a structure in which at least one light emitting organic layer is interposed between an anode and a cathode. In such a light emitting device, by applying an electric field between the cathode and the anode, electrons are injected into the light emitting layer from the cathode side and holes are injected from the anode side, and electrons and holes are injected into the light emitting layer. Recombination generates excitons, and when the excitons return to the ground state, the energy is emitted as light.

Examples of such a light emitting device include a hole injection layer, a charge generation layer (carrier generation layer), a hole transport layer, a light emitting layer, and an electron transport layer between the cathode and the anode from the cathode side to the anode side. Are known in this order (see, for example, Patent Document 1). In such a light emitting device, the charge generation layer generates carriers (holes and electrons) by contact with the hole transport layer and the hole injection layer. Therefore, the light emission efficiency of the light emitting element can be increased and the driving voltage of the light emitting element can be reduced.
However, in general, many materials constituting the carrier generation layer are easily crystallized when energized or heated. For this reason, the light-emitting element according to Patent Document 1 has a drawback in that the material forming the carrier generation layer is crystallized under a relatively high temperature environment, the drive voltage tends to be high, and the light emission lifetime is short.

Japanese Unexamined Patent Publication No. 2007-17379

  An object of the present invention is to provide a light emitting element capable of reducing a driving voltage while having excellent stability and durability (lifetime) at high temperatures, a display device including the light emitting element, and an electronic apparatus. It is in.

Such an object is achieved by the present invention described below.
The light emitting device of the present invention comprises an anode,
A cathode,
A light emitting layer provided between the anode and the cathode and configured to include a light emitting material;
A hole transport layer that is provided between the anode and the light emitting layer and is composed of a hole transport material having a function of transporting holes;
It is provided between the anode and the hole transport layer so as to be bonded to the hole transport layer, and has a carrier generation layer that generates holes and electrons,
The carrier generation layer includes, as a main material, a carrier generation material having a function of generating the holes and electrons by being in contact with the hole transport layer, and an inert material that is electrochemically inactive is added. It is characterized by having comprised.
As a result, it is possible to provide a light-emitting element capable of reducing the drive voltage while improving the stability and durability (life) at high temperatures.

In the light emitting device of the present invention, the absolute value of the difference between the energy level of the highest occupied molecular orbital of the inert material and the energy level of the lowest unoccupied molecular orbital of the carrier generating material is 0.20 eV or more. It is preferable.
As a result, the inert material is less likely to pass electrons to the carrier generating material, and there is less electrical interaction between the inert material and the carrier generating material.

In the light emitting device of the present invention, the absolute value of the difference between the energy level of the highest occupied molecular orbital of the hole transport material and the energy level of the lowest unoccupied molecular orbital of the carrier generating material is 0.15 eV or less. Preferably there is.
As a result, electrons in the highest occupied molecular orbital of the hole transporting material can easily move to the lowest unoccupied molecular orbital of the carrier generating material, and are sufficiently near the boundary between the carrier generating layer and the hole transporting layer. Holes and electrons are generated.

In the light emitting device of the present invention, the inert material is preferably present in an amorphous state in the carrier generation layer.
This prevents the carrier generating material from being regularly arranged along the crystal plane of the inert material in a high temperature environment, and the carrier generating material is more difficult to crystallize.
In the light emitting device of the present invention, the glass transition point of the inert material is preferably 85 ° C. or higher.
As a result, the inert material is prevented from being denatured even in a high temperature environment, and as a result, the carrier generating material is more reliably prevented from crystallizing.

In the light emitting device of the present invention, the inert material is preferably a hydrocarbon containing an aromatic ring.
Such a hydrocarbon containing an aromatic ring is a substance that is difficult to exchange electrons and is not easily altered at high temperatures. For this reason, it is suitably used as an inert substance.
In the light emitting device of the present invention, the inactive material preferably has a fluorene structure and / or a biphenyl structure.
An inert material having such a structure is a material in which the compound itself is difficult to be excited, and it is difficult to exchange electrons with other compounds. On the other hand, since it has a large amount of aromatic rings, the affinity with the carrier generating material as described above is good, and crystallization of the carrier generating material can be suitably prevented.

このような構造を有する不活性材料は、化合物自身が励起されにくい材料であると共に、他の化合物との電子の授受を行いにくいものである。一方で、芳香環を多量に有することから、上述したようなキャリア発生材料との親和性が良好であり、キャリア発生材料の結晶化を好適に防止することができる。 In the light emitting device of the present invention, the inert material preferably includes at least one of the compounds represented by the following chemical formulas 1 to 4.

An inert material having such a structure is a material in which the compound itself is difficult to be excited, and it is difficult to exchange electrons with other compounds. On the other hand, since it has a large amount of aromatic rings, the affinity with the carrier generating material as described above is good, and crystallization of the carrier generating material can be suitably prevented.

このように電子吸引性の高いシアノ基を複数有することにより、化５に示す化合物は、正孔輸送材料からより効率よく電子を引き抜くことができ、キャリア（電子および正孔）を十分に発生させることができる。 In the light emitting device of the present invention, the carrier generating material is preferably a hexaazatriphenylene derivative.
Such a compound has an excellent function as a carrier generating material and can sufficiently extract electrons from the hole transport layer.
In the light emitting device of the present invention, the carrier generating material is preferably a compound represented by the following chemical formula (5).

As described above, by having a plurality of cyano groups having high electron-withdrawing properties, the compound shown in Chemical formula 5 can extract electrons more efficiently from the hole-transporting material and sufficiently generate carriers (electrons and holes). be able to.

In the light emitting device of the present invention, the hole transport layer is preferably composed of a compound having a benzidine structure.
Accordingly, sufficient electrons and holes can be generated near the boundary between the hole transport layer and the carrier generation layer, and holes can be efficiently transported to the light emitting layer.

In the light emitting device of the present invention, when the content of the carrier generating material in the carrier generating layer is A [wt%] and the content of the inert material is B [wt%], 5 ≦ B / (A + B ) ≦ 30.
As a result, a sufficient amount of carriers can be generated between the carrier generation layer and the hole transport layer while more reliably preventing crystallization of the carrier generation material in a high temperature environment.

The display device of the present invention includes the light emitting element of the present invention.
Thereby, it is possible to provide a display device capable of displaying a high-quality image over a long period of time.
An electronic apparatus according to the present invention includes the display device according to the present invention.
Accordingly, an electronic device that can display a high-quality image over a long period of time can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a light-emitting element, a display device, and an electronic device according to the invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram schematically showing a longitudinal section of a light emitting device according to an embodiment of the present invention. In the following description, for convenience of explanation, the upper side in FIG.
Such a light-emitting element (electroluminescence element) 1 includes an anode 3, a carrier generation layer 4, a hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, an electron injection layer 8, and a cathode 9 stacked in this order. It will be.

In other words, the light-emitting element 1 includes a laminate 15 in which a carrier generation layer 4, a hole transport layer 5, a light-emitting layer 6, an electron transport layer 7, and an electron injection layer 8 are stacked in this order between two electrodes. (Between the anode 3 and the cathode 9).
The entire light emitting element 1 is provided on the substrate 2 and is sealed with a sealing member 10.

  In such a light emitting element 1, electrons are supplied (injected) from the cathode 9 side to the light emitting layer 6, and holes are supplied (injected) from the anode 3 side. In each light emitting layer, holes and electrons recombine, and excitons (excitons) are generated by the energy released during the recombination, and energy (fluorescence or phosphorescence) is generated when the excitons return to the ground state. Is emitted (emitted).

The substrate 2 supports the anode 3. Since the light-emitting element 1 of the present embodiment is configured to extract light from the substrate 2 side (bottom emission type), the substrate 2 and the anode 3 are substantially transparent (colorless transparent, colored transparent, or translucent), respectively. Has been.
Examples of the constituent material of the substrate 2 include resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, and polyarylate, quartz glass, and soda glass. Such glass materials can be used, and one or more of these can be used in combination.

Although the average thickness of such a board | substrate 2 is not specifically limited, It is preferable that it is about 0.1-30 mm, and it is more preferable that it is about 0.1-10 mm.
In the case where the light emitting element 1 is configured to extract light from the side opposite to the substrate 2 (top emission type), the substrate 2 can be either a transparent substrate or an opaque substrate.
Examples of the opaque substrate include a substrate made of a ceramic material such as alumina, an oxide film (insulating film) formed on the surface of a metal substrate such as stainless steel, and a substrate made of a resin material. It is done.
Hereinafter, each part which comprises the light emitting element 1 is demonstrated sequentially.

(anode)
The anode 3 is an electrode that injects holes into a carrier generation layer 4 described later. As a constituent material of the anode 3, it is preferable to use a material having a large work function and excellent conductivity.
Examples of the constituent material of the anode 3 include oxides such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO, Au, Pt, and Ag. Cu, alloys containing these, and the like can be used, and one or more of these can be used in combination.
The average thickness of the anode 3 is not particularly limited, but is preferably about 10 to 200 nm, and more preferably about 50 to 150 nm.

(Carrier generation layer)
The carrier generation layer 4 has a function of generating carriers (holes and electrons) by contact with a hole transport layer 5 described later.
Such a carrier generation layer 4 includes a carrier generation material as a main material, and is configured by adding an electrochemically inactive inert material.

  The carrier generating material has a function of generating holes and electrons by coming into contact with the hole transport layer 5. In other words, the carrier generating material is composed of a compound having a high electron withdrawing property, and has a function of extracting electrons from the hole transporting material constituting the hole transporting layer 5 by contacting with the hole transporting layer 5. Have. As a result, when the carrier generation layer 4 and the hole transport layer 5 are in contact with each other, electrons are present on the carrier generation layer 4 side in the vicinity of the interface between the carrier generation layer 4 and the hole transport layer 5 even if no voltage is applied. And holes are generated on the hole transport layer 5 side. When a driving voltage is applied between the anode 3 and the cathode 9 in such a state, holes and electrons generated near the interface between the carrier generation layer 4 and the hole transport layer 5 are transported by the driving voltage. This contributes to the light emission of the light emitting layer 6. As a result, even if the drive voltage is relatively low, the light emitting element 1 has sufficient light emission luminance.

Further, such a carrier generating material is usually present in an amorphous state in the carrier generating layer 4.
Such a carrier generating material is not particularly limited as long as it can exhibit the functions as described above. For example, a hexaazatriphenylene derivative represented by the following chemical formula 6 is preferably used.

In the above chemical formula 6, R is a cyano group (—CN), a sulfone group (—SO ₂ R ′), a sulfoxide group (—SOR ′), a sulfonamide group (—SO ₂ NR ′ ₂ ), a sulfonate group (—SO ₂ ). ₃ R ′), a nitro group (—NO ₂ ), or a trifluoromethane (—CF ₃ ) group, wherein R ′ is substituted or unsubstituted with an amine group, an amide group, an ether group, or an ester group. A C1-C60 alkyl group, an aryl group, or a heterocyclic group.

The compound shown in Chemical Formula 6 above has an excellent function as a carrier generating material and can sufficiently extract electrons from the hole transport layer 5.
In particular, as a carrier generating material, in the compound represented by Chemical Formula 6 as described above, R is preferably a cyano group. That is, it is preferable to use hexacyanohexaazatriphenylene as shown in the following chemical formula 7 as the carrier generating material. By having a plurality of cyano groups having a high electron-withdrawing property in this way, the compound shown in Chemical formula 7 can extract electrons more efficiently from the hole transporting material and sufficiently generate carriers (electrons and holes). be able to.

  The absolute value of the difference between the energy level of the highest occupied molecular orbital (HOMO) of the hole transporting material and the energy level of the lowest unoccupied molecular orbital (LUMO) of the carrier generating material may be 0.15 eV or less. Preferably, it is 0.10 eV or less. Thereby, the electrons in the highest occupied molecular orbital of the hole transport material can easily move to the lowest unoccupied molecular orbital of the carrier generating material. In other words, the carrier generating material can more easily extract electrons from the hole transport material.

  In addition, hexacyanohexaazatriphenylene as shown in the above chemical formula 7 has an energy level of the highest occupied orbital of −9.8 to −9.6 eV, that is, its absolute value is 9.6 to 9.8 eV. Further, the energy level of the lowest unoccupied orbital of hexacyanohexaazatriphenylene is about −5.5 eV, that is, the absolute value thereof is about 5.5 eV. A compound having such an energy level can have the energy level relationship as described above with respect to a hole transport material as described later.

Further, as described above, an electrically inactive inactive material is added to the carrier generation layer 4. Since the carrier generation layer 4 contains such an inert material, the generation of the carrier generation material in a high-temperature environment without inhibiting the generation of carriers between the carrier generation layer 4 and the hole transport layer 5. Can be prevented.
That is, the presence of the inert material in a high temperature environment prevents the molecules (atoms) of the carrier generating material from being regularly arranged, and as a result, crystallization of the carrier generating material is prevented. As a result, the light-emitting element 1 of the present invention has excellent stability and durability (lifetime) at high temperatures.

On the other hand, since the inert material is electrically inactive as described above, it does not interact electrically with the carrier generating material, and carriers are generated between the carrier generating material and the inert material. There is nothing to do.
As described above, by simultaneously using the carrier generating material and the inert material, the light emitting device 1 of the present invention can reduce the driving voltage while having excellent stability and durability (life) at high temperatures. Can do.

Note that in this specification, the “electrically inactive” state refers to a state in which the substance does not have a charge. That is, an “electrically inactive” substance is a substance that hardly emits electrons and that does not easily receive electrons, and is a substance that does not easily cause an electrical interaction with other substances.
Such an inert material is not particularly limited as long as it is electrically inactive, and examples thereof include hydrocarbons containing aromatic rings such as hydrocarbons having a fluorene structure, a biphenyl structure, and a naphthalene structure. Of these, one or two or more can be used in combination. Such a hydrocarbon containing an aromatic ring is a substance that is difficult to exchange electrons and is not easily altered at high temperatures. For this reason, it is suitably used as an inert substance.

Among these, the inert material preferably has at least one of a fluorene structure and a biphenyl structure. An inert material having such a structure is a material in which the compound itself is difficult to be excited, and it is difficult to exchange electrons with other compounds. On the other hand, since it has a large amount of aromatic rings, the affinity with the carrier generating material as described above is good, and crystallization of the carrier generating material can be suitably prevented.
In addition, among the above-described inert materials, it is preferable that the inert material includes at least one of the compounds represented by the following chemical formulas 8 to 11. By using these compounds as inert materials, the effects as described above can be obtained more remarkably.

  The absolute value of the difference between the energy level of the highest occupied molecular orbital (HOMO) of the inert material and the energy level of the lowest unoccupied molecular orbital (LUMO) of the carrier generating material is 0.20 eV or more. Is preferable, and is more preferably 0.30 eV or more. This more reliably prevents electrons in the highest occupied molecular orbital of the inert material from moving to the lowest unoccupied molecular orbital of the carrier generating material. In other words, the inert material is less likely to pass electrons to the carrier generating material and has less electrical interaction between the inert material and the carrier generating material.

  The inert material is preferably present in an amorphous state in the carrier generation layer. This prevents the carrier generating material from being regularly arranged along the crystal plane of the inert material in a high temperature environment, and the carrier generating material is more difficult to crystallize. As will be described later, the inert material and the carrier generation material in the carrier generation layer after film formation are formed by co-evaporating the inert material and the carrier generation material by vacuum deposition to form a carrier generation layer. It becomes an amorphous state.

  Further, the glass transition point of the inert material is preferably 85 ° C. or higher, and more preferably 90 ° C. or higher. As a result, the inert material is prevented from being denatured even in a high temperature environment, and as a result, the carrier generating material is more reliably prevented from crystallizing. In particular, when the inert material is amorphous in the carrier generation layer 4, such an effect becomes remarkable.

Further, the inert material is preferably uniformly distributed (dispersed) in the carrier generation layer 4. Thereby, crystallization of the carrier generating material can be prevented more reliably.
Further, when the content of the carrier generating material in the carrier generating layer 4 is A [wt%] and the content of the inert material is B [wt%], 5 ≦ B / (A + B) ≦ 30. Preferably, 5 ≦ B / (A + B) ≦ 20 is more preferable. As a result, a sufficient amount of carriers can be generated between the carrier generation layer 4 and the hole transport layer 5 while more reliably preventing crystallization of the carrier generation material in a high temperature environment.

(Hole transport layer)
The hole transport layer 5 has a function of transporting holes injected from the anode 3 through the carrier generation layer 4 to the light emitting layer 6.
As the constituent material of the hole transport layer 5, various p-type polymer materials and various p-type low-molecular materials can be used alone or in combination. '-Di (1-naphthyl) -N, N'-diphenyl-1,1'-diphenyl-4,4'-diamine (NPD), N, N'-diphenyl-N, N'-bis (3-methyl Phenyl) -1,1′-diphenyl-4,4′-diamine (TPD) and other tetraarylbenzidine derivatives, tetraaryldiaminofluorene compounds or derivatives thereof (amine compounds), and the like. Alternatively, two or more kinds can be used in combination.

Among the above-mentioned, the hole transport material preferably has a benzidine structure, and more preferably tetraarylbenzidine or a derivative thereof. Thereby, sufficient electrons and holes can be generated near the boundary between the hole transport layer 5 and the carrier generation layer 4, and holes can be efficiently transported to the light emitting layer 6. In particular, when the hole transport material is a compound represented by Chemical Formula 12, such an effect becomes more remarkable.
The average thickness of the hole transport layer 5 is not particularly limited, but is preferably about 10 to 150 nm, and more preferably about 10 to 100 nm.

(Light emitting layer)
The light emitting layer 6 includes a light emitting material. More specifically, the light emitting layer 6 includes a light emitting material and a host material using the light emitting material as a guest material. Such a light emitting layer 6 can be formed, for example, by doping a host material with a light emitting material as a guest material as a dopant.

In the luminescent material, electrons are supplied (injected) from the cathode 9 side, and holes are supplied (injected) from the anode 3 side, whereby the holes and electrons are recombined and released upon this recombination. Exciton (exciton) is generated by the generated energy, and energy (fluorescence or phosphorescence) is emitted (emitted) when the exciton returns to the ground state.
Such a light-emitting material is not particularly limited, and various fluorescent materials and various phosphorescent materials can be used alone or in combination of two or more.

  Examples of red fluorescent materials include perylene derivatives such as tetraphenyldiindenoperylene derivatives, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, Nile red, 2- (1,1-dimethylethyl). ) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolizin-9-yl) ethenyl) -4H-pyran- 4H-ylidene) propanedinitrile (DCJTB), 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran (DCM), and the like.

  Examples of the blue fluorescent material include distyryldiamine derivatives, distyryl derivatives, fluoranthene derivatives, pyrene derivatives, perylene and perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, chrysene derivatives, phenanthrene derivatives, dianthrene derivatives, Styrylbenzene derivative, tetraphenylbutadiene, 4,4′-bis (9-ethyl-3-carbazovinylene) -1,1′-biphenyl (BCzVBi), poly [(9.9-dioctylfluorene-2,7-diyl) -Co- (2,5-dimethoxybenzene-1,4-diyl)], poly [(9,9-dihexyloxyfluorene-2,7-diyl) -ortho-co- (2-methoxy-5- {2 -Ethoxyhexyloxy} phenylene-1 4-diyl)], poly [(9,9-dioctyl-2,7-diyl) - co - (ethyl benzene), and the like.

Examples of green fluorescent materials include coumarin derivatives, quinacridone derivatives, 9,10-bis [(9-ethyl-3-carbazole) -vinylenyl] -anthracene, poly (9,9-dihexyl-2,7-vinylene full) Orenylene), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (1,4-diphenylene-vinylene-2-methoxy-5- {2-ethylhexyloxy} benzene)], poly [ (9,9-dioctyl-2,7-divinylenefluorenylene) -ortho-co- (2-methoxy-5- (2-ethoxylhexyloxy) -1,4-phenylene)] and the like.
The yellow fluorescent material is, for example, a compound having a naphthacene skeleton such as a rubrene-based material, in which an aryl group (preferably a phenyl group) is substituted at any position (preferably 2 to 6) with an aryl group (preferably a phenyl group). Compounds, monoindenoperylene derivatives and the like can be used. Examples of the rubrene-based material include compounds as shown in the following chemical formula (13).

Examples of the red phosphorescent material include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium. At least one of the ligands of these metal complexes includes a phenylpyridine skeleton, a bipyridyl skeleton, and a porphyrin skeleton. And the like. More specifically, tris (1-phenylisoquinoline) iridium, bis [2- (2′-benzo [4,5-α] thienyl) pyridinate-N, C ³ ′] iridium (acetylacetonate) (btp2Ir ( acac)), 2,3,7,8,12,13,17,18-octaethyl-12H, 23H-porphyrin-platinum (II), bis [2- (2′-benzo [4,5-α] thienyl ) Pyridinate-N, C ³ '] iridium, bis (2-phenylpyridine) iridium (acetylacetonate).

Examples of the blue phosphorescent material include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium. More specifically, bis [4,6-difluorophenyl pyridinium sulfonate -N, ^{C 2} '] - picolinate - iridium, tris [2- (2,4-difluorophenyl) pyridinate -N, ^{C 2']} iridium , bis [2- (3,5-trifluoromethyl) pyridinate -N, ^{C 2} '] - picolinate - iridium, bis (4,6-difluorophenyl pyridinium sulfonate -N, ^{C 2')} iridium (acetylacetonate ).

Examples of the green phosphorescent material include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium. Among these, at least one of the ligands of these metal complexes preferably has a phenylpyridine skeleton, a bipyridyl skeleton, a porphyrin skeleton, or the like. More specifically, fac-tris (2-phenylpyridine) iridium (Ir (ppy) 3), bis (2-phenylpyridinate-N, C2 ′) iridium (acetylacetonate), fac-tris [5 -Fluoro-2- (5-trifluoromethyl-2-pyridine) phenyl-C, N] iridium.
A host material that uses such a light-emitting material as a guest material recombines holes and electrons to generate excitons and to transfer the exciton energy to the light-emitting material (Felster transfer or Dexter transfer). And has a function of exciting the light emitting material.

  As such a host material, a BU body, a benzoxazole derivative, a benzothiazole derivative, a quinoline derivative, 4,4′-bis (2) can be used as long as it exhibits the functions described above with respect to the light emitting material to be used. , 2′-diphenylvinyl) biphenyl (DPVBi) and the like, and one of them can be used alone or in combination of two or more. Preferably, when the luminescent material is blue or green, an anthracene derivative and a dianthracene derivative are preferable, and when the luminescent material is red, a naphthacene derivative and a perylene derivative are preferable.

As the host material, for example, when the light-emitting material includes a phosphorescent material, 3-phenyl-4- (1′-naphthyl) -5-phenylcarbazole, 4,4′-N, N′-dicarbazole biphenyl ( Carbazole derivatives such as CBP) and the like, and one of these may be used alone or two or more of them may be used in combination.
When using the light emitting material (guest material) and the host material as described above, the content (doping amount) of the light emitting material in the light emitting layer 6 is preferably 0.1 to 10 wt%, and 1 to 5 wt%. More preferably. Luminous efficiency can be optimized by setting the content of the light emitting material within such a range.

Moreover, although the average thickness of the light emitting layer 6 is not specifically limited, It is preferable that it is 1-100 nm, It is more preferable that it is 3-50 nm, It is further more preferable that it is 5-30 nm.
In the present embodiment, the light emitting unit is described as an example including one light emitting layer, but the light emitting unit may be provided with a plurality of light emitting layers. In this case, the light emission colors of the plurality of light emitting layers may be the same or different. For example, when the light emitting unit includes three light emitting layers of a red light emitting layer, a blue light emitting layer, and a green light emitting layer, the light emitting layer is a two light emitting layer of a blue light emitting layer and a yellow light emitting layer. , The entire light emitting unit can emit white light. In the case where the light emitting unit has a plurality of light emitting layers, an intermediate layer may be provided between the light emitting layers.

(Electron transport layer)
The electron transport layer 7 has a function of transporting electrons injected from the cathode 9 through the electron injection layer 8 to the light emitting layer 6.
Examples of the constituent material (electron transporting material) of the electron transport layer 7 include quinolines such as organometallic complexes having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum (Alq ₃ ) as a ligand. Derivatives, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like can be used, and one or more of these can be used in combination.
Although the average thickness of the electron carrying layer 7 is not specifically limited, It is preferable that it is about 0.5-100 nm, and it is more preferable that it is about 1-50 nm.

(Electron injection layer)
The electron injection layer 8 has a function of improving the electron injection efficiency of the cathode 9 and the like.
Examples of the constituent material (electron injection material) of the electron injection layer 8 include various inorganic insulating materials and various inorganic semiconductor materials.
Examples of such inorganic insulating materials include alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides. Of these, one or two or more of these can be used in combination. By forming the electron injection layer using these as main materials, the electron injection property can be further improved. In particular, alkali metal compounds (alkali metal chalcogenides, alkali metal halides, and the like) have a very low work function, and the light-emitting element 1 can be obtained with high luminance by forming the electron injection layer 8 using the work function. Become.

Examples of the alkali metal chalcogenide include Li ₂ O, LiO, Na ₂ S, Na ₂ Se, and NaO.
Examples of the alkaline earth metal chalcogenide include CaO, BaO, SrO, BeO, BaS, MgO, and CaSe.
Examples of the alkali metal halide include CsF, LiF, NaF, KF, LiCl, KCl, and NaCl.

Examples of the alkaline earth metal halide include CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ , and BeF ₂ .
In addition, as the inorganic semiconductor material, for example, an oxide including at least one element of Li, Na, Ba, Ca, Sr, Yb, Al, Ga, In, Cd, Mg, Si, Ta, Sb, and Zn , Nitrides, oxynitrides, and the like, and one or more of these can be used in combination.
The average thickness of the electron injection layer 8 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 0.2 to 100 nm, and about 0.2 to 50 nm. Further preferred.

(cathode)
The cathode 9 is an electrode that injects electrons into the electron transport layer 7 through the electron injection layer 8 described above. As a constituent material of the cathode 9, it is preferable to use a material having a small work function.
Examples of the constituent material of the cathode 9 include Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, and alloys containing these. These can be used alone or in combination of two or more thereof (for example, a multi-layer laminate).

In particular, when an alloy is used as the constituent material of the cathode 9, it is preferable to use an alloy containing a stable metal element such as Ag, Al, or Cu, specifically, an alloy such as MgAg, AlLi, or CuLi. By using such an alloy as the constituent material of the cathode 9, the electron injection efficiency and stability of the cathode 9 can be improved.
Although the average thickness of such a cathode 9 is not specifically limited, It is preferable that it is about 100-10000 nm, and it is more preferable that it is about 200-500 nm.
In addition, since the light emitting element 1 of this embodiment is a bottom emission type, the light transmittance of the cathode 9 is not particularly required.

(Sealing member)
The sealing member 10 is provided so as to cover the anode 3, the laminate 15, and the cathode 9, and has a function of hermetically sealing them and blocking oxygen and moisture. By providing the sealing member 10, effects such as improvement of the reliability of the light emitting element 1 and prevention of deterioration / deterioration (improvement of durability) can be obtained.
Examples of the constituent material of the sealing member 10 include Al, Au, Cr, Nb, Ta, Ti, alloys containing these, silicon oxide, various resin materials, and the like. In addition, when using the material which has electroconductivity as a constituent material of the sealing member 10, in order to prevent a short circuit, it is required between the sealing member 10 and the anode 3, the laminated body 15, and the cathode 9. Accordingly, it is preferable to provide an insulating film.

Further, the sealing member 10 may be formed in a flat plate shape so as to face the substrate 2 and be sealed with a sealing material such as a thermosetting resin.
According to the light emitting device 1 configured as described above, the hole transport layer 5 and the carrier generation layer 4 are provided in contact with each other, so that the carrier generation layer 4 and the hole transport layer 5 Electrons and holes can be generated. As a result, the generated holes and electrons can be effectively contributed to the light emission of the light emitting layer 6 to increase the light emission efficiency and reduce the drive voltage.

Further, since the carrier generation layer 4 includes an inert material in addition to the carrier generation material, crystallization of the carrier generation material can be prevented. As a result, even if the light emitting element 1 is exposed to a high temperature or the light emitting element 1 becomes high temperature due to long-term use, the carrier generating layer 4 is not affected by the anode 3, and the light emitting element is obtained by crystallization of the carrier generating layer 4. 1 characteristic change can be prevented. Therefore, the light emitting device 1 of the present invention is excellent in stability and durability at high temperatures.
The light emitting element 1 configured as described above can be manufactured, for example, as follows.
[1] First, the substrate 2 is prepared, and the anode 3 is formed on the substrate 2.
The anode 3 is, for example, a chemical vapor deposition method (CVD) such as plasma CVD or thermal CVD, a dry plating method such as vacuum deposition, a wet plating method such as electrolytic plating, a thermal spraying method, a sol-gel method, a MOD method, or a metal foil. It can be formed by using, for example, bonding.

[2] Next, the carrier generation layer 4 is formed on the anode 3.
The carrier generation layer 4 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering.
Thus, by forming the carrier generation layer 4 by a vapor phase process, the carrier generation material and the inactive material are in an amorphous state in the formed carrier generation layer 4. In particular, when vacuum deposition is used, the carrier generation material and the inert material in the carrier generation layer 4 can be more reliably made amorphous.

Moreover, when performing vacuum evaporation, it is preferable to vapor-deposit a carrier generating material and an inert material simultaneously. That is, it is preferable to perform co-evaporation using a carrier generating material and an inert material as materials. Thereby, the inert material is uniformly distributed in the carrier generation layer 4.
Prior to this step, the upper surface of the anode 3 may be subjected to oxygen plasma treatment. Thereby, it is possible to impart lyophilicity to the upper surface of the anode 3, remove (clean) organic substances adhering to the upper surface of the anode 3, adjust the work function near the upper surface of the anode 3, and the like. .
Here, the oxygen plasma treatment conditions include, for example, a plasma power of about 100 to 800 W, an oxygen gas flow rate of about 50 to 100 mL / min, a conveyance speed of the member to be treated (anode 3) of about 0.5 to 10 mm / sec, and a substrate. The temperature of 2 is preferably about 70 to 90 ° C.

[3] Next, the hole transport layer 5 is formed on the carrier generation layer 4.
The hole transport layer 5 can be formed, for example, by a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering.
Further, by supplying a hole transport layer forming material obtained by dissolving a hole transport material in a solvent or dispersing in a dispersion medium onto the carrier generation layer 4, drying (desolvation or dedispersion medium) is performed. Can also be formed.

As a method for supplying the hole transport layer forming material, for example, various coating methods such as a spin coating method, a roll coating method, and an ink jet printing method can be used. By using such a coating method, the hole injection layer 4 can be formed relatively easily.
Examples of the solvent or dispersion medium used for the preparation of the hole transport layer forming material include various inorganic solvents, various organic solvents, and mixed solvents containing these.
The drying can be performed, for example, by standing in an atmospheric pressure or a reduced pressure atmosphere, heat treatment, or blowing an inert gas.

[4] Next, the light emitting layer 6 is formed on the hole transport layer 5.
The first light emitting layer 6 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like.
[5] Next, the electron transport layer 7 is formed on the light emitting layer 6.
The electron transport layer 7 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like.
The electron transport layer 7 is dried (desolvent or dedispersed) after supplying an electron transport layer forming material obtained by, for example, dissolving an electron transport material in a solvent or dispersing in a dispersion medium onto the light emitting layer 6. It can also be formed by the medium.

[6] Next, the electron injection layer 8 is formed on the electron transport layer 7.
In the case where an inorganic material is used as the constituent material of the electron injection layer 8, the electron injection layer 8 is formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the application and baking of inorganic fine particle ink. Etc. can be used.
[7] Next, the cathode 9 is formed on the electron injection layer 8.
The cathode 9 can be formed by using, for example, a vacuum deposition method, a sputtering method, bonding of metal foil, application and firing of metal fine particle ink, or the like.
The light emitting element 1 is obtained through the steps as described above.
Finally, the sealing member 10 is covered so as to cover the obtained light emitting element 1 and bonded to the substrate 2.

The light emitting element 1 as described above can be used as, for example, a light source. Moreover, a display apparatus (display apparatus of this invention) can be comprised by arrange | positioning the several light emitting element 1 in matrix form. Since such a display device uses the light emitting element 1 as described above, it is possible to increase the light emission efficiency and reduce the driving voltage while being excellent in stability and durability in a high temperature environment. Therefore, a high-quality image can be displayed over a long period.
The driving method of the display device is not particularly limited, and may be either an active matrix method or a passive matrix method.
Next, an example of a display device to which the display device of the present invention is applied will be described.

FIG. 2 is a longitudinal sectional view showing an embodiment of a display device to which the display device of the present invention is applied.
The display device 100 shown in FIG. 2 includes a substrate 21, a plurality of light emitting elements 1R, 1G, and 1B and color filters 19R, 19G, and 19B provided corresponding to the sub-pixels 100R, 100G, and 100B, and each light emitting element 1R. And a plurality of driving transistors 24 for driving 1G and 1B, respectively. Here, the display device 100 is a display panel having a top emission structure.

A plurality of driving transistors 24 are provided on the substrate 21, and a planarizing layer 22 made of an insulating material is formed so as to cover these driving transistors 24.
Each driving transistor 24 includes a semiconductor layer 241 made of silicon, a gate insulating layer 242 formed on the semiconductor layer 241, a gate electrode 243 formed on the gate insulating layer 242, a source electrode 244, and a drain electrode. H.245.

On the planarization layer, light emitting elements 1R, 1G, and 1B are provided corresponding to the driving transistors 24, respectively.
In the light emitting element 1 </ b> R, a reflective film 32, a corrosion preventing film 33, an anode 3, a laminate (organic EL light emitting unit) 15, a cathode 9, and a cathode cover 34 are laminated on the planarizing layer 22 in this order. In the present embodiment, the anode 3 of each light emitting element 1R, 1G, 1B constitutes a pixel electrode and is electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. The cathodes 9 of the light emitting elements 1R, 1G, and 1B are common electrodes.

The configurations of the light emitting elements 1G and 1B are the same as the configuration of the light emitting element 1R. In FIG. 2, the same reference numerals are assigned to the same configurations as those in FIG. 1. Further, the configuration (characteristics) of the reflective film 32 may be different among the light emitting elements 1R, 1G, and 1B depending on the wavelength of light.
A partition wall 31 is provided between the adjacent light emitting elements 1R, 1G, and 1B. An epoxy layer 35 made of an epoxy resin is formed on the light emitting elements 1R, 1G, and 1B so as to cover them.

The color filters 19R, 19G, and 19B are provided on the epoxy layer 35 described above corresponding to the light emitting elements 1R, 1G, and 1B.
The color filter 19R converts the white light W from the light emitting element 1R into red. The color filter 19G converts the white light W from the light emitting element 1G into green. The color filter 19B converts the white light W from the light emitting element 1B into blue. By using such color filters 19R, 19G, and 19B in combination with the light emitting elements 1R, 1G, and 1B, a full color image can be displayed.

A light shielding layer 36 is formed between the adjacent color filters 19R, 19G, and 19B. Thereby, it is possible to prevent the unintended subpixels 100R, 100G, and 100B from emitting light.
A sealing substrate 20 is provided on the color filters 19R, 19G, 19B and the light shielding layer 36 so as to cover them.

The display device 100 as described above may be a single color display, and color display is also possible by selecting a light emitting material used for each light emitting element 1R, 1G, 1B.
Such a display device 100 (the display device of the present invention) can be incorporated into various electronic devices. Since such an electronic device uses the display device as described above, it is possible to increase the light emission efficiency and reduce the driving voltage while being excellent in stability and durability under a high temperature environment. Therefore, a high-quality image can be displayed over a long period.

FIG. 3 is a perspective view showing the configuration of a mobile (or notebook) personal computer to which the electronic apparatus of the present invention is applied.
In this figure, a personal computer 1100 includes a main body 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display. The display unit 1106 is rotatable with respect to the main body 1104 via a hinge structure. It is supported by.
In the personal computer 1100, the display unit included in the display unit 1106 is configured by the display device 100 described above.

FIG. 4 is a perspective view showing a configuration of a mobile phone (including PHS) to which the electronic apparatus of the present invention is applied.
In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204 and a mouthpiece 1206, and a display unit.
In the cellular phone 1200, the display unit is configured by the display device 100 described above.

FIG. 5 is a perspective view showing a configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.
Here, an ordinary camera sensitizes a silver salt photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an image sensor such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

A display unit is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to display based on an imaging signal from the CCD, and functions as a finder that displays an object as an electronic image.
In the digital still camera 1300, the display unit is configured by the display device 100 described above.

A circuit board 1308 is installed inside the case. The circuit board 1308 is provided with a memory that can store (store) an imaging signal.
A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side of the case 1302 (on the back side in the illustrated configuration).
When the photographer confirms the subject image displayed on the display unit and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory of the circuit board 1308.

  In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the data communication input / output terminal 1314 as necessary. Further, the imaging signal stored in the memory of the circuit board 1308 is output to the television monitor 1430 or the personal computer 1440 by a predetermined operation.

The electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, in addition to the personal computer (mobile personal computer) in FIG. 3, the mobile phone in FIG. 4, and the digital still camera in FIG. Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.
The light emitting element, the display device, and the electronic device of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.

Next, specific examples of the present invention will be described.
1. Production of light emitting device (Example 1)
<1> First, a transparent glass substrate having an average thickness of 0.5 mm was prepared. Next, an ITO electrode (anode) having an average thickness of 100 nm was formed on the substrate by sputtering.
And after immersing a board | substrate in order of acetone and 2-propanol and ultrasonically cleaning, the oxygen plasma process was performed.

<2> Next, on the ITO electrode, the compound represented by the chemical formula 7 as a carrier generating material and the compound represented by the chemical formula 8 as an inert material are vapor-deposited by a vacuum deposition method to obtain an average thickness. A carrier generation layer having a thickness of 30 nm was formed.
Further, the content of the carrier generating material in the carrier generating layer was 93.0 wt%, and the content of the inert material in the carrier generating layer was 7.0 wt%. Further, the absolute value of the LUMO energy level of the compound represented by Chemical formula 7 was 5.5 eV, and the absolute value of the HOMO energy level of the compound represented by Chemical formula 8 was 5.8 eV or more. Moreover, the glass transition point of the compound represented by Chemical formula 8 was 160 ° C. The absolute value of the HOMO energy level of the compound was measured using AC-1 (manufactured by Riken Keiki Co., Ltd.). Further, the absolute value of the HOMO energy level of each compound thereafter was measured in the same manner.

  In addition, the absolute value of the LUMO energy level of the compound represented by Chemical Formula 7 is subtracted from the absolute value of the HOMO energy level measured using AC-1 by the bandgap value calculated by the fluorescence spectrum method. And asked. Specifically, the band gap value of the compound represented by Chemical Formula 7 was determined as follows. First, a compound represented by Chemical Formula 7 was deposited on a glass plate to a thickness of 100 nm. Next, an excitation waveform (fluorescence excitation spectrum) and an emission waveform (fluorescence emission spectrum) of the compound deposited on the glass plate were measured by a fluorescence spectrum method. The intersection of the obtained excitation waveform and emission waveform was determined as the wavelength at the absorption edge of the excitation waveform: λ [nm]. Then, the band gap value: E [eV] was calculated by substituting the wavelength of the absorption edge into the formula: E [eV] = 1240 / λ [nm].

<3> Next, the compound represented by Chemical Formula 12 was vapor-deposited on the carrier generation layer by a vacuum vapor deposition method to form a hole transport layer having an average thickness of 20 nm. The absolute value of the energy level of HOMO of the compound represented by Chemical formula 12 was 5.4 eV.
<4> Next, a light emitting material (yellow light emitting material) and a host material were vapor-deposited on the hole transport layer by a vacuum vapor deposition method to form a light emitting layer having an average thickness of 40 nm.
Here, the rubrene-based material represented by the chemical formula 13 described above was used as the light emitting material (guest material), and the anthracene derivative represented by the chemical formula 14 described above was used as the host material. The content (dope concentration) of the light emitting material (dopant) in the light emitting layer was 3.0 wt%.

<5> Next, tris (8-quinolinolato) aluminum (Alq ₃ ) was formed on the light-emitting layer by a vacuum deposition method, thereby forming an electron transport layer having an average thickness of 30 nm.
<6> Next, on the electron transport layer, lithium fluoride (LiF) was formed by a vacuum vapor deposition method, thereby forming an electron injection layer having an average thickness of 0.5 nm.
<7> Next, Al was formed into a film by the vacuum evaporation method on the electron injection layer. Thereby, a cathode having an average thickness of 100 nm made of Al was formed.
<8> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
Through the above steps, a light emitting device as shown in FIG. 1 was manufactured.

(Example 2)
A light emitting device was manufactured in the same manner as in Example 1 except that the compound represented by Chemical Formula 9 was used as an inert material when forming the carrier generation layer.
Further, the content of the carrier generating material in the carrier generating layer was 93.0 wt%, and the content of the inert material in the carrier generating layer was 7.0 wt%. The absolute value of the HOMO energy level of the compound represented by Chemical formula 9 was 5.9 eV or more.

(Example 3)
A light emitting device was manufactured in the same manner as in Example 1 except that the compound represented by Chemical formula 10 was used as an inert material when forming the carrier generation layer.
Further, the content of the carrier generating material in the carrier generating layer was 93.0 wt%, and the content of the inert material in the carrier generating layer was 7.0 wt%. In addition, the absolute value of the HOMO energy level of the compound represented by Chemical formula 10 was 5.9 eV or more.

Example 4
A light emitting device was manufactured in the same manner as in Example 1 except that the compound represented by Chemical Formula 11 was used as an inert material when forming the carrier generation layer.
Further, the content of the carrier generating material in the carrier generating layer was 93.0 wt%, and the content of the inert material in the carrier generating layer was 7.0 wt%. Moreover, the absolute value of the energy level of HOMO of the compound represented by Chemical formula 11 was 5.9 eV or more.

(Example 5)
The light emitting device is the same as Example 1 described above except that the compound represented by Chemical Formula 11 is used as the inert material when forming the carrier generation layer, and the content of the inert material in the carrier generation layer is changed. Manufactured.
Further, the content of the carrier generating material in the carrier generating layer was 93.0 wt%, and the content of the inert material in the carrier generating layer was 7.0 wt%.
(Comparative example)
A light emitting device was manufactured in the same manner as in Example 1 except that the carrier generation layer was formed only from the compound represented by Chemical Formula 7 (carrier generation material).

2. Evaluation 2-1. Evaluation of Luminous Efficiency For each example and each comparative example, a constant current of 10 mA / cm ² was passed through the light emitting element using a DC power source, and the luminance (initial luminance) was measured using a luminance meter. The results are shown in Table 1. Table 1 also shows the chromaticity (x, y) at the time of the luminance measurement for each example and each comparative example.
FIG. 6 shows an emission spectrum of the light-emitting element of Example 1 at the time of luminance measurement. In addition, the emission spectrum of the light emitting element of Examples 2-5 and a comparative example also showed the same waveform.

2-2. Evaluation of Thermal Stability For each example and each comparative example, a driving voltage was measured when a constant current of 10 mA / cm ² was passed through the light emitting element immediately after manufacture using a direct current power source. Next, after the light emitting element was left in an environment of 85 ° C. for 100 hours, a driving voltage was measured when a constant current of 10 mA / cm ² was passed through the light emitting element using a DC power source. The results are shown in Table 1.

2-3. Evaluation of Luminous Life For each example and each comparative example, a constant current of 200 mA / cm ² was continuously supplied to the light emitting element using a direct current power source, while the luminance was measured using a luminance meter, and the luminance was the initial luminance. The time (LT50) to become 50% of was measured. The results are shown in Table 1. In each example and each comparative example, the half-life value was measured under an environment of 80 ° C. and a room temperature (25 ° C.).
As is clear from Table 1, the light-emitting elements of the examples are superior in thermal stability to the light-emitting elements of the comparative examples, and the drive voltage after leaving in a high-temperature environment is the drive voltage before leaving. It was almost the same value. Moreover, the light emitting element of each Example had a long life in a high temperature environment compared with the light emitting element of each comparative example.

It is a figure which shows typically the longitudinal cross-section of the light emitting element concerning 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows embodiment of the display apparatus to which the display apparatus of this invention is applied. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied. It is a graph which shows the emission spectrum of the light emitting element in Example 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 1G, 1R, 1B ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Carrier generation layer 5 ... Hole transport layer 6 ... Light emitting layer 7 ... Electron transport layer 8 ... Electron injection layer 9 …… Cathode 10 …… Sealing member 15 …… Laminate 19B, 19G, 19R …… Color filter 100 …… Display device 100R, 100G, 100B …… Subpixel 20 …… Sealing substrate 21 …… Substrate 22 …… Flattening layer 24 …… Drive transistor 241 …… Semiconductor layer 242 …… Gate insulating layer 243 …… Gate electrode 244 …… Source electrode 245 …… Drain electrode 27 …… Wiring 31 …… Partition wall 32 …… Reflective film 33… ... Corrosion-preventing film 34 ... Cathode cover 35 ... Epoxy layer 36 ... Light-shielding layer 1100 ... Personal computer 1102 ... Keyboard 1104 ... Main body 1106... Display unit 1200... Mobile phone 1202 .. Operation buttons 1204 .. Earpiece 1206 .. Mouthpiece 1300 .. Digital still camera 1302 .. Case (body) 1304. Button 1308 …… Circuit board 1312 …… Video signal output terminal 1314 …… Input / output terminal for data communication 1430 …… TV monitor 1440 …… Personal computer

Claims (14)

The anode,
A cathode,
A light emitting layer provided between the anode and the cathode and configured to include a light emitting material;
A hole transport layer that is provided between the anode and the light emitting layer and is composed of a hole transport material having a function of transporting holes;
It is provided between the anode and the hole transport layer so as to be bonded to the hole transport layer, and has a carrier generation layer that generates holes and electrons,
The carrier generation layer includes, as a main material, a carrier generation material having a function of generating the holes and electrons by being in contact with the hole transport layer, and an inert material that is electrochemically inactive is added. A light-emitting element having the structure described above.   The light emission according to claim 1, wherein the absolute value of the difference between the energy level of the highest occupied molecular orbital of the inert material and the energy level of the lowest unoccupied molecular orbital of the carrier generating material is 0.20 eV or more. element.   The absolute value of the difference between the energy level of the highest occupied molecular orbital of the hole transport material and the energy level of the lowest unoccupied molecular orbital of the carrier generating material is 0.15 eV or less. The light emitting element of description.   4. The light emitting device according to claim 1, wherein the inert material is present in an amorphous state in the carrier generation layer. 5.   The light emitting device according to claim 1, wherein the inert material has a glass transition point of 85 ° C. or higher.   The light emitting device according to claim 1, wherein the inert material is a hydrocarbon containing an aromatic ring.   The light emitting device according to any one of claims 1 to 6, wherein the inert material has a fluorene structure and / or a biphenyl structure. The light-emitting element according to claim 7, wherein the inert material includes at least one of compounds represented by the following chemical formulas 1 to 4.

  The light emitting device according to claim 1, wherein the carrier generating material is a hexaazatriphenylene derivative. The light emitting device according to any one of claims 1 to 9, wherein the carrier generating material is a compound represented by the following chemical formula (5).

  The light emitting device according to any one of claims 1 to 10, wherein the hole transport layer is composed of a compound having a benzidine structure.   5 ≦ B / (A + B) ≦ 30, where A [wt%] is the content of the carrier generating material in the carrier generation layer and B [wt%] is the content of the inert material. The light emitting device according to any one of 1 to 11.   A display device comprising the light-emitting element according to claim 1.   An electronic apparatus comprising the display device according to claim 13.

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