JP5533497B2 - LIGHT EMITTING ELEMENT, LIGHT EMITTING DEVICE, DISPLAY DEVICE, AND ELECTRONIC DEVICE - Google Patents

Description

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

  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 as a light emitting layer 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.

In such a light emitting device, in general, a hole injection layer and a hole transport layer are provided between the anode and the light emitting layer in order to improve the hole injection property and the transport property (for example, patents). Reference 1).
Further, in such a light emitting device, by adjusting the size of HOMO (maximum occupied orbit) and LUMO (lowest empty orbit) of the hole transport layer, the hole transport layer can be adjusted from the cathode side (light emitting layer side). It has been attempted to improve the light emission efficiency by blocking the electrons and confining the electrons and holes in the light emitting layer.

However, in the conventional light emitting device, the hole transport layer cannot sufficiently block electrons from the cathode side, and the electron that has passed through the hole transport layer due to long-term use causes the hole transport layer or hole to be blocked. There was a problem that the injection layer deteriorated. Such a problem becomes more prominent because the function of blocking electrons in the hole transport layer (electron blocking effect) decreases due to the band bending effect as the current density increases.
In order to enhance the electron blocking effect, it is conceivable to use a material having a large energy gap between HOMO and LUMO for the hole transport layer. However, this is difficult in practice.

Japanese Patent No. 3654909

  An object of the present invention is to provide a light-emitting element capable of extending the life, a light-emitting device including the light-emitting element, a display device, and an electronic apparatus.

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 that is provided between the anode and the cathode, and emits light when energized between the anode and the cathode;
An electron that is provided between the anode and the light emitting layer in contact with the light emitting layer and includes a hole transporting material having a hole transporting property and an electron trapping material having an electron trapping property. have a sum layer,
The electron neutralizing layer includes a compound represented by the following formula (2) as the hole transporting material, and a compound represented by the following formula (10) as the electron trapping material. To do.

  According to such a light emitting device of the present invention, the electron neutralizing layer can neutralize (annihilate) electrons from the light emitting layer. Thereby, even when an organic layer (for example, a hole injection layer or a hole transport layer) is provided on the anode side with respect to the electron neutralization layer, the organic layer can be prevented from being deteriorated by electrons. Therefore, even when driving with a current having a high current density, the lifetime of the light emitting element can be extended.

In the light emitting device of the present invention, it is preferable to have a hole transport layer provided between the anode and the electron neutralization layer and having a hole transport property.
Thereby, holes from the anode can be efficiently transported to the electron neutralization layer. As a result, the light emission efficiency of the light emitting element can be increased.
In the light emitting device of the present invention, it is preferable to have a hole injection layer provided between the anode and the hole transport layer and having a hole injection property.
Thereby, the hole injection property from an anode can be improved. As a result, the light emission efficiency of the light emitting element can be increased.

In the light emitting device of the present invention, the electron neutralizing layer preferably has a function of blocking electrons.
Thereby, the electron neutralization layer can block the electrons from the light emitting layer while transporting holes to the light emitting layer. Therefore, it is possible to efficiently confine electrons and holes in the light emitting layer and improve the light emission efficiency.

In the light emitting device of the present invention, the light emitting layer preferably contains a tetracene derivative as a host material and a diindenoperylene derivative as a guest material.
Thereby, a light emitting layer can be efficiently light-emitted red.

In the light emitting device of the present invention, the content of the electron trapping material in the electron neutralizing layer is preferably 30 wt% or more and 70 wt% or less.
As a result, the electron trapping property of the electron neutralizing layer can be made moderate while suppressing the driving voltage of the light emitting element.
In the light emitting device of the present invention, the average thickness of the electron neutralizing layer is preferably 20 nm or more and 60 nm or less.
As a result, the electron trapping property of the electron neutralizing layer can be made moderate while suppressing the driving voltage of the light emitting element.

The light-emitting device of the present invention includes the light-emitting element of the present invention.
Such a light-emitting device has a long-life light-emitting element, and thus has high reliability.
The display device of the present invention includes the light emitting device of the present invention.
Such a display device can display a high-quality image over a long period of time and has excellent reliability.
An electronic apparatus according to the present invention includes the display device according to the present invention.
Such an electronic device is excellent in reliability.

It is sectional drawing which shows typically the light emitting element which concerns on 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.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a light-emitting element, a light-emitting device, a display device, and an electronic device of the invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing 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. 1 will be described as “upper” and the lower side as “lower”.
1 includes an anode 3, a hole injection layer 4, a hole transport layer 5, an electron neutralizing layer (electron trap layer) 5X, a light emitting layer 6, an electron transport layer 7, and electrons. The injection layer 8 and the cathode 9 are laminated in this order. That is, in the light emitting element 1, between the anode 3 and the cathode 9, from the anode 3 side to the cathode 9 side, the hole injection layer 4, the hole transport layer 5, the electron neutralizing layer 5X, the light emitting layer 6, and the electron transport layer. 7 and the electron injection layer 8 are stacked in this order.

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 device 1, by applying a driving voltage to the anode 3 and the cathode 9, electrons are supplied (injected) from the cathode 9 side to the light emitting layer 6. Holes are supplied (injected) from the side. In the light emitting layer 6, holes and electrons are recombined, and excitons (excitons) are generated by the energy released upon the recombination, and energy (fluorescence or phosphorescence) is generated when the excitons return to the ground state. Is emitted (emitted). Thereby, the light emitting element 1 emits light.

In that case, in the light emitting element 1, since the electron neutralizing layer 5X includes a hole transporting material as will be described in detail later, the electron neutralizing layer 5X efficiently transports holes to the light emitting layer 6, and the light emitting layer. Electrons from 6 can be blocked. Therefore, electrons and holes can be efficiently confined in the light emitting layer 6. As a result, the light emission efficiency of the light emitting element 1 can be increased.
In particular, in the light-emitting element 1, since the electron neutralizing layer 5X includes an electron trapping material, the electron neutralizing layer 5X is capable of absorbing electrons from the light emitting layer 6 even if the electron neutralizing layer 5X cannot block the electrons. It can be summed (disappeared). Thereby, it is possible to prevent the organic layers (for example, the hole injection layer 4 and the hole transport layer 5) provided on the anode 3 side with respect to the electron neutralization layer 5X from being deteriorated by electrons. Therefore, the life of the light-emitting element 1 can be extended even when driven with a current at a high current density.

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.
In such a light-emitting element 1, the distance between the anode 3 and the cathode 9 (that is, the average thickness of the laminate 14) is preferably 150 to 300 nm, and more preferably 150 to 250 nm. 160 to 200 nm is more preferable. Thereby, the drive voltage of the light emitting element 1 can be set within a practical range easily and reliably.

Hereinafter, each part which comprises the light emitting element 1 is demonstrated sequentially.
[anode]
The anode 3 is an electrode that injects holes into the hole transport layer 5 through a hole injection 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, Ag Cu, alloys containing these, and the like can be used, and one or more of these can be used in combination.
In particular, the anode 3 is preferably made of ITO. ITO is a material having transparency, a large work function, and excellent conductivity. Thereby, holes can be efficiently injected from the anode 3 into the hole injection layer 4.

Further, the surface of the anode 3 on the hole injection layer 4 side (the upper surface in FIG. 1) is preferably subjected to plasma treatment. Thereby, the chemical and mechanical stability of the joint surface between the anode 3 and the hole injection layer 4 can be enhanced. As a result, the hole injection property from the anode 3 to the hole injection layer 4 can be improved. Such plasma treatment will be described in detail in the description of the method for manufacturing the light emitting element 1 described later.
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.

[cathode]
On the other hand, the cathode 9 is an electrode that injects electrons into the electron transport layer 7 through an electron injection layer 8 described later. 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, as a laminate of a plurality of layers, a mixed layer of a plurality of types, or the like).

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 100-500 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.

[Hole injection layer]
The hole injection layer 4 has a function of improving the hole injection efficiency from the anode 3 (that is, has a hole injection property).
Thus, by providing the hole injection layer 4 between the anode 3 and the hole transport layer 5 described later, the hole property from the anode 3 is improved, and as a result, the light emission efficiency of the light emitting element 1 is increased. Can do.

The hole injection layer 4 includes a material having a hole injection property (that is, a hole injection material).
Although it does not specifically limit as a hole injection material contained in this hole injection layer 4, For example, copper phthalocyanine, 4,4 ', 4''-tris (N, N-phenyl-3-methylphenylamino) Triphenylamine (m-MTDATA), N, N′-bis- (4-diphenylamino-phenyl) -N, N′-diphenyl-biphenyl-4-4′-diamine and the like represented by the following formula (1) Can be mentioned.

Among them, as the hole injecting material contained in the hole injecting layer 4, it is preferable to use an amine-based material from the viewpoint of excellent hole injecting property and hole transporting property, and a diaminobenzene derivative, a benzidine derivative (benzidine) It is more preferable to use a triamine-based compound or a tetraamine-based compound having both a “diaminobenzene” unit and a “benzidine” unit in the molecule.
The average thickness of the hole injection layer 4 is not particularly limited, but is preferably about 5 to 90 nm, and more preferably about 10 to 70 nm.
The hole injection layer 4 may be omitted depending on the constituent materials of the anode 3 and the hole transport layer 5.

(Hole transport layer)
The hole transport layer 5 has a function of transporting holes injected from the anode 3 through the hole injection layer 4 to the electron neutralization layer 5X (that is, has a hole transport property).
Thus, by providing the hole transport layer 5 between the anode 3 and the later-described electron neutralization layer 5X, holes from the anode 3 can be efficiently transported to the electron neutralization layer 5X. it can. As a result, the light emission efficiency of the light emitting element 1 can be increased.

The hole transport layer 5 includes a material having a hole transport property (that is, a hole transport material).
As the hole transporting material contained in the hole transporting layer 5, various p-type high molecular materials and various p-type low molecular materials can be used alone or in combination. For example, the following formula (2) N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPD), N, N′-diphenyl-N, Examples include tetraarylbenzidine derivatives such as N′-bis (3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (TPD), tetraaryldiaminofluorene compounds, or derivatives thereof (amine compounds). Of these, one or two or more of these can be used in combination.

Among them, the hole transport material contained in the hole transport layer 5 is preferably an amine-based material from the viewpoint of excellent hole injection property and hole transport property, and a benzidine derivative (a material having a benzidine skeleton). Is more preferable.
The average thickness of the hole transport layer 5 is not particularly limited, but is preferably about 5 to 90 nm, and more preferably about 10 to 70 nm.

(Electronic neutralization layer)
The electron neutralizing layer 5X is provided in contact with the light emitting layer 6 between the anode 3 and a light emitting layer 6 described later.
The electron neutralizing layer 5 </ b> X has a function of transporting holes from the hole transport layer 5 to the light emitting layer 6. Further, the electron neutralizing layer 5X has a function of capturing electrons from the light emitting layer 6 (that is, electron trapping property).

Such an electron neutralization layer 5X includes a hole transporting material having a hole transporting property and an electron trapping material having an electron trapping property.
Since such an electron neutralization layer 5X contains a hole transporting material, it can efficiently transport holes to the light emitting layer 6 and block electrons from the light emitting layer 6. Therefore, electrons and holes can be efficiently confined in the light emitting layer 6. As a result, the light emission efficiency of the light emitting element 1 can be increased.

  In particular, since the electron neutralizing layer 5X contains an electron trapping material, even if electrons from the light emitting layer 6 cannot be blocked and enter the electron neutralizing layer 5X (injected), It can be summed (disappeared). Thereby, it is possible to prevent the hole injection layer 4 and the hole transport layer 5 provided on the anode 3 side with respect to the electron neutralization layer 5X from being deteriorated by electrons. Therefore, the life of the light-emitting element 1 can be extended even when driven with a current at a high current density.

  As the hole transport material contained in the electron neutralization layer 5X, the same material as the hole transport material contained in the hole transport layer 5 described above can be used. That is, as the hole transporting material contained in the electron neutralizing layer 5X, for example, various p-type high molecular materials and various p-type low molecular materials can be used alone or in combination. Compound represented by (2), N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPD), N, N′-diphenyl -N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine (TPD) and other tetraarylbenzidine derivatives, tetraaryldiaminofluorene compounds or derivatives thereof (amine compounds) These can be used, and one or more of these can be used in combination.

Among these, the hole transporting material contained in the electron neutralizing layer 5X is preferably an amine material from the viewpoint of excellent hole injection and hole transporting properties, and a benzidine derivative (a material having a benzidine skeleton). Is more preferable.
Further, the hole transporting material contained in the electron neutralizing layer 5X may be the same as or different from the hole transporting material contained in the hole transporting layer 5, but the light emission efficiency of the light emitting device 1 is improved. From the viewpoint of enhancing, it is preferably the same as the hole transporting material contained in the hole transporting layer 5.

Further, as the hole transporting material contained in the electron neutralizing layer 5X, a material having a band gap (energy difference between the HOMO level and the LUMO level) capable of blocking electrons from the light emitting layer 6 is used. preferable. That is, the electron neutralizing layer 5X preferably has a function of blocking electrons.
Thereby, the electron neutralization layer 5X can block electrons from the light emitting layer 6 while transporting holes to the light emitting layer 6. Therefore, it is possible to efficiently confine electrons and holes in the light emitting layer 6 and improve the light emission efficiency.

  Thus, even when the electron neutralizing layer 5X has a function of blocking electrons, the electron neutralizing layer 5X cannot block electrons in driving at a high current density, and as a result, the electron neutralizing layer 5X. In some cases, electrons enter (inject) into the. Even in such a case, in the light emitting element 1, since the electron neutralizing layer 5X includes an electron trapping material, electrons that have entered the electron neutralizing layer 5X without being blocked by the electron neutralizing layer 5X are It can be summed (disappeared). Therefore, such electrons are prevented from reaching the hole transport layer 5 and the hole injection layer 4.

In addition, when the electron neutralization layer 5X is comparatively thin, the electron neutralization layer 5X itself may not have an electron block property. In this case, a layer adjacent to the anode 3 side with respect to the electron neutralization layer 5X (in this embodiment, the hole transport layer 5) is configured to have an electron blocking property, so that the light emitting layer 6 side can be efficiently disposed. Electrons and holes can be confined.
The electron trap material included in the electron neutralization layer 5X is a material that can accept electrons (that is, reduced and stable).

  More specifically, examples of the electron trapping material included in the electron neutralizing layer 5X include a host material and a guest material (light emitting material) included in the light emitting layer 6 described later, and an electron transport included in the electron transport layer 7. The same material as the light-emitting material can be used, but the host included in the light-emitting layer 6 is excellent in resistance to electrons and holes and has an appropriate electron trapping property (the electron trapping property is not too strong). It is preferable to use the same material as the material.

Specifically, the electron trapping material contained in the electron neutralizing layer 5X is not particularly limited, and examples thereof include anthracene derivatives such as distyrylarylene derivatives, naphthacene derivatives, and 9,10-di (2-naphthyl) anthracene. Naphthacene derivatives such as 5,12-diphenylnaphthacene, perylene derivatives, distyrylbenzene derivatives, quinolinolato metal complexes such as tris (8-quinolinolato) aluminum complex (Alq ₃ ), oxadiazole derivatives, rubrene and derivatives thereof, Silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi), etc. Among them, one of these can be used alone or two or more can be used in combination.

Among these, the electron trapping material contained in the electron neutralizing layer 5X is preferably an acene-based material.
The acene-based material has an appropriate electron trapping property. Therefore, it is possible to prevent the electrons from being consumed more than necessary in the electron neutralizing layer 5X, and to suppress the drive voltage of the light emitting element 1 from being increased by the electron neutralizing layer 5X. Acene-based materials are excellent in resistance to electrons and holes. Therefore, the deterioration of the electron neutralizing layer 5X due to electrons and holes can be prevented, and the life of the light emitting element 1 can be extended. Furthermore, since the acene-based material itself does not easily emit light, the electron neutralizing layer 5X can be prevented from adversely affecting the emission spectrum of the light-emitting element 1.

  Such an acene-based material is not particularly limited as long as it has an acene skeleton and exhibits the effects described above. For example, naphthalene derivatives, anthracene derivatives, naphthacene derivatives (tetracene derivatives), pentacene Derivatives, hexacene derivatives, heptacene derivatives, etc., and one or more of these can be used in combination, but anthracene derivatives and naphthacene derivatives are preferred, and anthracene derivatives (especially mono-anthracene or It is more preferable to use those having bis-anthracene as the main skeleton.

Such acene-based materials (particularly, anthracene derivatives and naphthacene derivatives) have an appropriate electron trapping property and can be formed with a high quality film quality relatively easily by using a vapor phase film forming method.
When the electron neutralizing layer 5X includes an acene-based material as an electron trapping material, the electron neutralizing layer 5X preferably includes an amine-based material as a hole transporting material. The amine material is excellent in hole transportability. Therefore, the electron neutralizing layer 5 </ b> X containing an amine material can quickly transport holes from the anode 3 to the light emitting layer 6.

In this case, the electron neutralizing layer 5X is preferably composed of a mixed material obtained by mixing an acene-based material and an amine-based material. Thereby, the balance of the hole transport property and the electron trap property of the electron neutralizing layer 5X can be adjusted to a suitable range relatively easily.
Further, as the electron trapping material contained in the electron neutralizing layer 5X, it is preferable to use a hydrocarbon compound (dielectric) composed only of carbon element and hydrogen element. Since such a compound does not have a polar group such as a hydroxyl group or a carboxyl group, it is generally poor in reactivity, relatively chemically stable, excellent in resistance to carriers (electrons and holes), and positive. There is little interaction with the hole transport material. For this reason, the characteristics of the light emitting element 1 can be improved over a long period of time.

The glass transition temperature (Tg) of the electron trapping material contained in the electron neutralizing layer 5X is preferably as high as possible, specifically, preferably 80 ° C. or higher, and 100 ° C. or higher. Is more preferable. Accordingly, when the light emitting device 1 is driven at a high current density, even if the light emitting device 1 reaches a high temperature, it is possible to prevent the performance of the light emitting device 1 from being deteriorated due to heat.
Further, the content of the electron trapping material in the electron neutralizing layer 5X is preferably 30 wt% or more and 70 wt% or less, more preferably 40 wt% or more and 60 wt% or less, and 50 wt% or more and 60 wt% or less. More preferably. Thereby, the electron trapping property of the electron neutralizing layer 5X can be made moderate while suppressing the driving voltage of the light emitting element 1.

  On the other hand, when the content is less than the lower limit, the electron trapping property of the electron neutralizing layer 5X tends to be lowered depending on the thickness of the electron neutralizing layer 5X, the type of the electron trapping material, or the like. Further, when the content is too small, the electron trapping material in the electron neutralizing layer 5X is easily excited, and the electron trapping material itself emits light, which adversely affects the emission spectrum of the entire light emitting element 1. There is. On the other hand, when the content exceeds the upper limit, depending on the thickness of the electron neutralizing layer 5X, the type of the electron trapping material, and the like, the electron trapping property of the electron neutralizing layer 5X is too strong and the light emitting element 1 is driven. It shows a tendency for the voltage to rise.

  The average thickness of the electron neutralizing layer 5X is preferably 20 nm or more and 60 nm or less, more preferably 20 nm or more and 50 nm or less, and further preferably 30 nm or more and 50 nm or less. Thereby, the electron trapping property of the electron neutralizing layer 5X can be made moderate while suppressing the driving voltage of the light emitting element 1. In addition, an optical gap capable of satisfactorily extracting light can be easily formed in the light emitting element 1.

On the other hand, when the average thickness is less than the lower limit, the electron trapping property of the electron neutralizing layer 5X tends to be lowered depending on the concentration of the electron trapping material of the electron neutralizing layer 5X, the constituent material, and the like. Show. On the other hand, when the average thickness exceeds the upper limit, it becomes difficult to form the optical gap, and the driving voltage of the light emitting element 1 tends to increase.
In consideration of light extraction from the light emitting element 1, the distance between the anode 3 and the light emitting layer 6 (that is, in the present embodiment, the hole injection layer 4, the hole transport layer 5, the electron neutralizing layer 5X, Is preferably 70 nm or less. Therefore, in the present embodiment, the electron neutralization layer 5X is formed according to the thickness of the hole injection layer 4 or the hole transport layer 5 so that the distance between the anode 3 and the light emitting layer 6 is within the above range. Is set.

(Light emitting layer)
The light emitting layer 6 emits light when energized between the anode 3 and the cathode 9 described above.
Such a light emitting layer 6 includes a light emitting material.
Such a light-emitting material is not particularly limited, and various fluorescent materials and various phosphorescent materials can be used singly or in combination of two or more.

  The fluorescent material that emits red fluorescence is not particularly limited, and examples thereof include perylene derivatives such as tetraaryldiindenoperylene derivatives represented by the following formula (3), europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives. Porphyrin derivative, 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- Examples include pyran (DCM).

The phosphorescent material that emits red phosphorescence is not particularly limited, and examples thereof include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, palladium, and at least one of the ligands of these metal complexes is phenyl. Those having a pyridine skeleton, a bipyridyl skeleton, a porphyrin skeleton and the like are also included. 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).

  The fluorescent material that emits blue fluorescence is not particularly limited. For example, a distyrylamine derivative such as a distyryldiamine compound represented by the following formula (4), a monostyryldiamine derivative, a fluoranthene derivative, a pyrene derivative, perylene, and Perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, chrysene derivatives, phenanthrene derivatives, distyrylbenzene derivatives, tetraphenylbutadiene, 4,4′-bis (9-ethyl-3-carbazovinylene) -1 , 1′-biphenyl (BCzVBi) and the like, and one of these can be used alone or in combination of two or more.

The phosphorescent material that emits blue phosphorescence is not particularly limited, and examples thereof 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 ).
The fluorescent material emitting green fluorescence is not particularly limited. For example, quinacridone such as coumarin derivatives, quinacridone derivatives represented by the following formula (5) and derivatives thereof, 9,10-bis [(9-ethyl-3- Carbazole) -vinylenyl] -anthracene and the like, and one of these may be used alone or two or more of them may be used in combination.

The phosphorescent material that emits green phosphorescence is not particularly limited, and examples thereof 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, C ² ′) iridium (acetylacetonate), fac-tris [ 5-fluoro-2- (5-trifluoromethyl-2-pyridine) phenyl-C, N] iridium.

The fluorescent material emitting yellow fluorescence is, for example, a compound having a naphthacene skeleton such as a rubrene-based material, in which an aryl group (preferably a phenyl group) has an arbitrary number (preferably 2 to 6) at an arbitrary position. ) Substituted compounds, monoindenoperylene derivatives and the like can be used.
Such light emitting materials (fluorescent materials and phosphorescent materials) can be used singly or in combination of two or more. When two or more kinds of light emitting materials are used in combination, the light emitting layer 6 may be in the form of a laminate in which a plurality of layers (light emitting layers) having different light emitting materials are laminated, or a mixture of plural kinds of light emitting materials. It is good also as a form of the layer comprised with the mixed material which did. In addition, when the light emitting layer 6 is comprised by the several light emitting layer, the layer (intermediate layer) which does not contribute to light emission may interpose between light emitting layers.

  As a constituent material of the light emitting layer 6, in addition to the light emitting material as described above, a host material to which this light emitting material is added (supported) as a guest material (dopant) may be used. This host material recombines holes and electrons to generate excitons and to transfer the exciton energy to the luminescent material (Felster movement or Dexter movement) to excite the luminescent material. Have. Such a host material can be used by, for example, doping a host material with a light-emitting material that is a guest material as a dopant.

Such a host material is not particularly limited as long as it exhibits the functions described above for the light emitting material to be used. When the light emitting material includes a fluorescent material, for example, a distyrylarylene derivative, the following formula A naphthacene derivative such as a compound represented by (7), a compound represented by the following formula (6), an anthracene derivative such as 2-t-butyl-9,10-di (2-naphthyl) anthracene (TBADN), a perylene derivative, Distyrylbenzene derivatives, distyrylamine derivatives, quinolinolato metal complexes such as tris (8-quinolinolato) aluminum complex (Alq ₃ ), triarylamine derivatives such as tetramers of triphenylamine, oxadiazole derivatives, rubrene and Its derivatives, silole derivatives, dicarbazole derivatives, oligothiophene Derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi), etc. Or in combination of two or more.

  In particular, when the electron trapping material contained in the electron neutralizing layer 5X is an acene-based material, the light-emitting layer 6 uses a tetracene derivative (naphthacene derivative) as a host material and a diindenoperylene-based material as a guest material. Derivatives are preferably used. The light emitting layer 6 containing such a tetracene derivative and a diindenoperylene derivative can efficiently emit red light.

When the light-emitting material includes a phosphorescent material, examples of the first host material include 3-phenyl-4- (1′-naphthyl) -5-phenylcarbazole, 4,4′-N, N′-di (). Examples thereof include carbazole derivatives such as carbazole biphenyl (CBP), and one of these can be used alone or in combination of two or more.
When the light emitting layer 6 contains a host material, the content (doping amount) of the light emitting material in the light emitting layer 6 is preferably 0.01 to 10 wt%, more preferably 0.1 to 5 wt%. . 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 about 1-60 nm, and it is more preferable that it is about 3-50 nm.

(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.
As a constituent material (electron transport material) of the electron transport layer 7, for example, 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum (Alq ₃ ) represented by the following formula (8) is used as a ligand. Quinoline derivatives such as organometallic complexes, azaindolizine derivatives such as compounds represented by the following formula (9), oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives These can be used, and one or more of these can be used in combination.

In addition, when the electron transport layer 7 is used in combination of two or more of the electron transport materials as described above, the electron transport layer 7 may be composed of a mixed material in which two or more electron transport materials are mixed, or different. You may be comprised by laminating | stacking the some layer comprised with the electron transport material.
When the electron transport layer 7 is formed by laminating a plurality of layers made of different electron transport materials, electrons are injected into the light emitting layer 6 as a constituent material of the anode side layer (first electron transport layer). For example, quinoline derivatives such as anthracene derivatives, organometallic complexes having 8-quinolinol or its derivatives such as tris (8-quinolinolato) aluminum (Alq ₃ ) as a ligand, etc. In addition, as a constituent material of the cathode side layer (second electron transport layer), the electron injection layer 8 can receive electrons and inject electrons into the first electron transport layer. However, it is preferable to use, for example, an azaindolizine derivative such as a compound represented by the above formula (9), a pyridine derivative, a phenanthrin derivative, or the like.

The average thickness of the first electron transport layer is preferably thinner than the average thickness of the second electron transport layer, and is 0.1 times the average thickness of the second electron transport layer. More preferably, it is 0.4 times or less. Thereby, the electron transport property and the electron injection property of the electron transport layer 7 can be made excellent.
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 from the cathode 9.
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 8 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.

(Sealing member)
The sealing member 10 is provided so as to cover the anode 3, the laminate 14, 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, between the sealing member 10 and the anode 3, the laminated body 14, and the cathode 9 is required. Accordingly, an insulating film is preferably provided.

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 element 1 configured as described above, since the electron neutralizing layer 5X includes a hole transporting material, the electron neutralizing layer 5X efficiently transports holes to the light emitting layer 6 and emits light. Electrons from 6 can be blocked. Therefore, electrons and holes can be efficiently confined in the light emitting layer 6. As a result, the light emission efficiency of the light emitting element 1 can be increased.

In particular, in the light-emitting element 1, since the electron neutralizing layer 5X includes an electron trapping material, the electron neutralizing layer 5X is capable of absorbing electrons from the light emitting layer 6 even if the electron neutralizing layer 5X cannot block the electrons. It can be summed (disappeared). Thereby, it is possible to prevent the organic layers (for example, the hole injection layer 4 and the hole transport layer 5) provided on the anode 3 side with respect to the electron neutralization layer 5X from being deteriorated by electrons. Therefore, the life of the light-emitting element 1 can be extended even when driven with a current at a high current density.
The above light emitting element 1 can be manufactured as follows, for example.

[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 hole injection layer 4 is formed on the anode 3.
The hole injection layer 4 is preferably formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.
For example, the hole injection layer 4 is dried (desolvent or desorbed) after supplying the hole injection layer forming material obtained by dissolving the hole injection material in a solvent or dispersing in a dispersion medium onto the anode 3. It can also be formed by using a dispersion medium.

As a method for supplying the hole injection 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 injection layer forming material include various inorganic solvents, various organic solvents, or 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.
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 hole injection layer 4.
The hole transport layer 5 is preferably formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum evaporation or sputtering.
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 hole injection layer 4 and then drying (desolving or dedispersing medium) Can also be formed.

[4] Next, the electron neutralization layer 5 </ b> X is formed on the hole transport layer 5.
The electron neutralizing layer 5X is preferably formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.
An electron neutralizing layer forming material obtained by dissolving a hole transporting material and an electron trapping material in a solvent or dispersing in a dispersion medium is supplied onto the hole transporting layer 5 and then dried (desolvent or dedispersed). It can also be formed by the medium.

[5] Next, the light emitting layer 6 is formed on the electron neutralizing layer 5X.
The light emitting layer 6 can be formed, for example, by a vapor phase process using a dry plating method such as vacuum deposition.
[6] Next, the electron transport layer 7 is formed on the light emitting layer 6.
The electron transport layer 7 is preferably formed, for example, by a vapor phase process using a dry plating method such as vacuum deposition.
For example, the electron transport layer 7 is dried (desolvent or dedispersion medium) after supplying an electron transport layer forming material obtained by dissolving an electron transport material in a solvent or dispersing in a dispersion medium onto the light emitting layer 6. ).

[7] 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.
[8] 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 device 1 as described above is used for, for example, a light source for an exposure head, a light source for a sensor, an illumination, a pico projector (handy projector) for an electrophotographic printer, copying machine, facsimile machine or the like. It can be used as a light source such as a light source, a light source for a scanner, and a light source for a front light of a reflective liquid crystal display device. Such a light-emitting device has a long-life light-emitting element, and thus has high reliability.

Further, by arranging a plurality of light emitting elements in a matrix, for example, a display device (display device of the present invention) can be configured. Such a display device can display a high-quality image over a long period of time and has excellent reliability.
The driving method of the display device is not particularly limited, and may be either an active matrix method or a passive matrix method.
In addition, an electronic device including the light emitting element, the light source device, or the display device of the present invention is excellent in reliability.

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 and a plurality of light emitting elements 1 _R , 1 _G , 1 _B and color filters 19 _R , 19 _G provided corresponding to the sub-pixels 100 _R , 100 _G , 100 _B. , 19 _B and a plurality of driving transistors 24 for driving the light emitting elements 1 _R , 1 _G , 1 _B , 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 planarizing layer, light emitting elements 1 _R , 1 _G , 1 _B are provided corresponding to the driving transistors 24.
In the light emitting element 1 _R , a reflective film 32, a corrosion preventing film 33, an anode 3, a laminate (organic EL light emitting unit) 14, a cathode 13, and a cathode cover 34 are laminated in this order on the planarizing layer 22. In this embodiment, the anode 3 of each light emitting element 1 _R , 1 _G , 1 _B constitutes a pixel electrode, and is electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. Yes. The cathodes 13 of the light emitting elements 1 _R , 1 _G , 1 _B are common electrodes.

The light-emitting element 1 _R in FIG. 2 is a white light. For example, the light emitting layer of the light-emitting element 1 _R is a laminate a light emitting layer are stacked emitting green light emitting layer emitting blue light emitting layer that emits red light, or a light-emitting layer and yellow emitting blue light It is composed of a laminate in which a light emitting layer that emits light is laminated.
The configurations of the light emitting elements 1 _G and 1 _B are the same as the configuration of the light emitting element 1 _R. 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 between the light emitting elements 1 _R , 1 _G , and 1 _B depending on the wavelength of light.

A partition wall 31 is provided between the adjacent light emitting elements 1 _R , 1 _G , 1 _B. An epoxy layer 35 made of an epoxy resin is formed on the light emitting elements 1 _R , 1 _G , 1 _B so as to cover them.
The color filters 19 _R , 19 _G , and 19 _B are provided on the epoxy layer 35 described above corresponding to the light emitting elements 1 _R , 1 _G , and 1 _B.

The color filter 19 _R is for converting the white light W from the light emitting element 1 _R red. The color filter 19 _G is for converting the white light W from the light emitting element 1 _G to green. The color filter 19 _B is for converting the white light W from the light emitting element 1 _B to blue. By using such color filters 19 _R , 19 _G and 19 _{B in combination} with the light emitting elements 1 _R , 1 _G and 1 _B , a full color image can be displayed.

A light shielding layer 36 is formed between the adjacent color filters 19 _R , 19 _G , and 19 _B. Thereby, it is possible to prevent the unintended subpixels 100 _R , 100 _G , and 100 _B from emitting light.
A sealing substrate 20 is provided on the color filters 19 _R , 19 _G , 19 _B and the light shielding layer 36 so as to cover them.
The display device 100 as described above may be a monochrome display, and color display is also possible by selecting a light emitting material used for each light emitting element 1 _R , 1 _G , 1 _B.

Such a display device 100 (the display device of the present invention) can be incorporated into various electronic devices.
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 halide 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 imaging device 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 input / output terminal 1314 for data communication 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 light emitting device, 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.
For example, in the above-described embodiment, the structure in which the hole injection layer and the hole transport layer are interposed between the anode and the electron neutralization layer has been described. Between the hole transport layer and between the hole transport layer and the electron neutralization layer, at least one other layer (for example, a layer for adjusting the injection and transport properties of electrons and holes) It may be interposed.

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, oxygen plasma treatment and argon plasma treatment were performed. Each of these plasma treatments was performed at a plasma power of 100 W, a gas flow rate of 20 sccm, and a treatment time of 5 seconds with the substrate heated to 70 to 90 ° C.

<2> Next, a benzidine derivative (hole injection material) represented by the formula (1) was deposited on the ITO electrode by a vacuum deposition method to form a hole injection layer having an average thickness of 40 nm.
<3> Next, a benzidine derivative (hole transporting material) represented by the above formula (2) was deposited on the hole injection layer by a vacuum deposition method to form a hole transport layer having an average thickness of 10 nm. .
<4> Next, on the hole transport layer, a benzidine derivative (hole transport material) represented by the above formula (2) and an anthracene derivative (electron trap material) represented by the following formula (10). Co-evaporation was performed by a vacuum deposition method to form an electron neutralization layer having an average thickness of 20 nm.
Here, the electron neutralizing layer is composed of a mixed material of a benzidine derivative (hole transporting material) represented by the above formula (2) and an anthracene derivative (electron trapping material) represented by the following formula (10). It had been. The mixing ratio (weight ratio) was (benzidine derivative) :( anthracene derivative) = 50: 50.

  <5> Next, the constituent material of the red light emitting layer was vapor-deposited on the electron neutralizing layer by a vacuum vapor deposition method to form a red light emitting layer (light emitting layer) having an average thickness of 40 nm. As a constituent material of the red light emitting layer, a tetraaryldiindenoperylene derivative represented by the above formula (3) is used as a red light emitting material (guest material), and a naphthacene derivative represented by the above formula (7) is used as a host material. It was. Further, the content (dope concentration) of the light emitting material (dopant) in the red light emitting layer was 1.0 wt%.

<6> Next, tris (8-quinolinolato) aluminum (Alq ₃ ) represented by the above formula (8) is formed on the red light emitting layer by a vacuum deposition method, and the first electron transport having an average thickness of 5 nm is performed. A layer was formed.
<7> Next, an azaindolizine derivative represented by the formula (9) was formed on the first electron transport layer by a vacuum deposition method, thereby forming a second electron transport layer having an average thickness of 25 nm. .
Thereby, an electron transport layer in which the first electron transport layer and the second electron transport layer were laminated was obtained.

<8> Next, on the second electron transport layer of the electron transport layer, lithium fluoride (LiF) was formed by a vacuum vapor deposition method to form an electron injection layer having an average thickness of 1 nm.
<9> 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 150 nm made of Al was formed.
<10> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
The light emitting device was manufactured through the above steps.

(Example 2)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the hole injection layer was 30 nm and the average thickness of the electron neutralizing layer was 30 nm.
(Example 3)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the hole injection layer was 10 nm and the average thickness of the electron neutralizing layer was 50 nm.

Example 4
The light emitting device is the same as Example 1 except that the average thickness of the hole injection layer is 5 nm, the average thickness of the hole transport layer is 5 nm, and the average thickness of the electron neutralizing layer is 60 nm. Manufactured.
(Example 5)
The average thickness of the hole injection layer is 10 nm, the average thickness of the electron neutralization layer is 50 nm, and the mixing ratio (weight ratio) of the benzidine derivative and the anthracene derivative in the electron neutralization layer is (benzidine derivative): (Anthracene derivative) = A light emitting device was produced in the same manner as in Example 1 except that 70:30.

(Example 6)
The average thickness of the hole injection layer is 10 nm, the average thickness of the electron neutralization layer is 50 nm, and the mixing ratio (weight ratio) of the benzidine derivative and the anthracene derivative in the electron neutralization layer is (benzidine derivative): (Anthracene derivative) = A light emitting device was produced in the same manner as in Example 1 except that 40:60.

(Example 7)
The average thickness of the hole injection layer is 10 nm, the average thickness of the electron neutralization layer is 50 nm, and the mixing ratio (weight ratio) of the benzidine derivative and the anthracene derivative in the electron neutralization layer is (benzidine derivative): (Anthracene derivative) = A light emitting device was produced in the same manner as in Example 1 except that the ratio was 20:80.

(Reference example)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the hole injection layer was 50 nm and the average thickness of the electron neutralizing layer was 10 nm.
(Comparative example)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the hole injection layer was 60 nm and the electron neutralization layer was omitted.

2. Evaluation 2-1. Evaluation of Luminous Life For Reference Examples, Examples and Comparative Examples, a constant current was continuously supplied to the light emitting element using a DC power source at a current density such that the initial luminance was 60000 cd / m ² , while a luminance meter was used. The luminance was measured, and the time (LT90) during which the luminance was 90% of the initial luminance was measured. And the time of LT90 in a comparative example was normalized as 1.00, and the time of LT90 of a reference example, a comparative example, and each Example was relatively evaluated.

2-2. Evaluation of luminous efficiency For the reference example, each example and comparative example, a current was passed through the light emitting element using a DC power source so that the initial luminance was 60000 cd / m ² while measuring the luminance using a luminance meter. The current at that time was measured. Further, the driving voltage applied to the light emitting element at this time was measured in the same manner.

2-3. Evaluation of light emission balance For reference examples, examples, and comparative examples, a current was passed through the light emitting element using a DC power supply so that the initial luminance was 60000 cd / m ² while measuring the luminance using a luminance meter. The chromaticity at that time was measured using a chromaticity meter.
The evaluation results are shown in Table 1.

  As can be seen from Table 1, the light emitting elements of the respective examples have a longer lifetime than the light emitting elements of the reference example and the comparative example.

_{1,1 R, 1 B, 1 G} ...... emitting element 2 ...... substrate 3 ...... anode 4 ...... hole injection layer 5 ...... hole transport layer 5X ...... electron neutralization layer 6 ...... emitting layer 7 ... ... Electron transport layer 8 ... Electron injection layer 9 ... Cathode 10 ... Sealing member 13 ... Cathode 14 ... Laminate 19 _B , 19 _G , 19 _R ... Color filter 100 ... Display device 100 _R , 100 _G , 100 _B ...... Subpixel 20 ...... Sealing substrate 21 ...... Substrate 22 ...... Flattened layer 24 ...... Driving transistor 241 ...... Semiconductor layer 242 ...... Gate insulating layer 243 ...... Gate electrode 244 ...... Source Electrode 245 ... Drain electrode 27 ... Wiring 31 ... Partition 32 ... Reflective film 33 ... Corrosion prevention film 34 ... Cathode cover 35 ... Epoxy layer 36 ... Shading layer 1100 ... Personal computer 1102 ... Key 1104 …… Main body 1106 …… Display unit 1200 …… Cellular phone 1202 …… Operation buttons 1204 …… Earpiece 1206 …… Speaker 1300 …… Digital still camera 1302 …… Case (body) 1304 …… Light reception Unit 1306 ... Shutter button 1308 ... Circuit board 1312 ... Video signal output terminal 1314 ... Input / output terminal for data communication 1430 ... TV monitor 1440 ... Personal computer

Claims (10)

The anode,
A cathode,
A light emitting layer that is provided between the anode and the cathode, and emits light when energized between the anode and the cathode;
An electron that is provided between the anode and the light emitting layer in contact with the light emitting layer and includes a hole transporting material having a hole transporting property and an electron trapping material having an electron trapping property. have a sum layer,
The electron neutralizing layer includes a compound represented by the following formula (2) as the hole transporting material, and a compound represented by the following formula (10) as the electron trapping material. Light emitting element.

  The light emitting device according to claim 1, further comprising a hole transporting layer provided between the anode and the electron neutralizing layer and having a hole transporting property.   The light emitting device according to claim 2, further comprising a hole injection layer provided between the anode and the hole transport layer and having a hole injection property.   The light emitting device according to claim 1, wherein the electron neutralizing layer has a function of blocking electrons. The light emitting element according to any one of claims 1 to 4, wherein the light emitting layer includes a tetracene derivative as a host material and a diindenoperylene derivative as a guest material. The content of the electron-trapping material in the electron neutralization layer, light-emitting device according to any one of claims 1 to 5 or less 30 wt% or more 70 wt%. The light emitting device according to any one of claims 1 to 6 , wherein an average thickness of the electron neutralizing layer is 20 nm or more and 60 nm or less. The light emitting device characterized in that it comprises a device as claimed in any of claims 1 to 7. A display device comprising the light-emitting device according to claim 8 . An electronic apparatus comprising the display device according to claim 9 .

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