JP2022008998A - Light-emitting element, display device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element which enables the achievement of a longer life by suppressing the degradation of the balance of white light emission.

SOLUTION: A light-emitting element 1 comprises: a cathode 12; an anode 3; a red light-emitting layer 6, a blue light-emitting layer 8 and a green-color light-emitting layer 9 which are provided between the cathode 12 and the anode 3; a first mid layer 7A provided between the red light-emitting layer 6 and the blue light-emitting layer 8 and serving to adjust movement of holes and electrons between the red light-emitting layer 6 and the blue light-emitting layer 8; and a second mid layer 7B provided between the blue light-emitting layer 8 and the green-color light-emitting layer 9 and serving to adjust movement of holes and electrons between the blue light-emitting layer 8 and the green-color light-emitting layer 9. The first mid layer 7A and the blue light-emitting layer 8 include an assistant dopant material; a concentration of the assistant dopant material in the first mid layer 7A is higher than a concentration of the assistant dopant material in the blue light-emitting layer 8.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to light emitting devices, display devices, and electronic devices.

An organic EL (electroluminescent) element is a light emitting element having a structure in which a light emitting layer is provided between an anode and a cathode. In the light emitting element, an electric field is applied between the cathode and the anode by the drive circuit, so that electrons are injected into the light emitting layer from the cathode side and holes are injected from the anode side. Then, electrons and holes are recombined in the light emitting layer, that is, carriers are recombined to generate excitons, and when the excitons return to the ground state, the energy component is emitted as light. To. The light emitting layer is usually formed by including a light emitting dopant material and a host material.

Further, in order to realize color display, a light emitting layer that emits red (hereinafter referred to as R), a light emitting layer that emits green (hereinafter referred to as G), and blue (hereinafter referred to as G) are contained in one light emitting element. , G) is known to be provided with a light emitting layer that emits light. In this configuration, a light emitting element including the above-mentioned three light emitting layers is uniformly formed on the substrate. In the above-mentioned configuration, there are a method of forming a different optical resonance structure by changing the optical path length on the substrate side for each RGB, and a method of extracting RGB light emission by forming a color filter and transmitting light from a light emitting element. At least one is used. When the light emitting element includes each light emitting layer of RGB, it is necessary to obtain light emission from each light emitting layer of RGB in a well-balanced manner in order to obtain white light emission.

For example, in Patent Document 1, a first intermediate layer is provided between a first light emitting layer and a second light emitting layer, and a second intermediate layer is provided between the second light emitting layer and the third light emitting layer. A light emitting device provided with a layer is disclosed. Each of the first intermediate layer and the second intermediate layer suppresses the transfer of exciton energy between the light emitting layers that occurs when there is no intermediate layer, and suppresses the bias of the emission luminance of each light emitting layer of RGB.
Further, Patent Document 2 describes that an intermediate layer is provided only between the first light emitting layer and the second light emitting layer. This intermediate layer contains a host material and an assist dopant material. One of the host material and the assist dopant material is a material having a high electron transport property, and the other is a material having a high hole transport property. Thereby, this intermediate layer adjusts the amount of carriers between the first light emitting layer and the second light emitting layer, and suppresses the bias of the emission brightness of each light emitting layer of RGB.

Japanese Unexamined Patent Publication No. 2011-151011 JP-A-2015-201499

By the way, in order to smoothly supply electrons to the first light emitting layer provided closest to the anode side, the first intermediate layer, the second light emitting layer, the second intermediate layer, and the third light emitting layer Uses a material with high electron transportability. Therefore, in the conventional light emitting device, the electron transport property is larger than that of the hole transport property, and the position where the carrier recombines (hereinafter referred to as “recombined site”) is the first intermediate layer and the second intermediate layer. It may be concentrated on the interface with the light emitting layer. Therefore, the conventional light emitting element has a problem that the luminance deterioration of the second light emitting layer becomes large and the life is shortened.

One of the problems to be solved in the present invention is to suppress deterioration of the balance of white light emission to extend the service life.

The light emitting element according to one aspect of the present invention includes a cathode, an anode, a first light emitting layer provided between the cathode and the anode, and a first light emitting layer that emits first light, and the cathode and the first. A third light emitting layer provided between the light emitting layer and the second light emitting layer that emits the second light, and a third light emitting layer that is provided between the cathode and the second light emitting layer and emits the third light. A second light emitting layer is provided between the first light emitting layer and the second light emitting layer, and regulates the movement of holes and electrons between the first light emitting layer and the second light emitting layer. The intermediate layer of 1 is provided between the second light emitting layer and the third light emitting layer, and moves holes and electrons between the second light emitting layer and the third light emitting layer. A second intermediate layer to be adjusted is provided, and each of the first light emitting layer, the second light emitting layer, and the third light emitting layer has hole transporting property or electron transporting property among carrier transporting properties. The second light emitting layer further includes an assist dopant material having a carrier transport property different from that of the host material contained in the second light emitting layer. Each of the first intermediate layer and the second intermediate layer contains the same host material as at least one of the host materials contained in the second light emitting layer or the third light emitting layer. The first intermediate layer further contains an assist dopant material having a carrier transport property different from that of the host material contained in the first intermediate layer, and is contained in the first intermediate layer. It is characterized in that the concentration of the assist dopant material is higher than the concentration of the assist dopant material in the second light emitting layer.

In one aspect of the present invention, the assist dopant material contained in the second light emitting layer has a carrier transport property opposite to that of the host material. Therefore, when the assist dopant material contained in the second light emitting layer has hole transportability, holes are easily transported more smoothly on the cathode side. Moreover, since the second intermediate layer containing the host material contained in the second light emitting layer or the same host material as the host material contained in the third light emitting layer is provided, the second light emitting layer and the third light emitting layer Can facilitate the transportation of carriers between. Therefore, the recombined sites concentrated in the second light emitting layer can be suitably spread over the second light emitting layer and the third light emitting layer. Therefore, the recombination site can be sufficiently separated from the vicinity of the interface between the first intermediate layer and the second light emitting layer, the deterioration of the light emitting dopant material in the second light emitting layer is suppressed, and the second It is possible to suppress the deterioration of the brightness of the light emitting layer and extend the life of the light emitting layer.

Further, according to the above-described aspect, the second intermediate layer is a host material contained in the second intermediate layer and an assist dopant material having a carrier transport property different from the carrier transport property of the host material. Among them, at least the host material is contained, and the third light emitting layer includes the host material contained in the third light emitting layer, the light emitting dopant material contained in the third light emitting layer, and the carrier transportability of the host material. The concentration of the assist dopant material in the second light emitting layer includes at least the host material and the light emitting dopant material among the assist dopant materials having carrier transport properties different from those of the second intermediate layer. It is preferable that the concentration of the assist dopant material in the second intermediate layer is higher than the concentration of the assist dopant in the third light emitting layer.

When this aspect is not satisfied, for example, when the concentration of the material of the assist dopant in the second intermediate layer or the concentration of the assist dopant in the third light emitting layer becomes higher than the concentration of the assist dopant in the second light emitting layer, it is repeated. It is preferable that the combined site is biased in the third light emitting layer and the light emitting brightness of the third light emitting layer becomes too high, so that the white light emitting balance can be made appropriate by adjusting the color filter and the drive circuit. It will not be in a state. Therefore, according to the above-described aspect, it is possible to more reliably suppress the deterioration of the white emission balance and extend the service life.

Further, according to the above-described aspect, the concentration of the assist dopant material in the second intermediate layer and the concentration of the assist dopant material in the third light emitting layer are 0% or more and 10% or less. Is preferable.

If this aspect is not satisfied, for example, if the concentration of the assist dopant material in the second intermediate layer or the concentration of the assist dopant material in the third light emitting layer exceeds 10%, the color filter adjustment and drive circuit The emission brightness of the second light emitting layer is lowered without achieving a preferable state in which the white emission balance can be appropriately adjusted by the adjustment. Therefore, according to the above-described aspect, it is possible to more reliably suppress the deterioration of the white emission balance and extend the service life.

Further, according to the above-described aspect, it is preferable that the film thickness of the second intermediate layer is 3 nm or more and 6 nm or less.

When this aspect is not satisfied, for example, if the film thickness of the second intermediate layer is thicker than 6 nm, energy transfer between the second light emitting layer and the third light emitting layer is suppressed, and the color filter is adjusted. In addition, the white light emission balance cannot be appropriately adjusted by adjusting the drive circuit, and the light emission efficiency of the third light emission layer is lowered. Further, if the film thickness of the second intermediate layer is thinner than 3 nm, it is not possible to obtain an appropriate white emission balance by adjusting the color filter and the drive circuit, and the emission of the third light emitting layer is not achieved. The brightness becomes high. Therefore, according to the above-described aspect, it is possible to more reliably suppress the deterioration of the white emission balance and extend the service life.

Further, according to the above-described aspect, it is preferable that the display device of the present invention includes the light emitting element of the present invention.

According to this aspect, it is possible to obtain a display device having a long life by a light emitting element having a long life by suppressing deterioration of the white light emission balance.

Further, according to the above-described aspect, it is preferable that the electronic device of the present invention includes the display device of the present invention.

According to this aspect, a long-life display device makes it possible to obtain a long-life electronic device.

Sectional drawing of the light emitting element 1 of this embodiment. The figure which shows the relationship between the white light emission balance and the life in an Example. FIG. 3 is a cross-sectional view of a display device 100 including a light emitting element 1. The perspective view of the head-mounted display 300 which concerns on this invention. The perspective view of the personal computer 400 which concerns on this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scale of each part are appropriately different from the actual ones. Further, since the embodiments described below are suitable specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention particularly limits the present invention in the following description. Unless otherwise stated, it is not limited to these forms.

A. Embodiment Hereinafter, the light emitting element 1 according to the present embodiment will be described.

A. 1. 1. Outline of the light emitting element 1 FIG. 1 schematically shows a cross-sectional view of the light emitting element 1 of the present embodiment. The light emitting element 1 shown in FIG. 1 is an element provided on the substrate 2. In the following description, the normal direction of the substrate 2 is referred to as a Z-axis direction (vertical direction). Further, of the Z-axis directions, the direction of the surface of the substrate 2 on which the light emitting element 1 is provided when viewed from the inside of the substrate 2 is referred to as the + Z direction, and the direction opposite to the + Z direction is referred to as the −Z direction. Further, the directions perpendicular to the Z-axis direction and further perpendicular to each other are referred to as an X-axis direction and a Y-axis direction. The cross-sectional view shown in FIG. 1 shows a cross section in which the light emitting element 1 is broken along the XZ plane.

As shown in FIG. 1, the light emitting element 1 has a hole injection layer 4, a hole transport layer 5, a red light emitting layer 6, and a first intermediate layer 7A between the anode 3 and the cathode 12. The blue light emitting layer 8, the second intermediate layer 7B, the green light emitting layer 9, the electron transport layer 10, and the electron injection layer 11 are laminated from the −Z direction in the order described. What is laminated between the anode 3 and the cathode 12 is referred to as a laminated body 15. Then, the sealing member 13 shown in FIG. 1 seals the anode 3, the laminate 15, and the cathode 12 so that the anode 3, the laminate 15, and the cathode 12 do not come into contact with the outside air.

In the light emitting element 1, electrons are supplied (injected) from the cathode 12 side and holes are supplied from the anode 3 side to each light emitting layer of the red light emitting layer 6, the blue light emitting layer 8, and the green light emitting layer 9 (injection). Is injected). Then, in each light emitting layer, holes and electrons are recombined, and excitone (excitator) is generated by the energy released at the time of this recombination, and energy (fluorescence or phosphorescence) is generated when the exciton returns to the ground state. The red light emitting layer 6, the blue light emitting layer 8, and the green light emitting layer 9 emit light to R, G, and B, respectively, for emission. As a result, the light emitting element 1 emits white light.

The substrate 2 supports the anode 3. Since the light emitting element 1 of the present embodiment has a configuration (top emission type) in which light is taken out from the + Z direction, either a transparent substrate or an opaque substrate can be used for the substrate 2. If the substrate 2 is a transparent substrate, the constituent materials of the substrate 2 include, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyether sulfone, polymethylmethacrylate, polycarbonate, and polyarylate. Examples thereof include a resin material, a glass material such as quartz glass or soda glass, and the like.
If the substrate 2 is an opaque substrate, the constituent material of the substrate 2 is, for example, a substrate made of a ceramic material such as alumina, or an oxide film (insulating film) on the surface of a metal substrate such as stainless steel. Examples thereof include a formed material or a substrate made of a resin material.
The substrate 2 is formed by using one or a combination of two or more of the above-mentioned materials.

(anode)
The anode 3 is an electrode for injecting holes into the hole transport layer 5 via the hole injection layer 4 described later. The constituent material of the anode 3 is preferably 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, or Au, Pt. , Ag, Cu, alloys containing these, and the like. The anode 3 is formed by one or a combination of two or more of the above-mentioned materials.

(cathode)
The cathode 12 is an electrode that injects electrons into the electron transport layer 10 via the electron injection layer 11 described later. The constituent material of the cathode 12 is preferably a material having a small work function.
Examples of the constituent material of the cathode 12 include Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, and alloys containing these. .. The cathode 12 is formed by combining one or more of these (for example, a multi-layered laminate).

In particular, when an alloy is used as the constituent material of the cathode 12, the constituent material of the cathode 12 may be an alloy containing a stable metal element such as Ag, Al, or Cu, specifically, an alloy such as MgAg. preferable. By using such an alloy as a constituent material of the cathode 12, the electron injection efficiency and stability of the cathode 12 can be improved.

(Hole injection layer)
The hole injection layer 4 has a function of improving the hole injection efficiency from the anode 3. The constituent material (hole injection material) of the hole injection layer 4 is not particularly limited, but for example, copper phthalocyanine or 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. The hole injection layer 4 is formed by one or a combination of two or more of these.

(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 red light emitting layer 6. The hole transport layer 5 is formed by using various p-type polymer materials or various p-type small molecule materials alone or in combination. Examples of the constituent materials of the hole transport layer 5 include 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, or tetraaryldiaminofluorene compounds or Examples thereof include derivatives (amine compounds).

(Red light emitting layer)
The red light emitting layer 6 includes a light emitting dopant material that emits red light (hereinafter, referred to as “red light emitting dopant material”) and a host material having hole transport property or electron transport property among carrier transport properties. A carrier is a particle responsible for charge transfer, and specifically, is a general term for holes and electrons. The carrier transport property is a general term for a hole transport property, which is a property for transporting carriers, specifically, a hole transport property, which is a property for transporting holes, and an electron transport property, which is a property for transporting electrons.
The red light emitting dopant material is not particularly limited, and one or more kinds of various red fluorescent materials and various red phosphorescent materials can be combined. The red fluorescent material is a perylene derivative such as a tetraaryldiindenoperylene derivative, a europium complex, a benzopyran derivative, a rhodamine derivative, a benzothioxanthene derivative, a porphyrin derivative, Nile Red, 2- (1,1-dimethylethyl) -6-. (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolysin-9-yl) ethenyl) -4H-pyran-4H-iriden) Examples thereof include propanedinitrile (DCJTB), 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran (DCM) and the like.
The red phosphorescent material is not particularly limited as long as it emits red phosphorescence, and examples thereof include metal complexes such as iridium, ruthenium, platinum, osmium, renium, and palladium, among the ligands of these metal complexes. Examples thereof include materials having at least one phenylpyridine skeleton, bipyridyl skeleton, porphyrin skeleton and the like.

The host material excites the red luminescent material by recombining holes and electrons to generate excitons and transferring the energy of the excitons described above to the red luminescent material (Felster transfer or Dexter transfer). .. When the red light emitting layer 6 is formed by using the above-mentioned host material, for example, the host material is doped with a light emitting dopant material to form the red light emitting layer 6. The constituent materials of the host material include anthracene derivatives, naphthacene derivatives, perylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolat-based metal complexes such as tris (8-quinolinolato) aluminum complex (Alq3), and triarylamine derivatives. Examples thereof include an oxadiazole derivative, a silol derivative, a dicarbazole derivative, an oligothiophene derivative, a benzopyran derivative, a triazole derivative, a benzoxazole derivative, or a benzothiazole derivative.

The average thickness of the red light emitting layer 6 is not particularly limited. Further, the red light emitting dopant material has a relatively small band gap, easily captures holes and electrons, and easily emits light. Therefore, by providing the red light emitting layer 6 on the anode 3 side, each light emitting layer can emit light in a well-balanced manner with the blue light emitting layer 8 and the green light emitting layer 9 having a large band gap and difficulty in emitting light as the cathode 12 side.

(First middle layer)
The first intermediate layer 7A is provided between the layers of the red light emitting layer 6 and the blue light emitting layer 8. The first intermediate layer 7A coordinates the movement of carriers between the red light emitting layer 6 and the blue light emitting layer 8. The first intermediate layer 7A contains the same host material as the host material contained in the blue light emitting layer 8 or the green light emitting layer 9. The first intermediate layer 7A is a non-light emitting layer that does not substantially contain a light emitting material. By adjusting the movement of the carriers, the first intermediate layer 7A can efficiently cause the red light emitting layer 6 and the blue light emitting layer 8 to emit light, respectively.

Further, the first intermediate layer 7A contains an assist dopant material having a carrier transport property different from that of the host material contained in the first intermediate layer 7A. Specifically, when the host material contained in the first intermediate layer 7A has a hole transporting property, the assist dopant material contained in the first intermediate layer 7A has an electron transporting property. When the host material contained in the first intermediate layer 7A has electron transportability, the assist dopant material contained in the first intermediate layer 7A has hole transportability.

Since the host material contained in the first intermediate layer 7A is the same as the host material contained in the blue light emitting layer 8 or the green light emitting layer 9, it is preferable to use an acene-based material. Examples of the constituent material of the assist dopant material contained in the first intermediate layer 7A include a tetraarylbenzidine derivative, a tetraaryldiaminofluorene compound or a derivative thereof (amine-based compound), an oxadiazole derivative, a perylene derivative, and a pyridine. Examples thereof include derivatives, pyrimidine derivatives, quinoxalin derivatives, diphenylquinone derivatives and the like. The assist dopant material contained in the first intermediate layer 7A is preferably an amine derivative.

The amine-based material (that is, the material having an amine skeleton) is excellent in hole transportability, and the above-mentioned acene-based material (that is, the material having an acene skeleton) is excellent in electron transportability. As a result, the first intermediate layer 7A has both electron transporting property and hole transporting property. That is, the first intermediate layer 7A has bipolarity. Since the first intermediate layer 7A has bipolarity, holes are smoothly transferred from the red light emitting layer 6 to the blue light emitting layer 8 via the first intermediate layer 7A, and the blue light emitting layer 8 to the first intermediate layer 8 to the first. Electrons can be smoothly transferred to the red light emitting layer 6 via the intermediate layer 7A. As a result, the first intermediate layer 7A can efficiently inject electrons and holes into the red light emitting layer 6 and the blue light emitting layer 8, respectively, to emit light.

(Blue light emitting layer)
The blue light emitting layer 8 includes a light emitting dopant material that emits blue light (hereinafter, referred to as “blue light emitting dopant material”) and a host material having hole transporting property or electron transporting property. The blue light emitting layer 8 further contains an assist dopant material having a carrier transport property different from that of the host material contained in the blue light emitting layer 8.
The blue light emitting dopant material is not particularly limited, and one or more kinds of various blue fluorescent materials and various blue phosphorescent materials can be combined.
The blue fluorescent material includes distyrylamine derivatives such as distyryldiamine compounds, fluorene derivatives, pyrene derivatives, perylene and perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzoimidazole derivatives, chrysene derivatives, phenanthrene derivatives, and di. Stylylbenzene derivative, tetraphenylbutadiene, 4,4'-bis (9-ethyl-3-carbazobinylene) -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} phenanthrene-1,4-diyl)], poly [(9,9-dioctylfluorene-2,7-diyl) -co- (ethylnylbenzene)] and the like.
The blue phosphorescent material is not particularly limited as long as it emits blue phosphorescence, and examples thereof include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium.

As the constituent material of the host material contained in the blue light emitting layer 8, the same material as the host material described in the red light emitting layer 6 can be used. Further, it is preferable to use an acene derivative (acene-based material) as the host material of such a blue light emitting layer 8. As a result, the blue light emitting layer 8 can be made to emit blue light with higher brightness and higher efficiency.
As the constituent material of the assist dopant material contained in the blue light emitting layer 8, any of the constituent materials that can be used for the assist dopant material contained in the first intermediate layer 7A described above can be adopted.

(Second middle layer)
The second intermediate layer 7B is provided between the blue light emitting layer 8 and the green light emitting layer 9. The second intermediate layer 7B coordinates the movement of carriers between the blue light emitting layer 8 and the green light emitting layer 9. The second intermediate layer 7B contains the same host material as the host material contained in the blue light emitting layer 8 or the green light emitting layer 9. The second intermediate layer 7B is a non-light emitting layer that does not substantially contain a light emitting material. By adjusting the carrier transfer, the energy transfer of the exciter between the blue light emitting layer 8 and the green light emitting layer 9 can be prevented, so that the energy transfer from the blue light emitting layer 8 to the green light emitting layer 9 can be prevented. By suppressing it, the blue light emitting layer 8 and the green light emitting layer 9 can each efficiently emit light. That is, since the blue light emitting layer 8 and the green light emitting layer 9 can emit light in a well-balanced manner, the light emitting element 1 can emit white light.

Further, the second intermediate layer 7B contains at least the above-mentioned host material among the host material and the assist dopant material having a carrier transport property different from the carrier transport property of the above-mentioned host material. In other words, the second intermediate layer 7B contains 0 wt% (% by weight) or more of the assist dopant material. In the following description, "%" is assumed to be wt%.

The host material contained in the second intermediate layer 7B is the same host material as the host material contained in the blue light emitting layer 8 or the green light emitting layer 9, and is configured to be substantially free of the light emitting material. The present invention is not particularly limited as long as it can exhibit the carrier adjustment function as described above. For example, as the second intermediate layer 7B, a material containing an acene-based material is preferably used as the same material as the host material contained in the blue light emitting layer 8 or the green light emitting layer 9.

With such a material, the energy rank of the highest occupied molecular orbital (HOMO) of the second intermediate layer 7B is lower than the energy rank of the highest occupied molecular orbital (HOMO) of both the blue light emitting layer 8 and the green light emitting layer 9. It can be set and further, the energy rank of the lowest unoccupied molecular orbital (LUMO) of the second intermediate layer 7B is higher than the energy rank of the lowest unoccupied molecular orbital (LUMO) of both the blue light emitting layer 8 and the green light emitting layer 9. Can be set. As a result, the energy transfer of excitons between the blue light emitting layer 8 and the green light emitting layer 9 is more reliably blocked. As a result, both the blue light emitting layer 8 and the green light emitting layer 9 can be made to emit light with high luminous efficiency, so that they can be made to emit light in a well-balanced manner, and the life of the blue light emitting layer 8 and the green light emitting layer 9 is extended. Can be planned.

Further, the host material contained in the second intermediate layer 7B is preferably the same as the host material of the blue light emitting layer 8. As a result, carriers can be smoothly transferred between the blue light emitting layer 8 and the second intermediate layer 7B having the same host material, and the increase in the drive voltage of the light emitting element 1 can be accurately suppressed or increased. It can be prevented and the diffusion of excitons can be accurately suppressed or prevented.

As the assist dopant material contained in the second intermediate layer 7B, any of the constituent materials that can be used for the assist dopant material contained in the first intermediate layer 7A described above can be adopted. The assist dopant material contained in the second intermediate layer 7B is preferably an amine derivative.

(Green light emitting layer)
The green light emitting layer 9 includes a light emitting dopant material that emits green light (hereinafter, referred to as “green light emitting dopant material”) and a host material having hole transporting property or electron transporting property.
Further, the green light emitting layer 9 is formed by at least the above-mentioned host material and the above-mentioned green light-emitting dopant among the host material, the green light-emitting dopant material, and the assist dopant material having a carrier transport property different from the carrier transport property of the above-mentioned host material. Including wood. In other words, the green light emitting layer 9 contains 0% or more of the assist dopant material.

The green light emitting dopant material is not particularly limited, and examples thereof include various green fluorescent materials and various green phosphorescent materials, and one or a combination of two or more of these can be used. Green fluorescent materials include quinacridone such as a quinacridone derivative and its derivatives, 9,10-bis [(9-ethyl-3-carbazole) -vinylenyl] -anthracene, poly (9,9-dihexyl-2,7-vinylenefluorene). Nilen), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (1,4-diphenylene-vinylene-2-methoxy-5- {2-ethylhexyloxy} benzene)], or poly [(9,9-Dioctyl-2,7-divinylene fluoreneylene) -ortho-co- (2-methoxy-5- (2-ethoxylhexyloxy) -1,4-phenylene)] and the like can be mentioned.
The green phosphorescent material is not particularly limited as long as it emits green phosphorescence, and examples thereof include metal complexes such as iridium, ruthenium, platinum, osmium, rhenium, and palladium. Among them, it is preferable that at least one of the ligands of these metal complexes has a phenylpyridine skeleton, a bipyridyl skeleton, a porphyrin skeleton, or the like.

As the host material contained in the green light emitting layer 9, the same host material as that described in the red light emitting layer 6 can be used. Further, it is preferable to use an acene derivative (acene-based material) as the host material of the green light emitting layer 9. As a result, the green light emitting layer 9 can emit blue light with higher brightness and higher efficiency.
Further, the host material of the green light emitting layer 9 is preferably the same as the host material of the blue light emitting layer 8. As a result, the light of B and the light of G can be emitted in a well-balanced manner in the blue light emitting layer 8 and the green light emitting layer 9.

As the constituent material of the assist dopant material contained in the green light emitting layer 9, any of the constituent materials that can be used for the assist dopant material contained in the first intermediate layer 7A described above can be adopted.

(Electron transport layer)
The electron transport layer 10 has a function of transporting electrons injected from the cathode 12 via the electron injection layer 11 to the green light emitting layer 9.
Examples of the constituent material (electron transport material) of the electron transport layer 10 include a phenanthroline derivative such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and tris (8-quinolinolato) aluminum (Alq3). A quinoline derivative such as an organic metal complex having a derivative thereof such as 8-quinolinol as a ligand, an azindridin derivative, an oxadiazole derivative, a perylene derivative, a pyridine derivative, a pyrimidine derivative, a quinoxalin derivative, a diphenylquinone derivative, or , Nitro-substituted fluorene derivatives and the like.

(Electron injection layer)
The electron injection layer 11 has a function of improving the electron injection efficiency from the cathode 12.
Examples of the constituent material (electron injection material) of the electron injection layer 11 include various inorganic insulating materials and various inorganic semiconductor materials.

Examples of the above-mentioned inorganic insulating material include alkali metal chalcogenides (oxides, sulfides, selenes, tellurides), alkaline earth metal chalcogenides, alkali metal halides, and alkaline earth metal halides. .. The electron injection layer 11 is formed by combining one or more of the above-mentioned materials. By constructing the electron injection layer 11 using these as the main materials, the electron injection property can be further improved. In particular, alkali metal compounds (alkali metal chalcogenides, alkali metal halides, etc.) have a very small work function. Therefore, by constructing the electron injection layer 11 using the alkali metal compound, the light emitting element 1 can obtain high brightness. Be done.

(Sealing member)
The sealing member 13 is provided so as to cover the anode 3, the laminate 15, and the cathode 12, and has a function of airtightly sealing them and blocking oxygen and moisture. By providing the sealing member 13, effects such as improvement of 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 13 include Al, Au, Cr, Nb, Ta, Ti or alloys containing these, silicon oxide, and various resin materials. When a conductive material is used as the constituent material of the sealing member 13, in order to prevent a short circuit, between the anode 3 and the sealing member 13, and between the laminate 15 and the sealing member 13. , And, if necessary, an insulating film is provided between the cathode 12 and the sealing member 13.

A. 2. 2. Effect of the present embodiment Here, the concentration of the assisted dopant material contained in the first intermediate layer 7A (hereinafter referred to as “IL1”) is the concentration of the assisted dopant material contained in the blue light emitting layer 8 (hereinafter referred to as “EML2”). ”) Higher. In other words, the relationship between the two concentrations described above satisfies the following equation (1).

IL1> EML2 (1)

By satisfying the equation (1), the blue light emitting layer 8 contains the assist dopant material, and the assist dopant material contained in the blue light emitting layer 8 has a hole transporting property, so that the holes are transferred to the cathode 12 side. It becomes easy to be smoothly transported, and the recombination sites concentrated in the blue light emitting layer 8 can be suitably spread over the blue light emitting layer 8 and the green light emitting layer 9. Therefore, the recombination site can be sufficiently separated from the vicinity of the interface between the first intermediate layer 7A and the blue light emitting layer 8, deterioration of the light emitting dopant material in the blue light emitting layer 8 is suppressed, and the blue light emitting layer is suppressed. It is possible to suppress the deterioration of the brightness of 8 and realize a long life. Here, the brightness of the green light emitting layer 9 becomes high, but by performing at least one of the adjustment of the color filter 19 (see FIG. 3) and the adjustment of the drive circuit, the red light emitting layer 6 and the blue light emitting layer 6 are adjusted. If the balance of the brightness of the light from 8 and the green light emitting layer 9 is within a certain range, the balance of the white light finally obtained can be made appropriate, so that the deterioration of the balance of the white light emission is suppressed and the length is long. It is possible to extend the service life.

Further, IL1, EML2, the concentration of the assisted dopant material contained in the second intermediate layer 7B (hereinafter referred to as "IL2"), and EML3 are the concentrations of the assisted dopant material contained in the green light emitting layer 9 (hereinafter referred to as "". EML3 ”) preferably satisfies the following equation (2).

IL1> EML2> IL2 ≧ EML3 ≧ 0 (2)

When the equation (2) is not satisfied, for example, when IL2 or EML3 is higher than EML2, the recombination site is biased in the green light emitting layer 9, and the emission brightness of the green light emitting layer 9 becomes too high, resulting in white. The light emission balance is greatly deteriorated. Therefore, by satisfying the equation (2), it is possible to extend the service life while suppressing the deterioration of the white emission balance more reliably than when the equation (1) is only satisfied.

Further, IL2 and EML3 preferably satisfy the following equation (3).

10% ≧ IL2 ≧ EML3 ≧ 0% (3)

By satisfying the equation (3), it is possible to extend the service life while suppressing the deterioration of the white emission balance more reliably than when the equation (2) is only satisfied. When the equation (2) is satisfied and the equation (3) is not satisfied, for example, when IL2 and EML3 exceed 10%, the white emission balance can be made appropriate by adjusting the color filter 19 and the drive circuit. The emission brightness of the blue light emitting layer 8 is lowered without achieving a possible preferable state.

Further, the film thickness of the second intermediate layer 7B preferably satisfies the following equation (4).

3 nm ≤ film thickness of the second intermediate layer 7B ≤ 6 nm (4)

By satisfying the equation (4), it is possible to extend the service life while suppressing the deterioration of the white emission balance more reliably than when the equations (2) and (3) are only satisfied. When the equations (2) and (3) are satisfied and the equation (4) is not satisfied, for example, when the thickness of the second intermediate layer 7B is thicker than 6 nm, the blue light emitting layer 8 and the green light emitting layer 9 are formed. The energy transfer between the two is suppressed, and the light emission efficiency of the green light emitting layer 9 is lowered without achieving a preferable state in which the white light emission balance can be appropriately adjusted by adjusting the color filter 19 and the drive circuit. It ends up. Further, when the film thickness of the second intermediate layer 7B is thinner than 3 nm, the green light emitting layer 9 is not in a preferable state in which the white light emission balance can be appropriately adjusted by adjusting the color filter 19 and the drive circuit. The emission brightness of is high.

In the present embodiment, the red light is an example of the "first light", and the red light emitting layer 6 is an example of the "first light emitting layer". Further, the blue light is an example of the "second light", and the blue light emitting layer 8 is an example of the "second light emitting layer". Further, the green light is an example of the "third light", and the green light emitting layer 9 is an example of the "third light emitting layer".

A. 3. 3. Examples Hereinafter, examples will be shown, but the present invention is not limited to the following examples.

FIG. 2 shows the relationship between the white emission balance and the life in the examples. In Table 200 of FIG. 2, whether or not each of Example A1, Example A2, Example A3, Example B1, Example B2, Example B3, and Example B4 satisfies the equation (2). Whether or not the formula (3) is satisfied, each value of IL1, EML2, IL2, and EML3, whether or not each of them satisfies the formula (4), and the film thickness of the second intermediate layer 7B, respectively. The white emission balance, the life, and the relative life of the above are shown. Examples A1, A2, and A3 are examples that satisfy all of the equations (2), (3), and (4). On the other hand, Example B1, Example B2, Example B3, and Example B4 are examples in which any of the equations (2), (3), and (4) is not satisfied. Here, the white emission balance in each of Example A1, Example A2, Example A3, Example B1, Example B2, Example B3, and Example B4 is 10 mA / cm ² for each light emitting element 1. It is a white emission balance when a current is passed, and indicates the emission brightness of the red light emitting layer 6: the emission brightness of the blue light emitting layer 8: the emission brightness of the green light emitting layer 9. Further, the life indicates the time until the brightness becomes 80% of the initial brightness (LT80) by passing a current of 100 mA / cm ² through each light emitting element 1. The relative life indicates the life when the life of Example B1 is 1.00. Further, "○" shown in Table 200 indicates that the formula corresponding to the item in which "○" is described among the formulas (2), (3), and (4) is satisfied. Similarly, "x" shown in Table 200 indicates that the equation corresponding to the item in which "x" is described among the equations (2), (3), and (4) is not satisfied.

Further, the film thickness of the hole transport layer 5 is 40 nm for each of Example A1, Example A2, Example A3, Example B1, Example B2, Example B3, and Example B4. Further, it is assumed that the film thickness of the red light emitting layer 6 is 5 nm, and the red light emitting layer 6 contains 1.5% of the electron transporting red light emitting dopant material. Further, it is assumed that the film thickness of the first intermediate layer 7A is 20 nm. It is assumed that the film thickness of the blue light emitting layer 8 is 15 nm, and that the blue light emitting layer 8 contains 8% of the electron transporting blue light emitting dopant material. Further, the film thickness of the green light emitting layer 9 is assumed to be 15 nm. Further, it is assumed that the film thickness of the electron transport layer 10 is 25 nm. It is assumed that the cathode 12 is formed of 10: 1 MgAg, and the film thickness of the cathode 12 is 10 nm.

For each of Example A1, Example A2, Example A3, Example B1, Example B2, Example B3, and Example B4, the white emission balance was 2 compared to 10:10:10 in Example B1. It is preferably / 3 times or more and up to 1.5 times. Hereinafter, this preferable state is referred to as "a preferable state of white emission balance". If it is 2/3 times or more and 1.5 times or more, the white emission balance after the color filter 19 is transmitted can be appropriately adjusted by performing at least one of the adjustment of the color filter 19 and the adjustment of the drive circuit. Is. Further, the life is 1.2 times or more that of "437h" of Example B1, that is, the relative life is 1.20 or more, which is effective.

A. 3.1. Example B1
IL1, EML2, IL2, and EML3 are set to 50%, 0%, 0%, and 0%, respectively, and the film thickness of the second intermediate layer 7B is set to 3 nm, which is the lower limit of the formula (4), and EML2 = IL2. Example B1 is an example in which the equation (2) is not satisfied and the equations (3) and (4) are satisfied by the point where = EML3 = 0%. Example B1 has a better white emission balance than Example A1, but the deterioration of the blue emission layer 8 is large.

A. 3.2. Example A1
IL1, EML2, IL2, and EML3 are 50%, 30%, 0%, and 0%, respectively, and the film thickness of the second intermediate layer 7B is 3 nm. An example of satisfying the formula 4) was referred to as Example A1. The white emission balance of the light emitting element 1 in Example A1 is 10: 8: 12, which is a preferable state of the white emission balance. Further, the life of the light emitting element 1 in Example A1 is 671 hours, and the relative life is 1.54, which realizes a long life. Example A1 is the best example of Example A1, Example A2, Example A3, Example B1, Example B2, Example B3, and Example B4.

A. 3.3. Example A2
IL1, EML2, IL2, and EML3 are set to 50%, 30%, 0%, and 0%, respectively, and the film thickness of the second intermediate layer 7B is set to 6 nm, which is the upper limit of the formula (4). An example satisfying the equation, the equation (3), and the equation (4) was referred to as Example A2. The white emission balance of the light emitting element 1 in Example A2 is 10:15: 7, which is a preferable state of the white emission balance. Further, the life of the light emitting element 1 in Example A2 is 564 hours, and the relative life is 1.29, which realizes a long life. In Example A2, since the film thickness of the second intermediate layer 7B was increased as compared with Example A1, the energy transfer from the blue light emitting layer 8 to the green light emitting layer 9 was reduced, and the emission luminance of the blue light emitting layer 8 was reduced. As a result, the emission brightness of the green light emitting layer 9 becomes low.

A. 3.4. Example A3
IL1, EML2, IL2, and EML3 are set to 50%, 30%, 10%, and 10%, respectively, and the film thickness of the second intermediate layer 7B is set to 3 nm, which is the lower limit of the formula (4). An example satisfying the equation, the equation (3), and the equation (4) was designated as Example A3. In Example A3, unlike Examples A1 and A2, IL2 and EML3 are larger than 0%. The white emission balance of the light emitting element 1 in Example A3 is 10: 7: 15, which is a preferable state of the white emission balance. Further, the life of the light emitting element 1 in Example A3 is 539 hours, and the relative life is 1.23, which realizes a long life. In Example A3, as compared with Example A1, the second intermediate layer 7B and the green light emitting layer 9 contain the assist dopant material, so that the recombination site is biased toward the green light emitting layer 9 and the electron transport layer. The electron transporting material of No. 10 is often deteriorated, resulting in a shortened life.

A. 3.5. Example B2
IL1, EML2, IL2, and EML3 are set to 50%, 30%, 0%, and 0%, respectively, and the film thickness of the second intermediate layer 7B is set to 7 nm, which exceeds the upper limit of the formula (4). An example in which the equation and the equation (3) were satisfied and the equation (4) was not satisfied was referred to as Example B2. The life of the light emitting element 1 in Example B2 is 544 hours, the relative life is 1.24, and a long life is realized, but the white light emission balance of the light emitting element 1 in Example B2 is 10:17 :. 5 is not a preferable state of white emission balance. Example B2 is an example in which the film thickness of the second intermediate layer 7B in Example A2 is further increased. As shown in Example B2, when the film thickness of the second intermediate layer 7B exceeds the upper limit of the equation (4), the energy transfer between the blue light emitting layer 8 and the green light emitting layer 9 is suppressed. The emission brightness of the green light emitting layer 9 becomes low, and the white emission balance cannot be made appropriate only by adjusting the color filter 19 and the drive circuit.

A. 3.6. Example B3
IL1, EML2, IL2, and EML3 are set to 50%, 30%, 0%, and 0%, respectively, and the film thickness of the second intermediate layer 7B is set to 2 nm, which is lower than the lower limit of the formula (4). An example in which the equation and the equation (3) were satisfied and the equation (4) was not satisfied was referred to as Example B3. The white light emitting balance of the light emitting element 1 in Example B3 is 10: 6: 15, which is not a preferable state of the white light emitting balance, and the life of the light emitting element 1 in Example B3 is 509 hours, which is a relative life. Is 1.16, which does not realize a long life. As shown in Example B3, when the film thickness of the second intermediate layer 7B is lower than the lower limit of the equation (4), the energy transfer between the blue light emitting layer 8 and the green light emitting layer 9 becomes larger than necessary. The emission brightness of the blue light emitting layer 8 becomes low, and the white emission balance cannot be made appropriate only by adjusting the color filter 19 and the drive circuit.

A. 3.7. Example B4
IL1, EML2, IL2, and EML3 are set to 50%, 30%, 20%, and 20%, respectively, and the film thickness of the second intermediate layer 7B is set to 3 nm, and the formula (2) is satisfied to obtain the formula (3). An example in which the equation (4) was satisfied without being satisfied was referred to as Example B4. The white emission balance of the light emitting element 1 in Example B4 is 10: 6: 16, which is not a preferable state of the white emission balance, and the life of the light emitting element 1 in Example B4 is 449 hours, which is a relative life. Is 1.03, which does not realize a long life. As shown in Example B4, if the equation (3) is not satisfied, the luminous efficiency of the blue light emitting layer 8 is lowered, and the white light emitting balance is made appropriate only by adjusting the color filter 19 and the drive circuit. I can't.

The light emitting element 1 as described above can be used as, for example, a light source or the like. Further, by arranging the plurality of light emitting elements 1 in a matrix, the display device 100 described later can be configured.
The drive system of the display device 100 is not particularly limited, and may be either an active matrix system or a passive matrix system.

B. Modification example Each of the above forms can be variously transformed. Specific modes of modification are illustrated below. Two or more embodiments arbitrarily selected from the following examples can be appropriately merged within a mutually consistent range. For the elements whose actions and functions are equivalent to those of the embodiment in the modified examples exemplified below, the reference numerals referred to in the above description will be diverted and detailed description of each will be omitted as appropriate.

In the above-described embodiment, the light emitting element 1 has three light emitting layers, that is, a red light emitting layer 6, a blue light emitting layer 8, and a green light emitting layer 9, but the light emitting layer may have four or more layers. .. Further, the emission color of the light emitting layer is not limited to R, G, and B of the above-described embodiment. Even when the number of light emitting layers is four or more, white light can be emitted by appropriately setting the light emission spectrum of each light emitting layer.
Further, the intermediate layer 7 may be provided between at least one layer between the light emitting layers, and may have two or more intermediate layers.

C. Application Example The light emitting element 1 according to the above-described embodiment can be applied to a display device 100 such as a display panel. Hereinafter, the display device 100 including the light emitting element 1 will be described.

FIG. 3 shows a cross-sectional view of the display device 100 including the light emitting element 1. The cross-sectional view shown in FIG. 3 shows a cross-sectional view of the display device 100 cut along the XZ plane. The display device 100 shown in FIG. 3 includes a substrate 21, a plurality of light emitting elements 1R, 1G, 1B and color filters 19R, 19G, 19B provided corresponding to the sub-pixels 100R, 100G, 100B, and each light emitting element 1R. It has 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 flattening layer 22 made of an insulating material is formed so as to cover these driving transistors 24.
Each drive transistor 24 includes a semiconductor layer 241 formed of silicon, a gate insulating layer 242 formed on the semiconductor layer 241, a gate electrode 243 formed on the gate insulating layer 242, and a source electrode 244. It has a drain electrode 245 and.
Light emitting elements 1R, 1G, and 1B are provided on the flattening layer corresponding to each driving transistor 24.

In the light emitting element 1R, a reflective film 32, a corrosion prevention film 33, an anode 3, a laminate (organic EL light emitting portion) 15, a cathode 12, and a cathode cover 34 are laminated in this order on the flattening layer 22. The anodes 3 of the light emitting elements 1R, 1G, and 1B form pixel electrodes, and are electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. Further, the cathode 12 of each light emitting element 1R, 1G, and 1B is a common electrode.

The configurations of the light emitting elements 1G and 1B are the same as the configurations of the light emitting elements 1R. Further, in FIG. 3, the same reference numerals are given to the same configurations as those in FIG. Further, the configuration (characteristics) of the reflective film 32 may differ between the light emitting elements 1R, 1G, and 1B depending on the wavelength of the light so that the optical resonance structure is formed.
A partition wall 31 is provided between the adjacent light emitting elements 1R, 1G, and 1B. Further, 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 above-mentioned epoxy layer 35 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. Further, the color filter 19G converts the white light W from the light emitting element 1G into green. Further, 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. Further, by adjusting the film thickness of the color filter 19, the white emission balance can be made appropriate.

Further, a light-shielding layer 36 is formed between the adjacent color filters 19R, 19G, and 19B. This makes it possible to prevent unintended sub-pixels 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 the light emitting materials used for the light emitting elements 1R, 1G, and 1B. When the display device 100 includes the light emitting element 1 of the present invention, it is possible to obtain a display device having a long life.
Such a display device 100 can be incorporated into various electronic devices.

FIG. 4 shows a perspective view showing the appearance of the head-mounted display 300 as an electronic device adopting the display device 100 of the present invention. As shown in FIG. 4, the head-mounted display 300 includes a temple 310, a bridge 320, a projection optical system 301L, and a projection optical system 301R. In FIG. 4, a display device 100 for the left eye (not shown) is provided behind the projection optical system 301L, and a display device 100 for the right eye (not shown) is provided behind the projection optical system 301R. Be done.
FIG. 5 shows a perspective view of a portable personal computer 400 that employs the display device 100. The personal computer 400 includes a display device 100 for displaying various images, and a main body unit 403 provided with a power switch 401 and a keyboard 402.
In addition to the devices illustrated in FIGS. 4 and 5, the electronic devices to which the display device 100 according to the present invention is applied include mobile phones, smartphones, personal digital assistants (PDAs), digital still cameras, and the like. Examples include TVs, video cameras, car navigation devices, in-vehicle displays (instrument panels), electronic notebooks, electronic papers, calculators, word processors, workstations, video telephones, personal digital assistants, and the like. Further, the display device 100 according to the present invention can be applied as a display unit provided in electronic devices such as printers, scanners, copiers, and video players.
Since the light emitting element 1 in the display device 100 has a long life, the electronic device incorporating the display device 100 can have a long life.

1, 1B, 1G, 1R ... light emitting element, 2 ... substrate, 3 ... anode, 4 ... hole injection layer, 5 ... hole transport layer, 6 ... red light emitting layer, 7A ... first intermediate layer, 7B ... first 2 intermediate layer, 8 ... blue light emitting layer, 9 ... green light emitting layer, 10 ... electron transport layer, 11 ... electron injection layer, 12 ... cathode, 13 ... sealing member, 15 ... laminated body, 19B, 19G, 19R ... Color filter, 20 ... encapsulation substrate, 21 ... substrate, 22 ... flattening layer, 24 ... drive transistor, 27 ... wiring, 31 ... partition wall, 32 ... reflective film, 33 ... corrosion prevention film, 34 ... cathode cover, 35 ... Epoxy layer, 36 ... Shading layer, 100 ... Display device, 241 ... Semiconductor layer, 242 ... Gate insulating layer, 243 ... Gate electrode, 244 ... Source electrode, 245 ... Drain electrode, 300 ... Head mount display, 400 ... Personal computer , IL1 ... Concentration of assisted dopant material contained in the first intermediate layer, IL2 ... Concentration of assisted dopant material contained in the second intermediate layer, EML2 ... Concentration of assisted dopant material contained in the blue light emitting layer, EML3 ... Green The concentration of the assist dopant material contained in the light emitting layer.

The light emitting element according to one aspect of the present invention includes a cathode, an anode, a first light emitting layer provided between the cathode and the anode, and a first light emitting layer that emits first light, and the cathode and the first. A third light emitting layer provided between the light emitting layer and the second light emitting layer that emits the second light, and a third light emitting layer that is provided between the cathode and the second light emitting layer and emits the third light. A second light emitting layer is provided between the first light emitting layer and the second light emitting layer, and regulates the movement of holes and electrons between the first light emitting layer and the second light emitting layer. The intermediate layer of 1 is provided between the second light emitting layer and the third light emitting layer, and moves holes and electrons between the second light emitting layer and the third light emitting layer. A second intermediate layer to be adjusted is provided, and each of the first light emitting layer, the second light emitting layer, and the third light emitting layer is an ascene system having a hole transporting property among carrier transporting properties. The second light emitting layer is an amine-based assist dopant material having an electron transport property different from that of the host material contained in the second light emitting layer. Each of the first intermediate layer and the second intermediate layer contains the host material, and the first intermediate layer is a front .
The concentration of the assist dopant material in the first intermediate layer, including the assist dopant material.
Is higher than the concentration of the assist dopant material in the second light emitting layer, and the second intermediate layer is
The third light emitting layer comprises the host material and the assist dopant material, and the third light emitting layer is a front.
The assis in the second light emitting layer, which comprises the host material and the assist dopant material.
The concentration of the dopant material is higher than the concentration of the assist dopant in the second intermediate layer.
The concentration of the assist dopant material in the second intermediate layer is the assist in the third light emitting layer.
It is characterized in that it is the same as the concentration of the dopant .

Claims (6)

With the cathode
With the anode
A first light emitting layer provided between the cathode and the anode and emitting the first light,
A second light emitting layer provided between the cathode and the first light emitting layer and emitting a second light,
A third light emitting layer provided between the cathode and the second light emitting layer and emitting a third light,
A first intermediate provided between the first light emitting layer and the second light emitting layer to regulate the movement of holes and electrons between the first light emitting layer and the second light emitting layer. Layers and
A second intermediate provided between the second light emitting layer and the third light emitting layer to regulate the movement of holes and electrons between the second light emitting layer and the third light emitting layer. Layers and
Equipped with
Each of the first light emitting layer, the second light emitting layer, and the third light emitting layer contains a host material having a hole transport property or an electron transport property among carrier transport properties, and a light emitting dopant material. ,
The second light emitting layer further contains an assist dopant material having a carrier transport property different from that of the host material contained in the second light emitting layer.
Each of the first intermediate layer and the second intermediate layer contains the same host material as at least one of the host material contained in the second light emitting layer or the third light emitting layer.
The first intermediate layer further contains an assist dopant material having a carrier transport property different from that of the host material contained in the first intermediate layer.
The concentration of the assist dopant material in the first intermediate layer is higher than the concentration of the assist dopant material in the second light emitting layer.
A light emitting element characterized by this. The second intermediate layer contains at least the host material among the host material contained in the second intermediate layer and the assist dopant material having a carrier transport property different from the carrier transport property of the host material.
The third light emitting layer has a carrier transport property different from that of the host material contained in the third light emitting layer, the light emitting dopant material contained in the third light emitting layer, and the host material. Includes at least the host material and the light emitting dopant material among the assist dopant materials.
The concentration of the assist dopant material in the second light emitting layer is higher than the concentration of the assist dopant in the second intermediate layer.
The concentration of the assist dopant material in the second intermediate layer is equal to or higher than the concentration of the assist dopant in the third light emitting layer.
The light emitting element according to claim 1. The second aspect of the present invention, wherein the concentration of the assist dopant material in the second intermediate layer and the concentration of the assist dopant material in the third light emitting layer are 0% or more and 10% or less. Light emitting element. The light emitting device according to any one of claims 1 to 3, wherein the film thickness of the second intermediate layer is 3 nm or more and 6 nm or less. A display device comprising the light emitting element according to any one of claims 1 to 4. An electronic device comprising the display device according to claim 5.

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