JP5104164B2 - LIGHT EMITTING ELEMENT, LIGHT EMITTING DEVICE, AND ELECTRONIC DEVICE - Google Patents

Description

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

The organic electroluminescence (EL) element in which the light emitting organic layer (organic electroluminescence layer) is provided between the cathode and the anode can greatly reduce the applied voltage compared to the inorganic EL element, and has a wide variety. A light emitting element can be manufactured.
In addition, since an organic EL element can be driven with low power consumption, an image display device using the organic EL element has been studied. In addition, an organic EL element that emits white light and each color filter that transmits only light in the blue, green, or red wavelength region are included in one of the configurations for full-color image display devices using such light emitting elements. There are combined configurations. In addition, as a light emitting element that emits white light, a device having a light emitting component of three wavelengths in which a blue light emitting layer, a green light emitting layer, and a red light emitting layer are sequentially laminated from the anode side is disclosed (for example, see Patent Document 1). ).

  However, such a light emitting device has the following problems. That is, such a light-emitting element has not been sufficiently high in luminous efficiency for each light-emitting layer. For this reason, it is difficult for such a light-emitting element to emit light with sufficiently high luminance. In addition, when the light emitting efficiency of each light emitting layer is not sufficiently high, electrons and holes that are not used for light emission deteriorate each member of the light emitting element, and the light emission lifetime (lifetime) of the light emitting element becomes short. There was a problem.

JP 2005-38819 A

  An object of the present invention is to provide a light-emitting element having high emission luminance and a long light emission lifetime, and a highly reliable light-emitting device and electronic device including the light-emitting element.

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 first blue light-emitting layer provided between the anode and the cathode and emitting blue light;
A second blue light-emitting layer that is provided between the cathode and the first blue light-emitting layer, is made of a material different from the first blue light-emitting layer, and emits blue light;
A red light emitting layer that is provided between the anode and the first blue light emitting layer and emits red light;
Provided between said second cathode of the blue light-emitting layer, have a green-emitting layer that emits green light,
The first blue light emitting layer includes a light emitting material having a function of capturing electrons including a fluoranthene derivative, and a host material supporting the light emitting material having a function of capturing the electrons. ,
The second blue light emitting layer includes a light emitting material having a function of capturing holes including a distyryldiamine derivative, and a host material supporting the light emitting material having a function of capturing holes. It is characterized by being.
Thus, a light-emitting element with high emission luminance and a long emission lifetime can be provided.
The first blue light-emitting layer and the second blue light-emitting layer each include a light-emitting material and a host material that supports the light-emitting material. An element can be provided.
Further, the light emitting material of the first blue light emitting layer has a function of capturing electrons, and the light emitting material of the second blue light emitting layer has a function of capturing holes, thereby emitting light. A light-emitting element with particularly high luminance can be provided.
In addition, since the light emitting material of the first blue light emitting layer contains a fluoranthene (including a dimer structure) derivative, a light emitting element with particularly high light emission luminance can be provided.
Furthermore, since the light emitting material of the second blue light emitting layer contains a distyryldiamine derivative, it is possible to provide a light emitting element with particularly high luminance of light emission.

In the light emitting device of the present invention, the host material of the first blue light emitting layer includes a compound having a function of transporting holes,
The host material for the second blue light-emitting layer preferably contains a compound having a function of transporting electrons.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.
In the light emitting device of the present invention, it is preferable that the first blue light emitting layer and the second blue light emitting layer are bonded.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.

In the light emitting device of the present invention, each of the red light emitting layer and the green light emitting layer includes a light emitting material and a host material supporting the light emitting material,
The energy gap between the highest occupied molecular orbital of the host material of the first blue light emitting layer and the lowest unoccupied molecular orbital between the highest occupied molecular orbital of the host material of the red light emitting layer and the lowest unoccupied molecular orbital. Is larger than the energy gap of
The energy gap between the highest occupied molecular orbital of the host material of the second blue light emitting layer and the lowest unoccupied molecular orbital is between the highest occupied molecular orbital of the host material of the green light emitting layer and the lowest unoccupied molecular orbital. It is preferable that it is larger than the energy gap.
Thus, a light-emitting element with high emission luminance and a long emission lifetime can be provided.

In the light emitting device according to the present invention, the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of the host material of the green light emitting layer is the highest occupied molecular orbital and the lowest unoccupied molecule of the host material of the red light emitting layer. It is preferable that it is more than the energy gap between the orbits.
Thus, a light-emitting element with high emission luminance and a long emission lifetime can be provided.
In the light emitting device of the present invention, the host material of the red light emitting layer and the green light emitting layer contains at least one selected from a naphthacene derivative, a perylene derivative, and a (tris (8-hydroxyquinolinol) aluminum) complex, respectively. It is preferable.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.

  In the light-emitting element of the present invention, the fluoranthene derivative preferably contains a dimer.

In the light emitting device of the present invention, it is preferable that the host material of the first blue light emitting layer contains a compound having an amine structure.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.
In the light-emitting device of the present invention, the compound having an amine in the structure is preferably a tetraarylbenzidine derivative.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.

In the light emitting device of the present invention, the content of the compound having an amine structure in the host material of the first blue light emitting layer is preferably 50 wt% or more.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.
In the light emitting device of the present invention, the host material of the second blue light emitting layer preferably contains an anthracene derivative.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.
In the light emitting device of the present invention, the content of the anthracene derivative in the host material of the second blue light emitting layer is preferably 50 wt% or more.
Thereby, a light emitting element with particularly high luminance of light emission can be provided.

The light-emitting device of the present invention includes the light-emitting element of the present invention.
Thus, a highly reliable light-emitting device including a light-emitting element with high emission luminance and a long emission lifetime can be provided.
An electronic apparatus according to the present invention includes the light emitting device according to the present invention.
Accordingly, a highly reliable electronic device including a light-emitting element with high emission luminance and a long emission lifetime can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the light-emitting element, the light-emitting device, and the electronic apparatus of the invention will be described with reference to the accompanying drawings. In the present invention, red light is light having a maximum emission wavelength at a wavelength of 580 nm or more, green light is light having a maximum emission wavelength at a wavelength of 490 nm to 550 nm, and blue light is maximum at a wavelength of 480 nm or less. Light having an emission wavelength.
<Light emitting element>
First, a first embodiment of the light emitting device of the present invention will be described.

FIG. 1 is a diagram schematically showing a longitudinal section of a first embodiment of a light emitting device of the present invention. In the following description, for convenience of explanation, the upper side in FIG.
A light-emitting element (organic electroluminescence element) 1 shown in FIG. 1 includes an anode 3 provided on a substrate 2, a cathode 9, and a hole injection layer in order from the anode 3 side between the anode 3 and the cathode 9. 4, a hole transport layer 5, a light emitting portion 6 composed of a light emitting layer of a plurality of colors, a laminate 15 formed by laminating an electron transport layer 7 and an electron injection layer 8, and the whole is sealed It is a top emission type light emitting device that is sealed with a sealing member 10 through a material 11 and the light emitting device 1 takes out from the sealing member 10 side.

The substrate 2 serves as a support of the light emitting element 1 (hereinafter simply referred to as “light emitting element 1”). Since the light emitting element 1 is configured to extract light from the sealing member 10 side (top emission type), the substrate 2 and the anode 3 are not required to have translucency, respectively.
Examples of the constituent material of the substrate 2 include ceramic materials such as alumina, resin materials such as polyethylene terephthalate and polymethyl methacrylate, and glass materials such as quartz glass and soda glass. One or two or more of them can be used in combination.

Moreover, although the average thickness of the 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 substrate 2 side (bottom emission type), the substrate 2 is substantially transparent (colorless transparent, colored transparent or translucent) among those described above. Is selected.

The anode 3 is an electrode that injects holes into 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 ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , Au, Cu, and alloys containing these, and one or two of them are used. A combination of more than one species can be used.
The average thickness of the anode 3 is not particularly limited, but is preferably about 10 to 200 nm, and more preferably about 30 to 150 nm.

On the other hand, the cathode 9 is an electrode for injecting electrons into 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 metals such as Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, and Al, or alloys containing them. Among them, one kind or a combination of two or more kinds (for example, a multi-layer laminate) can be used.

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 or Al, specifically an alloy such as MgAg or MgAl. 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 10-1000 nm, and it is more preferable that it is about 10-500 nm.
As in the present embodiment, in the case of the top emission type, the cathode 9 is made of a material having a small work function or an alloy containing these materials with a thickness of about 5 to 20 nm, and has transparency, and further has an upper surface such as ITO. It is also possible to form a stacked body in which a highly transmissive conductive material is formed with a thickness of about 100 to 500 nm.

On the anode 3, a hole injection layer 4 is provided in the present embodiment. The hole injection layer 4 has a function of receiving holes from the anode 3 when a voltage is applied between the anode 3 and the cathode 9. The hole injection layer 4 has a function of injecting holes received from the anode 3 into the hole transport layer 5.
Examples of the constituent material of the hole injection layer 4 include copper phthalocyanine, phthalocyanine, aromatic diamine, tetraamine compounds shown in the following chemical formula 1 and derivatives thereof, and one or more of these are used in combination. be able to.

The average thickness of the hole injection layer 4 is not particularly limited, but is preferably about 5 to 150 nm, and more preferably about 10 to 100 nm.
On the hole injection layer 4, a hole transport layer 5 is provided in the present embodiment. The hole transport layer 5 has a function of transporting holes injected from the hole injection layer 4 to the light emitting portion 6.
Examples of the constituent material of the hole transport layer 5 include tetraarylbenzidine compounds such as the compounds shown in the following chemical formula 2, tetraaryldiaminofluorene compounds or derivatives thereof, and one or more of these compounds. Can be used in combination.

The hole injection layer 4 and the hole transport layer 5 have a combination of constituent materials contained in the anode 3 and the light emitting portion 6 so that holes can be smoothly injected from the anode 3 to the light emitting portion 6. Can be omitted.
A light emitting part (organic light emitting part) 6 is provided on the hole transport layer 5. Electrons are supplied (injected) from the electron transport layer 7 to be described later, and holes are supplied from the hole transport layer 5 to the light emitting unit 6. In the light emitting section 6, holes and electrons are recombined, and excitons (excitons) are generated by the energy released during the recombination. When the excitons return to the ground state, energy (fluorescence or phosphorescence) is generated. ) Is emitted (emitted).

The present invention is characterized by the structure of the light emitting section 6. This will be described in detail later.
On the light emitting unit 6, an electron transport layer 7 for transporting electrons injected from the cathode 9 to the light emitting unit 6 is provided. By having such an electron transport layer 7, electrons can be efficiently transported to the light emitting portion 6.

As a constituent material (electron transport material) of the electron transport layer 7, for example, a quinoline derivative such as an organometallic complex having an 8-quinolinol or its derivative such as tris (8-quinolinolato) aluminum (Alq ₃ ) as a ligand. Oxadiazole derivatives, anthracene derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, etc., and one or more of these may be used in combination it can.

  The average thickness of the electron transport layer 7 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 0.5 to 100 nm, and further preferably about 1 to 50 nm. . This reduces the resistance and resistance of the electron transport layer 7 while preventing the durability and mechanical strength of the electron transport layer 7 from being lowered and the film formation time from becoming unnecessarily long. Fast response of the device 100) can be realized.

On the electron transport layer 7, an electron injection layer 8 having a function of improving the electron injection efficiency from the cathode 9 is provided.
Examples of the constituent material (electron injection material) of the electron injection layer 8 include various inorganic insulating materials and various inorganic semiconductor materials. By configuring the electron injection layer 8 with such a constituent material, current leakage can be effectively prevented, and electron injection properties can be improved and durability can be improved.

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

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

In addition, as the inorganic semiconductor material, for example, an oxide including at least one element of Li, Na, Ba, Ca, Sr, Yb, Al, Ga, In, Cd, Mg, Si, Ta, Sb, and Zn , Nitrides, oxynitrides, and the like, and one or more of these can be used in combination.
The average thickness of the electron injection layer 8 is not particularly limited, but is preferably about 0.1 to 100 nm, more preferably about 0.1 to 50 nm, and about 0.1 to 10 nm. Further preferred. Thereby, the resistance of the electron injection layer 8 is reduced while preventing the mechanical strength of the electron injection layer 8 from being lowered and the film formation time from becoming unnecessarily long, and the light emitting element 1 (display device 100). High-speed response can be realized.

The sealing member 10 covers the light emitting element 1 (the anode 3, the hole injection layer 4, the hole transport layer 5, the light emitting unit 6, the electron transport layer 7, the electron injection layer 8, and the cathode 9) so as to cover the light emitting element 1. And has a function of hermetically sealing them and blocking oxygen and moisture.
By providing such a 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, Cr, Nb, alloys containing these, silicon oxide, various resin materials, and the like.
In addition, when using the material which has electroconductivity as a constituent material of the sealing member 10, in order to prevent a short circuit, it is preferable to use the thing excellent in insulation as the sealing material 11. FIG.
As such a sealing material 11, what comprises thermosetting resin etc., such as an epoxy resin, can be used suitably, for example.

Next, the configuration of the light emitting unit 6 provided between the hole transport layer 5 and the electron transport layer 7 will be described.
The light emitting unit 6 is composed of four light emitting layers, and includes a red light emitting layer 61 that emits red light, a first blue light emitting layer 62 that emits blue light, and a second blue light emitting layer 63 that emits blue light. And a green light emitting layer 64 that emits green light. In addition, the light emitting unit 6 emits white light by having such four light emitting layers.

  As described above, the light-emitting element 1 of the present invention is characterized in that the light-emitting portion 6 has four light-emitting layers and two blue light-emitting layers. In general, the light emission of the organic EL element is highly likely to occur at the interface of the light emitting layer. For this reason, the area of the interface of a light emitting layer can be enlarged by increasing the number of light emitting layers from the past, and the light emitting element 1 becomes the origin excellent in luminous efficiency. That is, the light emitting element 1 can emit light with high luminance.

  In the present invention, two blue light emitting layers are provided. Conventionally, light emission by the blue light emitting layer has a low light emission efficiency. For this reason, in order to obtain white light, the conventional light emitting element needs to adjust the light emission intensity of other light emitting layers in accordance with the blue light emission intensity, and the light emitting element as a whole has excellent light emission efficiency. It did not become. However, in the present invention, by including two blue light emitting layers as described above, the blue light emission intensity can be increased, and the light emission intensity of other colors can also be increased. As a result, the light emission efficiency of the light emitting element 1 as a whole can be made excellent.

  In general, it is difficult for holes and electrons to be injected into the blue light-emitting layer. For this reason, for example, when a blue light-emitting layer is provided near the anode, a large amount of holes are stopped at the blue light-emitting layer, and sufficient holes are not supplied to the other light-emitting layers. It becomes. For example, when a blue light-emitting layer is provided in a portion close to the cathode, similarly, sufficient electrons are not supplied to the other light-emitting layers. That is, in the above case, the amount of holes and electrons between the light emitting layers is largely biased. As a result, each light emitting layer cannot emit light in a balanced manner, and the light emitting efficiency of the light emitting element 1 as a whole is lowered.

  However, in the present invention, the first blue light emitting layer 62 and the second blue light emitting layer 63 are provided between the red light emitting layer 61 and the green light emitting layer 64. That is, the first blue light-emitting layer 62 and the second blue light-emitting layer 63 are provided substantially at the center of the light-emitting portion 6. Thereby, the amount of electrons and holes in each light emitting layer can be made more uniform between the light emitting layers. As a result, each light emitting layer is supplied with a sufficient amount of electrons and holes, and has high light emission intensity.

  In addition, when the light emitting efficiency of the light emitting element is not excellent, in general, most of the holes and electrons injected from the anode 3 and the cathode 9 pass through the light emitting portion 6. Thus, the electrons that have passed through the light-emitting portion 6 reduce, for example, constituent materials such as the hole injection layer 4 and deteriorate them. On the other hand, the holes that have passed through the light-emitting portion 6 are combined with electrons on the cathode 9 side and generate heat, causing the cathode 9 and the electron injection layer 8 or the electron injection layer 8 and the electron transport layer 7 to peel off. It becomes.

  However, the light-emitting element 1 of the present invention is excellent in luminous efficiency and prevents most holes and electrons from passing through the light-emitting part 6 by consuming most of the electrons and holes in the light-emitting part 6. Can do. For this reason, the above-described deterioration of the hole injection layer 4 and the like and separation between the respective layers can be prevented, and the light emitting element 1 can emit light efficiently over a long period of time. That is, the light emitting element 1 has a long light emission lifetime.

Hereinafter, each light emitting layer which comprises the light emission part 6 is demonstrated in detail.
(Red light emitting layer)
A red light emitting layer 61 that emits red light is provided closest to the anode 3 of the light emitting unit 6.
The red light emitting layer 61 includes a red light emitting material that emits red light.
The red light emitting material that can be used for the red light emitting layer 61 is not particularly limited, and various red fluorescent materials and red phosphorescent materials can be used singly or in combination.

  The red fluorescent material is not particularly limited as long as it emits red fluorescence. For example, perylene derivatives, europium complexes, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, porphyrin derivatives, Nile red, 2- (1, 1-dimethylethyl) -6- (2- (2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H-benzo (ij) quinolidin-9-yl) ethenyl)- 4H-pyran-4H-ylidene) 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, rhenium, and palladium. Among the ligands of these metal complexes, And those having at least one of phenylpyridine skeleton, bipyridyl skeleton, porphyrin skeleton and the like. More specifically, tris (1-phenylisoquinoline) iridium, bis [2- (2′-benzo [4,5-α] thienyl) pyridinate-N, C ³ ′] iridium (acetylacetonate) (btp2Ir ( acac)), 2,3,7,8,12,13,17,18-octaethyl-12H, 23H-porphyrin-platinum (II), bis [2- (2′-benzo [4,5-α] thienyl ) Pyridinate-N, C ³ '] iridium, bis (2-phenylpyridine) iridium (acetylacetonate).

Among the above-mentioned, the red light emitting material preferably contains a perylene derivative. A perylene derivative is a light-emitting material with particularly high luminous efficiency. The perylene derivative has a particularly excellent function of capturing electrons. For this reason, the electrons injected from the cathode 9 side can be reliably captured in the red light emitting layer 61 closest to the anode 3 of the light emitting unit 6, and reliably prevented from passing through the light emitting unit 6. Can do. For this reason, it can prevent reliably that an electron reduces and degrades the constituent material of the positive hole injection layer 4 or the positive hole transport layer 5. FIG.
The red light emitting material preferably includes dibenzodiindenoperylene and derivatives thereof among the perylene derivatives. Specific examples of dibenzodiindenoperylene and its derivatives include compounds shown in the following chemical formula 3, for example.

  Further, as a constituent material of the red light emitting layer 61, the red light emitting material as described above is used as a guest material, and in addition to this, a host material supporting the guest material can be used. In this case, for example, the host material can be used by doping a red light emitting material as a guest material as a dopant. The host material recombines holes and electrons to generate excitons, and the exciton energy is transferred to the red light-emitting material (Forster transfer or Dexter transfer) to excite the red light-emitting material. Have

Such a host material is not particularly limited, but when the red light emitting material includes a red fluorescent material, for example, a distyrylarylene derivative, a naphthacene derivative such as bis p-biphenylylnaphthacene shown in the following chemical formula 4, Perylene derivatives such as bis-ortho-biphenylylperylene shown in 5, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolato metal complexes such as tris (8-quinolinolato) aluminum complex (Alq ₃ ), and tetramer of tetraphenylamine Triarylamine derivatives, oxadiazole derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2, 2'-Diff Enylvinyl) biphenyl (DPVBi) and the like, and one of these may be used alone or in combination of two or more.

  When the red light emitting material includes a red phosphorescent material, examples of the host material include 3-phenyl-4- (1′-naphthyl) -5-phenylcarbazole, 4,4′-N, N′-dicarbazole. Quinolinolato compounds such as carbazole derivatives such as biphenyl (CBP), phenanthroline derivatives, triazole derivatives, tris (8-quinolinolato) aluminum (Alq), bis- (2-methyl-8-quinolinolato) -4- (phenylphenolato) aluminum Metal complex, N-dicarbazolyl-3,5-benzene, poly (9-vinylcarbazole), 4,4 ′, 4 ″ -tris (9-carbazolyl) triphenylamine, 4,4′-bis (9-carbazolyl) ) -2,2'-dimethylbiphenyl and other carbalisol-containing compounds, 2,9-dimethyl-4,7 Include diphenyl-1,10-phenanthroline (BCP) and the like, may be used alone among these individually or in combination of two or more.

Among the above, the red light-emitting layer 61 preferably contains at least one selected from a quinolinolato-based metal complex, a perylene derivative, and a naphthacene derivative as a host material, and includes tris (8-quinolinolato) aluminum (Alq ₃ ), More preferably, it contains at least one selected from a naphthacene derivative represented by Formula 4 and a perylene derivative represented by Formula 5. Such a material can excite the red light emitting material efficiently, and can make the light emitting efficiency of the red light emitting layer 61 particularly excellent.

  When the red light emitting layer 61 includes a host material in addition to the light emitting material, the content (doping amount) of the red light emitting material in the red light emitting layer 61 is preferably 0.01 to 20 wt%. More preferably, it is 1-10 wt%. Thereby, the red light-emitting layer 61 can transport holes to the first light-emitting layer 62 particularly efficiently while making the light emission amount sufficiently large when a certain amount of current is passed through the light-emitting element 1. it can.

  Although the average thickness of such a red light emitting layer 61 is not specifically limited, It is preferable that it is 0.1-30 nm, and it is more preferable that it is 1-15 nm.

(First blue light emitting layer)
On the red light emitting layer 61, a first blue light emitting layer 62 that emits blue light is provided.
The first blue light emitting layer 62 includes a blue light emitting material that emits blue light.
The blue light-emitting material that can be used for the first blue light-emitting layer 62 is not particularly limited, and various blue fluorescent materials and blue phosphorescent materials can be used singly or in combination.

  The blue fluorescent material is not particularly limited as long as it emits blue fluorescence. For example, a distyryl derivative, a distyryldiamine derivative, a fluoranthene (including a dimer) derivative, a pyrene derivative, a perylene and a perylene derivative, 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) etc. are mentioned, Among these, it can also be used individually by 1 type or in combination of 2 or more types.

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. 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 ).

Among these, the blue light emitting material preferably has a function of capturing electrons. Thus, when the blue light emitting material captures electrons and emits light, the first blue light emitting layer 62 can emit light efficiently while transporting holes.
Examples of such a blue light emitting material include a fluoranthene derivative. The fluoranthene (including dimer) derivative has an excellent function of capturing electrons, and the second blue light-emitting layer 62 can emit light particularly efficiently by including the fluoranthene derivative. Even such a fluoranthene derivative is preferably a diphenylbenzofluoranthene derivative, more preferably a diphenylbenzofluoranthene derivative represented by the following chemical formula 6, and the above-described effects can be remarkably obtained.

  An anthracene derivative may be used as such a blue light emitting material. The anthracene derivative is a material that can emit blue light and has an excellent function of transporting electrons, and the first blue light-emitting layer 62 includes an anthracene derivative, whereby electrons are transferred to the red light-emitting layer 61. It can be transported particularly efficiently. Even such an anthracene derivative is more preferably an anthracene derivative represented by the following chemical formula 7, and the effects as described above can be remarkably obtained.

Further, as a constituent material of the first blue light emitting layer 62, the blue light emitting material as described above is used as a guest material, and in addition to this, a host material supporting the blue light emitting material can be used.
In addition, the host material used for the first blue light-emitting layer 62 preferably has a function of transporting holes, and the function of transporting holes is superior to the host material used for the second blue light-emitting layer 63. It is more preferable. Thereby, holes can be efficiently supplied to the second blue light emitting layer 63 and the green light emitting layer 64 on the cathode 9 side, and the amount of light emitted from the second blue light emitting layer 63 and the green light emitting layer can be increased. It can be.

In particular, when the host material of the first blue light emitting layer 62 has a function of transporting holes, and the light emitting material of the second blue light emitting layer 63 has a function of capturing holes, the second blue light emitting layer 62 has a function of transporting holes. The light emitting layer 63 has a particularly large light emission amount.
The band gap of the host material of the first blue light emitting layer 62 is preferably larger than the band gap of the host material of the red light emitting layer 61. Thereby, the amount of electrons supplied to the red light emitting layer 61 and the amount of holes supplied to the first blue light emitting layer 62 can be adjusted more easily. As a result, the amount of holes and electrons in each light emitting layer can be made more uniform between the light emitting layers, and the balance of the amount of light emitted between the light emitting layers can be more easily achieved. That is, the light-emitting element 1 can emit light that is closer to white in a particularly efficient manner, and the light-emitting efficiency is particularly excellent. The light emitting element 1 has a particularly long light emission lifetime.

In this specification, the band gap refers to an energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a compound.
Such a host material is not particularly limited, but when the blue light emitting material includes a blue fluorescent material, for example, an amine compound, a distyrylarylene derivative, a stilbene derivative, a carbazole derivative, an arylamine derivative, an anthracene (a dimer) (Including) derivatives, pyrene derivatives, coronene derivatives, bis (2-methyl-8-quinolinolato) (p-phenylphenolato) aluminum (BAlq), and the like.
When the blue light emitting material includes a blue phosphorescent material, for example, a host material corresponding to the red phosphorescent material of the red light emitting layer 61 described above can be used.

  The host material of the first blue light-emitting layer 62 is not particularly limited, but preferably includes a compound having a function of transporting holes. As such a compound, it is more preferable to use a compound having an amine structure (amine compound), and it is more preferable to include a tetraarylbenzidine compound. As a compound having such an amine structure, for example, a benzidine compound represented by the following chemical formula 8 can be mentioned. The compound as described above is particularly excellent in the function of transporting holes. Therefore, the first light-emitting layer 62 can efficiently supply holes to the second blue light-emitting layer 63 and the green light-emitting layer 64 on the cathode 9 side. The light emission amount of the light emitting layer 64 can be increased, and the light emission amount of each light emitting layer can be particularly easily balanced.

Further, the content of the compound having an amine structure in the host material in the first blue light-emitting layer 62 is preferably 50 wt% or more. Thereby, when a certain amount of current is passed through the light emitting element 1, the first blue light emitting layer 62 can transport holes particularly efficiently, and the second blue light emitting layer 63 and the green light emitting layer 64 can be transported. The light emission amount can be particularly large.
Further, the host material of the first blue light emitting layer 62 may contain a compound having a function of transporting electrons. As a result, electrons can be efficiently supplied to the red light emitting layer 61 on the anode 3 side, the light emitting amount of the red light emitting layer 61 can be increased, and the balance of the light emitting amount of each light emitting layer is particularly balanced. Easy to take.

  As such a host material, for example, an anthracene derivative can be used, and specifically, an anthracene derivative represented by Chemical Formula 7 is preferably used. Thereby, the effects as described above can be obtained more remarkably. This anthracene derivative can also function as a light emitting material, and a light emitting layer containing such an anthracene derivative as a host material is particularly easy to emit light.

  In such a case, the content of the anthracene derivative in the host material of the first blue light emitting layer 62 is preferably 10 to 50 wt%, and more preferably 20 to 50 wt%. Thus, when a certain amount of current is passed through the light emitting element 1, the first blue light emitting layer 62 can transport electrons particularly efficiently, and the light emitting amount of the red light emitting layer 61 is particularly large. be able to.

When the first blue light-emitting layer 62 includes a host material in addition to the light-emitting material, the content (dope amount) of the blue light-emitting material in the first blue light-emitting layer 62 is 1 to 20 wt%. Preferably, it is 2-15 wt%. As a result, the light emission amount of the first blue light-emitting layer 62 can be increased when a certain amount of current is passed through the light-emitting element 1.
Further, the average thickness of the first blue light emitting layer 62 is preferably 0.1 to 50 nm, and more preferably 1 to 20 nm. Accordingly, the driving voltage of the light emitting element 1 can be made relatively low while transporting holes and electrons to the second blue light emitting layer 63 and the red light emitting layer 61 particularly efficiently.

(Second blue light emitting layer)
On the first blue light-emitting layer 62, a second blue light-emitting layer 63 that emits blue light made of a material different from that of the second blue light-emitting layer is provided.
The second blue light emitting layer 63 includes a blue light emitting material that emits blue light.
In the present embodiment, the first blue light-emitting layer 62 and the second blue light-emitting layer 63 are joined. Thereby, the first blue light-emitting layer 62 and the second blue light-emitting layer 63 have particularly large light emission amounts. This is considered as follows. Usually, relatively large energy is required for blue light emission. For this reason, the energy of excitons generated in the blue light-emitting layer needs to be relatively large. Such exciton energy is easy to move to other layers, and is difficult to be efficiently supplied to the blue light-emitting material. However, in the present embodiment, by joining the first blue light emitting layer 62 and the second blue light emitting layer 63, the energy of excitons generated in each blue light emitting layer can be more easily emitted. It can be given to the material and can be used efficiently as energy of blue light emission. As a result, the light emission amounts of the first blue light emitting layer 62 and the second blue light emitting layer 63 are particularly large.

The blue light emitting material of the second blue light emitting layer 63 is not particularly limited, and for example, various blue fluorescent materials and blue phosphorescent materials as described above can be used singly or in combination.
Among these, the blue light emitting material preferably has a function of capturing holes. Thereby, the second blue light-emitting layer 63 can generate excitons mainly by recombination of holes and electrons near the interface with the first blue light-emitting layer 62. For this reason, the energy of excitons generated in the second blue light emitting layer 63 can be used more efficiently as the energy of blue light emission.

  Examples of such a blue light emitting material include distyryldiamine derivatives. The distyryldiamine derivative has an excellent function of capturing holes, and the second blue light-emitting layer 63 can emit light particularly efficiently by containing the distyryldiamine derivative. Even such a distyryldiamine derivative is preferably a distyryldiamine derivative represented by the following chemical formula 9, and the effects as described above can be remarkably obtained.

Further, as the constituent material of the second blue light emitting layer 63, the blue light emitting material as described above is used as a guest material, and in addition to this, a host material supporting the blue light emitting material can be used.
Such a host material is not particularly limited, and one or a combination of two or more compounds that can be used for the first blue light emitting layer 62 described above can be used.
The host material used for the second blue light-emitting layer 63 preferably has a function of transporting electrons, and more preferably has a function of transporting electrons than the host material of the first blue light-emitting layer 62. Thereby, electrons can be efficiently transported to the first blue light emitting layer 62, and the first blue light emitting layer 62 can be made to emit light more easily. In addition, since more electrons can be transported to the red light emitting layer 61 described above, the light emitting efficiency of the light emitting element 1 as a whole is excellent.

In particular, when the host material of the second blue light-emitting layer 63 has a function of transporting electrons and the light-emitting material of the first blue light-emitting layer 62 has a function of capturing electrons, the first blue light-emitting layer 62 has a particularly large light emission amount.
Further, the band gap of the host material of the second blue light emitting layer 63 is preferably larger than the band gap of the host material of the green light emitting layer 64 described later. Thereby, the amount of holes supplied to the green light emitting layer 64 and the amount of electrons supplied to the second blue light emitting layer 63 can be adjusted more easily. As a result, the amount of holes and electrons in each light-emitting layer can be made more uniform between the light-emitting layers, and the balance of light emission amounts between the light-emitting layers can be more easily achieved. That is, the light-emitting element 1 can emit light that is closer to white in a particularly efficient manner, and the light-emitting efficiency is particularly excellent.

  The host material of the second blue light-emitting layer 63 is not particularly limited, but preferably includes a compound having a function of transporting electrons. As such a compound, for example, an anthracene derivative can be used, and specifically, an anthracene derivative represented by Formula 8 is preferably used. Thereby, the effects as described above can be obtained more remarkably. The compound as described above is particularly excellent in the function of transporting holes. Thereby, electrons can be efficiently transported to the first blue light emitting layer 62, and the first blue light emitting layer 62 can be made to emit light more easily.

  When the host material contains an anthracene derivative, the content of the anthracene derivative in the host material in the second blue light-emitting layer 63 is preferably 50 wt% or more, and preferably 60 wt% or more. Thereby, electrons can be transported particularly efficiently to the first blue light-emitting layer 62, and the amount of light emitted from the first blue light-emitting layer 62 can be made sufficiently large.

  When the second blue light-emitting layer 63 includes a host material in addition to the light-emitting material, the content (dope amount) of the blue light-emitting material in the second blue light-emitting layer 63 is 1 to 20 wt%. Preferably, it is 2-15 wt%. Thereby, when a certain amount of current is passed through the light emitting element 1, the light emitting material of the second blue light emitting layer 63 can be made larger. In addition, when a light emitting material having a function of capturing holes is used as the light emitting material, the second blue light emitting layer 63 surely captures holes and the electrons are particularly efficiently transferred to the first blue light emitting layer 62. Can be transported.

The average thickness of the second blue light emitting layer 63 is preferably 1 to 50 nm, and more preferably 5 to 25 nm. Thereby, the drive voltage of the light emitting element 1 can be lowered. In addition, the amount of light emitted from the second blue light-emitting layer 63 can be made sufficiently large while allowing electrons and holes to pass through particularly efficiently.
Further, the total average thickness of the blue light-emitting layers (in this embodiment, the total average thickness of the first blue light-emitting layer 62 and the second blue light-emitting layer 63) is 3 to 50 nm. Preferably, it is 10-40 nm. Thereby, when a certain amount of current is passed through the light emitting element 1, the amount of light emitted from the first blue light emitting layer 62 and the second blue light emitting layer 63 is made sufficiently large, while a sufficient amount of holes and Electrons can be transported to other light emitting layers.

(Green light emitting layer)
A green light-emitting layer 64 that emits green light is provided on the second blue light-emitting layer 63.
The green light emitting layer 64 includes a green light emitting material that emits green light.
The green light emitting material that can be used for the green light emitting layer 64 is not particularly limited, and various green fluorescent materials and green phosphorescent materials can be used singly or in combination.

  The green fluorescent material is not particularly limited as long as it emits green fluorescence. For example, a coumarin derivative, a quinacridone derivative such as a compound shown in the following chemical formula 10, 9,10-bis [(9-ethyl-3- Carbazole) -vinylenyl] -anthracene, diarylnaphthacene derivatives and the like, and one of these may be used alone, or two or more thereof may be used in combination.

  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 these, at least one of the ligands of these metal complexes preferably has a phenylpyridine skeleton, a bipyridyl skeleton, a porphyrin skeleton, or the like. More specifically, fac-tris (2-phenylpyridine) iridium (Ir (ppy) 3), bis (2-phenylpyridinate-N, C2 ′) iridium (acetylacetonate), fac-tris [5 -Fluoro-2- (5-trifluoromethyl-2-pyridine) phenyl-C, N] iridium.

Further, as the constituent material of the green light emitting layer 64, the green light emitting material as described above is used as a guest material, and in addition to this, a host material supporting the green light emitting material can be used.
Such a host material is not particularly limited as long as it exhibits the functions described above with respect to the green light emitting material to be used. For example, a host material that can be used for the above-described red light emitting layer 61 is used. be able to.

Among these, the green light-emitting layer 64 preferably contains at least one selected from a quinolinolato-based metal complex, a perylene derivative, and a naphthacene derivative as a host material, such as tris (8-quinolinolato) aluminum (Alq ₃ ), More preferably, it contains at least one selected from a naphthacene derivative represented by Formula 4 and a perylene derivative represented by Formula 5 above. Such a material can excite the green light emitting material particularly efficiently, and the amount of light emitted from the green light emitting layer 64 can be made sufficient.

  Further, when the band gap of the first blue light emitting layer 62 is larger than the band gap of the red light emitting layer 61 and the band gap of the second blue light emitting layer 63 is larger than the band gap of the green light emitting layer 64, the green light emitting layer The band gap of the host material used for 64 is preferably greater than or equal to the band gap of the host material used for the red light emitting layer 61. Thereby, the amount of holes and electrons between the light emitting layers can be made more uniform, and the amount of light emission between the light emitting layers can be more easily balanced. That is, the light emitting element 1 can emit light near white in a particularly efficient manner. In addition, since the light emitting element 1 has particularly excellent luminous efficiency, holes and electrons are easily consumed in the light emitting part 6, and the holes and electrons are prevented from passing through the light emitting part 6. Can do. For this reason, the above-described deterioration of the hole injection layer 4 and the like and separation between the respective layers can be prevented, and the light emitting element 1 can emit light efficiently over a long period of time. That is, the light emitting element 1 has a particularly long light emission lifetime.

Moreover, when the green light emitting layer 64 contains a host material in addition to the light emitting material, the content (dope amount) of the green light emitting material in the green light emitting layer 64 is preferably 1 to 20 wt%, and 2 to 15 wt%. It is more preferable that Thus, when a certain amount of current is passed through the light emitting element 1, the green light emitting layer 64 can make the light emission amount sufficiently large, and can supply electrons to other light emitting layers particularly efficiently. it can.
Although the average thickness of such a green light emitting layer 64 is not specifically limited, It is preferable that it is 5-40 nm, and it is more preferable that it is 10-30 nm. Thus, when a certain amount of current is passed through the light emitting element 1, the green light emitting layer 64 can make the light emission amount sufficiently large, and can supply electrons to other light emitting layers particularly efficiently. it can.

Moreover, it is preferable that the average thickness of the light emission part 6 is 5-100 nm, and it is more preferable that it is 20-80 nm. Thereby, even when the voltage applied to the light emitting element 1 is relatively low, the light emission efficiency of the light emitting element 1 can be made sufficiently high, and the light emission lifetime of the light emitting element 1 is made sufficiently long. be able to.
Such a light emitting element 1 is a top emission type that extracts light from the sealing member 10 side, but the light emitting element of the present invention is also a bottom emission type light emitting element that extracts light from the substrate 2 side. Can be applied.

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 formed by, for example, chemical vapor deposition (CVD) such as plasma CVD or thermal CVD, dry plating such as vacuum deposition or sputtering, wet plating such as electrolytic plating, thermal spraying, sol-gel method, MOD method, It can be formed by joining metal foils or the like.

[2] Next, the hole injection layer 4 is formed on the anode 3.
The hole injection layer 4 can be formed by, for example, a vacuum evaporation method.
In addition, the hole injection layer 4 is dried (desolvent or desolvent) after supplying the hole injection layer forming material obtained by, for example, 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 and / or argon plasma treatment. Thereby, organic substances adhering to the upper surface of the anode 3 can be removed (cleaned), and the work function near the upper surface of the anode 3 can be adjusted.
Here, the oxygen and / or argon 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, and a conveying speed of the member to be treated (anode 3) of 0.5 to 10 mm / sec. It is preferable to set the degree.

[3] Next, the hole transport layer 5 is formed on the hole injection layer 4.
The hole transport layer 5 can be formed by a process using, for example, a vacuum deposition method.
[4] Next, the light emitting portion 6 is formed on the hole transport layer 5.
The light emitting unit 6 is obtained by forming each light emitting layer (a red light emitting layer 61, a first blue light emitting layer 62, a second blue light emitting layer 63, and a green light emitting layer 64) in order from the anode side. .
Each light emitting layer can be formed, for example, by a process using a vacuum deposition method or the like.

[5] Next, the electron transport layer 7 is formed on the light emitting portion 6.
The electron transport layer 7 can be formed by a process using, for example, vacuum deposition.
[6] Next, the electron injection layer 8 is formed on the electron transport layer 7.
In the case where an inorganic material is used as the constituent material of the electron injection layer 8, the electron injection layer 8 is formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the application and baking of inorganic fine particle ink. Etc. can be used.

[7] Next, the cathode 9 is formed on the electron injection layer 8.
The cathode 9 can be formed by using, for example, a vacuum deposition method, a sputtering method, bonding of metal foil, application and firing of metal fine particle ink, or the like.
The light emitting element 1 is obtained through the steps as described above.
Finally, the sealing member 10 is placed in a state where the sealing material 11 is interposed so as to cover the obtained light emitting element 1, and the sealing material 11 is cured to be bonded to the substrate 2.

Such a light emitting element 1 can be used as, for example, a light source. Further, a display device (the light emitting device of the present invention) can be configured by arranging a plurality of light emitting elements 1 in a matrix and covering the arranged light emitting elements 1 with a color filter.
The driving method of the display device is not particularly limited, and may be either an active matrix method or a passive matrix method.

Next, an example of a display device to which the light emitting 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 light emitting device of the present invention is applied.
A display device 100 shown in FIG. 2 includes a base body (substrate) 20, a plurality of light emitting elements 1 provided on the base body (substrate) 20, and a color filter 40 provided on the plurality of light emitting elements 1. Has been.

The base body 20 includes a substrate 21 and a circuit unit 22 formed on the substrate 21.
The circuit unit 22 includes a protective layer 23 made of, for example, a silicon oxide layer formed on the substrate 21, a driving TFT (switching element) 24 formed on the protective layer 23, a first interlayer insulating layer 25, And a second interlayer insulating layer 26.
The driving TFT 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 245. have.
On such a circuit portion 22, the light emitting element 1 is provided corresponding to each driving TFT 24. Adjacent light emitting elements 1 are partitioned by a first partition wall portion 31 and a second partition wall portion 32.

In the present embodiment, the anode 3 of each light emitting element 1 constitutes a pixel electrode and is electrically connected to the drain electrode 245 of each driving TFT 24 by the wiring 27. The cathode 9 of each light emitting element 1 is a common electrode.
Then, a sealing member (not shown) is bonded to the base 20 so as to cover each light emitting element 1, and each light emitting element 1 is sealed.

Further, a color filter 40 is provided on the light emitting element 1 via a sealing member and a sealing material (not shown). The color filter 40 includes a substrate 41, a plurality of partition walls 42, and a plurality of coloring portions 43.
The substrate 41 is made of a light-transmitting material and carries the coloring portion 43 and the partition wall 42.

The partition wall 42 is provided on the substrate 41 and partitions the substrate 41. Further, the partition wall 42 has a function of allowing white light emitted from each light emitting element 1 to pass through only the target colored portion 43. The partition wall 42 is usually made of a black material, and expresses black when the light emitting element 1 is not emitting light.
Further, the coloring portion 43 is provided in a space partitioned by the partition wall 42 and is disposed in a space corresponding to the light emitting element 1. In addition, the coloring unit 43 emits white light from the light emitting element 1 in the direction of the arrow in the drawing while converting the light into a target color. Each coloring part 43 can be made into the coloring part 43R which converts white light into red, the coloring part 43G which converts into green, and the coloring part 43B which converts into blue.
The display device 100 may be a single color display or a color display.
Such a display device 100 (the light emitting 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 image sensor such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

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

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

  In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the figure, a television monitor 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the 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.

As mentioned above, although the light emitting element of this invention, the light-emitting device, and the electronic device were demonstrated based on embodiment of illustration, this invention is not limited to these.
For example, in the light-emitting element of the present invention, one or more desired layers can be provided in at least one of the layers. For example, the light emitting device of the present invention may further include one or a plurality of blue light emitting layers in addition to the blue light emitting layer described above. For example, the light-emitting element may have a light-emitting layer other than the above-described colors such as cyan, magenta, and yellow.

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

<2> Next, the tetraamine compound shown in Chemical 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 tetraarylbenzidine compound represented by Chemical Formula 2 was deposited on the ITO electrode by a vacuum deposition method to form a hole transport layer having an average thickness of 20 nm.
<4-1> Next, the constituent material of the red light emitting layer was deposited on the ITO electrode by a vacuum vapor deposition method to form a red light emitting layer having an average thickness of 7 nm. As a constituent material of the red light emitting layer, dibenzodiindenoperylene represented by Chemical Formula 3 was used as a light emitting material (dopant), and bis p-biphenylnaphthacene represented by Chemical Formula 4 was used as a host material. The content (dope concentration) of the light emitting material in the red light emitting layer was 1.0 wt%.

  <4-2> Next, a constituent material of the first blue light-emitting layer was deposited on the red light-emitting layer by a vacuum vapor deposition method to form a first blue light-emitting layer having an average thickness of 8 nm. As a constituent material of the first blue light emitting layer, a distyryldiamine derivative represented by the chemical formula 9 was used as a light emitting material (dopant), and a benzidine compound represented by the chemical formula 8 was used as a host material. In addition, the content (dope concentration) of the light emitting material in the first blue light emitting layer was 8.0 wt%.

  <4-3> Next, the constituent material of the second blue light-emitting layer was deposited on the first blue light-emitting layer by a vacuum evaporation method to form a second blue light-emitting layer having an average thickness of 15 nm. As a constituent material of the second blue light emitting layer, a distyryldiamine derivative represented by the chemical formula 9 was used as a light emitting material (dopant), and an anthracene derivative represented by the chemical formula 7 was used as a host material. In addition, the content (dope concentration) of the light emitting material in the first blue light emitting layer was 8.0 wt%.

  <4-4> Next, on the red light emitting layer, the constituent material of the green light emitting layer was vapor-deposited by a vacuum evaporation method to form a green light emitting layer having an average thickness of 20 nm. As a constituent material of the green light emitting layer, a quinacridone derivative as shown in the chemical formula 10 was used as a light emitting material (dopant), and bis p-biphenylnaphthacene shown in the chemical formula 4 was used as a host material. Further, the content (dope concentration) of the light emitting material in the green light emitting layer was 5.0 wt%.

<5> Next, on the second blue light-emitting layer, tris (8-quinolinolato) aluminum (Alq ₃ ) was formed by a vacuum deposition method to form an electron transport layer having an average thickness of 15 nm.
<6> Next, on the electron transport layer, lithium fluoride (LiF) was formed by a vacuum vapor deposition method, thereby forming an electron injection layer having an average thickness of 0.5 nm.
<7> Next, Al was formed into a film by the vacuum evaporation method on the electron injection layer. Thereby, a cathode having an average thickness of 100 nm made of Al was formed.
<8> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
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 anthracene derivative shown in Chemical Formula 7 was used as the light emitting material in Step <4-2>. The anthracene derivative functions as a light emitting material and at the same time has an excellent function of transporting electrons. In addition, the content (dope concentration) of the anthracene derivative shown in Chemical Formula 7 in the first blue light-emitting layer was 8.0 wt%.

(Example 3)
A light emitting device was manufactured in the same manner as in Example 1 except that the anthracene derivative represented by Chemical Formula 7 and the benzidine compound represented by Chemical Formula 8 were used as host materials in Step <4-2>. In addition, the contents of the anthracene derivative represented by the chemical formula 7 and the benzidine compound represented by the chemical formula 8 in the host material in the first blue light emitting layer were 45.7 wt% and 54.3 wt%, respectively. .

Example 4
A light emitting device was manufactured in the same manner as in Example 1 except that the diphenylbenzofluoranthene derivative shown in Chemical Formula 6 was used as the light emitting material in the above step <4-2>. Further, the content (dope concentration) of the diphenylbenzofluoranthene derivative shown in Chemical Formula 6 in the first blue light emitting layer was 8.0 wt%.

(Example 5)
In the step <4-2>, light emission was performed in the same manner as in Example 3, except that the diphenylbenzofluoranthene derivative represented by the chemical formula 6 was used instead of the distyryldiamine derivative represented by the chemical formula 9 as the light emitting material. A device was manufactured. Further, the content (dope concentration) of the diphenylbenzofluoranthene derivative shown in Chemical Formula 6 in the first blue light emitting layer was 8.0 wt%.

(Example 6)
A light emitting device was produced in the same manner as in Example 1 except that in the step <4-4>, bis-ortho-biphenylylperylene (perylene derivative) shown in Chemical Formula 5 was used as a host material. In the manufactured light emitting device, the host material used for the green light emitting layer had a larger band gap than the host material used for the red light emitting layer.
(Example 7)
A light emitting device was produced in the same manner as in Example 6 except that in the step <4-1>, bis-ortho-biphenylylperylene (perylene derivative) shown in Chemical Formula 5 was used as a host material.

(Comparative Example 1)
A light emitting device was produced in the same manner as in Example 1 except that the step <4-3> was not performed and the anthracene derivative shown in Chemical Formula 7 was used as the host material for all light emitting layers. That is, the light emitting element has a configuration in which the second blue light emitting layer is omitted and the green light emitting layer is provided on the second blue light emitting layer. Moreover, the average thickness of each light emitting layer was 10 nm, respectively.

2. Evaluation 2-1. Evaluation of Luminance For the light emitting devices of each Example and Comparative Example 1, immediately after manufacture, a current of 100 mA / cm ² was passed between the anode and the cathode from the DC power source, and the luminance at this time was measured. In each example and comparative example 1, the luminance was measured for each of five light emitting elements.

Then, using the light luminance measured in Comparative Example 1 as a reference value, the light luminance measured in each of Examples 1 to 7 was evaluated according to the following four criteria.
A: 1.8 times or more the luminance of Comparative Example 1.
○: The brightness of Comparative Example 1 is 1.5 times or more and less than 1.8 times.
Δ: 1.1 times or more and less than 1.5 times the luminance of Comparative Example 1.
X: Less than 1.1 times the luminance of Comparative Example 1.

2-2. Evaluation of Luminous Life For each of the light emitting devices of each Example and Comparative Example 1, a current of 100 mA / cm ² was passed from the DC power source between the anode and the cathode, and the luminance at this time was measured. Subsequently, a current was continuously supplied to the light emitting element under the same conditions, and the time (half life) during which the luminance became half of the initial luminance was measured. In each example and comparative example 1, half-life values were measured for five light emitting elements.

Then, using the half-life measured in Comparative Example 1 as a reference value, the half-lives measured in Examples 1 to 7 were each evaluated according to the following four criteria.
(Double-circle): It is 11.0 times or more with respect to the half life of the comparative example 1.
○: The half-life of Comparative Example 1 is 8.0 times or more and less than 11.0 times.
Δ: 1.0 times or more and less than 8.0 times the half-life of Comparative Example 1.
X: It is less than 1.0 time with respect to the half life of the comparative example 1.

2-3. Evaluation of Chromaticity With respect to the light-emitting elements of each Example and Comparative Example 1, a current of 100 mA / cm ² was passed between the anode and the cathode from the DC power source, and the chromaticity (x , Y). At the same time, the spectrum (emission spectrum) of the light emitted from the light emitting devices of the examples and comparative example 1 was measured. When the emitted light is close to white, the light chromaticity (x, y) is close to (0.33, 0.33).

These evaluation results are shown in Table 1 below. Table 1 also shows the constituent materials of the light emitting portion of each light emitting element. In the table, “RD” is dibenzodiindenoperylene represented by Chemical Formula 3, “BD1” is a distyryldiamine derivative represented by Chemical Formula 9, “BD2” is a diphenylbenzofluoranthene derivative represented by Chemical Formula 6, “GD” "Is a quinacridone derivative as shown in Chemical Formula 10," H1 "is bis p-biphenylnaphthacene as shown in Chemical Formula 4," H2 "is a benzidine compound as shown in Chemical Formula 8, and" H3 "is as shown in Chemical Formula 7. The anthracene derivative “H4” represents bis-ortho-biphenylylperylene shown in Chemical Formula 5 above.
Moreover, the emission spectrum obtained by each Example and the comparative example 1 is shown in FIGS.

As shown in Table 1, each of the light-emitting elements of each example had higher luminance of emitted light and higher luminous efficiency than the light-emitting element of Comparative Example 1. In addition, each of the light-emitting elements of each example had a longer light emission lifetime than the light-emitting element of Comparative Example 1.
Furthermore, the light emitted from the light emitting elements of the respective examples had a chromaticity close to (0.33, 0.33) and extremely close to white. As shown in FIGS. 6 to 12, the emission spectrum of each example has a higher spectral luminance at each wavelength of red, green, and blue and a good balance compared to the emission spectrum of the comparative example shown in FIG. 13. It can be seen that light of each wavelength is emitted.

In contrast, the light emitting device manufactured in Comparative Example 1 did not provide satisfactory results.
In any of the examples, the host material of the first blue light-emitting layer had a larger band gap than the host material of the red light-emitting layer. In any of the examples, the host material of the second blue light emitting layer had a larger band gap than the host material of the green light emitting layer. On the other hand, in Comparative Example 1, the band gaps were all equal between the host materials of the light emitting layers.

It is a figure which shows typically the longitudinal cross-section of the light emitting element of this invention. It is a longitudinal cross-sectional view which shows embodiment of the display apparatus to which the light-emitting device of this invention is applied. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied. It is the emission spectrum of the light which the light emitting element of Example 1 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 2 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 3 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 4 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 5 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 6 of this invention emitted. It is an emission spectrum of the light which the light emitting element of Example 7 of this invention emitted. 3 is an emission spectrum of light emitted from the light emitting device of Comparative Example 1.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Hole injection layer 5 ... Hole transport layer 6 ... Light emitting part 61 ... Red light emitting layer 62 ... First blue light emitting layer 63 ... Second blue light emitting layer 64... Green light emitting layer 7... Electron transport layer 8... Electron injection layer 9... Cathode 10 .. Sealing member 11. ...... Substrate 21 ...... Substrate 22 ...... Circuit part 23 ...... Protective layer 24 ...... Drive TFT 241 ...... Semiconductor layer 242 ...... Gate insulating layer 243 ...... Gate electrode 244 ...... Source electrode 245 ...... Drain electrode 25 …… First interlayer insulating layer 26 ...... Second interlayer insulating layer 27 ...... Wiring 31 ...... First partition wall portion 32 ...... Second partition wall portion 40 ...... Color filter 41 ...... Substrate 42 ...... Section wall 43, 43 </ b> R, 43G, 43B ... Coloring section 1100 ... Personal computer 1102 ... Keyboard 1104 ... Main body 1106 ... Display unit 1200 ... Mobile phone 1202 ... Operation buttons 1204 ... Earpiece 1206 ... Mouthpiece 1300 ... Digital still camera 1302 ... ... Case (Body) 1304 ... Light-receiving unit 1306 ... Shutter button 1308 ... Circuit board 1312 ... Video signal output terminal 1314 ... I / O terminal for data communication 1430 ... TV monitor 1440 ... Personal computer

Claims (14)

The anode,
A cathode,
A first blue light-emitting layer provided between the anode and the cathode and emitting blue light;
A second blue light-emitting layer that is provided between the cathode and the first blue light-emitting layer, is made of a material different from the first blue light-emitting layer, and emits blue light;
A red light emitting layer that is provided between the anode and the first blue light emitting layer and emits red light;
Provided between said second cathode of the blue light-emitting layer, have a green-emitting layer that emits green light,
The first blue light emitting layer includes a light emitting material having a function of capturing electrons including a fluoranthene derivative, and a host material supporting the light emitting material having a function of capturing the electrons. ,
The second blue light emitting layer includes a light emitting material having a function of capturing holes including a distyryldiamine derivative, and a host material supporting the light emitting material having a function of capturing holes. light-emitting element, characterized in that the are. The host material of the first blue light-emitting layer includes a compound having a function of transporting holes,
The light-emitting element according to claim 1 , wherein the host material of the second blue light-emitting layer contains a compound having a function of transporting electrons. The light emitting device according to claim 1 or 2 is joined to the second blue emitting layer and the first blue light emitting layer. Each of the red light emitting layer and the green light emitting layer includes a light emitting material and a host material that supports the light emitting material.
The energy gap between the highest occupied molecular orbital of the host material of the first blue light emitting layer and the lowest unoccupied molecular orbital between the highest occupied molecular orbital of the host material of the red light emitting layer and the lowest unoccupied molecular orbital. Is larger than the energy gap of
The energy gap between the highest occupied molecular orbital of the host material of the second blue light emitting layer and the lowest unoccupied molecular orbital is between the highest occupied molecular orbital of the host material of the green light emitting layer and the lowest unoccupied molecular orbital. light-emitting device according to any one of claims 1 to 3 is larger than the energy gap of. The energy gap between the highest occupied molecular orbital of the host material of the green light emitting layer and the lowest unoccupied molecular orbital is the energy gap between the highest occupied molecular orbital of the host material of the red light emitting layer and the lowest unoccupied molecular orbital. The light emitting device according to claim 4 , which is as described above. The host material of the red light-emitting layer and the green luminescent layer, respectively, naphthacene derivatives, perylene derivatives and (tris (8-hydroxy quinolinol) aluminum) according to claim 4 or 5 is intended to include at least one or more kinds selected from the complex Light emitting element.   The light-emitting element according to claim 1, wherein the fluoranthene derivative contains a dimer. The light emitting device according to any one of claims 1 to 7 , wherein a host material of the first blue light emitting layer contains a compound having an amine structure. The light emitting device according to claim 8 , wherein the compound having an amine as a structure is a tetraarylbenzidine derivative. The light emitting device according to claim 8 or 9 , wherein a content of the compound having an amine structure in the host material of the first blue light emitting layer is 50 wt% or more. The light emitting device according to any one of claims 1 to 10 , wherein a host material of the second blue light emitting layer contains an anthracene derivative. The light emitting device according to claim 11 , wherein the content of the anthracene derivative in the host material of the second blue light emitting layer is 50 wt% or more. The light emitting device characterized in that it comprises a device as claimed in any of claims 1 to 12. An electronic apparatus comprising the light emitting device according to claim 13 .

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