JP5304910B2 - LIGHT EMITTING ELEMENT, DISPLAY DEVICE, AND ELECTRONIC DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element which has excellent light emission efficiency and durability (service life) and to provide a reliable display device and electronic device provided with the light-emitting element. <P>SOLUTION: A light-emitting element 1 comprises: a cathode 12; an anode 3; a red light-emitting layer 6 which is provided between the cathode 12 and the anode 3 and emits red light; a blue light-emitting layer 8 which is provided between the red light-emitting layer 6 and the cathode 12 and emits blue light; and an intermediate layer 7 which is provided between the red light-emitting layer 6 and the blue light-emitting layer 8 in contact therewith and has a function of blocking transfer of energy of exciton between the red light-emitting layer 6 and the blue light-emitting layer 8. The intermediate layer 7 contains acene-based material and amine-based material. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

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

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

  As such a light-emitting element, for example, three light-emitting layers corresponding to three colors of R (red), G (green), and B (blue) are stacked between a cathode and an anode to emit white light. Those are known (for example, see Patent Document 1). Such a light emitting element that emits white light displays a full color image by using a color filter in which three colors of R (red), G (green), and B (blue) are separately applied to each pixel. Can do.

Moreover, in the light emitting element concerning patent document 1, the transfer of the energy of the exciton between light emitting layers can be prevented by providing an intermediate | middle layer between light emitting layers. At that time, by making the intermediate layer bipolar so that both electrons and holes can move, the intermediate layer has excellent resistance to electrons and holes, and electrons and holes are introduced into each light emitting layer. Can be injected. From these things, each light emitting layer can be light-emitted with sufficient balance, and white light can be emitted.
However, the light emitting device according to Patent Document 1 has low durability because the intermediate layer is composed of only a general hole transport material or electron transport material. This is presumably because electrons and holes are recombined in the bipolar intermediate layer to generate excitons, and the intermediate layer has low resistance to the excitons.

JP 2006-172762 A

  An object of the present invention is to provide a light emitting element that is excellent in luminous efficiency and durability (lifetime), and a highly reliable display device and electronic apparatus 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 a cathode,
The anode,
A first light-emitting layer provided between the cathode and the anode and emitting light in a first color;
A second light-emitting layer provided between the first light-emitting layer and the cathode and emitting light in a second color different from the first color;
It is provided between the first light-emitting layer and the second light-emitting layer so as to be in contact therewith, and the excited state energy moves between the first light-emitting layer and the second light-emitting layer. An intermediate layer having a function of preventing
The intermediate layer is composed of a acene-based material and an amine-based material,
The acene-based material is an anthracene derivative in which a naphthyl group is introduced at each of the 9th and 10th positions of the anthracene skeleton,
The amine-based material is a benzidine-based amine derivative into which two or more naphthyl groups are introduced,
The intermediate layer has an average film thickness of 1 to 100 nm.

Thereby, since the intermediate layer prevents the energy transfer in the excited state (exciton transfer) between the first light emitting layer and the second light emitting layer, the first light emitting layer and the second light emitting layer are Each can emit light efficiently. At that time, the amine-based material (that is, the material having an amine skeleton) has a hole transporting property, and the acene-based material (that is, the material having an acene skeleton) has an electron-transporting property. While making the resistance excellent, it is possible to emit light by injecting electrons and holes into the first light-emitting layer and the second light-emitting layer, respectively.
In particular, since the acene-based material has excellent resistance to excitons, deterioration of the intermediate layer due to excitons can be prevented or suppressed, and the durability of the light-emitting element can be improved.
In addition, since the acene-based material is an anthracene derivative, the electron transport property of the acene-based material (and thus the intermediate layer) is excellent, and the resistance to excitons is increased, so that a uniform intermediate layer can be easily formed. can do.
In addition, since the anthracene derivative is one in which a naphthyl group is introduced into each of the 9th and 10th positions of the anthracene skeleton, the electron transport property of the acene-based material (and thus the intermediate layer) is more reliably improved. , The resistance to excitons can be increased, and the formation of a homogeneous intermediate layer can be facilitated.
Moreover, since the average film thickness of the intermediate layer is 1 to 100 nm, the intermediate layer more reliably transfers the energy in the excited state between the first light-emitting layer and the second light-emitting layer while suppressing the driving voltage. Can be prevented.

In the light emitting device of the present invention, the electron mobility of the acene material is preferably higher than the electron mobility of the amine material.
Acene-based materials are generally excellent in electron transport properties. Therefore, electrons can be smoothly transferred from the second light emitting layer to the first light emitting layer through the intermediate layer.
In the light emitting device of the present invention, it is preferable that the hole mobility of the amine material is higher than the hole mobility of the acene material.
Amine-based materials are generally excellent in hole transportability. Therefore, holes can be smoothly transferred from the first light emitting layer to the second light emitting layer through the intermediate layer.

In the light emitting device of the present invention, the first color and the second color are provided between the first light emitting layer and the anode or between the second light emitting layer and the cathode. Preferably has a third light-emitting layer that emits light of a different third color.
Thus, for example, a light emitting element that emits white light by emitting R (red), G (green), and B (blue) can be realized.

In the light emitting device of the present invention, it is preferable that the first light emitting layer is a red light emitting layer that emits red light as the first color.
The red light emitting material has a relatively small band gap and easily emits light. Therefore, the first light-emitting layer provided on the anode side is a red light-emitting layer, and the light-emitting layer having a wide band gap and difficult to emit light is used as the second light-emitting layer or the third light-emitting layer on the cathode side. The first light-emitting layer, the second light-emitting layer, and the third light-emitting layer can emit light with a good balance.

In the light-emitting element of the present invention, the third light-emitting layer is a green light-emitting layer that is provided between the second light-emitting layer and the cathode and emits green as the third color. The light emitting layer is preferably a blue light emitting layer that emits blue light as the second color.
Thereby, it is possible to emit R (red), G (green), and B (blue) in a balanced manner and emit white light relatively easily.

In the light emitting device of the present invention, the third light emitting layer is a blue light emitting layer that is provided between the first light emitting layer and the anode, and emits blue as the third color, and the second light emitting layer. The light emitting layer is preferably a green light emitting layer that emits green light as the second color.
Thereby, it is possible to emit R (red), G (green), and B (blue) in a balanced manner and emit white light relatively easily.

The display device of the present invention includes the light emitting element of the present invention.
Thereby, a display device having excellent reliability can be provided.
An electronic apparatus according to the present invention includes the display device according to the present invention.
Thereby, an electronic device having excellent reliability can be provided.

It is a figure which shows typically the longitudinal cross-section of 1st Embodiment of the light emitting element of this invention. It is a figure which shows typically the longitudinal cross-section of 2nd Embodiment 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 display apparatus of this invention is applied. 1 is a perspective view showing a configuration of a mobile (or notebook) personal computer to which an electronic apparatus of the present invention is applied. It is a perspective view which shows the structure of the mobile telephone (PHS is also included) to which the electronic device of this invention is applied. It is a perspective view which shows the structure of the digital still camera to which the electronic device of this invention is applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a light-emitting element, a display device, and an electronic device according to the invention will be described with reference to the accompanying drawings.
<First Embodiment>
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. 1 will be described as “upper” and the lower side as “lower”.

A light-emitting element (electroluminescence element) 1 shown in FIG. 1 emits white light by emitting R (red), G (green), and B (blue).
Such a light emitting device 1 includes an anode 3, a hole injection layer 4, a hole transport layer 5, a red light emitting layer (first light emitting layer) 6, an intermediate layer 7, and a blue light emitting layer (second light emitting layer) 8. And a green light emitting layer (third light emitting layer) 9, an electron transport layer 10, an electron injection layer 11, and a cathode 12 are laminated in this order.

In other words, the light emitting device 1 includes the hole injection layer 4, the hole transport layer 5, the red light emission layer 6, the intermediate layer 7, the blue light emission layer 8, the green light emission layer 9, the electron transport layer 10, and the electron injection layer 11. A laminated body 15 in which the cathode 12 is laminated in this order is interposed between two electrodes (between the anode 3 and the cathode 12).
The entire light emitting element 1 is provided on the substrate 2 and is sealed with a sealing member 13.

  In such a light emitting element 1, electrons are supplied (injected) from the cathode 12 side to the light emitting layers of the red light emitting layer 6, the blue light emitting layer 8, and the green light emitting layer 9, and the anode 3 side. Holes are supplied (injected). In each light emitting layer, holes and electrons recombine, and excitons (excitons) are generated by the energy released during the recombination, and energy (fluorescence or phosphorescence) is generated when the excitons return to the ground state. Is emitted (emitted). Thereby, 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 is configured to extract light from the substrate 2 side (bottom emission type), the substrate 2 and the anode 3 are substantially transparent (colorless transparent, colored transparent, or translucent), respectively. Has been.
Examples of the constituent material of the substrate 2 include resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, and polyarylate, quartz glass, and soda glass. Such glass materials can be used, and one or more of these can be used in combination.

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

Hereinafter, each part which comprises the light emitting element 1 is demonstrated sequentially.
(anode)
The anode 3 is an electrode that injects holes into the hole transport layer 5 through a hole injection layer 4 described later. As a constituent material of the anode 3, it is preferable to use a material having a large work function and excellent conductivity.

Examples of the constituent material of the anode 3 include oxides such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO, Au, Pt, and Ag. Cu, alloys containing these, and the like can be used, and one or more of these can be used in combination.
The average thickness of the anode 3 is not particularly limited, but is preferably about 10 to 200 nm, and more preferably about 50 to 150 nm.

(cathode)
On the other hand, the cathode 12 is an electrode that injects electrons into the electron transport layer 10 via an electron injection layer 11 described later. As a constituent material of the cathode 12, it is preferable to use 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. These can be used alone or in combination of two or more thereof (for example, a multi-layer laminate).

In particular, when an alloy is used as the constituent material of the cathode 12, it is preferable to use an alloy containing a stable metal element such as Ag, Al, or Cu, specifically, an alloy such as MgAg, AlLi, or CuLi. By using such an alloy as the constituent material of the cathode 12, the electron injection efficiency and stability of the cathode 12 can be improved.
Although the average thickness of such a cathode 12 is not specifically limited, It is preferable that it is about 100-10000 nm, and it is more preferable that it is about 200-500 nm.
In addition, since the light emitting element 1 of this embodiment is a bottom emission type, the cathode 12 is not particularly required to have light transmittance.

(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. For example, copper phthalocyanine or 4,4 ′, 4 ″ -tris (N, N-phenyl-3-methylphenyl) Amino) triphenylamine (m-MTDATA) and the like.
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.
The hole injection layer 4 can be omitted.

(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.
As the constituent material of the hole transport layer 5, various p-type polymer materials and various p-type low-molecular materials can be used alone or in combination.
The average thickness of the hole transport layer 5 is not particularly limited, but is preferably about 10 to 150 nm, and more preferably about 10 to 100 nm.
The hole transport layer 5 can be omitted.

(Red light emitting layer)
The red light emitting layer (first light emitting layer) 6 includes a red light emitting material that emits red light (first color).
Such a red light emitting material 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).

  As a constituent material of the red light emitting layer 6, in addition to the red light emitting material as described above, a host material using the red light emitting material as a guest material can be used. This host material recombines holes and electrons to generate excitons, and excites the red light-emitting material by transferring the exciton energy to the red light-emitting material (Felster movement or Dexter movement). It has a function. In the case of using such a host material, for example, a red light-emitting material that is a guest material can be used as a dopant by doping the host material.

Such a host material is not particularly limited as long as it exhibits the functions described above for the red light emitting material to be used. For example, when the red light emitting material contains a red fluorescent material, for example, a distyrylarylene derivative , Naphthacene derivatives, perylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, quinolinolato metal complexes such as tris (8-quinolinolato) aluminum complex (Alq ₃ ), triarylamine derivatives such as tetramers of triphenylamine, Oxadiazole derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, benzoxazole derivatives, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2,2′-diphenylvinyl) biphenyl ( DPV Bi) etc. are mentioned, Among these, it can also be used individually by 1 type or in combination of 2 or more types.
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. Examples thereof include carbazole derivatives such as biphenyl (CBP), and one of these can be used alone or in combination of two or more.

When the red light emitting material (guest material) and the host material as described above are used, the content (dope amount) of the red light emitting material in the red light emitting layer 6 is preferably 0.01 to 10 wt%. It is more preferable that it is 1 to 5 wt%. By setting the content of the red light emitting material within such a range, the light emission efficiency can be optimized, and the red light emitting layer is balanced with the light emitting amount of the blue light emitting layer 8 and the green light emitting layer 9 described later. 6 can emit light.
In addition, the red light-emitting material as described above has a relatively small band gap, easily captures holes and electrons, and easily emits light. Therefore, by providing the red light emitting layer on the anode 3 side, the blue light emitting layer 8 and the green light emitting layer 9 which have a large band gap and are difficult to emit light can be used as the cathode side, and each light emitting layer can emit light in a balanced manner.

(Middle layer)
The intermediate layer 7 is provided between the red light emitting layer 6 and the blue light emitting layer 8 described later so as to be in contact therewith. The intermediate layer 7 has a function of preventing exciton energy from moving between the red light emitting layer 6 and the blue light emitting layer 8. With this function, the red light emitting layer 6 and the blue light emitting layer 8 can each emit light efficiently.
In particular, the intermediate layer 7 includes an acene-based material and an amine-based material.

  An amine-based material (that is, a material having an amine skeleton) has a hole transporting property, and an acene-based material (that is, a material having an acene skeleton) has an electron-transporting property. Thereby, the intermediate layer 7 has an electron transport property and a hole transport property. That is, the intermediate layer 7 has a bipolar property. Thus, when the intermediate layer 7 has bipolar properties, holes are smoothly transferred from the red light emitting layer 6 to the blue light emitting layer 8 through the intermediate layer 7, and the red light is transmitted from the blue light emitting layer 8 through the intermediate layer 7. Electrons can be smoothly transferred to the light emitting layer 6. As a result, electrons and holes can be efficiently injected into the red light emitting layer 6 and the blue light emitting layer 8 to emit light.

  In addition, since the intermediate layer 7 has bipolar properties, it has excellent resistance to carriers (electrons and holes). In addition, since the acene-based material is excellent in exciton resistance, even if electrons and holes are recombined in the intermediate layer 7 to generate excitons, the deterioration of the intermediate layer 7 is prevented or suppressed. be able to. Thereby, deterioration by the exciton of the intermediate layer 7 can be prevented or suppressed, and as a result, the durability of the light emitting element 1 can be made excellent.

The amine-based material used for such an intermediate layer 7 is not particularly limited as long as it has an amine skeleton and exhibits the effects described above. Of these, materials having an amine skeleton can be used, but a benzidine-based amine derivative is preferably used.
In particular, among the benzidine-based amine derivatives, the amine-based material used for the intermediate layer 7 is preferably one in which two or more naphthyl groups are introduced. Examples of such benzidine-based amine derivatives include N, N′-bis (1-naphthyl) -N, N′-diphenyl [1,1′-biphenyl] -4, represented by the following chemical formula 1. Examples thereof include 4′-diamine (α-NPD) and N, N, N ′, N′-tetranaphthyl-benzidine (TNB) represented by the following chemical formula 2.

Such amine-based materials are generally excellent in hole transport properties, and the hole mobility of amine-based materials is higher than the hole mobility of acene-based materials described later. Therefore, holes can be smoothly transferred from the red light emitting layer 6 to the blue light emitting layer 8 through the intermediate layer 7.
The content of the amine-based material in the intermediate layer 7 is not particularly limited, but is preferably 10 to 90 wt%, more preferably 30 to 70 wt%, and 40 to 60 wt%. Further preferred.

  On the other hand, the acene-based material used for the intermediate layer 7 is not particularly limited as long as it has an acene skeleton and exhibits the effects as described above. For example, naphthalene derivatives, anthracene derivatives, tetracene derivatives , Pentacene derivatives, hexacene derivatives, heptacene derivatives, and the like. Among these, one or a combination of two or more can be used, but anthracene derivatives are preferably used.

Anthracene derivatives can be easily formed by a vapor deposition method while having excellent electron transport properties. Therefore, by using an anthracene derivative as the acene-based material, it is possible to easily form the homogeneous intermediate layer 7 while improving the electron transport property of the acene-based material (and thus the intermediate layer 7).
In particular, among the anthracene derivatives, the acene-based material used for the intermediate layer 7 is preferably one in which a naphthyl group is introduced at each of the 9th and 10th positions of the anthracene skeleton. Thereby, the effect mentioned above becomes remarkable. Examples of such anthracene derivatives include 9,10-di (2-naphthyl) anthracene (ADN) represented by the following chemical formula 3, and 2-t-butyl- represented by the chemical formula 4 shown below. 9,10-di (2-naphthyl) anthracene (TBADN), 2-methyl-9,10-di (2-naphthyl) anthracene (MADN) represented by the following chemical formula 5 and the like can be mentioned.

Such an acene-based material is generally excellent in electron transport properties, and the electron mobility of the acene-based material is higher than that of the amine-based material described above. Therefore, electrons can be smoothly transferred from the blue light emitting layer 8 to the red light emitting layer 6 through the intermediate layer 7.
The content of the acene-based material in the intermediate layer 7 is not particularly limited, but is preferably 10 to 90 wt%, more preferably 30 to 70 wt%, and 40 to 60 wt%. Further preferred.

Further, when the content of the acene-based material in the intermediate layer 7 is A [wt%] and the content of the amine-based material in the intermediate layer 7 is B [wt%], B / (A + B) is It is preferably 0.1 to 0.9, more preferably 0.3 to 0.7, and still more preferably 0.4 to 0.6. Thereby, it is possible to emit light by injecting electrons and holes into the red light emitting layer 6 and the blue light emitting layer 8, respectively, while making the intermediate layer 7 more excellent in resistance to carriers and excitons.
Moreover, although the average thickness of the intermediate | middle layer 7 is not specifically limited, It is preferable that it is 1-100 nm, It is more preferable that it is 3-50 nm, It is further more preferable that it is 5-30 nm. Thereby, the intermediate layer 7 can more reliably prevent the exciton energy transfer between the red light emitting layer 6 and the blue light emitting layer 8 while suppressing the driving voltage.

  On the other hand, when the average thickness of the intermediate layer 7 exceeds the upper limit, depending on the constituent material of the intermediate layer 7, the driving voltage becomes remarkably high, or the light emission of the light emitting element 1 (particularly white light emission) becomes difficult. Sometimes. On the other hand, when the average thickness of the intermediate layer 7 is less than the lower limit, the intermediate layer 7 is excited between the red light emitting layer 6 and the blue light emitting layer 8 depending on the constituent material of the intermediate layer 7, the driving voltage, and the like. It is difficult to prevent or suppress energy transfer by the child, and the resistance of the intermediate layer 7 to carriers and excitons tends to decrease.

(Blue light emitting layer)
The blue light emitting layer (second light emitting layer) 8 includes a blue light emitting material that emits blue light (second color).
Such a blue light emitting material is not particularly limited, and various blue fluorescent materials and blue phosphorescent materials can be used alone or in combination of two or more.

  The blue fluorescent material is not particularly limited as long as it emits blue fluorescence. For example, distyryl derivatives, fluoranthene derivatives, pyrene derivatives, perylene and perylene derivatives, anthracene derivatives, benzoxazole derivatives, benzothiazole derivatives, benzimidazoles Derivatives, chrysene derivatives, phenanthrene derivatives, distyrylbenzene derivatives, tetraphenylbutadiene, 4,4′-bis (9-ethyl-3-carbazovinylene) -1,1′-biphenyl (BCzVBi), poly [(9.9- Dioctylfluorene-2,7-diyl) -co- (2,5-dimethoxybenzene-1,4-diyl)], poly [(9,9-dihexyloxyfluorene-2,7-diyl) -ortho-co- (2-methoxy-5- {2-ethoxyhexylo Si} phenylene-1,4-diyl)]], poly [(9,9-dioctylfluorene-2,7-diyl) -co- (ethylnylbenzene)] and the like, and one of these may be used alone. Alternatively, two or more kinds can be used in combination.

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 ).
As a constituent material of the blue light emitting layer 8, in addition to the blue light emitting material as described above, a host material that uses this blue light emitting material as a guest material can be used in the same manner as the red light emitting layer 6.

(Green light emitting layer)
The green light emitting layer (third light emitting layer) 9 includes a green light emitting material that emits green light (third color).
Such a green light emitting material 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, coumarin derivatives, quinacridone derivatives, 9,10-bis [(9-ethyl-3-carbazole) -vinylenyl] -anthracene, poly (9,9-dihexyl-2,7-vinylenefluorenylene), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (1,4-diphenylene-vinylene-2-methoxy-5) -{2-ethylhexyloxy} benzene)], poly [(9,9-dioctyl-2,7-divinylenefluorenylene) -ortho-co- (2-methoxy-5- (2-ethoxyhexyloxy)- 1,4-phenylene)] and the like, and one of these may be used alone or two or more of them 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 9, in addition to the green light emitting material as described above, a host material that uses this green light emitting material as a guest material can be used as in the case of the red light emitting layer 6.

(Electron transport layer)
The electron transport layer 10 has a function of transporting electrons injected from the cathode 12 through the electron injection layer 11 to the green light emitting layer 9.
As a constituent material (electron transport material) of the electron transport layer 10, 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, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like, and one or more of these can be used in combination.
Although the average thickness of the electron carrying layer 10 is not specifically limited, It is preferable that it is about 0.5-100 nm, and it is more preferable that it is about 1-50 nm.

(Electron injection layer)
The electron injection layer 11 has a function of improving the efficiency of electron injection 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 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 small work function, and the light-emitting element 1 can have high luminance by forming the electron injection layer 11 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 11 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 0.2 to 100 nm, and about 0.2 to 50 nm. Further preferred.

(Sealing member)
The sealing member 13 is provided so as to cover the anode 3, the laminate 15, and the cathode 12, and has a function of hermetically sealing them and blocking oxygen and moisture. By providing the sealing member 13, effects such as improvement in reliability of the light emitting element 1, prevention of deterioration / deterioration (improvement in durability), and the like can be obtained.

Examples of the constituent material of the sealing member 13 include Al, Au, Cr, Nb, Ta, Ti, alloys containing these, silicon oxide, various resin materials, and the like. In addition, when using the material which has electroconductivity as a constituent material of the sealing member 13, in order to prevent a short circuit, it is required between the sealing member 13 and the anode 3, the laminated body 15, and the cathode 12. Accordingly, it is preferable to provide an insulating film.
Further, the sealing member 13 may be formed in a flat plate shape so as to face the substrate 2 and be sealed with a sealing material such as a thermosetting resin.

  According to the light-emitting element 1 configured as described above, the intermediate layer 7 including the acene-based material and the amine-based material has an exciton energy between the red light-emitting layer 6 and the blue light-emitting layer 8. Since the movement is prevented, the red light emitting layer 6 and the blue light emitting layer 8 can each emit light efficiently. At that time, the amine-based material (that is, the material having an amine skeleton) has a hole transporting property, and the acene-based material (that is, the material having an acene skeleton) has an electron-transporting property. In addition, it is possible to emit light by injecting electrons and holes into the red light emitting layer 6 and the blue light emitting layer 8 respectively, while making the resistance to light excellent.

In particular, since the acene-based material is excellent in exciton resistance, deterioration of the intermediate layer 7 due to excitons can be prevented or suppressed, and the durability of the light-emitting element 1 can be improved.
In this embodiment, the red light emitting layer 6, the intermediate layer 7, the blue light emitting layer 8, and the green light emitting layer 9 are provided in this order from the anode 3 side to the cathode 12 side, so that R (red), G (green) and B (blue) can be emitted in a well-balanced manner to emit white light.

The above light emitting element 1 can be manufactured as follows, for example.
[1] First, the substrate 2 is prepared, and the anode 3 is formed on the substrate 2.
The anode 3 is, for example, a chemical vapor deposition method (CVD) such as plasma CVD or thermal CVD, a dry plating method such as vacuum deposition, a wet plating method such as electrolytic plating, a thermal spraying method, a sol-gel method, a MOD method, or a metal foil. It can be formed by using, for example, bonding.

[2] Next, the hole injection layer 4 is formed on the anode 3.
The hole injection layer 4 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.
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 plasma treatment. Thereby, it is possible to impart lyophilicity to the upper surface of the anode 3, remove (clean) organic substances adhering to the upper surface of the anode 3, adjust the work function near the upper surface of the anode 3, and the like. .
Here, the oxygen plasma treatment conditions include, for example, a plasma power of about 100 to 800 W, an oxygen gas flow rate of about 50 to 100 mL / min, a conveyance speed of the member to be treated (anode 3) of about 0.5 to 10 mm / sec, and a substrate. The temperature of 2 is preferably about 70 to 90 ° C.

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

[4] Next, the red light emitting layer 6 is formed on the hole transport layer 5.
The red light emitting layer 6 can be formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.
[5] Next, the intermediate layer 7 is formed on the red light emitting layer 6.
The intermediate layer 7 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like.

[6] Next, the blue light emitting layer 8 is formed on the intermediate layer 7.
The blue light emitting layer 8 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering.
[7] Next, the green light emitting layer 9 is formed on the blue light emitting layer 8.
The green light emitting layer 9 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or the like.

[8] Next, the electron transport layer 10 is formed on the green light emitting layer 9.
The electron transport layer 10 can be formed by a vapor phase process using, for example, a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like.
Further, the electron transport layer 10 is dried (desolvent or dedispersed) after supplying an electron transport layer forming material obtained by, for example, dissolving an electron transport material in a solvent or dispersing in a dispersion medium onto the green light emitting layer 9. It can also be formed by the medium.

[9] Next, the electron injection layer 11 is formed on the electron transport layer 10.
When an inorganic material is used as the constituent material of the electron injection layer 11, the electron injection layer 11 is formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition or sputtering, or coating and baking of inorganic fine particle ink. Etc. can be used.
[10] Next, the cathode 12 is formed on the electron injection layer 11.
The cathode 12 can be formed using, for example, a vacuum evaporation method, a sputtering method, bonding of metal foil, application and baking of metal fine particle ink, and the like.
The light emitting element 1 is obtained through the steps as described above.
Finally, the sealing member 13 is covered so as to cover the obtained light emitting element 1 and bonded to the substrate 2.

Second Embodiment
FIG. 2 is a view schematically showing a longitudinal section of a second embodiment of the light emitting device of the present invention. In the following description, for convenience of explanation, the upper side in FIG. 2 will be described as “upper” and the lower side as “lower”.
The light emitting device 1A according to the present embodiment is the same as the light emitting device 1 of the first embodiment described above except that the stacking order of each light emitting layer and the intermediate layer is different.

That is, the light emitting element 1A shown in FIG. 2 includes an anode 3, a hole injection layer 4, a hole transport layer 5, a blue light emitting layer (third light emitting layer) 8, and a red light emitting layer (first light emitting layer) on the substrate 2. A light emitting layer) 6, an intermediate layer 7, a green light emitting layer (second light emitting layer) 9, an electron transport layer 10, an electron injection layer 11, and a cathode 12 are laminated in this order, and these are sealed with a sealing member 13. ing.
In other words, the light-emitting element 1 includes a hole injection layer 4, a hole transport layer 5, a blue light-emitting layer 8, a red light-emitting layer 6, an intermediate layer 7, and a green light-emitting layer 9 between the anode 3 and the cathode 12. A laminated body 15A in which the electron transport layer 10 and the electron injection layer 11 are laminated in this order from the anode 3 side to the cathode 12 side is inserted, and these are provided on the substrate 2 and sealed with the sealing member 13. It has been stopped.

Even with the light emitting element 1A having the above-described configuration, the same effects as those of the light emitting element 1 of the first embodiment described above can be exhibited.
In particular, in this embodiment, by providing the blue light emitting layer 8, the red light emitting layer 6, the intermediate layer 7, and the green light emitting layer 9 in this order from the anode 3 side to the cathode 12 side, R (red), G (green) and B (blue) can be emitted in a well-balanced manner to emit white light.

The light emitting element 1 and the light emitting element 1A as described above can be used as a light source, for example. Moreover, a display apparatus (display apparatus of the present invention) can be configured by arranging a plurality of light emitting elements 1 and light emitting elements 1A in a matrix.
The driving method of the display device is not particularly limited, and may be either an active matrix method or a passive matrix method.

Next, an example of a display device to which the display device of the present invention is applied will be described.
FIG. 3 is a longitudinal sectional view showing an embodiment of a display device to which the display device of the present invention is applied.
The display device 100 shown in FIG. 3 includes a substrate 21, a plurality of light emitting elements 1R, 1G, 1B and color filters 19R, 19G, 10B provided corresponding to the sub-pixels 100R, 100G, 100B, and each light emitting element 1R. And a plurality of driving transistors 24 for driving 1G and 1B, respectively. Here, the display device 100 is a display panel having a top emission structure.

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

On the planarization layer, light emitting elements 1R, 1G, and 1B are provided corresponding to the driving transistors 24, respectively.
In the light emitting element 1 </ b> R, a reflective film 32, a corrosion prevention film 33, an anode 3, a laminate (organic EL light emitting unit) 15, a cathode 12, and a cathode cover 34 are laminated in this order on a planarization layer 22. In the present embodiment, the anode 3 of each light emitting element 1R, 1G, 1B constitutes a pixel electrode and is electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. Moreover, the cathode 12 of each light emitting element 1R, 1G, 1B is a common electrode.

The configurations of the light emitting elements 1G and 1B are the same as the configuration of the light emitting element 1R. In FIG. 3, the same reference numerals are assigned to the same configurations as those in FIG. 1. Further, the configuration (characteristics) of the reflective film 32 may be different among the light emitting elements 1R, 1G, and 1B depending on the wavelength of light.
A partition wall 31 is provided between the adjacent light emitting elements 1R, 1G, and 1B. An epoxy layer 35 made of an epoxy resin is formed on the light emitting elements 1R, 1G, and 1B so as to cover them.

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

A light shielding layer 36 is formed between the adjacent color filters 19R, 19G, and 19B. Thereby, it is possible to prevent the unintended subpixels 100R, 100G, and 100B from emitting light.
A sealing substrate 20 is provided on the color filters 19R, 19G, 19B and the light shielding layer 36 so as to cover them.
The display device 100 as described above may be a single color display, and color display is also possible by selecting a light emitting material used for each light emitting element 1R, 1G, 1B.
Such a display device 100 (the display device of the present invention) can be incorporated into various electronic devices.

FIG. 4 is a perspective view showing a 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. 5 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. 6 is a perspective view showing the configuration of a digital still camera to which the electronic apparatus of the present invention is applied. In this figure, connection with an external device is also simply shown.
Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an imaging device such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.

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

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

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

  In addition to the personal computer (mobile personal computer) in FIG. 4, the mobile phone in FIG. 5, and the digital still camera in FIG. 6, the electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.

The light emitting element, the display device, and the electronic device of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.
For example, in the above-described embodiment, the light emitting element has three light emitting layers. However, the light emitting layer may be two layers or four or more layers. Further, the emission color of the light emitting layer is not limited to R, G, and B in the above-described embodiment. Even when there are two or more light emitting layers, white light can be emitted by appropriately setting the emission spectrum of each light emitting layer.
Moreover, the intermediate | middle layer should just be provided between the at least 1 interlayer of light emitting layers, and may have an intermediate | middle layer of two or more layers.

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

<2> Next, HI406 (manufactured by Idemitsu Kosan Co., Ltd.) 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, HT320 (manufactured by Idemitsu Kosan Co., Ltd.) was deposited on the hole injection layer by a vacuum deposition method to form a hole transport layer having an average thickness of 20 nm.
<4> Next, the constituent material of the red light-emitting layer was deposited on the hole transport layer by a vacuum vapor deposition method to form a red light-emitting layer (first light-emitting layer) having an average thickness of 10 nm. As a constituent material of the red light emitting layer, RD001 (made by Idemitsu Kosan Co., Ltd.) was used as a red light emitting material (guest material), and rubrene was used as a host material. The content (dope concentration) of the light emitting material (dopant) in the red light emitting layer was 1.0 wt%.

  <5> Next, the constituent material of the intermediate layer was vapor-deposited on the red light emitting layer by a vacuum vapor deposition method to form an intermediate layer having an average thickness of 7 nm. As the constituent material of the intermediate layer, α-NPD represented by Chemical Formula 1 described above was used as an amine-based material, and ADN represented by Chemical Formula 3 was used as an acene-based material. In addition, the content of the amine-based material in the intermediate layer was 50 wt%, and the content of the acene-based material in the intermediate layer was 50 wt%.

  <6> Next, the constituent material of the blue light emitting layer was vapor-deposited on the intermediate layer by a vacuum evaporation method to form a blue light emitting layer (second light emitting layer) having an average thickness of 15 nm. As a constituent material of the blue light emitting layer, BD102 (made by Idemitsu Kosan Co., Ltd.) was used as a blue light emitting material, and BH215 (made by Idemitsu Kosan Co., Ltd.) was used as a host material. Further, the content (dope concentration) of the blue light emitting material (dopant) in the blue light emitting layer was 5.0 wt%.

  <7> Next, the constituent material of the green light emitting layer was deposited on the blue light emitting layer by a vacuum evaporation method to form a green light emitting layer (third light emitting layer) having an average thickness of 25 nm. As a constituent material of the green light emitting layer, GD206 (made by Idemitsu Kosan Co., Ltd.) was used as a green light emitting material (guest material), and BH215 (made by Idemitsu Kosan Co., Ltd.) was used as a host material. Further, the content (dope concentration) of the green light emitting material (dopant) in the green light emitting layer was 8.0 wt%.

<8> Next, tris (8-quinolinolato) aluminum (Alq ₃ ) was formed on the green light-emitting layer by a vacuum deposition method, thereby forming an electron transport layer having an average thickness of 20 nm.
<9> Next, on the electron transport layer, lithium fluoride (LiF) was formed by a vacuum deposition method to form an electron injection layer having an average thickness of 0.5 nm.
<10> Next, Al was formed into a film by the vacuum evaporation method on the electron injection layer. Thereby, a cathode having an average thickness of 150 nm made of Al was formed.
<11> Next, a glass protective cover (sealing member) was placed over the formed layers, and fixed and sealed with an epoxy resin.
Through the above steps, a light emitting device as shown in FIG. 1 was manufactured.

(Example 2)
A light emitting device was manufactured in the same manner as in Example 1 except that the intermediate layer was formed using TBADN represented by Chemical Formula 4 as an acene-based material.
(Example 3)
A light emitting device was manufactured in the same manner as in Example 1 except that the intermediate layer was formed using MADN represented by Chemical Formula 5 as an acene-based material.
Example 4
A light emitting device was manufactured in the same manner as in Example 1 except that the intermediate layer was formed using TNB represented by Chemical Formula 2 as an amine material.

(Example 5)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the intermediate layer was 15 nm.
(Example 6)
A light emitting device was manufactured in the same manner as in Example 1 except that the average thickness of the intermediate layer was 20 nm.

(Example 7)
On the substrate, an anode, a hole injection layer, a hole transport layer, a blue light emitting layer, a red light emitting layer, an intermediate layer, a green light emitting layer, an electron transport layer, an electron injection layer, and a cathode are formed in this order. A light emitting device was manufactured in the same manner as in Example 1 except that the thickness of each of the red light emitting layer and the intermediate layer and the doping amount of the blue light emitting material in the blue light emitting layer were changed. Thus, a light emitting device as shown in FIG. 2 was manufactured.
Here, the average thickness of the blue light emitting layer was 15 nm, the average thickness of the red light emitting layer was 5 nm, and the average thickness of the intermediate layer was 10 nm. Further, the doping amount of the blue light emitting material in the blue light emitting layer was 8%.

(Comparative Example 1)
A light emitting device was manufactured in the same manner as in Example 1 except that the intermediate layer was formed only with α-NPD without using ADN.
(Comparative Example 2)
A light emitting device was manufactured in the same manner as in Example 7 except that the intermediate layer was formed only with α-NPD without using ADN.

2. Evaluation 2-1. Evaluation of Luminous Efficiency For each example and each comparative example, a constant current of 100 mA / cm ² was passed through the light emitting element using a DC power source, and the luminance (initial luminance) was measured using a luminance meter. In each example and each comparative example, the luminance was measured for five light emitting elements.
Here, for Examples 1 to 6, the light luminance measured in Comparative Example 1 was used as a reference value, and for Example 7, the light luminance measured in Comparative Example 2 was used as a reference value. The brightness of the light measured in Examples 1 to 7 is shown in Table 1.

2-2. Evaluation of Luminous Life For each example and each comparative example, a constant current of 100 mA / cm ² was continuously supplied to the light emitting element using a direct current power source, while the luminance was measured using a luminance meter, and the luminance was the initial luminance. The time (LT80) to be 80% of was measured. In each example and each comparative example, the half-life value was measured for each of five light emitting elements.
For Examples 1-6, the half-life measured in Comparative Example 1 was used as a reference value, and for Example 7, the half-life measured in Comparative Example 2 was used as a reference value. The measured half-life is shown in Table 1.

2-3. Evaluation of Chromaticity For each example and each comparative example, a constant current of 100 mA / cm ² was passed through the light emitting element using a DC power source, and the chromaticity (x, y) of light was obtained using a chromaticity meter.
As can be seen from Table 1, the light-emitting elements of the respective examples are superior in durability while maintaining the same chromaticity balance and light-emitting efficiency as compared with the light-emitting elements of the comparative examples. .

  1, 1A, 1B, 1G, 1R ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Hole injection layer 5 ... Hole transport layer 6 ... Red light emitting layer 7 ... 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, 15 </ b> A laminated body 19 B, 19 G, 19 R …… Color filter 100 …… Display Device 20 ... Sealing substrate 21 ... Substrate 22 ... Planarization layer 23 ... Protection layer 24 ... Driving transistor 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 ...... Partition wall 32 ...... Reflective film 33 …… Corrosion prevention film 34 …… Cathode cover 35 …… Epoxy 36 …… Light-shielding layer 1100 …… Personal computer 1102 …… Keyboard 1104 …… Main body 1106 …… Display unit 1200 …… Cellular phone 1202 …… Operation buttons 1204 …… Earpiece 1206 …… Speaker 1300 …… Digital still Camera 1302 …… Case (Body) 1304 …… Light receiving unit 1306 …… Shutter button 1308 …… Circuit board 1312 …… Video signal output terminal 1314 …… Input / output terminal for data communication 1430 …… TV monitor 1440 …… Personal computer

Claims (9)

A cathode,
The anode,
A first light-emitting layer provided between the cathode and the anode and emitting light in a first color;
A second light-emitting layer provided between the first light-emitting layer and the cathode and emitting light in a second color different from the first color;
It is provided between the first light-emitting layer and the second light-emitting layer so as to be in contact therewith, and the excited state energy moves between the first light-emitting layer and the second light-emitting layer. An intermediate layer having a function of preventing
The intermediate layer is composed of a acene-based material and an amine-based material,
The acene-based material is an anthracene derivative in which a naphthyl group is introduced at each of the 9th and 10th positions of the anthracene skeleton,
The amine-based material is a benzidine-based amine derivative into which two or more naphthyl groups are introduced,
The average thickness of the intermediate layer is 1 to 100 nm.   The light emitting device according to claim 1, wherein the electron mobility of the acene material is higher than the electron mobility of the amine material.   The light emitting element according to claim 1, wherein the hole mobility of the amine material is higher than the hole mobility of the acene material. A third color different from the first color and the second color is provided between the first light emitting layer and the anode or between the second light emitting layer and the cathode. light-emitting device according to any one of claims 1 to 3 having a third light-emitting layer that emits light. The light-emitting element according to claim 4 , wherein the first light-emitting layer is a red light-emitting layer that emits red light as the first color. The third light emitting layer is a green light emitting layer provided between the second light emitting layer and the cathode and emitting green as the third color, and the second light emitting layer is the first light emitting layer. The light-emitting device according to claim 5 , wherein the light-emitting element is a blue light-emitting layer that emits blue light as a second color. The third light emitting layer is a blue light emitting layer provided between the first light emitting layer and the anode and emitting blue as the third color, and the second light emitting layer is the first light emitting layer. The light emitting device according to claim 5 , wherein the light emitting element is a green light emitting layer that emits green light as the second color. Display apparatus comprising: a light-emitting device according to any one of claims 1 to 7. An electronic apparatus comprising the display device according to claim 8 .

Images