JP2009301858A - Light-emitting element, display device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element capable of having excellent luminous efficiency (current efficiency) in a configuration in which light is emitted from a cathode side, and also to provide a display device and electronic equipment capable of displaying a high-quality image over a long period of time. <P>SOLUTION: The light-emitting element 1<SB>R</SB>includes the cathode 12, an anode 3, and a first light-emitting layer 6, a second light-emitting layer 8 and a third light-emitting layer 9 which are provided between the cathode 12 and the anode 3. The cathode 12 has functions which transmit a portion of light from the first light-emitting layer 6, the second light-emitting layer 8 and the third light-emitting layer 9 and reflects the remaining portion thereof. The cathode 12 is equipped with an Ag alloy layer 121 which is configured with a metal material as a main material formed by adding an addition metal having an atomic radius different from that of Ag to Ag. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

An organic electroluminescence element (so-called organic EL element) is a light emitting element having a structure in which at least one light emitting organic layer (light emitting 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 (see, for example, Patent Document 1 and Non-Patent Document 1).
In the so-called top emission type light emitting element, as disclosed in Patent Document 1, generally, the cathode has a semi-transmission property, and light is emitted from the cathode side.

  In the light emitting device according to Patent Document 1, the cathode is made of a thin film of MgAg (Mg: Ag = 9: 1) so that the cathode has electron injecting property and semi-transmitting property. In such a light emitting element, the anode is reflective, and the light generated in the light emitting layer is resonated between the cathode and the anode. Thereby, the brightness | luminance (and by extension, current efficiency) of the light radiate | emitted from a light emitting element can be improved.

However, in the light emitting element according to Patent Document 1, since the cathode is made of MgAg as described above, the reflectance of the cathode with respect to the light generated in the light emitting layer is low. Therefore, the luminance of light emitted from the light emitting element cannot be sufficiently increased.
Ag is generally known as a highly reflective metal. However, when a thin film that is semi-transparent is formed using Ag, fine irregularities due to nuclei in which Ag atoms are aggregated by surface diffusion or surface migration are formed. The thin film which has is formed. Such a thin film has a problem that it exhibits optical characteristics different from that of bulk Ag due to plasmon absorption, and a high reflectance cannot be obtained.

Japanese Patent Laid-Open No. 2003-77681 Hitoshi Kuma. Et. Al ,. SID DIGEST, P1504 (2007)

  An object of the present invention is to provide a light-emitting element that can have excellent light emission efficiency (current efficiency) in a configuration in which light is emitted from the cathode side, and to display a high-quality image over a long period of time. It is an object of the present invention to provide a display device and an electronic device that can perform the above.

Such an object is achieved by the present invention described below.
The light emitting device of the present invention comprises a cathode,
The anode,
Having at least one light emitting layer provided between the cathode and the anode;
The cathode has a function of transmitting a part of the light from the light emitting layer and reflecting the remaining part,
The cathode includes an Ag alloy layer composed mainly of a metal material obtained by adding an additive metal having an atomic radius different from that of Ag to Ag.
Thereby, when forming a thin Ag alloy layer (cathode), a thin film having excellent surface properties (flatness) by preventing generation of fine irregularities due to nuclei in which Ag atoms are aggregated by surface diffusion or surface migration. A shaped Ag alloy layer can be formed. Therefore, it is possible to make the cathode semi-transmissive and have excellent reflectivity. As a result, the luminance of light emitted from the cathode side of the light emitting element can be increased, and the current efficiency of the light emitting element can be improved.

In the light emitting device of the present invention, the difference between the atomic radius of Ag and the atomic radius of the additive metal is preferably 10% or more of the atomic radius of Ag.
Thereby, when forming a thin Ag alloy layer (cathode), it is possible to more reliably prevent the occurrence of fine irregularities due to nuclei in which Ag atoms are aggregated by surface diffusion or surface migration.

In the light emitting device of the present invention, the additive metal is preferably any one of Mg, Cu, Zn, Al, and Nd, or a combination of two or more thereof.
Thereby, the electron injection property of the Ag alloy layer can be made excellent while the reflectance of the Ag alloy layer is made excellent. Further, such an Ag alloy layer can be easily formed by various vapor deposition methods.

In the light emitting device of the present invention, it is preferable that the metal material has an Ag content of 80 to 99.9 atomic% and an additive metal content of 0.1 to 20 atomic%.
Thereby, the reflectance of an Ag alloy layer can be made excellent.
In the light emitting device of the present invention, it is preferable that the cathode includes an injection electrode layer made of a material bonded to the Ag alloy layer and having a work function smaller than that of the metal material.
Thereby, the electron injection property of a cathode can be improved. As a result, the light emission efficiency of the light emitting element can be improved.

In the light emitting device of the present invention, the injection electrode layer is preferably provided on the light emitting layer side with respect to the Ag alloy layer.
Thereby, the electron injection property of the injection electrode layer and the reflection property of the Ag alloy layer can be effectively exhibited.
In the light emitting device of the present invention, it is preferable that the injection electrode layer is composed mainly of an alloy containing at least one of Mg, Al, Ca, Sr, and Ba.
Thereby, the electron injection property and stability of the injection electrode layer (and hence the electron injection property and stability of the cathode) can be made excellent.

In the light emitting device of the present invention, it is preferable to have a reflective layer provided on the opposite side of the light emitting layer from the cathode and having a function of reflecting light from the light emitting layer.
Thereby, the light from the light emitting layer and the reflected light from the cathode are reflected by the reflective layer, and the luminance of the light emitting element can be increased.
The light emitting element of the present invention is preferably configured to resonate light from the light emitting layer between the Ag alloy layer and the reflective layer.
Thereby, the brightness | luminance and color purity of the light radiate | emitted from a light emitting element can be improved.

In the light emitting device of the present invention, the Ag alloy layer is preferably formed using a vacuum deposition method.
As a result, a thin film cathode having excellent surface properties (flatness) can be formed relatively easily.
In the light emitting device of the present invention, the Ag alloy layer is preferably formed by co-evaporation of Ag and the additive metal.
This makes it possible to relatively easily form a thin film cathode having excellent surface properties (flatness) while increasing the range of selection of the additive metal to be used.

In the light emitting device of the present invention, the reflectance of the Ag alloy layer with respect to light from the light emitting layer is preferably 20 to 80%.
Thereby, the brightness | luminance (current efficiency) of the light radiate | emitted from a light emitting element can be improved effectively.
In the light emitting device of the present invention, the Ag alloy layer preferably has a thickness of 1 to 50 nm.
Thereby, the Ag alloy layer can be made semi-transparent (function of transmitting a part of light from the light emitting layer and reflecting the remaining part).

The light emitting device of the present invention preferably has a top emission structure for emitting light from the light emitting layer from the cathode side.
The cathode of such a top emission type light emitting element is semi-transmissive. Therefore, by applying the present invention to such a top emission type light emitting element, a light emitting element having a relatively simple configuration and excellent current efficiency can be provided.

In the light emitting device of the present invention, it is preferable that the at least one light emitting layer is composed of a plurality of light emitting layers having different emission spectra from each other, and the entire light emitting layer of the plurality of layers is configured to emit white light. .
Accordingly, various colors can be separated from one light emitting element and used.
In the light emitting device of the present invention, the at least one light emitting layer includes a red light emitting layer that emits red light, a green light emitting layer that emits green light, and a blue light emitting layer that emits blue light. Is preferred.
Thereby, it is possible to emit white light over the plurality of light emitting layers relatively easily and reliably.

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

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a light emitting device manufacturing method, a display device, and an electronic apparatus according to the present invention are described below with reference to the accompanying drawings.
1 is a schematic cross-sectional view illustrating an example of a display device (display device) including the light-emitting element of the present invention, and FIG. 2 schematically illustrates a vertical cross-section of the light-emitting element included in the light-emitting device illustrated in FIG. FIG. In the following description, for convenience of explanation, the upper side in FIG. 1 and FIG. 2 will be described as “upper” and the lower side as “lower”.

(Display device)
Display device shown in FIG. 1 100, a plurality of light-emitting elements _{1 R,} 1 G, and the light emitting device 101 comprising a _{1 B,} the light-emitting elements _{1 R,} 1 G, ₁ filter unit 19 provided corresponding to the _{B R} , 19 _G and 19 _B.
In such a display device 100, a plurality of light emitting elements 1 _R , 1 _G , 1 _B and a plurality of filter units 19 _R , 19 _G , 19 _B are provided corresponding to the sub-pixels 100 _R , 100 _G , 100 _B. It constitutes a display panel with a top emission structure.
In the present embodiment, an example in which an active matrix method is employed as a display device driving method will be described. However, a passive matrix method may be employed.
The light emitting device 101 includes a substrate 21, a plurality of light emitting elements 1 _R , 1 _G , 1 _B, and a plurality of switching elements 24.

The substrate 21 supports the plurality of light emitting elements 1 _R , 1 _G , 1 _B and the plurality of switching elements 24. Each light emitting element 1 _R , 1 _G , 1 _B of the present embodiment has a configuration for extracting light from the side opposite to the substrate 21 (top emission type). Accordingly, the substrate 21 can be either a transparent substrate or an opaque substrate. In the case where the light-emitting elements 1 _R, 1 _G, 1 _B is a structure in which light is extracted from the substrate 21 side (bottom emission type), the substrate 21 is substantially transparent (colorless and transparent, colored transparent or semi-transparent ).

  Examples of the constituent material of the substrate 21 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.

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.
Although the average thickness of such a board | substrate 21 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.
On such a substrate 21, a plurality of switching elements 24 are arranged in a matrix.

Each switching element 24 is provided corresponding to the respective light emitting elements _{1 R, 1 G, 1 B} , a driving transistor for driving the light emitting elements _{1 R, 1 G, 1 B} .
Each switching element 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.
A planarizing layer 22 made of an insulating material is formed so as to cover the plurality of switching elements 24.

On the planarization layer 22, light emitting elements 1 _R , 1 _G , 1 _B are provided corresponding to the switching elements 24.
The light emitting element 1 _R is configured by laminating a reflective film 32, a corrosion preventing film 33, an anode 3, a laminate (organic EL light emitting unit) 15, a cathode 12, and a cathode cover 34 in this order on a planarizing layer 22. Yes. In this embodiment, the anode 3 of each light emitting element 1 _R , 1 _G , 1 _B constitutes a pixel electrode, and is electrically connected to the drain electrode 245 of each driving transistor 24 by a conductive portion (wiring) 27. Yes. The cathode 12 of the light-emitting elements _{1 R, 1 G, 1 B} is a common electrode.

The light emitting elements 1 _R , 1 _G , and 1 _B will be described in detail later.
A partition wall 31 is provided between the adjacent light emitting elements 1 _R , 1 _G , 1 _B.
The color filter 102 is bonded to the light emitting device 101 configured as described above via a resin layer 35 formed of a thermosetting resin such as an epoxy resin.
The color filter 102 includes a substrate 20, a plurality of filter parts 19 _R , 19 _G , 19 _B, and a light shielding part 36.

The substrate (sealing substrate) 20 supports the filter portions 19 _R , 19 _G , 19 _B and the light shielding layer 36. A transparent substrate is used as the substrate 20.
Such a constituent material of the substrate 20 is not particularly limited as long as the substrate 20 is light transmissive, and the same constituent materials as those of the substrate 21 described above can be used.
The filter units 19 _R , 19 _G , and 19 _B are provided corresponding to the light emitting elements 1 _R , 1 _G , and 1 _B.

Filter unit 19 _R is for converting light _{W R} from the light emitting element _{1 R} red. The filter unit 19 _G is for converting light _{W G} from the light-emitting element _{1 G} to green. The filter unit 19 _B is for converting light _{W B} from the light-emitting element _{1 B} to blue. By using such filter units 19 _R , 19 _G , and 19 _{B in combination} with the light emitting elements 1 _R , 1 _G , and 1 _B , a full color image can be displayed.
A light shielding layer 36 is formed between adjacent filter portions 19 _R , 19 _G , 19 _B.
The light shielding layer 36 has a function of preventing unintended subpixels 100 _R , 100 _G , and 100 _B from emitting light.

(Light emitting element)
Here, based on FIG. 2, the light emitting elements 1 _R , 1 _G , and 1 _B will be described in detail.
The light-emitting elements (electroluminescent elements) 1 _R 1, 1 _G , and 1 _B shown in FIG. 2 are respectively R (red), G having different emission spectra between two electrodes (between the anode 3 and the cathode 12). A laminate 15 including three light emitting layers of (green) and B (blue) is interposed. As shown in FIG. 2, the laminate 15 includes a hole injection layer 4, a hole transport layer 5, a first light emitting layer (red light emitting layer) 6, and an intermediate layer 7 from the anode 3 side to the cathode 12 side. A second light emitting layer (blue light emitting layer) 8, a third light emitting layer (green light emitting layer) 9, an electron transport layer 10, and an electron injection layer 11 are laminated in this order.

In other words, each light emitting element 1 _R , 1 _G , 1 _B includes the anode 3, the hole injection layer 4, the hole transport layer 5, the first light emitting layer 6, the intermediate layer 7, and the second light emitting layer 8. The third light emitting layer 9, the electron transport layer 10, the electron injection layer 11, and the cathode 12 are laminated in this order.
In this embodiment, a reflective film 32 and a corrosion prevention film 33 are provided between the anode 3 and the planarizing layer 22, and a cathode cover (sealing) is provided on the opposite side of the cathode 12 from the laminate 15. Layer) 34 is provided.

In each of the light emitting elements 1 _R , 1 _G , and 1 _B , the cathode 12 side with respect to the light emitting layers of the first light emitting layer 6, the second light emitting layer 8, and the third light emitting layer 9. Electrons are supplied (injected) from, and holes are supplied (injected) from the anode 3 side. In each light emitting layer, holes and electrons recombine, and excitons (excitons) are generated by the energy released during the recombination, and energy (fluorescence or phosphorescence) is generated when the excitons return to the ground state. Is emitted (emitted).

In each of such light emitting elements 1 _R , 1 _G , 1 _B , the first light emitting layer 6, the second light emitting layer 8, and the third light emitting layer 9 are composed of a plurality of light emitting layers having different emission spectra. In addition, the entire light emitting layer of the plurality of layers is configured to emit white light. Therefore, while the light emitting elements 1 _R , 1 _G , and 1 _B have light emitting layers having the same configuration, desired colors can be separated and used by the light emitting elements 1 _R , 1 _G , and 1 _B , respectively. That is, various colors can be separated from one light emitting element.

In particular, since R, G, and B are combined to emit white light in the entire light emitting layer, white light can be emitted in the entire light emitting layer in a relatively simple and reliable manner.
Hereinafter, it will be described in order components constituting the light-emitting element 1 _R. Hereinafter, the light emitting element 1 _R will be described as a representative. The light-emitting elements 1 _G and 1 _B will be described with a focus on matters different from the light-emitting element 1 _R, and the description of the same matters will be omitted.

(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 anode 3 has a thickness such that a distance between an Ag alloy layer 121 of the cathode 12 described later and the reflection film 32 corresponds to the wavelength of light emitted from the light emitting element 1 _R (red wavelength). Is preferably adjusted.

Incidentally, the anode 3 For the light emitting element 1 _G, the distance is as the so that the thickness becomes that depends on the wavelength of the light emitted from the light emitting element 1 _G (green wavelength) between the Ag alloy layer 121 and the reflective film 32 There is preferable to be adjusted, also, the anode 3 for the light emitting element 1 _B, the wavelength distance of the light emitted from the light emitting element 1 _B between the Ag alloy layer 121 and the reflective film 32 (wavelength of blue) It is preferable that the thickness is adjusted so as to comply. This can increase the brightness of the desired chromaticity of the light emitting element 1 _R, 1 _G, 1 each emitted light _B. In this case, the thicknesses of the anodes 3 of the light emitting elements 1 _R , 1 _G and 1 _B are different from each other according to the wavelength of the emitted light.
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.
In the present embodiment, the anode 3 has optical transparency. Thereby, the reflective film 32 can reflect the light from each light emitting layer.

(Hole injection layer)
The hole injection layer 4 has a function of improving the hole injection efficiency from the anode 3 (that is, hole injection property).
The constituent material (hole injection material) of the hole injection layer 4 is not particularly limited as long as the hole injection layer 4 exhibits hole injection properties as described above. For example, copper phthalocyanine or N, N′-bis- (4-diphenylamino-phenyl) -N, N′-diphenyl-biphenyl-4,4′-diamine represented by the following chemical formula 1, 4,4 ′, 4 ″ -tris (N, N-phenyl-3-methylphenylamino) triphenylamine (m-MTDATA), N, N′-di (naphthylene-1-yl) -N, N represented by the following chemical formula 3 '-Bidiphenyl-benzidine (NPD) and the like can be mentioned, and one or more of these can be used in combination.

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.
(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 first 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. For example, N, N′-di (1-naphthyl) ) -N, N′-diphenyl-1,1′-diphenyl-4,4′-diamine (NPD), N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1 ′ -A tetraarylbenzidine derivative such as -diphenyl-4,4'-diamine (TPD), a tetraaryldiaminofluorene compound or a derivative thereof (amine-based compound), etc. may be mentioned, and one or more of these may be combined Can be used.
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.

(First light emitting layer)
The first light-emitting layer 6 includes a first light-emitting material that emits light in a first color and a first host material that uses the first light-emitting material as a guest material. Such a first light-emitting layer 6 can be formed, for example, by doping the first host material as a dopant with the first light-emitting material that is a guest material. Note that the first host material can be omitted.
The first light emitting material is a red light emitting material that emits red light.
Such a red light emitting material is not particularly limited, and a red fluorescent material can be suitably used by using various red fluorescent materials and red phosphorescent materials in combination of one or more kinds.

  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 12 side can be reliably captured by the first light-emitting layer 6 and can be prevented from being injected into the hole transport layer 5. As a result, it is possible to prevent the constituent materials of the hole injection layer 4 and the hole transport layer 5 from being reduced and deteriorated by electrons.
In particular, as the perylene derivative used for the red light emitting material, for example, a tetraphenyldiindenoperylene derivative such as a compound represented by the following chemical formula 4 is preferably used.

The first host material having such a red light emitting material as a guest material recombines holes and electrons to generate excitons, and transfers the exciton energy to the red light emitting material (Förster transfer). Or a Dexter movement) to excite the red light emitting material.
Such a first host material is not particularly limited as long as it exhibits the above-described function with respect to the red light emitting material to be used. When the red light emitting material includes a red fluorescent material, for example, Styrylarylene derivatives, tetracene derivatives (naphthacene derivatives) such as compounds represented by the following chemical formula 5, anthracene derivatives such as compounds represented by the chemical formula 6 below, perylene derivatives, distyrylbenzene derivatives, distyrylamine derivatives, tris (8-quinolinolato) ) Quinolinolato metal complexes such as aluminum complexes (Alq ₃ ), triarylamine derivatives such as tetramers of triphenylamine, oxadiazole derivatives, silole derivatives, dicarbazole derivatives, oligothiophene derivatives, benzopyran derivatives, triazole derivatives, Benzoxazole Examples include conductors, benzothiazole derivatives, quinoline derivatives, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi), and one of these may be used alone or in combination of two or more. You can also.

Among these, the first light emitting material preferably includes a tetracene derivative or a perylene derivative as described above. Thereby, holes from the first light emitting layer 6 to the second light emitting layer 8 can be transferred more smoothly through the intermediate layer 7.
Further, when the red light emitting material includes a red phosphorescent material, examples of the first host material include 3-phenyl-4- (1′-naphthyl) -5-phenylcarbazole, 4,4′-N, N ′. -Carbazole derivatives, such as dicarbazole biphenyl (CBP), 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 (guest material) and the first host material as described above are used, the content (dope amount) of the red light emitting material in the first light emitting layer 6 is 0.1 to 10 wt%. Is preferable, and it is more preferable that it is 1-5 wt%. By setting the content of the red light emitting material in such a range, the light emission efficiency can be optimized, and the amount of light emitted from the second light emitting layer 8 and the third light emitting layer 9 described later is balanced. In addition, the first light emitting layer 6 can emit light.

Further, since the red light emitting material as described above has a relatively small band gap, it easily emits light. Therefore, by providing the red light emitting layer closest to the anode 3, the blue light emitting layer and the green light emitting layer, which have a relatively large band gap and are difficult to emit light, can be set to the cathode 12 side, and each light emitting layer can emit light in a balanced manner.
Moreover, the average thickness of the 1st light emitting layer 6 is although it does not specifically limit, 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.

(Middle layer)
The intermediate layer 7 is provided between and in contact with the first light-emitting layer 6 and the second light-emitting layer 8 described later. The intermediate layer 7 has a function of preventing exciton energy from moving between the first light emitting layer 6 and the second light emitting layer 8. With this function, the first light emitting layer 6 and the second light emitting layer 8 can each emit light efficiently.

The constituent material of the intermediate layer 7 is not particularly limited as long as the intermediate layer 7 can exhibit the functions as described above, and an amine material or the like can be used.
The amine-based material used for the intermediate layer 7 is not particularly limited as long as it has an amine skeleton and the intermediate layer 7 exhibits the function described above. Among the hole transport materials, materials having an amine skeleton can be used, but benzidine-based amine derivatives are 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] -4,4′-diamine (α-NPD). And N, N, N ′, N′-tetranaphthyl-benzidine (TNB) and the like.

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 first light emitting layer 6 to the second 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.

(Second light emitting layer)
The second light-emitting layer 8 includes a second light-emitting material that emits light in the second color and a second host material that uses the second light-emitting material as a guest material. Similar to the first light emitting layer 6 described above, the second light emitting layer 8 can be formed, for example, by doping the second host material as a dopant with the second light emitting material as a guest material. it can. Note that the second host material can be omitted.
The second light emitting material is a blue light emitting material that emits blue light.
Such a blue light-emitting material is not particularly limited, and a blue fluorescent material can be suitably used by using various blue fluorescent materials and blue phosphorescent materials in combination of one or more.

  The blue fluorescent material is not particularly limited as long as it emits blue fluorescence. For example, a distyryldiamine derivative, a distyryl derivative, a fluoranthene derivative, a pyrene derivative, a perylene, and a perylene derivative such as a compound represented by the following chemical formula 7 , Anthracene derivative, benzoxazole derivative, benzothiazole derivative, benzimidazole derivative, chrysene derivative, phenanthrene derivative, distyrylbenzene derivative, tetraphenylbutadiene, 4,4′-bis (9-ethyl-3-carbazovinylene) -1,1 '-Biphenyl (BCzVBi), poly [(9.9-dioctylfluorene-2,7-diyl) -co- (2,5-dimethoxybenzene-1,4-diyl)], poly [(9,9-dihexyl) Oxyfluorene-2,7-diyl)- L-co- (2-methoxy-5- {2-ethoxyhexyloxy} phenylene-1,4-diyl)], poly [(9,9-dioctylfluorene-2,7-diyl) -co- (ethylnyl) Benzene)] and the like, and one of these may be used alone or in combination of two or more.

In particular, since the distyryldiamine derivative such as the compound represented by Chemical Formula 7 as described above is excellent in the function of capturing holes, the second light emitting layer 8 contains a distyryldiamine derivative. The second light emitting layer 8 can emit light efficiently.
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 the second host material, the same material as the first host material of the first light emitting layer 6 described above can be used.
When the blue light emitting material (guest material) and the second host material as described above are used, the content (dope amount) of the blue light emitting material in the second light emitting layer 8 is 0.1 to 20 wt%. Is preferable, and it is more preferable that it is 5-20 wt%. By setting the content of the blue light emitting material in such a range, the light emission efficiency can be optimized, and the balance with the light emission amount of the first light emitting layer 6 described above and the third light emitting layer 9 described later. The second light emitting layer 8 can emit light while taking
The average thickness of the second light emitting layer 8 is not particularly limited, but is preferably 1 to 100 nm, more preferably 5 to 60 nm, and further preferably 10 to 40 nm.

(Third light emitting layer)
The third light-emitting layer 9 includes a third light-emitting material that emits light in the third color and a third host material that uses the third light-emitting material as a guest material. Similar to the first light emitting layer 6 described above, the third light emitting layer 9 can be formed, for example, by doping a third host material as a dopant with a third light emitting material as a guest material. it can. Note that the third host material can be omitted.

The third light emitting material is a green light emitting material that emits green light.
Such a green light emitting material is not particularly limited, and a green fluorescent material can be suitably used by using various green fluorescent materials and green phosphorescent materials in combination of one or more kinds.
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 represented by the following chemical formula 8, 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-ethoxylhexyloxy) -1,4-phenylene)] and the like, and one of these may be used alone or in combination of two or more. That.

  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.

As the third host material, the same material as the first host material of the first light emitting layer 6 described above can be used.
When the green light emitting material (guest material) and the third host material as described above are used, the content (dope amount) of the green light emitting material in the third light emitting layer 9 is 0.1 to 20 wt%. Is preferable, and it is more preferable that it is 1-20 wt%. By setting the content of the green light emitting material within such a range, it is possible to optimize the light emission efficiency, and to balance the light emission amounts of the first light emitting layer 6 and the second light emitting layer 8 described above. In addition, the third light emitting layer 9 can emit light.
Moreover, the average thickness of the 3rd light emitting layer 9 is although it does not specifically limit, It is preferable that it is 1-100 nm, It is more preferable that it is 5-60 nm, It is further more preferable that it is 10-40 nm.

(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 third 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.
The electron transport layer 10 can be omitted.

(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, an alkali metal compound (alkali metal chalcogenide, alkali metal halide, etc.) has a very small work function, and the light-emitting element 1 _R can obtain high luminance by forming the electron injection layer 11 using the work function. It becomes.

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 100 nm, more preferably about 0.2 to 10 nm, and about 0.2 to 5 nm. Further preferred.
The electron injection layer 11 can be omitted.

(cathode)
The cathode 12 is an electrode that injects electrons into the electron transport layer 10 via the electron injection layer 11 described above.
The cathode 12 has a function of transmitting a part of light from at least one of the first light-emitting layer 6, the second light-emitting layer 8, and the third light-emitting layer 9 and reflecting the remainder. It also has. Thereby, the light emitting element _1R can emit light from the cathode 12 side. Further, it is possible to improve the luminous efficiency of the light-emitting element 1 _R by effectively utilizing the light reflected by the cathode 12.

In the present embodiment, the cathode 12 includes an Ag alloy layer 121 and an injection electrode layer 122.
The Ag alloy layer 121 is composed mainly of a metal material obtained by adding an additive metal having an atomic radius different from that of Ag to Ag.

Such a metal material can prevent Ag atoms from aggregating due to surface diffusion and surface migration when the thin film is formed. Therefore, the thin film obtained has excellent surface properties (flatness) by preventing the occurrence of fine irregularities due to nuclei in which Ag atoms are aggregated. Therefore, the Ag alloy layer 121 mainly composed of such a metal material can have excellent reflectivity while having translucency. Therefore, the cathode 12 provided with such an Ag alloy layer 121 can have excellent reflectivity while having translucency. As a result, increase the intensity of the light emitted from the light emitting element 1 _R, it is possible to improve the current efficiency of the light emitting element 1 _R.

  The additive metal is not particularly limited as long as it is a metal having an atomic radius different from the atomic radius of Ag (metal bond radius) and can form an Ag alloy, and various metals can be used. It is preferable to use a metal in which the difference between the atomic radius and the atomic radius of the added metal is 10% or more of the atomic radius of Ag. Thereby, when forming the thin Ag alloy layer 121 (cathode 12), it is possible to more surely prevent the occurrence of fine irregularities due to nuclei in which Ag atoms are aggregated by surface diffusion or surface migration.

Among the additive metals having such an atomic radius, it is preferable to use a material having a small work function as the additive metal. Specifically, the additive metal is preferably any one of Mg, Cu, Zn, Al, and Nd, or a combination of two or more of these, and Mg and Cu are particularly preferable. Can be used.
Thereby, it is possible to make the electron injection property of the Ag alloy layer 121 excellent while making the reflectance of the Ag alloy layer 121 excellent. Such an Ag alloy layer 121 can be easily formed by various vapor deposition methods.

  Further, the metal material preferably has an Ag content of 80 to 99.9 atomic%, an additive metal content of 0.1 to 20 atomic%, and an Ag content of 90 to 99.9. It is more preferable that the content of the additive metal is 0.1 to 10 atomic%. Thereby, the reflectance of the Ag alloy layer 121 can be made excellent. On the other hand, if the Ag content exceeds the upper limit value or the additive metal content is less than the lower limit value, depending on the thickness of the Ag alloy layer 121, the type of the additive metal, etc., Minute unevenness may occur. On the other hand, when the Ag content is less than the lower limit or the additive metal content exceeds the upper limit, the reflectivity of the Ag alloy layer 121 depends on the thickness of the Ag alloy layer 121, the type of the added metal, and the like. Shows a tendency to decrease.

In addition, the Ag alloy layer 121 is preferably formed using a vapor phase film forming method. Thereby, the thin-film Ag alloy layer 121 (cathode 12) having excellent surface properties (flatness) can be formed relatively easily.
In particular, the Ag alloy layer 121 is preferably formed by co-evaporation of Ag and an additive metal. Thereby, it is possible to relatively easily form the thin-film Ag alloy layer 121 (cathode 12) having excellent surface properties (flatness) while increasing the range of selection of the additive metal to be used.

The reflectance of the Ag alloy layer 121 for the light from the light-emitting layer (the desired wavelength emitted from the light emitting element _{1 R)} is preferably from 20 to 80%, and more preferably from 40 to 80. This can increase the brightness of the light emitted from the light emitting element 1 _R (current efficiency) effectively.
In addition, the thickness of the Ag alloy layer 121 is not particularly limited as long as it can exhibit the function as described above, but is preferably 1 to 50 nm, and more preferably 1 to 30 nm. Thereby, the Ag alloy layer 121 can be made semi-transmissive (function of transmitting a part of light from the light emitting layer and reflecting the remaining part). On the other hand, when the thickness is less than the lower limit, it is difficult to form a homogeneous Ag alloy layer 121 depending on the constituent material of the Ag alloy image 121 and the like. On the other hand, when the thickness exceeds the upper limit, depending on the constituent material of the Ag alloy layer 121, it is difficult to make the Ag alloy layer 121 semi-permeable.

The injection electrode layer 122 is bonded to the Ag alloy layer 121 and is made of a material having a work function smaller than that of the metal material of the Ag alloy layer 121 described above. By providing the injection electrode layer 122 with the cathode 12, the electron injection property of the cathode 12 can be improved. As a result, the light emission efficiency of the light emitting element _1R can be improved.
Further, the injection electrode layer 122 is provided on the light emitting layer side (the side opposite to the substrate 21) with respect to the Ag alloy layer 121. Thereby, since the injection electrode layer 122 comes into contact with the electron injection layer 11, the electron injection property of the injection electrode layer 122 can be effectively exhibited. As a result, the electron injection property of the injection electrode layer 122 and the reflection property of the Ag alloy layer 121 can be effectively exhibited. Here, the injection electrode layer 122 has optical transparency.

Examples of the constituent material of the injection electrode layer 122 include Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, Yb, Ag, Cu, Al, Cs, Rb, and the like. An alloy etc. are mentioned, It can be used combining 1 type, or 2 or more types of these (for example, a laminated body of a plurality of layers, etc.).
In particular, when an alloy is used as the constituent material of the injection electrode layer 122, an alloy containing a stable metal element such as Mg, Al, Ca, Sr, or Ba, specifically, an alloy such as MgAg or MgAl is used. Is preferred. By using such an alloy as a constituent material of the injection electrode layer 122, the electron injection efficiency and stability of the injection electrode layer 122 (and thus the cathode 12) can be made excellent.

The average thickness of the injection electrode layer 122 is not particularly limited, but is preferably about 1 to 100 nm, and more preferably about 1 to 50 nm.
The thickness of the injection electrode layer 122 is adjusted so that the distance L between the Ag alloy layer 121 and the reflective film 32 corresponds to the wavelength of light emitted from the light emitting element 1 _R (red wavelength). May be. That is, the thicknesses of the injection electrode layers 122 of the light emitting elements 1 _R , 1 _G , and 1 _B may be different from each other according to the wavelength of the emitted light.
The injection electrode layer 122 can be omitted when the Ag alloy layer 121 has a sufficient electron injection property.

(Reflective film)
The reflective film (reflective layer) 32 is provided on the side opposite to the cathode 12 with respect to the first light emitting layer 6, the second light emitting layer 8, and the third light emitting layer 9 described above. That is, the first light emitting layer 6, the second light emitting layer 8, and the third light emitting layer 9 are provided between the reflective film 32 and the cathode 12.
Such a reflective film 32 has a function of reflecting light from at least one of the first light emitting layer 6, the second light emitting layer 8, and the third light emitting layer 9. This allows the reflected light from the optical and the cathode 12 from at least one layer of the light-emitting layer is reflected by the reflecting film 32, increasing the luminance of the light emitting element 1 _R. As a result, the light emission efficiency of the light emitting element _1R can be improved.

The reflective film 32 is preferably configured to resonate light from at least one light emitting layer with the Ag alloy layer 121 described above. This makes it possible to increase the strength and color purity of light emitted from the light-emitting element 1 _R. In this case, the reflective film 32 can resonate light with the cathode 12 by setting the distance L to the cathode 12 (Ag alloy layer 121) to a desired value. More specifically, when the wavelength of the chromaticity whose luminance is desired to be increased is λ, the distance L is set to about nλ / 2 while taking into account the phase change at the time of light reflection at the reflective film 32 or the Ag alloy layer 121. (Where n is a natural number).

The constituent material of the reflective film 32 is not particularly limited as long as the reflective film 32 can exhibit the above-described function, and Al, Ni, Co, Ag, an alloy containing these, or the like Can be used.
The reflective film 32 can also be formed of a dielectric multilayer film (optical multilayer thin film) in which high refractive index layers and low refractive index layers are alternately stacked.

The material constituting the high refractive index layer, for _{example, Ti 2 O, Ta 2 O} 5, niobium _{oxide, Al 2 O 3, HfO 2} , ZrO 2, although ThO ₂ and the like, in particular, _Ti 2 O, Ta ₂ O ₅ , niobium oxide and the like are preferably used.
Examples of the material constituting the low refractive index layer include MgF ₂ and SiO ₂ , and SiO ₂ is particularly preferably used.

The number and thickness of the high refractive index layer and the low refractive index layer constituting the reflection film 32 are set according to the required optical characteristics. In general, when a reflective film is formed of a dielectric multilayer film, the number of layers required to obtain the optical characteristics is 12 or more.
In the present embodiment, since the light-emitting element 1 _R is a top emission type, light transmitting the reflective film 32 is not required.

The thickness of the reflective film 32 is not particularly limited as long as it exhibits the function described above, but is preferably about 10 to 1000 nm.
The reflective film 32 can be omitted. In this case, the same effect as that of the reflective film 32 can be exhibited by configuring the above-described anode 3 to have reflectivity. Thus, while also maintaining a simple layer structure of the light-emitting element 1 _R, the reflected light from the optical and the cathode 12 from the light-emitting layer is reflected by the anode 3, it is possible to increase the luminance of the light emitting element 1 _R.

(Corrosion prevention film)
The corrosion prevention film 33 has a function of preventing the reflection film 32 from being corroded.
The constituent material of the corrosion prevention film 33 is not particularly limited as long as the corrosion prevention film 33 exhibits the function described above and does not impair the function of the reflection film 32 described above. Inorganic materials can be used.
The corrosion prevention film 33 may be omitted.

(Cathode cover)
The cathode cover 34 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 cathode cover 34, effects such as improvement of the reliability of the light emitting element 1 _R and prevention of deterioration / deterioration (improvement of durability) can be obtained.

  Examples of the constituent material of the cathode cover 34 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 cathode cover 34, in order to prevent a short circuit, between the cathode cover 34 and the anode 3, the laminated body 15, and the cathode 12 as needed. Thus, an insulating film is preferably provided.

In this embodiment, the resin layer 35 (sealing layer) and the color filter 102 (sealing member) shown in FIG. 1 are also provided so as to cover the anode 3, the laminate 15, and the cathode 12. Sealing, and has a function of blocking oxygen and moisture.
According to the light emitting device 1 _R configured as described above, since the cathode 12 includes the Ag alloy layer 121, Ag atoms are aggregated by surface diffusion or surface migration when the thin film cathode 12 is formed. Generation of fine irregularities due to nuclei can be prevented, and a thin film cathode 12 having excellent surface properties (flatness) can be formed. Therefore, the cathode 12 can be made to have excellent reflectivity while having translucency. As a result, increase the intensity of the light emitted from the light emitting element 1 _R, it is possible to improve the current efficiency of the light emitting element.
Such invention, by applying the light-emitting element 1 _R of the top emission type, it is possible to provide a light-emitting element 1 _R with a current efficiency excellent with a relatively simple configuration.

(Manufacturing method of light emitting element)
The light emitting element 1 _R configured as described above can be manufactured, for example, as follows.
[1] First, the substrate 21 is prepared, and the reflective film 32, the corrosion prevention layer 22, and the anode 3 are laminated on the substrate 21 in this order.
The reflective film 32, the corrosion prevention layer 22 and the anode 3 are respectively formed by, for example, chemical vapor deposition (CVD) such as plasma CVD and thermal CVD, dry plating such as vacuum deposition, wet plating such as electrolytic plating, and thermal spraying. Sol-gel method, MOD method, metal foil bonding, and 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 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 first light emitting layer 6 is formed on the hole transport layer 5.
The first light emitting layer 6 can be formed by, for example, a vapor phase process using a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like.
[5] Next, the intermediate layer 7 is formed on the first 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 second light emitting layer 8 is formed on the intermediate layer 7.
The second 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, or the like.
[7] Next, the third light emitting layer 9 is formed on the second light emitting layer 8.
The third 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.

[8] Next, the electron transport layer 10 is formed on the third 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.
In addition, the electron transport layer 10 is dried (desolvent or solvent-free) 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 third light emitting layer 9. It can also be formed by dedispersing 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. More specifically, the injection electrode layer 122 and the Ag alloy layer 121 are laminated on the electron injection layer 11 in this order.
The injection electrode layer 122 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, or the like.

A method for forming the Ag alloy layer 121 is not particularly limited, but a vapor deposition method (vapor phase process) using a CVD method, a dry plating method such as vacuum deposition, sputtering, or the like can be suitably used. In particular, it is preferable to use a vacuum evaporation method.
In forming the Ag alloy layer 121 using the vacuum evaporation method, it is preferable to co-evaporate Ag and the additive metal.
Through the steps as described above, the light emitting element 1 _R is obtained.
The display device 100 (the display device of the present invention) as described above can be incorporated into various electronic devices.

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

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

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

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

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

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

  The electronic apparatus of the present invention includes, for example, a television, a video camera, a viewfinder type, in addition to the personal computer (mobile personal computer) in FIG. 3, the mobile phone in FIG. 4, and the digital still camera in FIG. Monitor direct-view video tape recorder, laptop personal computer, car navigation system, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV Monitors, electronic binoculars, POS terminals, devices equipped with touch panels (for example, cash dispensers and automatic ticket vending machines for financial institutions), medical devices (for example, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiographs, ultrasound diagnostic devices, internal Endoscope display device), fish finder, various measuring instruments, Vessels such (e.g., gages for vehicles, aircraft, and ships), a flight simulator, various monitors, and a projection display such as a projector.

The light emitting element, the 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, each light emitting element has been described as having three light emitting layers. However, the light emitting layer may be one layer, two layers, or four layers or more. 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. For example, when there are two light emitting layers, white light can be emitted by combining a blue light emitting layer and a yellow light emitting layer.

Next, specific examples of the present invention will be described.
1. Measurement of surface roughness of film A film composed of Ag (sample 1) and a film composed of Ag alloy (samples 2 to 5) were formed on a glass substrate by vacuum deposition. Here, as a constituent material of each film, Ag in sample 1, AgMg (Ag: Mg = 10: 1) in sample 2, AgCu (Ag: Cu = 10: 1) in sample 3, AgZn (Ag: Zn = 10: 1) and Sample 5 were made of AgNd (Ag: Nd = 10: 1), and the thicknesses of Samples 1 to 5 were 10 nm.
And about each sample 1-5, surface roughness (root mean square surface roughness [nm]) was measured using AFM (atomic force microscope). The results are shown in Table 1.

  As is clear from Table 1, the films of Samples 2 to 5 using an Ag alloy all have extremely superior flatness than the film of Sample 1 using Ag (that is, reflection of light). It is understood that the property is excellent. In particular, the flatness of the film of Sample 2 using AgMg was excellent.

2. Production of light-emitting elements (Examples)
<1> First, a transparent glass substrate having an average thickness of 0.5 mm was prepared. Next, an Ag reflective film and an ITO electrode (anode) were formed on the substrate in this order by sputtering. Here, the average thickness of the ITO electrode for the R pixel was 110 nm, the average thickness of the ITO electrode for the G pixel was 70 nm, and the average thickness of the ITO electrode for the B pixel was 30 nm. The average thickness of the Ag reflection film was 100 nm.
And after immersing a board | substrate in order of acetone and 2-propanol and ultrasonically cleaning, the oxygen plasma process was performed.

<2> Next, a tetraamine compound represented by 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, on the hole injection layer, NPD represented by the above chemical formula 3 was vapor-deposited by a vacuum vapor 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, a compound represented by the above chemical formula 4 was used as a red light emitting material (guest material), and a compound represented by the above chemical formula 5 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, NPD represented by the above chemical formula 3 was used as an amine-based material.
<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, a compound represented by the above chemical formula 7 was used as a blue light emitting material, and a compound represented by the above chemical formula 6 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 6.0 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, a compound represented by the above chemical formula 8 was used as a green light emitting material (guest material), and a compound represented by the above chemical formula 6 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 1.0 wt%.

<8> Next, on the green 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 10 nm.
<9> Next, on the electron transport layer, LiF was deposited by a vacuum deposition method to form an electron injection layer having an average thickness of 1 nm.
<10> Next, an MgAg (Mg: Ag = 10: 1) film was formed on the electron injection layer by a vacuum evaporation method to form an injection electrode layer having an average thickness of 5 nm.

<11> Next, AgMg (Ag: Mg = 10: 1) was formed on the injection electrode layer by a vacuum evaporation method (co-evaporation method) to form an Ag alloy layer having an average thickness of 12 nm.
As described above, a light emitting element for each of R, G, and B pixels was formed on the substrate.
(Comparative example)
A light emitting element for each of R, G, and B pixels was manufactured in the same manner as in Example 1 except that the Ag alloy layer was omitted and the average thickness of the injection electrode layer was 10 nm.

3. Evaluation Regarding the light-emitting elements of the pixels of the examples and comparative examples, a constant current of 10 mA / cm ² was passed to each light-emitting element using a DC power source, and the luminance of each light-emitting element was measured using a luminance meter. Luminous efficiency was calculated from the results, and the results are shown in Table 2.

In addition, with respect to the light-emitting elements of the pixels of the examples and comparative examples, a constant current of 10 mA / cm ² was passed through each light-emitting element using a DC power source, and the driving voltage at that time is shown in Table 2.
As can be seen from Table 2, each light emitting device of the example has higher brightness and superior current efficiency than each light emitting device of the comparative example. In addition, each of the light emitting elements of the example could reduce the driving voltage as compared with each of the light emitting elements of the comparative example.

It is typical sectional drawing which shows an example (display apparatus) of a display apparatus provided with the light emitting element of this invention. It is a figure which shows typically the longitudinal cross-section of the light emitting element with which the light-emitting device shown in FIG. 1 was equipped. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 _B , 1 _G , 1 _R ... Light emitting element 2 ... Substrate 3 ... Anode 4 ... Hole injection layer 5 ... Hole transport layer 6 ... 1 light emitting layer (red light emitting layer) 7 ... ... Intermediate layer 8 …… Second light emitting layer (blue light emitting layer) 9 …… Third light emitting layer (green light emitting layer) 10 …… Electron transport layer 11 …… Electron injection layer 12 …… Cathode 15 …… Laminate 19 _B , 19 _G , 19 _R ...... Filter 100 ...... Display device 100 _B , 100 _R , 100 _G ...... Subpixel 101 ...... Light emitting device 102 ...... Color filter 121 ...... Ag alloy layer 122 ...... Injection electrode layer 20 …… Substrate (sealing substrate) 21 …… Substrate 22 …… Planarization layer 23 …… Protective layer 24 …… Drive 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 .. Reflecting film 33 .. Corrosion-preventing film 34 .. Cathode cover 35 .. Resin layer 36. 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 ...... receiving unit 1306 ...... shutter button 1308 ...... circuit board 1312 ...... video signal output terminal 1314 ...... output terminal 1430 ...... television monitor 1440 ...... personal computer W _B for data communication, _W G, _{W R} ……light

Claims (18)

A cathode,
The anode,
Having at least one light emitting layer provided between the cathode and the anode;
The cathode has a function of transmitting a part of the light from the light emitting layer and reflecting the remaining part,
The light-emitting element, wherein the cathode includes an Ag alloy layer composed mainly of a metal material obtained by adding an additive metal having an atomic radius different from that of Ag to Ag.   The light emitting device according to claim 1, wherein a difference between an atomic radius of Ag and an atomic radius of the additive metal is 10% or more of an atomic radius of Ag.   The light emitting device according to claim 2, wherein the additive metal is any one of Mg, Cu, Zn, Al, and Nd, or a combination of two or more thereof.   4. The light emitting device according to claim 1, wherein the metal material has an Ag content of 80 to 99.9 atomic% and an additive metal content of 0.1 to 20 atomic%.   5. The light emitting device according to claim 1, wherein the cathode includes an injection electrode layer that is bonded to the Ag alloy layer and is made of a material having a work function smaller than that of the metal material.   The light emitting device according to claim 5, wherein the injection electrode layer is provided on the light emitting layer side with respect to the Ag alloy layer.   The light-emitting element according to claim 5, wherein the injection electrode layer is composed mainly of an alloy containing at least one of Mg, Al, Ca, Sr, and Ba.   The light emitting element according to any one of claims 1 to 7, further comprising a reflective layer provided on a side opposite to the cathode with respect to the light emitting layer and having a function of reflecting light from the light emitting layer.   The light emitting device according to claim 8, wherein the light emitting element is configured to resonate light from the light emitting layer between the Ag alloy layer and the reflective layer.   The light-emitting element according to claim 1, wherein the Ag alloy layer is formed using a vacuum deposition method.   The light emitting device according to claim 10, wherein the Ag alloy layer is formed by co-evaporation of Ag and the additive metal.   The light emitting element according to any one of claims 1 to 11, wherein a reflectance of the Ag alloy layer with respect to light from the light emitting layer is 20 to 80%.   The light emitting device according to claim 1, wherein the Ag alloy layer has a thickness of 1 to 50 nm.   The light emitting element according to claim 1, wherein the light emitting element has a top emission structure that emits light emitted from the light emitting layer from the cathode side.   The at least one light emitting layer is composed of a plurality of light emitting layers having different emission spectra, and the entire light emitting layer of the plurality of layers is configured to emit white light. Light emitting element.   The light emitting element according to claim 15, wherein the at least one light emitting layer includes a red light emitting layer that emits red light, a green light emitting layer that emits green light, and a blue light emitting layer that emits blue light. .   A display device comprising the light-emitting element according to claim 1.   An electronic apparatus comprising the display device according to claim 17.

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