JP2004103577A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting element exhibiting a high luminous brightness and luminous efficiency and excellent in color purity (especially, for a blue color) and durability. <P>SOLUTION: The lighting element is provided with at least one organic layer including a luminous layer between a pair of electrodes. At least one of the organic layers substantially contains at least one kind of compound composed of carbon atom, fluorine atom, and silicon atom. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a light emitting device, and particularly to a light emitting device having high luminance, high luminous efficiency, and excellent durability.

Organic electroluminescence (EL) elements have been actively researched and developed in recent years because they can emit light with high brightness when driven at a low voltage. In general, an organic EL element is composed of a light-emitting layer and a pair of counter electrodes sandwiching the layer, and excitons generated by recombination of electrons injected from the cathode and holes injected from the anode in the light-emitting layer. The light emission from is used.

In recent years, the efficiency of organic EL devices has increased, and the external quantum efficiency of organic EL devices using iridium complexes as light-emitting materials has exceeded the conventional limit of 5% and has reached 8% (non- Patent Document 1).
On the other hand, an organic EL element using a material composed only of carbon atoms and fluorine atoms is disclosed (see Patent Document 1).
However, the durability of conventional organic EL elements is not sufficient, and the present situation is that there is a strong demand for the development of organic EL elements that exhibit high luminance and luminous efficiency and are excellent in durability.

However, the durability of conventional organic EL elements is not sufficient, and the present situation is that there is a strong demand for the development of organic EL elements that exhibit high luminance and luminous efficiency and are excellent in durability.
JP 2001-247498 A Applied Physics Letters, 75, 4 pages, published in 1999

Accordingly, an object of the present invention is to provide a light-emitting element that exhibits high light emission luminance and light emission efficiency and is excellent in durability. Another object is to provide a light-emitting element that is particularly excellent in blue purity.

The object has been achieved by the following means.
<1> A light emitting device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein at least one layer of the organic layer is substantially composed of carbon atoms, fluorine atoms, and silicon atoms. A light-emitting element containing at least one compound.

<2> The light-emitting device according to <1>, wherein the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is represented by the following general formula (I): .

In general formula (I), Ar ¹ , Ar ² , Ar ^3, and Ar ⁴ represent an aryl group consisting of only a carbon atom and a fluorine atom.

<3> The light-emitting device according to <1>, wherein the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is represented by the following general formula (II): .

In the general formula (II), Ar ²¹ , Ar ²² , Ar ²³ , Ar ²⁴ , Ar ²⁵ , and Ar ²⁶ represent an aryl group consisting of only a carbon atom and a fluorine atom. L represents a divalent arylene group consisting only of carbon atoms and fluorine atoms.

<4> The above-described <1> to <3>, wherein the glass transition temperature of the compound substantially composed of carbon atoms, fluorine atoms, and silicon atoms is 130 ° C. or higher and 400 ° C. or lower. It is a light emitting element in any one.

<5> The light-emitting element according to any one of <1> to <4>, wherein light emission from an excited triplet state is used.

<6> The lowest excited triplet energy level of the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is 65 kcal / mol (272.35 kJ / mol) or more and 95 kcal / mol (398. The light emitting element according to <5>, wherein the light emitting element is less than or equal to 05 kJ / mol).

According to the light emitting device of the present invention, it is possible to provide a light emitting device exhibiting high light emission luminance and light emission efficiency and excellent in durability. In addition, a light-emitting element that is particularly excellent in blue purity can be provided.

Hereinafter, the light emitting device of the present invention will be described in detail.
The light emitting device of the present invention is a light emitting device having at least one organic layer including a light emitting layer between a pair of electrodes, wherein at least one of the organic layers is substantially composed of carbon atoms, fluorine atoms, and silicon. It is characterized by containing at least one compound composed of atoms (hereinafter referred to as “specific compound” as appropriate).

In the specific compound, “substantially composed of a carbon atom, a fluorine atom, and a silicon atom” means an atom other than a carbon atom, a fluorine atom, and a silicon atom in the compound, that is, a hydrogen atom. It means that it is most preferable not to contain any other atoms such as. However, regarding the hydrogen atom, even if about 6 or less (more preferably 1 or less) hydrogen atoms are contained in 6 carbon atoms contained in the compound, the effects of the present invention are sufficiently exhibited. can do.

In the specific compound, the ratio of fluorine atoms to the number of carbon atoms contained in the molecule is preferably 55% or more and 90% or less, more preferably 57% or more and 88% or less, and further preferably 60% or more and 85% or less.

The glass transition temperature (Tg) of the specific compound is preferably 130 ° C. or higher and 400 ° C. or lower, more preferably 135 ° C. or higher and 400 ° C. or lower, more preferably, considering the durability of the light emitting device. It is 140 degreeC or more and 400 degrees C or less, Especially preferably, they are 150 degreeC or more and 400 degrees C or less, Most preferably, they are 160 degreeC or more and 400 degrees C or less.
Here, the glass transition temperature (Tg) can be confirmed by thermal measurement such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA), X-ray diffraction (XRD), and observation with a polarizing microscope.

As will be described later, the light-emitting element of the present invention may use light emitted from an excited singlet state or light emitted from an excited triplet state, but uses light emitted from an excited triplet state. In the case of a light-emitting element, the lowest excited triplet energy level (T ₁ level) of the specific compound is 65 kcal / mol (272.35 kJ / mol) or more and 95 kcal / mol (398.05 kJ / mol). ) Or less, more preferably 67 kcal / mol (280.73 kJ / mol) or more, 95 kcal / mol (398.05 kJ / mol) or less, more preferably 69 kcal / mol (289.11 kJ / mol) or more, 95 kcal / Mol (398.05 kJ / mol) or less, particularly preferably 71 kcal / m l (297.49kJ / mol) or more and less 95kcal / mol (398.05kJ / mol).

Hereinafter, the compound (specific compound) substantially composed of a carbon atom, a fluorine atom, and a silicon atom will be described in detail.

<Compound represented by formula (I)>
Among the specific compounds used in the present invention, a compound represented by the following general formula (I) is preferable.

In the general formula (I), Ar ¹ , Ar ² , Ar ³ and Ar ⁴ represent an aryl group consisting of only a carbon atom and a fluorine atom.

Hereinafter, the compound represented by formula (I) will be described in detail.
In the general formula (I), the aryl groups consisting of only carbon atoms and fluorine atoms represented by Ar ¹ , Ar ² , Ar ³ and Ar ⁴ may be the same or different from each other, and may be monocyclic or two A condensed ring in which the above rings are condensed may be used.

Ar ¹ , Ar ² , Ar ³ and Ar ⁴ are preferably perfluorophenyl group, perfluorobiphenyl group, perfluoronaphthyl group, perfluoroanthracenyl group, perfluorophenanthryl group, perfluoropyrenyl group, perfluoronaphthacenyl group. Perfluoroperenyl group, and the like, preferably a perfluorophenyl group, a perfluorobiphenyl group, and a perfluoronaphthyl group.

In addition, Ar ¹ , Ar ² , Ar ³ and Ar ⁴ may be further substituted with an aryl group consisting of only a carbon atom and a fluorine atom at any position, and only the carbon atom and fluorine atom used as a substituent As the aryl group consisting of, those similar to those exemplified as the groups represented by Ar ¹ , Ar ² , Ar ³ and Ar ⁴ can be applied, and preferred ranges are also the same.

<Compound represented by formula (II)>
Among the specific compounds used in the present invention, preferred other compounds include compounds represented by the following general formula (II).

In the general formula (II), Ar ²¹ , Ar ²² , Ar ²³ , Ar ²⁴ , Ar ²⁵ , and Ar ²⁶ represent an aryl group consisting of only a carbon atom and a fluorine atom. L represents a divalent arylene group consisting only of carbon atoms and fluorine atoms.

Hereinafter, the compound represented by formula (II) will be described in detail.
The aryl group consisting only of the carbon atom and fluorine atom represented by Ar ²¹ , Ar ²² , Ar ²³ , Ar ²⁴ , Ar ²⁵ , and Ar ²⁶ is Ar ¹ , Ar ² , Ar ³ in the general formula (I). And Ar ⁴ is synonymous with the aryl group represented, and the preferred range is also the same.
Said L represents the bivalent arylene group which consists only of a carbon atom and a fluorine atom, and the following are mentioned as a specific example.

Specific examples of specific compounds in the present invention (Exemplary compounds (I-1 to I-16) and (II-1 to II-9)) are listed below, but the present invention is not limited thereto. Absent.

The specific compound can be synthesized by various known synthesis methods. For example, it can be synthesized by reacting a monometalated perfluoroaryl derivative (for example, pentafluorophenyl lithium) with tetrachlorosilane.

The light-emitting element of the present invention may be one that utilizes light emission from an excited singlet state or one that utilizes light emission from an excited triplet state. As the light emitting device of the present invention, it is preferable to utilize light emission from an excited triplet state. Note that in this specification, light emission from the excited singlet state is synonymous with fluorescence, and light emission from the excited triplet state is synonymous with phosphorescence.

When the light-emitting element of the present invention utilizes light emission from an excited triplet state, a material that emits phosphorescence (hereinafter, appropriately referred to as “phosphorescent material”) is not particularly limited, but is preferably a transition metal. Complexes, more preferably iridium, platinum, rhenium, and ruthenium complexes, more preferably iridium and platinum complexes, and particularly preferably iridium complexes. Among the transition metal complexes, orthometalated complexes are particularly preferable. The orthometalated complex is the authors of Akio Yamamoto, “Organic Metal Chemistry Fundamentals and Applications”, pages 150 and 232 (Hanafusa, 1982) and H. Yersin, “Photochemistry and Photophysics of Coordination Compounds” 71. -77 and 135-146 (Springer-Verlag, 1987), etc.

The phosphorescent light emitting material preferably has a phosphorescence quantum yield of 70% or higher at 20 ° C., more preferably 80% or higher, and still more preferably 85% or higher. In this case, the maximum phosphorescence quantum yield is 100%, and most preferably 100%. The phosphor maximum wavelength is preferably 300 nm or more and 500 nm or less, more preferably 305 nm or more and 495 nm or less, further preferably 310 nm or more and 490 nm or less, and particularly preferably 315 nm or more and 480 nm or less. .

As the light emitting element system of the light emitting element of the present invention, an organic EL element is preferable. In the organic EL device, the specific compound is preferably used as an electron transport material (including a hole blocking material) or a host material used in the same layer as the light emitting material, and the form used as the electron transport material is the most. preferable.

The components of the light emitting device of the present invention will be described in more detail.
As described above, the light emitting device of the present invention has at least one organic layer including a light emitting layer between a pair of electrodes (anode and cathode), and at least one of the organic layers contains the specific compound. It is characterized by that.

The mass ratio of the compound in the organic layer containing the specific compound is preferably 60 to 100% by mass, and more preferably 70 to 100% by mass when used as an electron transport material. When used as a host material, it is preferably 50 to 99.9% by mass, and more preferably 60 to 99% by mass.

The method for forming the organic layer in the light emitting device of the present invention is not particularly limited, and resistance heating vapor deposition, electrophotography, electron beam, sputtering, molecular lamination, coating (spray coating, dip coating, impregnation) Method, roll coat method, gravure coat method, reverse coat method, roll brush method, air knife coat method, curtain coat method, spin coat method, flow coat method, bar coat method, micro gravure coat method, air doctor coat, blade coat Methods, squeeze coating methods, transfer roll coating methods, kiss coating methods, cast coating methods, extrusion coating methods, wire bar coating methods, screen coating methods, etc.), inkjet methods, printing methods, transfer methods, and the like. Among these, the resistance heating vapor deposition method, the coating method, and the transfer method are preferable in consideration of the characteristics of the device, the ease of manufacturing, the cost, and the like.
When the light-emitting element has a stacked structure of two or more layers, it can be manufactured by combining the above methods.

When the coating method is used as the method for forming the organic layer, the material and the resin component contained in each layer can be dissolved or dispersed together when adjusting the coating solution. Examples of the resin component used at this time include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, poly (N-vinylcarbazole), hydrocarbon resin, ketone resin, phenoxy resin, and polyamide. , Ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicon resin and the like.
In addition, the light emitting device of the present invention can exhibit excellent light emitting characteristics even when the light emitting layer is formed by a coating method in which it is difficult to obtain high light emission efficiency.

The organic layer in the light emitting device of the present invention includes at least a light emitting layer, but may further have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, and the like. Each of these layers may have other functions. The specific compound may be contained in any of these layers. Details of each layer will be described below.

The material of the hole injection layer and the hole transport layer has any one of the function of injecting holes from the anode, the function of transporting holes, and the function of blocking electrons injected from the cathode. That's fine. Specific examples include carbazole, imidazole, triazole, oxazole, oxadiazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic third Conductive polymer oligomers such as quaternary amine compounds, styrylamines, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, polythiophenes, or these compounds And the like.

The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm. is there.
The hole transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

The material for the electron injection layer and the electron transport layer may be any material that has any one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes injected from the anode. . Specific examples include, for example, triazole, triazine, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, silole, naphthaleneperylene, and the like. Aromatic metal tetracarboxylic anhydrides, phthalocyanines, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, various metal complexes represented by metal complexes having benzoxazole or benzothiazole as ligands, or derivatives of the above compounds Can be mentioned.

Although the film thickness of an electron injection layer and an electron carrying layer is not specifically limited, The thing of the range of 1 nm-5 micrometers is preferable normally, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

As a material of the light emitting layer, a fluorescent material, a phosphorescent light emitting material, an anode or a hole injection layer when an electric field is applied, a hole can be injected from a hole transport layer, and a cathode or an electron injection layer, an electron transport layer can be used. The material is particularly limited as long as it can form a layer having a function of injecting electrons, a function of moving injected charges, and a function of emitting light by providing a recombination field of holes and electrons. Not.

Examples of the compound used in the light emitting layer include benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, pyrazine, cyclohexane. Pentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, styrylamine, aromatic dimethylidin compounds, metal complexes of 8-quinolinol derivatives, metal complexes of phenylpyridine derivatives, organometallic complexes and rare earth complexes Examples thereof include metal complexes, polymer compounds such as polythiophene, polyphenylene, and polyphenylene vinylene, or derivatives of the above compounds.
However, at least one of the materials contained in the light emitting layer is preferably the above-described phosphorescent light emitting material.

The film thickness of the light emitting layer is not particularly limited, but is usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm.

As a material for the protective layer, any material may be used as long as it has a function of suppressing the entry of elements that promote element deterioration such as moisture and oxygen into the element.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychloro Trifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer, and a copolymer main chain A fluorine-containing copolymer having a cyclic structure, a water-absorbing substance having a water absorption rate of 1% or more, Examples include moisture-proof substances having a water content of 0.1% or less.

There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation) (Ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, ink jet method, printing method, transfer method, and electrophotographic method can be applied.

The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like.
As a material for the anode, a metal, an alloy, a metal oxide, an electrically conductive compound, a mixture thereof, or the like can be used, and a material having a work function of 4 eV or more is preferable. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide, and indium tin oxide (ITO), or metals such as gold, silver, chromium, and nickel, and these metals and conductive metal oxides. Or an inorganic conductive material such as copper iodide or copper sulfide, an organic conductive material such as polyaniline, polythiophene, or polypyrrole, and a mixture or laminate of these with ITO. The conductive metal oxide is preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

Although the film thickness of the anode can be appropriately selected depending on the material, it is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, and further preferably 100 nm to 500 nm.

As the anode, a layer formed on a soda-lime glass, non-alkali glass, a transparent resin substrate or the like is usually used. When glass is used, alkali-free glass is preferably used for the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. The thickness of the substrate is not particularly limited as long as the thickness is sufficient to maintain the mechanical strength, but when glass is used, a thickness of usually 0.2 mm or more, preferably 0.7 mm or more is used.

Various methods are used for producing the anode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, an ion plating method, a chemical reaction method (sol-gel method, etc.), A film is formed by a method such as spraying, dipping, thermal CVD, plasma CVD, or ITO dispersion coating.
The anode can be driven to lower the drive voltage of the element and increase the light emission efficiency by washing or other processing. For example, in the case of ITO, UV-ozone treatment, plasma treatment, etc. are effective.

The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, and stability of the electron injection layer, the electron transport layer, the light emitting layer, etc. with the adjacent layer. It is selected in consideration of etc.
As a material for the cathode, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.) or fluorides thereof, alkaline earth metals (eg, Mg, Ca, etc.) or fluorides thereof, gold, silver, lead, aluminum, sodium-potassium. Examples include alloys or mixed metals thereof, lithium-aluminum alloys or mixed metals thereof, magnesium-silver alloys or mixed metals thereof, and rare earth metals such as indium and ytterbium. Among these, a material having a work function of 4 eV or less is preferable, and aluminum, a lithium-aluminum alloy or a mixed metal thereof, a magnesium-silver alloy, or a mixed metal thereof is more preferable.

The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, and further preferably 100 nm to 1 μm.

For production of the cathode, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, and a coating method are used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.
The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

The light-emitting element of the present invention can be suitably used for display elements, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

[Synthesis Example 1]
<Synthesis of Exemplary Compound (I-1)>
5.0 g of pentafluorobenzene (Tokyo Kasei Co., Ltd.) was dissolved in 120 mL of tetrahydrofuran, and the solution was cooled to -70 ° C. 18.6 mL of n-butyllithium / n-hexane solution (1.6M) (Wako Pure Chemical Industries, Ltd.) was slowly added dropwise over 30 minutes, and after completion of the addition, the mixture was stirred at -70 ° C for 30 minutes. A solution of tetrachlorosilane (Tokyo Kasei Co., Ltd.) 1.26 g in tetrahydrofuran (50 mL) was added dropwise at −70 ° C., then the mixture was warmed to room temperature and stirred at room temperature for 1 hour. The reaction mixture was poured into water, and the precipitated white solid was collected by filtration and washed well with water and methanol. The structure of exemplary compound (I-1) was confirmed by mass spectrum after drying.

[Example 1]
<Production of organic EL element>
A transparent support substrate was formed by depositing ITO with a thickness of 150 nm on a glass substrate of 25 mm × 25 mm × 0.7 mm (manufactured by Tokyo Sanyo Vacuum Co., Ltd.). This transparent support substrate was etched and washed, and then TPD (N, N′-diphenyl-N, N′-di (m-tolyl) -benzidine) was deposited to a thickness of 50 nm. : 36 nm was vapor-deposited by the mass ratio of 2: 2, and also on this, exemplary compound (I-3) was vapor-deposited 36 nm.
A patterned mask (with a light emission area of 4 mm × 5 mm) was mounted on the obtained organic thin film, and after 3 nm of lithium fluoride was deposited, 60 nm of aluminum was deposited to produce the organic EL device of Example 1. .

<Evaluation>
-Evaluation method-
A DC constant voltage was applied to the obtained organic EL element using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd. to emit light, and the luminance was measured by using a luminance meter BM-8 of Topcon Co., Ltd. The measurement was performed using a spectrum analyzer PMA-11 manufactured by Photonics.
-Evaluation results-
Light emission with a CIE chromaticity coordinate of (x, y) = (0.19, 0.49) was obtained, and the external quantum efficiency was 8.4% (light emission from an excited triplet state).
This device was allowed to stand at room temperature for a week and then evaluated in the same manner. As a result, the external quantum efficiency was 8.2%.

[Comparative Example 1]
An organic EL device of Comparative Example 1 was produced in the same manner as in Example 1 except that the following compound c was used instead of the exemplified compound (I-3).

When the obtained organic EL device was evaluated in the same manner as in Example 1, light emission with a CIE chromaticity coordinate of (x, y) = (0.24, 0.55) was obtained, and the external quantum efficiency was 1. 7%.
This device was allowed to stand at room temperature for a week and then evaluated in the same manner. As a result, the external quantum efficiency was 0.4%.

[Example 2]
Α-NPD (N, N′-diphenyl-N, N′-di (α-naphthyl) -benzidine) was vapor-deposited on the ITO substrate washed in the same manner as in Example 1, and the following compound d (blue) The light emitting material) was deposited by 20 nm, and the exemplified compound (I-1) was deposited thereon by 40 nm. A patterned mask (with a light emitting area of 4 mm × 5 mm) is mounted on the obtained organic thin film, and magnesium: silver = 10: 1 is co-evaporated to 50 nm, and then 50 nm of silver is deposited. An element was produced.

When the obtained organic EL device was evaluated in the same manner as in Example 1, light emission with CIE chromaticity coordinates of (x, y) = (0.15, 0.27) was obtained, and the external quantum efficiency was 3. 4% (emission from excited singlet state).
When this device was allowed to stand at room temperature for one week and then evaluated in the same manner, the external quantum efficiency was 3.0%.

[Comparative Example 2]
An organic EL device was produced in the same manner as in Example 2 except that the compound c was used instead of the exemplified compound (I-1).

When the obtained organic EL device was evaluated in the same manner as in Example 1, light emission with CIE chromaticity coordinates of (x, y) = (0.25, 0.47) was obtained, and the external quantum efficiency was 1. It was 8%.
This device was allowed to stand at room temperature for a week and then evaluated in the same manner. As a result, the external quantum efficiency was 1.0%.

[Example 3]
BaytronP (manufactured by Bayer) was applied to the ITO substrate washed in the same manner as in Example 1 by spin coating, and vacuum dried at 150 ° C. for 1.5 hours to obtain a thin film having a thickness of 70 nm. A solution obtained by dissolving 40 mg of poly (N-vinylcarbazole) and 1 mg of the compound b in 2.5 mL of dichloroethane was spin-coated thereon to form a film having a thickness of 100 nm.
Furthermore, 40 nm of exemplary compound (I-1) was vapor-deposited on this. A patterned mask (with a light emission area of 4 mm × 5 mm) was mounted on the obtained organic thin film, and after 3 nm of lithium fluoride was deposited, 60 nm of aluminum was deposited to produce the organic EL device of Example 3.

When the obtained organic EL device was evaluated in the same manner as in Example 1, light emission with CIE chromaticity coordinates of (x, y) = (0.19, 0.51) was obtained, and the external quantum efficiency was 2.1. % (Emission from excited triplet state).
When the device was allowed to stand at room temperature for a week and then evaluated in the same manner, the external quantum efficiency was 1.6%.

[Comparative Example 3]
An organic EL device of Comparative Example 3 was produced in the same manner as Example 3 except that the compound c was used instead of the exemplified compound (I-1).

When the obtained organic EL device was evaluated in the same manner as in Example 1, light emission with CIE chromaticity coordinates of (x, y) = (0.25, 0.53) was obtained, and the external quantum efficiency was 0. 2%.
The device was evaluated in the same manner after being left at room temperature for one week, but did not emit light.

From the results of Examples 1 to 3 and Comparative Examples 1 to 3, it was found that the light emitting device of the present invention was excellent in light emission characteristics (high luminance and high light emission efficiency) and excellent in durability.
That is, the light-emitting element of the present invention was manufactured by a coating method in which the light-emitting layer is usually low in light emission efficiency, regardless of whether the light emission from the excited triplet state or the light emission from the excited singlet state is used. Even in this case, it was found that the light emitting device had high external quantum efficiency, excellent light emission characteristics, and excellent durability. Furthermore, it was found that the light-emitting element had improved color purity of the emission color (particularly blue purity).

Claims (6)

A light-emitting element having at least one organic layer including a light-emitting layer between a pair of electrodes, wherein at least one of the organic layers is substantially composed of a carbon atom, a fluorine atom, and a silicon atom. A light-emitting element containing at least one kind. The light-emitting device according to claim 1, wherein the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is represented by the following general formula (I).

(In general formula (I), Ar ¹ , Ar ² , Ar ³ and Ar ⁴ represent an aryl group consisting of only a carbon atom and a fluorine atom.) The light emitting device according to claim 1, wherein the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is represented by the following general formula (II).

(In the general formula (II), Ar ²¹ , Ar ²² , Ar ²³ , Ar ²⁴ , Ar ²⁵ , and Ar ²⁶ represent an aryl group consisting of only a carbon atom and a fluorine atom. L represents only a carbon atom and a fluorine atom. Represents a divalent arylene group consisting of The light emission according to any one of claims 1 to 3, wherein a glass transition temperature of the compound substantially composed of a carbon atom, a fluorine atom, and a silicon atom is 130 ° C or higher and 400 ° C or lower. element. The light-emitting element according to claim 1, wherein light emission from an excited triplet state is used. The compound having a carbon atom, a fluorine atom, and a silicon atom substantially has a minimum excited triplet energy level of 65 kcal / mol (272.35 kJ / mol) or more and 95 kcal / mol (398.05 kJ / mol). The light-emitting device according to claim 5, wherein: