JP2011251921A - Iridium complex, and organic electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an iridium complex useful as a dopant for use in an organic electroluminescent element.SOLUTION: The iridium complex is represented by formula (1) (in the formula, Rrepresents a 1-10C alkyl group).

Description

  The present invention relates to, for example, an iridium complex useful as a dopant for an organic electroluminescence element (hereinafter also referred to as an organic EL element) and an organic electroluminescence element using the iridium complex.

Conventionally, various iridium complexes have been proposed as dopants for organic EL devices for the purpose of improving efficiency, improving color purity, and extending the lifetime (see, for example, Patent Documents 1 and 2). Many derivatives of the material FIrpic ((2-pyridinecarboxylato-κN ¹ , κO ² ) bis [2- (2-pyridinyl-κN) -3,5-difluorophenyl-κC)] iridium) have been studied. .
By the way, FIrpic derivatives of the present invention include 3- (pyridin-2-yl) -2,6-difluorotoluene (also known as 2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl- iridium complex having a structure in which a trifluoromethyl group is introduced for the purpose of improving the blue purity of the ligand (for example, see Non-Patent Document 1) or iridium having a cyano group introduced. Complexes (for example, see Non-Patent Document 2) are disclosed. Any of these substituents is an electron-withdrawing group.
Moreover, as the complex into which an electron donating group is introduced, only a derivative using acetylacetone as an auxiliary ligand is disclosed (see, for example, Patent Document 3), and the existence of the tris form of the present invention is clearly shown. Was not.

International Publication No. 2002/015645 International Publication No. 2008/156879 JP 2002-117978 A

Chemistry Letters, 35, 748 (2006) Organic Electronics, 10, 170 (2009)

  The subject of this invention is providing the iridium complex useful as a dopant of an organic electroluminescent element which solves the said trouble.

  The subject of the present invention is that the general formula (1)

（式中、Ｒ^１は炭素原子数１〜１０のアルキル基を示す。）
で示されるイリジウム錯体によって解決される。

(In the formula, R ¹ represents an alkyl group having 1 to 10 carbon atoms.)
It is solved by the iridium complex shown by.

  By this invention, the iridium complex which can be used conveniently as a blue dopant of an organic EL element can be provided.

It is a figure which shows the layer structure of the organic EL element manufactured by the element manufacture example 1. FIG.

The iridium complex of the present invention is represented by the general formula (1). In the general formula (1), R ¹ represents an alkyl group having 1 to 10 carbon atoms such as a methyl group, an ethyl group or a propyl group, preferably an alkyl group having 1 to 6 carbon atoms, more preferably methyl. Group, ethyl group, particularly preferably methyl group. These groups include various isomers.

  The ligand of the iridium complex of the present invention can be synthesized by any method of the following formula (2) or (3).

(Wherein, X ¹ and X ² may be the same or different and each represents a halogen atom, P represents a leaving group, and R ¹ has the same meaning as described above.)

X ¹ is preferably a bromine atom, and X ² is preferably a chlorine atom. The leaving group P is preferably a dihydroxyboryl group or a dialkoxyboryl group (two alkyl groups may be bonded to each other to form a ring).

  In addition, the iridium complex of the present invention can be synthesized using iridium chloride as a starting material as shown in the formula (4).

(In the formula, R ¹ has the same meaning as described above.)

  Further, as shown in the formula (5), tris (acetylacetonato) iridium can be synthesized as a starting material.

(In the formula, R ¹ has the same meaning as described above.)

(Organic electroluminescence device)
Next, the organic electroluminescence element of the present invention will be described. In the organic EL device of the present invention, the iridium complex of the present invention is contained in the light emitting layer, but other known materials can be used together.

  The organic EL element is preferably an organic EL element having a single-layer or multi-layer organic compound layer between a pair of electrodes, and includes the compound of the present invention in at least one of the organic compound thin layers. The organic compound layer includes a buffer layer, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like.

  A single layer type organic EL element has a light emitting layer between an anode and a cathode. The light emitting layer contains a light emitting material, and further, a material used for an organic compound layer for transporting holes injected from the anode or electrons injected from the cathode to the light emitting material, for example, a hole transport material or an electron transport material. It may contain.

  Examples of multilayer organic EL devices include (anode / buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode) and (anode / buffer layer / hole transport layer / light emitting layer / electron transport). (Anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / metal oxide layer / cathode), (anode / hole injection) Multilayer structures such as (layer / light emitting layer / cathode), (anode / light emitting layer / electron transport layer / cathode), (anode / hole injection layer / light emitting layer / electron transport layer / cathode), and the like. It is not limited.

  In addition, each of the buffer layer, the hole transport layer, the electron transport layer, and the light emitting layer may have a single layer structure or a multilayer structure. Further, each of the hole transport layer and the electron transport layer can be provided separately with an injection function layer (hole injection layer and electron injection layer) and a transport function layer (hole transport layer and electron transport layer). .

  Hereinafter, the components of the organic EL device of the present invention will be described in detail by taking as an example the device configuration of (anode / buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode).

  In the organic EL device of the present invention, as a material used as a host for the light emitting layer of the organic layer, any material can be selected from known host materials. For example, 4,4′-di (N-carbazolyl) -1,1′-biphenyl (CBP), 1,3-di (N-carbazolyl) benzene (mCP), 2,2′-di [4 ″- (N-carbazolyl) phenyl] -1,1′-biphenyl (4CzPBP), diphenyldi (o-tolyl) silane, p-bis (triphenylsilyl) benzene, 4, 4 ′, 4 ″ -tris (N— Carbazolyl) -triphenylamine (TCTA), 49,10-bis- [1,1,3 ′, 1 ″] terphenyl-5′-yl-anthracene, and the like. Absent.

  When the light emitting material is used in combination with the host material, the light emitting material is preferably 0.005 to 80% by mass with respect to the host material.

  Examples of known materials used as the hole blocking layer (hereinafter referred to as hole blocking material) include 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline and bis (2-methyl-). 8-quinolinolato) (p-phenylphenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, bis (m-terphenyl-5′-yl) sulfone (BTPS) and the like. However, it is not limited to these.

  Materials used for the electron transport layer (hereinafter referred to as electron transport materials) are known materials such as fluorene, phenanthroline, bathophenanthroline, bathocuproine, anthraquinodimethane, diphenoquinone, oxazole, oxadiazole, triazole, imidazole. , Anthraquinodimethane, 4,4′-N, N′-dicarbazole biphenyl (CBP) and the like, compounds thereof, metal complex compounds or nitrogen-containing five-membered ring derivatives. Specific examples of the metal complex compound include 8-hydroxyquinolinate lithium, tris (8-hydroxyquinolinate) aluminum, tri (2-methyl-8-hydroxyquinolinato) aluminum, tris (8-hydroxyquinate). Norinato) gallium, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (10-hydroxybenzo [h] quinolinato) zinc, bis (2-methyl-8-quinolinato) (o-cresolate) gallium, bis ( 2-methyl-8-quinolinato) (1-naphtholato) aluminum, bis (2-methyl-8-quinolinato) -4-phenylphenolate, and the like, but are not limited thereto. The nitrogen-containing five-membered ring derivative is preferably an oxazole, thiazole, oxadiazole, thiadiazole or triazole derivative. Specifically, 2,5-bis (1-phenyl) -1,3,4-oxazole, 2,5-bis (1-phenyl) -1,3,4-thiazole, 2,5-bis (1 -Phenyl) -1,3,4-oxadiazole, 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl) 1,3,4-oxadiazole, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole, 1,4-bis [2- (5-phenylthiadiazolyl)] benzene, 2,5-bis (1-naphthyl) -1,3, Examples include 4-triazole, 3- (4-biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole, but are not limited thereto. Furthermore, a polymer material used for a polymer-organic light emitting device can also be used. Examples thereof include polyparaphenylene and derivatives thereof, fluorene and derivatives thereof, but are not limited thereto.

  On the other hand, the material used for the hole transport layer (hereinafter referred to as hole transport material) can be selected from known materials. For example, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′diamine (TPD) and 4,4′-bis [N- (naphthyl) -N-phenyl-amino ] Aromatic diamine compounds such as biphenyl (α-NPD), stilbene derivatives, pyrazoline derivatives, polyarylalkanes, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenyl Examples of the polymer material include amine (m-MTDATA), 2,2 ′, 7,7′-tetrakis- (N, N-diphenylamino) -9,9′-spirobifluorene, and polyvinylcarbazole. It is not limited to this.

  In addition, the organic EL element can be provided with a buffer layer for improving hole injectability, but a material used for the buffer layer can be selected from known materials. More preferably, the hole transport material doped with 1 to 30% by mass of molybdenum oxide is used, but is not limited thereto.

  Examples of the conductive material used for the anode include those having a work function larger than about 4 eV, such as carbon atoms, aluminum, vanadium, iron, cobalt, nickel, tungsten, silver, gold, platinum, palladium and alloys thereof, ITO (Substance in which tin oxide is added to indium oxide in an amount of 5 to 10% by mass) A metal oxide such as tin oxide or indium oxide used for a substrate or a NESA substrate, or an organic conductive resin such as polythiophene or polypyrrole can be used. However, it is desirable to use a material having a work function of 0.1 eV or more higher than that of the conductive material used for the cathode of the element.

  As the conductive material used for the cathode, a material having a work function smaller than about 4 eV, such as magnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese, aluminum, or an alloy thereof is used. Here, examples of the alloy include magnesium / silver, magnesium / indium, and lithium / aluminum. The ratio of the alloy is not particularly limited and is controlled by the temperature of the vapor deposition source, the atmosphere, the degree of vacuum, and the like. However, the work function of these conductive materials used for the cathode is preferably smaller than the work function of the conductive material used for the anode of the element by 0.1 eV or more.

  In the organic EL device of the present invention, a metal oxide layer can be provided between the light emitting layer and the electrode in order to improve the electron injection property. Alternatively, the electron transport material may be doped with a metal oxide.

Examples of the metal oxide used include alkali metal fluorides such as LiF; alkaline earth metal fluorides such as BaF ₂ and SrF ₂ ; alkali metal oxides such as Li ₂ O; alkaline earth metals such as RaO and SrO. Oxides are used.

  If necessary, the anode and the cathode may be formed of two or more layers.

  As for the organic EL element of this invention, it is desirable that at least one surface is transparent in the light emission wavelength region of the element. The substrate is also preferably transparent.

  The transparent electrode is obtained by using the conductive material described above and setting so as to ensure a predetermined translucency by a method such as vapor deposition or sputtering.

  The electrode on the light emitting surface preferably has a light transmittance of 10% or more.

  The substrate is not particularly limited as long as it has mechanical and thermal strength and has transparency, but a glass substrate or a transparent resin film is used.

  Examples of the transparent resin film include polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, and polyether. Ether ketone, polysulfone, polyether sulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoro Ethylene, polyvinylidene fluoride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene And the like.

  In the organic EL device of the present invention, a protective layer may be provided on the surface of the device, or the entire device may be protected with silicon oil, resin, or the like, in order to improve stability against temperature, humidity, atmosphere, and the like.

  In addition, each layer of the organic EL element can be formed by applying a dry film forming method such as vacuum deposition, sputtering, plasma, or ion plating, or a wet film forming method such as spin coating, dipping, or flow coating. it can. The film thickness is not particularly limited, but is preferably 0.1 nm to 10 μm, more preferably 0.5 nm to 0.2 μm.

  In the case of a wet film formation method, a thin film can be prepared by dissolving or dispersing the material in a solvent such as ethanol, chloroform, tetrahydrofuran, or dioxane on each layer. In this case, it is possible to coexist the above materials.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Reference Example 1 (R ¹ = methyl group, X ¹ = bromine atom; synthesis of 3-bromo-2,6-difluorotoluene)

In a 200 ml glass three-necked flask equipped with a thermometer, reflux condenser and stirrer, 30.0 g (234 mmol) of 2,6-difluorotoluene and 780 mg (14.0 mmol) of iron powder were added under a nitrogen atmosphere. After that, the mixed solution was cooled to 5 ° C. Subsequently, 44.7 g (280 mmol) of bromine was dropped into the mixed solution while adjusting the liquid temperature to 20 ° C. or lower. After completion of the dropwise addition, the reaction was allowed to proceed at room temperature with stirring. After completion of the reaction, hexane and an aqueous sodium hydrogen carbonate solution were added to the reaction solution for liquid separation. The obtained organic layer was washed with an aqueous sodium hydrogen carbonate solution and then dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure to obtain 45.0 g of 3-bromo-2,6-difluorotoluene as a pale yellow solution (isolated yield; 92.7%).
In addition, 3-bromo-2,6-difluorotoluene is a compound represented by the following physical property values.

¹ H-NMR (CDCl ₃ , δ (ppm)); 7.34 (1H, m), 6.75 (1H, m)

Reference Example 2 (R ¹ = methyl group; synthesis of 2- (2,4-difluoro-3-methylphenyl) pyridine)

In a 1 L glass four-necked flask equipped with a thermometer, a reflux condenser and a stirrer, 32.1 g of 3-bromo-2,6-difluorotoluene having a purity of 90% by mass synthesized in the same manner as in Reference Example 1 ( 140 mmol) and 500 ml of dehydrated tetrahydrofuran were added, and nitrogen was bubbled through the mixed solution for 1 hour. Next, 4.04 g (3.50 mmol) of tetrakistriphenylphosphine palladium (0) was added, and 200 ml of a 0.5 mol / ml 2-pyridylzinc bromide tetrahydrofuran solution (100 mmol, manufactured by Aldrich) was added with stirring. And allowed to react for 24 hours. After completion of the reaction, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The obtained concentrate was subjected to silica gel column chromatography (developing solvent: ethyl acetate → hexane / ethyl acetate (volume ratio; 500/10) → hexane / chloroform (volume ratio; 2/1) → hexane / ethyl acetate (volume ratio; 500/15)) to obtain 5.60 g of 2- (2,4-difluoro-3-methylphenyl) pyridine as a colorless transparent liquid (isolation yield: 27%).
In addition, 2- (2,4-difluoro-3-methylphenyl) pyridine is a compound represented by the following physical property values.

¹ H-NMR (CDCl ₃ , δ (ppm)); 8.70 (1H, m), 7.75 (3H, m), 7.25 (1H, m), 6.95 (1H, m)

Example 1 (R ¹ = methyl group; synthesis of di-μ-chlorotetrakis- [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] diiridium)

250 mg (1.22 mmol) of 2- (2,4-difluoro-3-methylphenyl) pyridine synthesized in the same manner as in Reference Example 2 in a 100 ml glass three-necked flask equipped with a thermometer, a reflux condenser and a stirrer. And 20 ml of ethoxyethanol were added, and nitrogen was bubbled through the mixed solution for 1 hour. Next, 150 mg (0.488 mmol) of iridium trichloride trihydrate was added, and the mixture was reacted at 125 to 135 ° C. for 20 hours with stirring. After completion of the reaction, the reaction solution was cooled to room temperature and concentrated under reduced pressure, and 5 ml (1 mmol) of a 2 mol / l potassium carbonate aqueous solution was added to the resulting concentrate, followed by sonication. The obtained suspension was filtered, and the residue was washed with water and then dried under vacuum. After drying, the obtained solid was washed with hexane and dried to obtain 220 mg of 2- (2,4-difluoro-3-methylphenyl) pyridine chlorobridge dimer as an ocherous solid (isolation yield; 56). .4%).
Di-μ-chlorotetrakis- [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] diiridium was a novel compound.

Example 2 (R ¹ = methyl group; synthesis of tris [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] iridium (hereinafter referred to as [Ir (ftpy) ₃ ]) There is also))

  Di-μ-chlorotetrakis- [2- (2-pyridinyl-κN) -3 synthesized in the same manner as in Example 1 in a 100 ml glass three-necked flask equipped with a thermometer, a reflux condenser, and a stirring device 5-difluoro-4-methylphenyl-κC] diiridium 3.37 g (2.65 mmol), 1.63 g (7.95 mmol) of 2- (2,4-difluoro-3-methylphenyl) pyridine and 150 ml of diglyme were added. Nitrogen was bubbled through for 1 hour. Next, 2.72 g (10.6 mmol) of silver trifluoromethanesulfonate was added to the mixed solution, and the mixture was reacted at 140 to 150 ° C. for 92 hours with stirring. After completion of the reaction, the reaction solution is cooled to room temperature and purified by silica gel column chromatography three times (developing solvent: hexane / ethyl acetate (volume ratio; 3/1) → hexane / methylene chloride (volume ratio; 3/1). → After performing hexane / methylene chloride (volume ratio; 4/1), the obtained solid was washed with hexane. Further, the solid was sublimated to obtain 270 mg of tris [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] iridium as a yellow powder (isolation yield; 6. 3%).

  Tris [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] iridium was a novel compound represented by the following physical property values.

EI-MS; 805 (M)
¹ H-NMR (CD ₂ Cl ₂ , δ (ppm)); 8.29 (3H, m), 7.66 (3H, m), 7.45 (3H, m), 6.91 (3H, m) ), 6.17 (3H, m), 2.03 (9H, m)

Example 3 (Synthesis of R ¹ = methyl group; tris [2- (2-pyridinyl-κN) -3,5-difluoro-4-methylphenyl-κC] iridium))

  20 ml of glycerin was added to a 100 ml glass three-necked flask equipped with a thermometer, a reflux condenser and a stirrer, heated to 140-150 ° C. and aerated with nitrogen for 1 hour. The mixture was then cooled to 50 ° C. and 250 mg (1.22 mmol) of 2- (2,4-difluoro-3-methylphenyl) pyridine and 100 mg (0.200 μmol) of iridium (III) trisacetylacetonate were added, The reaction was carried out at 190 to 200 ° C. for 28 hours with stirring. After completion of the reaction, the reaction solution was cooled to room temperature, and water and chloroform were added for liquid separation, and the aqueous layer was extracted with chloroform and then combined with the organic layer. The obtained organic layer was washed with water and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure, and the resulting concentrate was purified by silica gel column chromatography (developing solvent: hexane / chloroform (volume ratio; 3/1)) to give iridium (III) tris as a yellow powder. 5 mg of 3- (pyridin-2-yl) -2,6-difluorotoluene was obtained (isolation yield; 1.5%).

Reference Example 3 (P = 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl group; 2- (2,4-difluoro-3-methylphenyl) -4,4,5 , 5-Tetramethyl-1,3,2-dioxaborolane)

In a 200 ml glass four-necked flask equipped with a thermometer, a reflux condenser and a stirrer, 5.18 g (25.0 mmol) of 2,4-difluoro-3-methylbromobenzene synthesized earlier, bis (pinacolato) ) 7.62 g (30.0 mmol) of diboron, 7.36 g (75.0 mmol) of potassium acetate and 100 ml of dehydrated N, N-dimethylformamide were added, and nitrogen was bubbled through the mixed solution for 1 hour. Next, 610 mg (747 μmol) of 1,1′-bis (diphenylphosphinoferrocene) dichloropalladium (II) methylene chloride adduct was added and reacted at 80 to 90 ° C. for 1 hour with stirring. After completion of the reaction, the reaction solution was cooled to room temperature, water and hexane were added for liquid separation, and the aqueous layer was extracted with hexane. The obtained organic layers were combined, washed with water, and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure, and the resulting concentrate was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate (volume ratio; 1/1)) to give 2- (2,4 -Difluoro-3-methylphenyl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane 1.50 g (isolated yield; 23.6%) was obtained.
The physical properties of 2- (2,4-difluoro-3-methylphenyl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane were as follows.

¹ H-NMR (CDCl ₃ , δ (ppm)); 7.41 (1H, m), 6.85 (1H, m), 2.25 (3H, s), 1.85 (12H, s)

Reference Example 4 (P = 4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl group, X ² = chlorine atom; 2- (2,4-difluoro-3-methylphenyl) Synthesis of pyridine)

  2- (2,4-difluoro-3-methylphenyl) -4,4,5, synthesized as described above in a 100 ml glass three-necked flask equipped with a thermometer, a reflux condenser and a stirrer. 5-tetramethyl-1,3,2-dioxaborolane 2.0 g (7.87 mmol), 2-chloropyridine 0.81 g (7.15 mmol), 1.35 mol / l aqueous potassium phosphate solution 16 ml (21.6 mmol) and 50 ml of 1,4-dioxane was added, and nitrogen was bubbled through the mixed solution for 1 hour. Next, 0.13 g (0.14 mmol) of tris (dibenzylidene) dipalladium (0) and 0.10 g (0.36 mmol) of tricyclohexylphosphine were added to the mixed solution, and the mixture was reacted at 80 to 83 ° C. with stirring. After completion of the reaction, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The obtained concentrate was purified by silica gel chromatography (developing solvent: hexane / ethyl acetate (volume ratio; 4/1)) to give 2- (2,4-difluoro-3-methylphenyl) pyridine as a yellow liquid. 54 g (isolated yield; 36.8%). In addition, 2-chloropyridine contained slightly.

  Next, an example of producing an organic EL device using the iridium compound of the present invention will be described.

Example 4 (Production of an organic EL device containing the iridium complex of the present invention)
As shown in FIG. 1, an organic EL device including a transparent substrate 1, an anode 2, a buffer layer 3, a hole transport layer 4, a light emitting layer 5, a hole blocking layer 6, an electron transport layer 7, and a cathode 8 from the substrate side. Was prepared by the following method.

A glass substrate (transparent substrate 1) on which a patterned transparent conductive film (ITO) (anode 2) is formed with a film thickness of 110 nm is subjected to ultrasonic cleaning with pure water and a surfactant, flowing water cleaning with pure water, and pure water. Washing was performed in the order of ultrasonic cleaning with a 1: 1 mixed solution of isopropyl alcohol and isopropyl alcohol, followed by boiling cleaning with isopropyl alcohol. The substrate was slowly pulled up from the boiling isopropyl alcohol, dried in isopropyl alcohol vapor, and finally subjected to ultraviolet ozone cleaning. Using this substrate as an anode, it is placed in a vacuum chamber and evacuated to 7.5 × 10 ⁻³ Pa. In this chamber, each molybdenum board filled with a vapor deposition material is formed in a predetermined pattern. A deposition mask is installed, and the board is energized and heated to evaporate the deposition material, so that the buffer layer 3, the hole transport layer 4, the light emitting layer 5, the hole blocking layer 6, An electron transport layer 7 was formed.

NS21 (manufactured by Nippon Steel Chemical Co., Ltd.), which is a hole transport material, and molybdenum trioxide (MoO ₃ ) are co-deposited on the substrate to form NS21: MoO ₃ = 80: 20 with a film thickness of 13.6 nm. After the film formation, KLHT03 (manufactured by Chemipro Kasei Co., Ltd.): MoO ₃ = 80: 20 was formed to a film thickness of 5 nm to form the buffer layer 3. Subsequently, KLHT03 was formed in a film thickness of 15 nm to form the hole transport layer 4. The light-emitting layer 5 was formed to a thickness of 10 nm with TCTA: [Ir (ftpy) ₃ ] (synthesized in the same manner as in Example 3) = 80: 20. Bis (m-terphenyl-5′-yl) sulfone (BTPS) was formed to a thickness of 8 nm on the light emitting layer 5 to form a hole blocking layer 6.

  Further, on the hole blocking layer 6, KLET 03 (manufactured by Chemipro Kasei Co., Ltd.) is formed with a film thickness of 58 nm, and 8-hydroxyquinolinatolithium (Liq) is formed with a film thickness of 1 nm to form the electron transport layer 7. did. On top of that, aluminum (Al) was deposited to a thickness of 100 nm to form the cathode 8.

  Here, bis (m-terphenyl-5'-yl) sulfone (BTPS) is an organic sulfur compound represented by the following structural formula.

  The laminated structure thus formed was combined with another glass substrate and sealed with a UV curable resin to complete the device.

Simplified layer structure of this element
Anode 2: ITO (110 nm),
Buffer layer 3: NS21: MoO ₃ (13.6 nm, 80:20) / KLHT03: MoO ₃ = (5 nm, 80:20),
Hole transport layer 4: KLHT03 (15 nm),
Light-emitting layer 5: TCTA: [Ir (ftpy) ₃ ] (10 nm, 80/20),
Hole blocking layer 6: BTPS (8 nm),
Electron transport layer 7: KLET03 (58 nm) / Liq (1 nm),
Cathode 8: Al (100 nm)
It is.

Comparative Example 1 (Manufacture of an organic EL device containing FIrpic)
A device was fabricated in the same manner as in Example 4 by using [Ir (ftpy) ₃ ] of the light emitting layer as FIrpic.

  Here, FIrpic is a dopant represented by the following structural formula.

  As described above, the organic EL device produced in Example 4 and Comparative Example 1 was connected to a power source (“2400” manufactured by KTHELEY), and a multi-channel analyzer (“CS-2000” manufactured by Konica Minolta Co., Ltd.) was used. The external quantum efficiency, luminous efficiency, and energy conversion efficiency were measured. The results are shown in Table 1.

The various efficiencies of the organic EL device using the iridium complex [Ir (ftpy) ₃ ] of the present invention for the light emitting layer were all superior to those using FIrpic, which is a known high efficiency blue light emitting material.

  According to the present invention, an iridium complex useful as a dopant for an organic electroluminescence device and an organic electroluminescence device using the iridium complex are provided.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Anode 3 Buffer layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer
8 Cathode

Claims (2)

General formula (1)

(In the formula, R ¹ represents an alkyl group having 1 to 10 carbon atoms.)
An iridium complex represented by   An organic electroluminescence device comprising the iridium complex according to claim 1.

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