JP4392721B2 - Organic electroluminescence device using phosphorescence - Google Patents

Description

  The present invention relates to an organic electroluminescent device using phosphorescence using a novel compound having a large excited triplet energy (hereinafter, an organic electroluminescent device using phosphorescence is abbreviated as a phosphorescent device).

  A phosphorescent light emitting device having a multilayer structure is already known (see Patent Document 1). In the case of emitting light using only fluorescence, since the excited singlet state is used, the theoretical limit value of the internal quantum efficiency is 25%, but in the phosphorescent light emitting element, the excitation energy of the triplet state contributes to light emission. Therefore, the theoretical limit value of internal quantum efficiency is considered to be 100%. Therefore, the phosphorescent light emitting element is superior to the fluorescent light emitting element because it can improve the light emission efficiency, that is, the ratio of the light emission luminance to the driving current density.

  The phosphorescent light-emitting device can be obtained by doping a small amount of a phosphorescent phosphorescent dopant into the host compound of the light-emitting layer. The host compound must have an excited triplet energy greater than that of the phosphorescent dopant, and the available compounds are limited. For example, carbazole derivatives disclosed in Non-Patent Document 1 and compounds disclosed in Patent Document 2 and Non-Patent Document 2 are used as phosphorescent host compounds. However, since a phosphorescent light emitting device using an existing phosphorescent host compound has problems such as a high voltage during driving, development of a new host compound is required.

Several compounds are known as triphenylene compounds having a substituent containing silicon (see Patent Documents 3 to 5). Patent Documents 3 and 4 disclose compounds in which a side chain containing silicon is bonded to a triphenylene skeleton via an oxygen atom. Patent Document 5 discloses a compound in which a side chain containing silicon is directly bonded to a triphenylene skeleton via silicon. However, a triphenylene compound having a silylethynyl group has not been known.
US Pat. No. 6,097,147 JP 2004-103463 A JP 2003-252818 A Japanese Patent Laid-Open No. 11-255781 JP 2003-252880 A Appl. Phys. Lett. , 75, 4 (1999) Appl. Phys. Lett. , 83, 3818 (2003)

  An object of the present invention is to provide a novel phosphorescent light emitting device capable of being driven at a low voltage by using a specific compound in a light emitting layer of the phosphorescent light emitting device.

  As a result of intensive studies, the present inventors used a newly synthesized compound represented by the following general formula (I) as a host compound in a light emitting layer of a phosphorescent light emitting device and doped a phosphorescent dopant to the light emitting device. The present inventors have found that phosphorescence can be extracted at a low voltage from the above, and the present invention has been completed based on this finding. That is, the present invention is as follows.

(1) An organic electroluminescence device using phosphorescence having at least a pair of electrodes and a light emitting layer disposed between the electrodes, wherein the light emitting layer is at least one compound represented by the general formula (I), And an organic electroluminescence device using phosphorescence, containing a phosphorescent dopant.
(2) In the general formula (I), all of R ^{1 to} R ⁶ are substituents represented by the general formula (II), and in the general formula (II), R ^a , R ^b , R ^The organic electroluminescent element using phosphorescence of (1), wherein each ^c is independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms.
(3) An organic electroluminescence device using phosphorescence of (1) or (2), wherein in the general formula (II), all of the substituents R ^a , R ^b and R ^c are alkyl groups.
(4) The organic electroluminescence device utilizing phosphorescence of (3), wherein the alkyl group is an isopropyl group or a methyl group.
(5) In the general formula (I), any one or two of R ^{1 to} R ⁶ are substituents represented by the general formula (II), and in the general formula (II), The organic electroluminescent element using phosphorescence of (1), wherein R ^a , R ^b and R ^c are phenyl groups.
(6) The organic electroluminescent device using phosphorescence according to any one of (1) to (5), wherein the phosphorescent dopant is at least one selected from an iridium complex, a platinum complex, an osmium complex, and a gold complex. .
(7) Organic electroluminescence using phosphorescence according to any one of (1) to (6), further comprising an electron transport layer, a hole blocking layer, a hole transport layer and a hole injection layer between at least a pair of electrodes element.

The compound used in the present invention has a large excitation triplet energy and is suitable as a host compound of a light emitting layer in a phosphorescent light emitting device, and can provide a novel phosphorescent light emitting device.

First, the compound represented by the general formula (I) contained in the light emitting layer of the phosphorescent device of the present invention will be described.
R ^{1 to} R ⁶ are each independently H or a substituent of the following general formula (II), and at least one of R ^{1 to} R ⁶ is a substituent of the general formula (II). Preferably, 3 to ⁶ of R ^{1 to} R ⁶ are substituents represented by the general formula (II), more preferably all ⁶ of R ^{1 to} R ⁶ are represented by the general formula (II). It is a substituent.
The substituents represented by the general formula (II) may be different from each other in R ^{1 to} R ⁶ , but are preferably the same.

In the general formula (II), R ^a , R ^b and R ^c are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms or a phenyl group, and more preferably each independently having 1 to 10 carbon atoms. It is an aliphatic hydrocarbon group, More preferably, it is a C1-C8 aliphatic hydrocarbon group each independently. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be branched. In the case of an unsaturated aliphatic hydrocarbon group, there may be a plurality of double bonds. The type of the aliphatic hydrocarbon group is not particularly limited as long as it has 1 to 10 carbon atoms, and examples thereof include the following substituents such as a methyl group and an ethyl group, and an isopropyl group or a methyl group is particularly preferable. Note that R ^a , R ^b , and R ^c may be the same substituent as each other or different from each other. When all of R ^a , R ^b and R ^c are phenyl groups, the number of substituents represented by the general formula (II) in the compound represented by the general formula (I) is preferably 1 or 2. .
As the compound of the general formula (I), 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene, 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) is particularly preferable. ) Triphenylene and the like.

^Hereinafter, R ^a, R b, examples of ^{R c is,} R ^a, R b, ^{R c} is not limited thereto.

(Example of alkyl group)
-CH ₃
-CH ₂ CH ₃
-CH ₂ CH ₂ CH ₃
-CH ₂ CH ₂ CH ₂ CH _{3
-CH 2 CH 2 CH 2 CH 2} CH 3
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 3
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 2 CH 3
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 2 CH 2 CH 3
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 2 CH 2 CH 2 CH 3
_{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 2 CH 2 CH 2 CH 2 CH 3
(The alkyl group may be branched as in the following example.)

(Example of unsaturated hydrocarbon group)
-C≡C-R (R is H, preferably a linear or branched alkyl group having 1 to 8 carbon atoms)
—CH═CR ₂ (R is preferably H, a linear or branched alkyl group having 1 to 8 carbon atoms. When the types of R are different, cis and trans do not matter.)
—CH ₂ —CH═CR ₂ (R is preferably H, a linear or branched alkyl group having 1 to 7 carbon atoms. When the types of R are different, cis and trans do not matter.)

(Phenyl group)

The method for producing the compound of general formula (I) is not particularly limited as long as the compound is obtained. For example, it can be produced by reacting the compound of general formula (III) with the compound of general formula (IV). .

In the general formula (III), X ^{1 to} X ⁶ are each independently a hydrogen atom, bromine atom or iodine atom, and at least one of X ^{1 to} X ⁶ is either a bromine atom or an iodine atom. It is particularly preferable that all of X ^{1 to} X ⁶ are bromine atoms. The compound (III) can be obtained, for example, by bromination or iodination of triphenylene as shown in the Examples.
In general formula (IV), R ^<a> , R ^<b> , R ^<c> is respectively independently a C1-C10 aliphatic hydrocarbon group or a phenyl group. The aliphatic hydrocarbon group may be saturated or unsaturated, and may be branched. In the case of an unsaturated aliphatic hydrocarbon group, there may be a plurality of double bonds. The aliphatic hydrocarbon group is not particularly limited as long as it has 1 to 10 carbon atoms, and examples thereof include the above-described substituents such as an ethyl group, an isopropyl group, and a methyl group, and an isopropyl group or a methyl group is particularly preferable. Note that R ^a , R ^b , and R ^c may be the same substituent as each other or different from each other. The compound of IV can be obtained, for example, by the Grignard reaction as shown in the Examples.

Reaction of III and IV can be performed according to a normal halogen substitution reaction. The reaction is preferably performed using a catalyst. The type of catalyst is not particularly limited as long as it can promote the reaction, but (PPh ₃ ) ₂ PdCl ₂ / CuI, (PPh ₃ ) ₄ Pd / CuI, (PPh ₃ ) ₂ PdCl ₂ / CuAc ₂ , etc. Can be mentioned. The solvent used in the reaction is not particularly limited as long as III and IV can be dissolved and reacted, and examples thereof include diisopropylamine, triethylamine, diethylamine, and pyridine.
The compound obtained by the above reaction can be recovered by a normal isolation operation such as column chromatography. The structure of the compound can be confirmed by X-ray crystal structure analysis or NMR.

Hereinafter, the phosphorescent device of the present invention will be described.
The phosphorescent light emitting device of the present invention is a phosphorescent light emitting device having at least a pair of electrodes and a light emitting layer disposed between the electrodes, wherein the light emitting layer is at least one compound represented by the general formula (I), And a phosphorescent light emitting device containing a phosphorescent dopant.
As the anode, metals, alloys, electrically conductive compounds, and mixtures thereof having a work function larger than 4 eV can be used. Specific examples thereof include metals such as Au, CuI, indium-tin oxide (hereinafter abbreviated as ITO), SnO ₂ , ZnO, and the like.

  As the cathode material, metals, alloys, electrically conductive compounds, and mixtures thereof having a work function smaller than 4 eV can be used. Specific examples thereof are aluminum, calcium, magnesium, lithium, magnesium alloy, aluminum alloy and the like. Specific examples of the alloy include aluminum / lithium fluoride, aluminum / lithium, magnesium / silver, and magnesium / indium. In order to efficiently extract light emitted from the phosphorescent light emitting element, it is desirable that at least one of the electrodes has a light transmittance of 10% or more. The sheet resistance as the electrode is preferably several hundred Ω / □ or less. Although the film thickness depends on the properties of the electrode material, it is usually set in the range of 10 nm to 1 μm, preferably 10 to 400 nm. Such an electrode can be produced by forming a thin film by a method such as vapor deposition or sputtering using the electrode material described above.

The light emitting layer of the phosphorescent light emitting device of the present invention contains the compound of general formula (I) as a host compound and further contains a phosphorescent dopant that emits phosphorescence. The compound of general formula (I) contained in a light emitting layer may be one type, and may be two or more types. Preferred compounds as phosphorescent dopants include, but are not limited to, iridium complexes, platinum complexes, osmium complexes, and gold complexes. Specific examples thereof include tris [2- (2-pyridinyl) phenyl-C, N] -iridium (hereinafter referred to as Ir (ppy) 3), bis [(4,6-difluorophenyl) -pyridinate-N. , C ^{2 ′} ] pinacolate iridium, bis (4 ′, 6′-difluorophenylpyridinate) tetrakis (1-pyrazolyl) borate, bis (2-phenylbenzothiazole) iridium acetylacetonate and 2,3,7, 8,12,13,17,18-octaethynyl-21H, 23H-porphyrin platinum (II) and the like, compounds listed in page 13 of the Chemical Industry June 2004 issue and references cited therein, etc. It is done. The phosphorescent dopant contained in the light emitting layer may be two or more kinds of compounds.

The amount of dopant used varies depending on the dopant and may be determined according to the characteristics of the dopant. The standard of the amount of the dopant used is 0.001 to 50% by weight, preferably 0.1 to 10% by weight, based on the entire light emitting material.
The phosphorescent device of the present invention preferably includes an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer between the electrodes.
The order of lamination of the layers of the phosphorescent light emitting device of the present invention is not particularly limited, but it is more preferred that the layers are laminated in the order of cathode, electron transport layer, hole blocking layer, hole transport layer, hole injection layer and anode.

  Specific examples of materials used for the electron transport layer of the phosphorescent light emitting device of the present invention include quinolinol-based metal complexes, phenanthroline derivatives, pyridine derivatives, oxadiazole derivatives, triazole derivatives, quinoxaline derivatives, triazine derivatives, and borane derivatives. It is not limited to these. Specific examples of the quinolinol-based metal complex include tris (8-hydroxyquinoline) aluminum (hereinafter abbreviated as Alq3), bis (2-methyl-8-hydroxyquinoline)-(4-phenylphenol) aluminum (hereinafter abbreviated as BAlq). ) Etc. Specific examples of the phenanthroline derivative include 4,7-diphenyl-1,10-phenanthroline, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (hereinafter abbreviated as BCP) and the like. Specific examples of the pyridine derivative are 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl) -1,1-dimethyl-3,4-diphenylsilole, 9,10-di (2 ′, 2 ″). -Bipyridyl) anthracene, 2,5-di (2 ', 2 "-bipyridyl) thiophene and the like.

  Specific examples of materials used for the hole blocking layer of the phosphorescent light emitting device of the present invention include, but are not limited to, quinolinol-based metal complexes, phenanthroline derivatives, oxadiazole derivatives, triazole derivatives, borane derivatives, and anthracene derivatives. It is not a thing. Specific examples of the quinolinol-based metal complex and the phenanthroline derivative are the aforementioned BAlq and BCP. Specific examples of oxadiazole derivatives include 2- (4′-tert-butylphenyl) -5- (4 ″ -biphenyl-1,3,4-oxadiazole), etc. Specific examples of triazole derivatives include 1- Phenyl-2-biphenyl-5-para-tert-butylphenyl-1,3,4-triazole, etc. Specific examples of anthracene derivatives are 9,10-bisnaphthylanthracene and the like.

  Specific examples of the material used for the hole injection layer and the material used for the hole transport layer of the phosphorescent light emitting device of the present invention include, but are not limited to, a carbazole derivative, a triarylamine derivative, and a phthalocyanine derivative. . Specific examples of the carbazole derivative include 4,4'-bis (carbazol-9-yl) -biphenyl (hereinafter referred to as CBP), polyvinyl carbazole, and the like. Specific examples of the triarylamine derivatives include polymers having an aromatic tertiary amine in the main chain or side chain, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl- N, N′-di (3-methylphenyl) -4,4′-diaminobiphenyl, N, N′-diphenyl-N, N′-dinaphthyl-4,4′-diaminobiphenyl (hereinafter abbreviated as NPD). ), 4,4 ′, 4 ″ -tris {N- (3-methylphenyl) -N-phenylamino} triphenylamine, starburst amine derivatives, etc. Specific examples of phthalocyanine derivatives include metal-free phthalocyanine, copper Such as phthalocyanine.

Each layer constituting the phosphorescent light emitting device of the present invention can be formed by forming a material to constitute each layer into a thin film by a method such as vapor deposition, spin coating, or casting. The thickness of each layer formed in this way is not particularly limited and can be appropriately set according to the properties of the material, but is usually in the range of 2 nm to 5000 nm. Note that it is preferable to employ a vapor deposition method as a method of thinning the light emitting material from the standpoint that a homogeneous film can be easily obtained and pinholes are hardly generated. When a thin film is formed by using a vapor deposition method, the vapor deposition conditions vary depending on the type of the light emitting material of the present invention, the target crystal structure and associated structure of the molecular accumulation film, and the like. Deposition conditions generally include a boat heating temperature of 50 to 400 ° C., a degree of vacuum of 10 ⁻⁶ to 10 ⁻³ Pa, a deposition rate of 0.01 to 50 nm / second, a substrate temperature of −150 to + 300 ° C., and a film thickness of 5 nm to 5 μm. It is preferable to set appropriately within the range.

  The phosphorescent light emitting device of the present invention is preferably supported by a substrate regardless of the structure described above. The substrate only needs to have mechanical strength, thermal stability, and transparency, and glass, a transparent plastic film, and the like can be used.

  Next, as an example of a method for producing a phosphorescent light emitting device using the compound of general formula (I) (host compound), the above-mentioned anode / hole injection layer / hole transport layer / host compound of general formula (I) A method for manufacturing a phosphorescent light emitting device composed of + dopant (light emitting layer) / hole blocking layer / electron transport layer / cathode will be described. A thin film of an anode material is formed on a suitable substrate by vapor deposition to produce an anode, and then a thin film of a hole injection layer and a hole transport layer is formed on the anode. A host compound of general formula (I) and a dopant are co-deposited thereon to form a thin film to form a light emitting layer. A hole blocking layer and an electron transport layer are formed on the light emitting layer, and further comprises a cathode material. By forming a thin film by a vapor deposition method as a cathode, a target phosphorescent light emitting device can be obtained. In the above phosphorescent light emitting device, the fabrication order is reversed, and the cathode, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode may be fabricated in this order. Is possible.

When a DC voltage is applied to the phosphorescent device thus obtained, the anode may be applied with a positive polarity and the cathode with a negative polarity. When a voltage of about 2 to 40 V is applied, a transparent or translucent electrode is applied. Luminescence can be observed from the side (anode or cathode and both). The phosphorescent light emitting element also emits light when an alternating voltage is applied. The alternating current waveform to be applied may be arbitrary.
Hereinafter, the present invention will be described in more detail based on examples.

1. Synthesis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene (2,3,6,7,10,11-Hexakis (trimethylsilyletynyl) triphenylene; general formula (V)) as shown below By the procedure, 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene was synthesized.

1.1. Synthesis of triphenylene Triphenylene was synthesized according to the following reaction formula.
(Charge amount)
2-Bromofluorobenzene (Tokyo Kasei, 99%) 10.12 g / 5.73 x 10 ^-2 mol
Mg (Wako, sharpened, 99.5%) 1.54 g / 6.30 x 10 ^-2 mol
THF (benzophenone ketyl treatment) 85 + 15 mL
(Operation and result)
A 200 mL three-necked flask equipped with a dropping funnel, a Dimroth, and a spinner was flamed out and purged with argon. Mg was placed in the flask and activated at 180 ° C for 2 hours. 85 mL of THF was placed in a flask, and 2-Bromofluorobenzene and 15 mL of THF were placed in a dropping funnel, and dropped over 20 minutes (exotherm immediately after dropping). After completion of the dropwise addition, the mixture was refluxed at a THF reflux temperature for 6 hours. After washing with saturated NH ₄ Cl aqueous solution (100 mL × 3), the aqueous phase was extracted with Benzene (50 mL × 2), and the organic phases were combined and dried over anhydrous MgSO ₄ . After removing the solvent, the product was purified by sublimation and recrystallization, and the target product was obtained as colorless transparent needle crystals in a yield of 789 mg and a yield of 18%.

1.2. Synthesis of 2,3,6,7,10,11-hexabromotriphenylene (2,3,6,7,10,11-Hexabromotriphenylene) 2,3,6,7,10,11 -Hexabromotriphenylene was synthesized.
(Charge amount)
Triphenylene (synthetic product) 2.00 g / 8.51 x 10 ^-3 mol
Br ₂ (Wako) 4.0 mL
Fe (powder) 0.484 g / 3.29 x 10 ^-3 mol
PhNO ₂ (Kanto, simple distillation) 80 mL
(Operation and result)
A 200 mL three-necked flask equipped with a dropping funnel, Dimroth, and spinner was flamed out and replaced with Ar. Triphenylene, Fe powder, and PhNO ₂ were placed in a flask. Br ₂ was placed in the dropping funnel and dropped over 15 minutes. After completion of dropping, the mixture was stirred at room temperature for 10 hours and then stirred at 200 ° C for 2 hours. After cooling, Et ₂ O was added to the reaction mixture, insolubles were filtered off, and recrystallized with 800 mL of o-Dichlorobenzene to obtain the target product as a white powder, yield 5.18 g, yield 87%. .

1.3. Synthesis of Trimethylsilylacetylene Trimethylsilylacetylene was synthesized according to the following reaction formula.
(Charge amount)
Acetylene (bomb, kansan)
EtMgBr (prepared product, 1.5 M in THF) 400 mL / 600 mmol
Me ₃ SiBr (Nisso, 99%) 85.54 g / 553 mmol
THF (benzophenone ketyl treatment) 200 mL
(Operation and result)
A 2000 mL four-necked flask equipped with a dropping funnel, a Dimroth, and a spinner was flamed out and replaced with Ar. The flask was charged with 200 mL of THF. After bubbling acetylene gas in an ice bath for 1.5 hours, EtMgBr prepared separately from a dropping funnel was added dropwise over 1 hour and 50 minutes. After completion of the dropwise addition, the mixture was stirred for 30 minutes with bubbling, stopped and stopped for 40 minutes. The bath was changed to a dry ice-methanol bath, and Me ₃ SiBr was dropped from the dropping funnel over 40 minutes. The mixture was stirred for 30 minutes in a dry ice-methanol bath, then returned to room temperature and stirred overnight. The reaction was completed again by putting into an ice bath and adding 200 mL of saturated aqueous ammonium chloride solution. The organic phase was collected by liquid separation and dried over anhydrous MgSO ₄ . Atomic pressure distillation, followed by fractionation using a convection tower, gave the target compound as a colorless transparent liquid to obtain trimethylsilylacetylene.

1.4. Preparation of dichlorobis (triphenylphosphine) palladium (II) (Dichlorobis (triphenylphosphine) palladium (II)) Dichlorobis (triphenylphosphine) palladium (II) was synthesized according to the following reaction formula.
(Charge amount)
PdCl ₂ (Wako, 98%) 1.00 g / 5.54 x 10 ^-3 mol
PPh ₃ (Kanto, 99%) 3.00 g / 1.14 x 10 ^-2 mol
conc. HCl aq. (Kanto, 35-37%) 0.17 mL
EtOH (simple distillation) 50 mL
H ₂ O (ion exchange water) 100 mL
(Operation and result)
Ion-exchanged water, concentrated hydrochloric acid, and PdCl ₂ were placed in a 200 mL three-necked flask and slowly dropped into the EtOH solution of PPh ₃ using a cannula while stirring (while heating to 60 ° C in an oil bath) . After completion of dropping, the mixture was stirred at 60 ° C for 3 hours. Insoluble matter (target product) was filtered off and washed with 100 mL of boiling water, 100 mL of hot EtOH, and 100 mL of hot Et ₂ O in this order (crude yield 2.09 g, crude yield 53%). 1 g of this was taken and dissolved in 50 mL of hot CHCl ₃ , and 150 mL of hexane was added thereto to precipitate (PPh ₃ ) ₂ PdCl ₂ . The obtained (PPh ₃ ) ₂ PdCl ₂ was heated and dried at 100 ° C. using phosphorus pentachloride (yellow fine powder crystals, recovered 0.83 g, recovery rate 83%).

1.5. Synthesis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene was synthesized according to the following reaction formula.
(Charge amount)
2,3,6,7,10,11-hexabromotriphenylene 205 mg / 2.92 x 10 ^-4 mol
trimethylsilylacetylene 1.68 g / 1.71 x 10 ^-2 mol
(PPh ₃ ) ₂ PdCl ₂ 245 mg / 3.49 x 10 ^-4 mol
CuI (Wako) 66 mg / 3.47 x 10 ^-4 mol
i-Pr ₂ NH (Tokyo Kasei, distilled from CaH ₂ ) 200 mL
(Operation and result)
A 300 mL three-necked flask equipped with a dropping funnel, a Dimroth, and a spinner was flamed out and replaced with N ₂ . The flask was charged with 2,3,6,7,10,11-hexabromotriphenylene and (PPh ₃ ) ₂ PdCl ₂ , CuI, i-Pr ₂ NH. Me ₃ SiC≡CH was dropped from the dropping funnel over 30 minutes (the solution was immediately yellow → brown). Thereafter, the mixture was stirred for 3 hours under reflux. After removing the solvent with a rotary evaporator, the insoluble matter is removed with a flash column (Wakogel C-60, benzene), and the wet column (first time; Wakogel C-60, hexane / Et ₂ O = 9/1, second time; Wakogel C-60, hexane / CH ₂ Cl ₂ = 8/2), and collected 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene as a yellow crystal in a yield of 210 mg. Obtained at a rate of 90%.

2. Analysis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene 2.1. X-ray crystal structure analysis Identification was performed using various spectra, and the structure was finally determined by X-ray crystal structure analysis.
The spectral data of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene were as follows.
MS (mass spectrometry) (EI, 70 eV) m / z (%) 804 (M ⁺ , 83), 789 (3), 731 (3), 716 (7), 701 (8), 73 (100)
IR (infrared absorption spectrum) (KBr) cm ^-1 2959, 2899, 2162, 1483, 1404, 1248, 1190, 1146, 997, 864, 845, 760, 650
¹ H NMR (nuclear magnetic resonance spectrum) (500 MHz, CDCl ₃ ) δ 0.34 (s, 54H), 8.63 (s, 6H) ppm
¹³ C NMR (126 MHz, CDCl ₃ ) δ 0.06, 99.88, 103.03, 124.91, 127.91, 128.51 ppm
²⁹ Si NMR (99 MHz, CDCl ₃ ) δ -17.2 ppm
Melting point 300 ° C (decomposition and polymerization)

  Recrystallization from a mixed solvent of dichloromethane, hexane, and ethanol gave 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene yellow transparent crystals. Figures 1 to 4 show the results of X-ray crystal structure analysis. The triphenylene ring had a substantially planar structure, but the trimethylsilylethynyl group was slightly off the ring plane. A summary of the bond distance and bond angle is shown in FIGS. The aromatic ring had a longer bond distance than the other while the substituents were bonded. The carbon-carbon triple bond is slightly shorter than the normal value (1.2 Å) (av. 1.181 Å). Disorders were found in the carbon of one trimethylsilyl group. Looking at the packing, each molecule was stacked in an arrowhead shape. The closest distance between parallel layers is 4.5 sp between sp carbons. The distance between silicon atoms located diagonally is about 16 mm.

2.2. Properties of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene, etc. 2.2.1. Physical properties
2,3,6,7,10,11-Hexakis (trimethylsilylethynyl) triphenylene does not show a clear melting point, and when heated to about 300 ° C., the crystal turns orange, It turns brown at ° C (observed with a melting point instrument). From this, it was considered that polymerization occurred in the crystal, and later thermogravimetric analysis revealed that polymerization had occurred.
The solubility is considered to be improved compared to the parent triphenylene. It is soluble in common organic solvents (hexane, benzene, toluene, acetone, Et ₂ O, THF, CH ₂ Cl ₂ , CHCl ₃ ) and hardly soluble in EtOH and MeOH.
Even if it is left in the air in the crystalline state, the transparency and the like do not change.

2.2.2. UV-visible absorption spectrum
FIG. 7 shows the results of measuring UV-visible absorption spectra of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene in hexane at room temperature. Table 1 summarizes the values of the absorption maximum and molar extinction coefficient (ε) of each absorption band. As for any peak, it can be seen that 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene is shifted by about 40 to 50 nm longer wavelength. The value of the molar extinction coefficient is also increasing.

2.2.3. Luminescence (fluorescence, phosphorescence) spectrum
The fluorescence spectra of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene were measured in 3-methylpentane (3-MP) at a degassed tube, at room temperature, and at an excitation wavelength of 296 nm. It is shown in FIG. The fluorescence maxima are 415, 428, and 439 nm, which is shifted about 60 nm longer than the corresponding fluorescence maxima of triphenylene, and the intensity is also strong. The quantum yield of fluorescence calculated based on triphenylene (Φ _f = 0.09) is Φ _f = 0.16.
Figure 9 shows the results of emission spectrum measurement of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene in 3-MP, degassed sealed tube, excitation wavelength 296 nm, 77K. Each emission maximum observed a long wavelength shift of about 60 nm. Thus, it was found that 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene can be used for the light emitting layer of the phosphorescent device.

Synthesis and spectral analysis of 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene First, triisopropylsilylacetylene was synthesized by the following reaction.

By reacting this with 2,3,6,7, -10,11-hexabromotriphenylene, 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene (general formula (VI)) ) Was synthesized. The reaction was carried out in the same manner as 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene. The yield was 55%.

The ultraviolet-visible absorption spectrum of 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene was measured in hexane at room temperature. The results are shown in FIG. 10 together with data on triphenylene and 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene.
2,3,6,7,10,11-Hexakis (triisopropylsilylethynyl) triphenylene also showed a long wavelength shift compared to triphenylene.

The fluorescence spectrum of 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene was measured in 3-methylpentane (3-MP) at a degassed sealed tube at room temperature and an excitation wavelength of 296 nm. The results are shown in FIG. 11 together with data on triphenylene and 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene.
It was found that 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene was also shifted by about 60 nm longer than the corresponding fluorescence maximum of triphenylene and increased in intensity.

The emission (fluorescence / phosphorescence) spectrum of 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene was measured in 3-MP in a degassed sealed tube with an excitation wavelength of 296 nm and 77K. The results are shown in FIG. 12 together with data on triphenylene and 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene.
A long wavelength shift was also observed for 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene. Thus, it was found that 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene can be used for the light emitting layer of the phosphorescent light emitting device.

Production of phosphorescent light emitting device using 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene (compound 1) as a host compound and confirmation of light emission ITO was deposited on a glass substrate to a thickness of 150 nm. This was a transparent support substrate. This transparent support substrate is fixed to the substrate holder of the vapor deposition apparatus, and a molybdenum vapor deposition boat containing copper phthalocyanine (hereinafter referred to as CuPc), a molybdenum vapor deposition boat containing NPD, and Ir (ppy) 3 Molybdenum vapor deposition boat, molybdenum vapor deposition boat containing compound 1, molybdenum vapor deposition boat containing BCP, molybdenum vapor deposition boat containing Alq3, molybdenum vapor deposition boat containing lithium fluoride, And a tungsten evaporation boat containing aluminum.

Depressurize the vacuum chamber to 1 × 10 ⁻³ Pa, heat the vapor deposition boat containing CuPc and deposit it to a film thickness of 25 nm to form a hole injection layer, and then vapor deposition for NPD The boat was heated and evaporated to a film thickness of 35 nm to form a hole transport layer. Next, the boat containing Ir (ppy) 3 and the boat containing Compound 1 were heated at the same time and evaporated to a film thickness of 35 nm to form a light emitting layer. Next, the boat containing BCP was heated and evaporated to a thickness of 10 nm to obtain a hole blocking layer. The deposition rate was adjusted so that the weight ratio of Ir (ppy) 3 to Compound 1 was approximately 5 to 95. Thereafter, the evaporation boat containing Alq3 was heated to a thickness of 40 nm to form an electron transport layer.

The deposition rate of each layer was 0.001 to 3.0 nm / sec. Thereafter, the evaporation boat containing lithium fluoride is heated to deposit at a deposition rate of 0.003 to 0.01 nm / second so that the film thickness becomes 0.5 nm, and then the evaporation boat containing aluminum is heated. The phosphorescent light-emitting device was obtained by vapor deposition at a vapor deposition rate of 0.1 to 1 nm / second so that the film thickness was 100 nm.
When a 7V DC voltage is applied using an ITO electrode as an anode and a lithium fluoride / aluminum electrode as a cathode, a current of about 3.0 mA / cm ² flows and has a spectrum derived from Ir (ppy) 3 having a peak at a wavelength of 510 nm. A green light emission was obtained.

[Comparative Example 1]
In Example 1, a phosphorescent light emitting device was obtained in exactly the same manner except that CBP was used instead of the compound 1 used in the light emitting layer.
When a 7V DC voltage is applied using an ITO electrode as an anode and a lithium fluoride / aluminum electrode as a cathode, a current of about 1.5 mA / cm ² flows and has a spectrum derived from Ir (ppy) 3 having a peak at a wavelength of 510 nm. A green light emission was obtained.

ORTEP diagram (viewed from above) showing the results of X-ray crystal structure analysis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene. ORTEP diagram (side view) showing the results of X-ray crystal structure analysis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene. ORTEP diagram showing the results of X-ray crystal structure analysis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene (viewed from the a-axis direction). ORTEP diagram showing the results of X-ray crystal structure analysis of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene (viewed from the b-axis direction). The figure which shows the bond distance of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene. The figure which shows the bond angle of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene. The figure which shows the ultraviolet-visible absorption spectrum of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene. The figure which shows the fluorescence spectrum of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene. Diagram showing emission spectrum of 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene and triphenylene in 3-MP, degassed sealed tube, excitation wavelength 296 nm, 77K. The figure which shows the ultraviolet-visible absorption spectrum of each triphenylene compound. 1 represents 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene, and 2 represents 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene. The figure which shows the fluorescence spectrum of each triphenylene compound. 1 represents 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene, and 2 represents 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene. The figure which shows the emission spectrum in 3-MP, a deaeration sealed tube, excitation wavelength 296nm, 77K of each triphenylene compound. 1 represents 2,3,6,7,10,11-hexakis (trimethylsilylethynyl) triphenylene, and 2 represents 2,3,6,7,10,11-hexakis (triisopropylsilylethynyl) triphenylene.

Claims (7)

An organic electroluminescence device using phosphorescence having at least a pair of electrodes and a light emitting layer disposed between the electrodes, wherein the light emitting layer is at least one compound represented by the general formula (I), and a phosphorescent dopant An organic electroluminescent device using phosphorescence, comprising:
In the general formula (I), all of R ^{1 to} R ⁶ are substituents represented by the general formula (II), and in the general formula (II), R ^a , R ^b and R ^c are respectively The organic electroluminescent element using phosphorescence according to claim 1, which is independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms. The organic electroluminescent element using phosphorescence according to claim 1 or 2, wherein in the general formula (II), all of the substituents R ^a , R ^b , and R ^c are alkyl groups.   The organic electroluminescence device using phosphorescence according to claim 3, wherein the alkyl group is an isopropyl group or a methyl group. In the general formula (I), any one or two of R ^{1 to} R ⁶ are substituents represented by the general formula (II), and in the general formula (II), R ^a , The organic electroluminescent element using phosphorescence according to claim 1, wherein R ^b and R ^c are phenyl groups.   6. The organic electroluminescence device using phosphorescence according to claim 1, wherein the phosphorescent dopant is at least one selected from an iridium complex, a platinum complex, an osmium complex, and a gold complex.   The organic electroluminescent element using phosphorescence according to any one of claims 1 to 6, further comprising an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer between the electrodes.