JP2006100537A - Organic electroluminescence element, lighting device, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescence element material which has high emission efficiency and a long life, and an organic electroluminescence element, a lighting device, and a display device using the material. <P>SOLUTION: The organic electroluminescence element has a component layer which at least includes a phosphorescent light-emitting layer, and a hole preventive layer between a pair of electrodes. The hole preventive layer contains at least one kind of the compound represented by the general formula (1). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescence element, a lighting device, and a display device.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also referred to as organic EL elements).

  Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements.

  On the other hand, an organic EL element has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. By injecting electrons and holes into the light emitting layer and recombining them, excitons (exciton) are obtained. And emits light using the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a light-emitting type, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

  For the development of organic EL elements for practical use in the future, organic EL elements that emit light efficiently and with high brightness with lower power consumption are desired. For example, stilbene derivatives, distyrylarylene derivatives, or tris A technique for doping a styrylarylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device (see, for example, Patent Document 1), and 8-hydroxyquinoline aluminum complex as a host compound. A device having an organic light-emitting layer doped with a trace amount of phosphor (for example, see Patent Document 2), a device having an organic light-emitting layer doped with a quinacridone dye as a host compound using 8-hydroxyquinoline aluminum complex (for example, , See Patent Document 3).

  In the technique disclosed in the above-mentioned patent document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

  However, since Princeton University has reported on organic EL devices that use phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature has become active. (For example, see Non-Patent Document 2 and Patent Document 4.)

  When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and attracts attention.

  For example, many compounds have been studied focusing on heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).

  Further, studies using tris (2-phenylpyridine) iridium as a dopant have been made (for example, see Non-Patent Document 2).

In addition, L ₂ Ir (acac), for example, (ppy) ₂ Ir (acac) (see, for example, Non-Patent Document 4) as a dopant, and tris (2- (p-tolyl) pyridine) iridium (as a dopant) Studies using Ir (ptpy) ₃ ), tris (benzo [h] quinoline) iridium (Ir (bzq) ₃ ), Ir (bzq) ₂ ClP (Bu) _3, etc. (for example, see Non-Patent Document 5). Has been done.

  In order to obtain high luminous efficiency, a hole transporting compound is used as a host of the phosphorescent compound (see, for example, Non-Patent Document 6).

  Further, various electron transporting materials are used as phosphorescent compound hosts by doping them with a novel iridium complex (for example, see Non-Patent Document 4). Furthermore, high luminous efficiency is obtained by introducing a hole blocking layer (see, for example, Non-Patent Document 5).

  Currently, further improvement in light emission efficiency and life of organic EL elements using phosphorescence emission are being studied.

However, although the external extraction efficiency of 20%, which is the theoretical limit for green light emission, has been achieved, it is only in the low current region (low luminance region), and the theoretical limit is still in the high current region (high luminance region). Not achieved. Furthermore, sufficient efficiency has not yet been obtained for other luminescent colors, and improvements are required. In addition, organic EL devices for practical application in the future will emit light efficiently and with high brightness. Development of the organic EL element which does is desired. Particularly, there is a demand for an element that emits light with high efficiency in an organic EL element that emits blue phosphorescence.
Japanese Patent No. 3093796 Japanese Unexamined Patent Publication No. 63-264692 JP-A-3-255190 US Pat. No. 6,097,147 M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001) M.M. E. Thompson et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Moon-Jae Youn. 0 g, Tetsuo Tsutsui et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Ikai et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu)

  An object of the present invention is to provide an organic EL element material with high luminous efficiency, an organic EL element, an illumination device, and a display device using the organic EL element material. Furthermore, it is providing the organic EL element material which becomes long life, the organic EL element using this organic EL element material, an illuminating device, and a display apparatus.

  The above object of the present invention has been achieved by the following configurations 1 to 8.

(Claim 1)
It has a constitutional layer including at least a phosphorescent light emitting layer and a hole blocking layer between a pair of electrodes, and the hole blocking layer contains at least one compound represented by the following general formula (1). An organic electroluminescence element.

[Wherein, A ₁ represents a substituent. Z ₁ and Z ₂ each represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₁ and R ₂ each represent a substituent, and when there are a plurality of R ₁ and R ₂ , they may be different or the same. n1 represents an integer of 0 to 3, and n2 represents an integer of 1 to 3. At least one of R ₂ represents a substituent having σp of −0.20 or less. ]
(Claim 2)
It has a constituent layer including at least a phosphorescent light emitting layer and a hole blocking layer between a pair of electrodes, and the hole blocking layer contains at least one compound represented by the following general formula (2). An organic electroluminescence element.

[Wherein A ₂ represents a substituent. Z ₃ represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₃ and R ₄ each represent a substituent, and when there are a plurality of R ₃ and R ₄ , they may be different or the same. n3 represents an integer of 0 to 3, and n4 represents an integer of 1 to 4. At least one of R ₄ represents a substituent having σp of −0.20 or less. ]
(Claim 3)
The organic electroluminescent element according to claim 2, wherein the compound represented by the general formula (2) is represented by the following general formula (3).

[Wherein A ₃ represents a substituent. Z ₃ represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₅ and R ₆ each represent a substituent, and when there are a plurality of R ₅ and R ₆ , they may be different or the same. n5 represents an integer of 0 to 3, and n6 represents an integer of 0 to 2. R ₇ and R ₈ represent a hydrogen atom or a substituent, and at least one of R ₇ and R ₈ represents a substitution with σp of −0.20 or less. ]
(Claim 4)
The organic electroluminescent element according to claim 1, wherein the phosphorescent light emitting layer contains osmium, iridium, rhodium, or a platinum complex compound.

(Claim 5)
The organic electroluminescence element according to any one of claims 1 to 4, wherein the organic electroluminescence element emits white light.

(Claim 6)
A display device comprising the organic electroluminescence element according to claim 1.

(Claim 7)
An illuminating device comprising the organic electroluminescence element according to claim 1.

(Claim 8)
A display device comprising: the lighting device according to claim 7; and a liquid crystal element as a display unit.

  According to the present invention, an organic EL element having high emission efficiency and a long emission lifetime can be provided. Furthermore, a high-luminance lighting device and display device including the organic EL element could be provided.

  In the organic electroluminescence device of the present invention, an organic EL device having high emission efficiency and a long light emission lifetime can be obtained by adopting the configuration defined in any one of claims 1 to 5. . Furthermore, a high-luminance display device and illumination device could be obtained using the organic EL element.

  Hereinafter, details of each component according to the present invention will be sequentially described.

  As a result of various studies on the above-mentioned problems, the inventors of the present invention have the reason why the organic electroluminescence device of the present invention has improved the light emission efficiency and extended the light emission lifetime, as shown in FIG. Description will be made using a schematic diagram showing an example of an energy level diagram of an organic EL element.

  In FIG. 8, ITO constitutes the anode of the organic EL element, and Al constitutes the cathode. A hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, and an electron transport layer are formed between ITO and Al, and FIG. 8 schematically shows the energy level diagram of each layer. Yes.

  The inventors of the present invention can improve the characteristics of the device (high luminous efficiency and long life) by using the compound represented by the general formula (1), (2) or (3) for the hole blocking layer. The reason for this is that the use of the above compound in the hole blocking layer reduced the LUMO gap difference Δ between the light emitting layer and the hole blocking layer, which facilitated the transfer of electrons to and from the host compound. I think that the.

<< Compound Represented by Formula (1) >>
The compound represented by the general formula (1) according to the present invention will be described.

In the general formula (1), examples of the substituent represented by A _1, for example, in the present invention, the substituents, an alkyl group (e.g., methyl group, an ethyl group, a propyl group, an isopropyl group, tert- butyl group, Pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group, etc.), Alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group (eg, phenyl group, etc.), aromatic heterocyclic group (eg, furyl group, thienyl group, pyridyl group, pyridazyl group, pyrimidyl group, pyrazyl group, triazyl group) Group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolyl group, phthalazyl group, etc.), complex Group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.) , Cycloalkoxyl groups (for example, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy groups (for example, phenoxy group, naphthyloxy group, etc.), alkylthio groups (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group) Group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (For example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl Group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl) Cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy) Group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexyl group) Carbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino , Naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexyl) Aminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido) Group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group) , Ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethyl Sulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group) , Ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2 Pyridylamino groups, etc.), halogen atoms (eg, fluorine atoms, chlorine atoms, bromine atoms, etc.), fluorinated hydrocarbon groups (eg, fluoromethyl groups, trifluoromethyl groups, pentafluoroethyl groups, pentafluorophenyl groups, etc.), And cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

In the general formula (1), Z ₁ and Z ₂ each form a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom, for example, pyridine ring, pyridazine ring, pyrimidine ring, triazine Ring, pyrazine ring and the like. The 6-membered aromatic heterocyclic ring may have a substituent represented by A ₁ in the general formula (1).

In general formula (1), the substituents represented by R ₁ and R ₂ have the same meaning as the substituent represented by A ₁ in general formula (1). Here, at least one of R ₂ represents a substituent having σp of −0.20 or less, and the substituent according to the present invention has a σp value of −0.20 or less (which is an electron-donating substituent). As, for example, a cyclopropyl group (−0.21), 3.4- (CH ₂ CH ₂ CH ₂ ) (− 0.26), 3.4- (CH ₂ ) ₄ (−0.48), C (CH ₃ ) ₃ (−0.20), CH ₂ Si (CH ₃ ) ₃ (−0.21), cyclohexyl group (−0.22), amino group (−0.66), hydroxylamino group ( -0.34), hydrazino group (-0.55), carbamoylamino group (-0.24), methylamino group (-0.84), ethylamino group (-0.61), butylamino group (- 0.51), ethylcarbamoyl amino group _{(-0.26), OCH 2 COOH (} -0.33), phenyl Amino group _{(-0.40), N = CHC 6} H 5 (-0.55), dialkylamino group (e.g., dimethylamino group (-0.83), diethylamino group (-0.90), dipropylamino Group (−0.93), diisopropylamino group, etc.), alkoxyl group (for example, methoxy group (−0.27), ethoxy group (−0.24), propoxy group (−0.25), butoxy group (− 0.32), a pentyloxy group (−0.34)) and the like, among which a dialkylamino group and an alkoxyl group are preferable.

  Here, for Hammett's σp value, for example, the following documents can be referred to.

Hammett's σp value
The Hammett σp value according to the present invention refers to Hammett's substituent constant σp. Hammett's σp value is a substituent constant determined by Hammett et al. From the electronic effect of the substituent on the hydrolysis of ethyl benzoate. “Structure-activity relationship of drugs” (Nanedo: 1979), “Substituent” The groups described in “Constants for Correlation Analysis in chemistry and biology” (C. Hansch and A. Leo, John Wiley & Sons, New York, 1979) can be cited.

<< Compound Represented by Formula (2) >>
The compound represented by the general formula (2) according to the present invention will be described.

In the general formula (2), the substituent represented by A ₂ has the same meaning as the substituent represented by A ₁ in the general formula (1).

In the general formula (2), a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom formed by Z ₃ is formed by Z ₁ and Z ₂ in the general formula (1). It is synonymous with a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom.

In general formula (2), the substituents represented by R ₃ and R ₄ have the same meaning as the substituent represented by A ₁ in general formula (1). Here, at least one of R ₄ represents a substituent having σp of −0.20 or less, and the substituent is synonymous with the group represented by R ₂ in the general formula (1).

<< Compound Represented by Formula (3) >>
In the present invention, among the compounds represented by the general formula (2), the compound represented by the general formula (3) is preferably used.

In the general formula (3), the substituent represented by A ₃ has the same meaning as the substituent represented by A ₁ in the general formula (1).

In the general formula (3), the 6-membered aromatic heterocycle formed by Z ₃ together with at least one nitrogen atom as a constituent atom is a structure in which Z ₁ and Z ₂ each form in the general formula (1). It is synonymous with a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as an atom.

In the general formula (3), the substituents represented by R ₅ and R ₆ and the substituents represented by R ₇ and R ₈ are the substituents represented by A ₁ in the general formula (1), respectively. It is synonymous with.

Here, at least one of R ₇ and R ₈ represents a substituent having σp of −0.20 or less, and the substituent is synonymous with the group represented by R ₂ in the general formula (1). is there.

  Hereinafter, although the specific example of a compound represented by General formula (1), (2) or (3) is shown, this invention is not limited to these.

  Although an example of a compound synthesis | combination represented by general formula (1), (2) or (3) based on this invention is shown below, this invention is not limited to these.

  << Synthesis of Compound 5 >>

  Dibenzylideneacetone palladium (774 mg) and diphenylphosphinoferrocene (748 mg) were stirred under a nitrogen stream, and toluene (90 ml), 3-amino-2-bromopyridine (9.2 g), 4-iodoanisole (15.0 g), sodium tertiary butoxide (6.7 g). And heated to reflux for 5 hours. Water and tetrahydrofuran were added thereto, and extraction, drying, concentration, and purification by column chromatography yielded 2 g of compound (A).

  Next, 3.5 g of compound (A) was dissolved in 150 ml of DMF, and the atmosphere was replaced with nitrogen. Then, 141 mg of palladium acetate and 1.9 g of sodium carbonate were added, and the mixture was heated to reflux for 10 hours. 1.6 g of compound (B) was obtained by adding water and tetrahydrofuran to this, extracting, drying, concentrating, and refine | purifying with column chromatography.

  Next, 104 mg of palladium acetate and 0.44 ml of tritertiary butylphosphine were stirred under a nitrogen stream, and 10 ml of dehydrated xylene, 1.3 g of diiodoxylene, 1.55 g of compound (B), and 89 mg of sodium tertiary butoxide were added thereto. In addition, the mixture was heated to reflux for 16 hours. Water and tetrahydrofuran were added thereto, and extraction, drying, concentration, and purification by column chromatography yielded 320 mg of the target compound 5. The structure of the compound was confirmed by mass and NMR (nuclear magnetic resonance spectrum).

<< Application of the compound represented by the general formula (1), (2) or (3) to an organic EL device >>
When producing an organic EL device using at least one compound represented by each of the general formula (1), (2) or (3), in the constituent layers of the organic EL device (details will be described later) By forming the light emitting layer and the hole blocking layer, the effects described in the present invention can be obtained.

  Next, although the preferable specific example of the layer structure of the organic EL element of this invention is shown below, this invention is not limited to these.

I: Anode / light emitting layer / cathode
II: Anode / light-emitting layer / electron transport layer / cathode
III: Anode / anode buffer layer / light emitting layer / cathode
IV: anode / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode V: anode / hole transport layer / light emitting layer / electron transport layer / cathode
VI: Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode
VII: Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode
VIII: Anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode << light emitting layer >>
The light-emitting layer according to the present invention contains a light-emitting material, and is a layer that emits light by recombination of electrons and holes injected from an electrode, an electron transport layer, or a hole transport layer, and the light-emitting portion is a light-emitting layer The interface between the light emitting layer and the adjacent layer may be used.

  In the present invention, a phosphorescent compound is preferably used as the light emitting material. Thereby, high light emission luminance and light emission efficiency can be obtained. A phosphorescent compound is a compound in which light emission from an excited triplet is observed, is a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 0.01 or more at 25 ° C. It is. The phosphorescence quantum yield is preferably 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence quantum yield used in the present invention only needs to achieve the above phosphorescence quantum yield in any solvent.

  There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is phosphorescent. Energy transfer type to obtain light emission from the phosphorescent compound by transferring to the compound, the other is that the phosphorescent compound becomes a carrier trap, carrier recombination occurs on the phosphorescent compound, and from the phosphorescent compound In any case, the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device.

  The mixing ratio with the light emitting dopant to the light emitting host which is the host compound which is the main component in the light emitting layer (the phosphorescent compound according to the present invention, which will be described later, is a kind of light emitting dopant) is preferably mass. It is adjusting to the range of 0.1 mass%-less than 30 mass%.

  In the present invention, the phosphorescent compound is preferably an osmium, iridium, rhodium or platinum complex compound, whereby the luminance and luminous efficiency can be further improved.

  The phosphorescent compound (also referred to as phosphorescent compound) used in the present invention preferably has a phosphorescence quantum yield in solution of 0.001 or more at 25 ° C., more preferably 0.01 or more. Particularly preferably, it is 0.1 or more.

  The host compound used in the present invention is a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.01 at room temperature (25 ° C.) among compounds contained in the light emitting layer.

The phosphorescence quantum yield can be measured by the method described in the fourth edition of Experimental Chemistry Course 7, Spectroscopy II, page 398 (1992 edition, Maruzen). Specific examples of the phosphorescent compound used in the present invention are as follows. Examples are shown, but the invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In addition, as the phosphorescent compound (luminescent dopant), the compounds described in the following public relations can also be used.

  For example, International Publication No. 00/70655 pamphlet, Japanese Patent Application Laid-Open No. 2002-280178, Japanese Patent Application Laid-Open No. 2001-181616, Japanese Patent Application Laid-Open No. 2002-280179, Japanese Patent Application Laid-Open No. 2001-181617, and Japanese Patent Application Laid-Open No. 2002-280180. JP, 2001-247859, JP, 2002-299060, JP, 2001-313178, JP, 2002-302671, JP, 2001-345183, JP, 2002-324679, International, Publication No. 02/15645, JP 2002-332291 A, JP 2002-50484 A, JP 2002-332292 A, JP 2002-83684 A, JP 2002-540572 A, JP 2002-117978, JP 2002-338588, JP 2002-170684, JP 2002-352960, WO 01/93642, JP 2002-50483, JP 2002-1000047, JP JP 2002-173684 A, JP 2002-359082 A, JP 2002-17584 A, JP 2002-363552 A, JP 2002-184582 A, JP 2003-7469 A, Special Table 2002. No. 525808, JP 2003-7471, JP 2002-525833, JP 2003-31366, JP 2002-226495, JP 2002-234894, JP 2002-233506 Japanese Patent Laid-Open No. 2002-24175 JP, JP 2001-319779, JP 2001-319780, JP 2002-62824, JP 2002-1000047, JP 2002-203679, 2002-343572. JP, 2002-203678, A, etc. are mentioned.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited, and in principle, the emission wavelength obtained by selecting a central metal, a ligand, a ligand substituent, and the like. However, it is preferable that the phosphorescence emission wavelength of the phosphorescent compound has a maximum phosphorescence emission wavelength of 380 to 480 nm. Such a blue phosphorescent organic EL element or a white phosphorescent organic EL element can be an organic electroluminescent element having higher emission luminance and a longer half-life.

  In addition, by using a plurality of phosphorescent compounds, it is possible to mix different light emission, thereby obtaining an arbitrary emission color. White light emission is possible by adjusting the kind of phosphorescent compound and the amount of doping, and can also be applied to lighting devices and backlights.

  In the light emitting layer, a plurality of known host compounds may be used in combination. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. As these known host compounds, compounds having a hole transporting ability and an electron transporting ability, preventing the emission of longer wavelengths, and having a high Tg (glass transition temperature) are preferable.

  Specific examples of known host compounds include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  Further, the light emitting layer may contain a fluorescent compound having a longer fluorescent maximum wavelength. In this case, energy transfer from the host compound and the phosphorescent compound to the fluorescent compound enables electroluminescence as an organic EL element to be emitted from the fluorescent compound. The fluorescent compound preferably has a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield of the fluorescent compound is preferably 10% or more, particularly preferably 30% or more. Specific fluorescent compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzoanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes. , Stilbene dyes, polythiophene dyes, and the like. The fluorescence quantum yield can be measured by the method described in 362 (1992, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.

  The color emitted in this specification is the spectral radiance meter CS-1000 (Minolta) in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Society for Color Science, University of Tokyo Press, 1985). It is determined by the color when the measured result is applied to the CIE chromaticity coordinates.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an ink jet method, but preferably by a spin coating method. is there. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, 5 nm-5 micrometers, Preferably it is chosen in the range of 5 nm-200 nm. The light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are composed of one or more kinds, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Good.

<Blocking layer: hole blocking layer, electron blocking layer>
The hole blocking layer is an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes. By blocking holes while transporting electrons, And the recombination probability of holes can be improved.

  The hole blocking layer has a role of blocking the holes moving from the hole transport layer from reaching the cathode and a compound that can efficiently transport the electrons injected from the cathode toward the light emitting layer. It is formed. The physical properties required of the material constituting the hole blocking layer are higher than the ionization potential of the light emitting layer in order to have high electron mobility and low hole mobility and to efficiently confine holes in the light emitting layer. It is preferable to have a value of ionization potential or a band gap larger than that of the light emitting layer.

  In the organic electroluminescence device of the present invention, it is preferable to provide a hole blocking layer adjacent to the light emitting layer. Thereby, the light emission luminance and the light emission efficiency can be further improved.

  In the present invention, the hole blocking layer contains at least one compound represented by the general formula (1) or at least one compound represented by the general formula (2). The effect described in the present invention, that is, a device having a high light emission luminance and light emission efficiency and having a long lifetime can be obtained. Among the compounds represented by the general formula (2), the compound represented by the general formula (3) is preferable.

  In the organic EL device of the present invention, the hole blocking layer preferably contains at least one compound represented by the general formula (1), thereby further improving the light emission luminance and the light emission efficiency. be able to.

  On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.

《Hole transport layer》
The hole transport layer which is one of the constituent layers of the organic EL device of the present invention will be described.

  The hole transport layer is made of a material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer and the electron transport layer can be provided as a single layer or a plurality of layers.

  As the hole transport material, conventionally, any of photoconductive materials conventionally used as a charge injection transport material for holes, or a known material used for a hole injection layer or a hole transport layer of an EL element is arbitrarily selected. Can be selected and used.

  The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N′-diphenyl-N, N ′ − (4-methoxyphenyl) -4,4′-diaminobiphenyl; N, N, N ′, N′-tetraphenyl-4,4′-diaminodiphenyl ether; 4,4′-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 ′-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-30 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 688 are linked in a starburst type (MTDATA).

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  In the present invention, the hole transport material of the hole transport layer preferably has a fluorescence maximum wavelength at 415 nm or less. That is, the hole transport material is preferably a compound that has a hole transport ability, prevents the emission of light from becoming longer, and has a high Tg.

  This hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, it is about 5-5000 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (100 μm or more) Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1000 nm, preferably 50 nm to 200 nm. In order to transmit light, if either the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.

  Next, an injection layer, a hole transport layer, an electron transport layer, etc. used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, exists between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. You may let them.

  An injection layer is a layer provided between an electrode and an organic layer in order to lower drive voltage or improve light emission luminance. “Organic EL element and its forefront of industrialization (issued on November 30, 1998 by NTS Corporation) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. Among these, those using polydioxythiophenes are preferable, and thereby, an organic EL device that exhibits higher light emission luminance and light emission efficiency and has a longer lifetime can be obtained. The anode buffer layer is preferably provided between the anode and the light emitting layer and adjacent to the cathode and the light emitting layer. Thereby, it can be set as the organic EL element which shows much higher light-emitting luminance and luminous efficiency, and is further long-life.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specific examples thereof include strontium and aluminum. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.

  The buffer layer (injection layer) is preferably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 100 nm.

  As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, it is described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer used in the present invention can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, this electron transport layer is used as an electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Examples of materials (hereinafter referred to as electron transport materials) used in the following are nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadi And azole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.

  Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu Metal complexes replaced with Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC. A semiconductor can also be used as an electron transport material.

  It is preferable that the preferable compound used for an electron carrying layer has a fluorescence maximum wavelength in 415 nm or less. That is, the compound used for the electron transport layer is preferably a compound that has an electron transport ability, prevents emission of longer wavelengths, and has a high Tg.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, it is about 5-5000 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The substrate that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, and the like, and is not particularly limited as long as it is transparent. , Quartz, and a light-transmitting resin film. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.

  Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include films made of triacetate (TAC), cellulose acetate propionate (CAP), and the like.

  An inorganic or organic coating or a hybrid coating of both may be formed on the surface of the resin film.

  The external extraction efficiency at room temperature of light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 2% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  Further, a hue improving filter such as a color filter may be used in combination.

  The multicolor display device of the present invention comprises at least two kinds of organic EL elements having different light emission maximum wavelengths, and a preferred example for producing the organic EL elements will be described.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / anode buffer layer / light emitting layer / hole blocking layer / electron transport layer / cathode will be described.

  First, a layer made of a desired electrode material, for example, an anode material is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 nm to 200 nm. Make it. Next, an organic compound thin film of an anode buffer layer, a light emitting layer, a hole blocking layer, and an electron transport layer, which are element materials, is formed thereon.

As described above, there are spin coating methods, casting methods, ink jet methods, vapor deposition methods, printing methods, and the like as methods for thinning the organic compound thin films, but it is easy to obtain a uniform film and pinholes are not easily generated. In view of the above, the vacuum deposition method or the spin coating method is particularly preferable. Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 ° C. to 450 ° C., a vacuum degree of 10 ⁻⁶ Pa to 10 ⁻² Pa, and a vapor deposition rate of 0 It is desirable to select appropriately within a range of 0.01 nm to 50 nm / second, a substrate temperature of −50 to 300 ° C., and a film thickness of 0.1 nm to 5 μm.

  After the formation of these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.

  In the display device of the present invention, a shadow mask is provided only at the time of forming a light emitting layer, and the other layers are common, and a layer can be formed on one surface by a vapor deposition method, a cast method, a spin coating method, an ink jet method, a printing method, or the like.

  It is also possible to make each layer by reversing the production order.

  When a DC voltage is applied to the display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even when a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The alternating current waveform to be applied may be arbitrary.

  The display device of the present invention uses the organic EL element of the present invention and can be used as a display device, a display, or various light sources. In a display device or display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.

  Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  The lighting device of the present invention uses the organic EL element of the present invention, and is used for home lighting, interior lighting, clock backlight, billboard advertisement, traffic light, light source of optical storage medium, light source of electrophotographic copying machine, optical communication. Examples include, but are not limited to, a light source for a processing machine and a light source for an optical sensor. It can also be used as a backlight for liquid crystal display devices and the like.

  Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.

  Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.

  As described above, the organic EL element of the present invention may be used as one kind of lamp for illumination or exposure light source, or a projection device for projecting an image, or directly viewing a still image or a moving image. It may be used as a type of display device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using three or more organic EL elements of the present invention having different emission colors. Alternatively, it is possible to make one color emission color, for example, white emission, into BGR by using a color filter to achieve full color. Furthermore, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.

  An example of a display device composed of the organic EL element of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.

  The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 2 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below. FIG. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel.

  The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 3, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.

  When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.

  When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.

  The organic EL material according to the present invention can also be applied to an organic EL element that emits substantially white light as a lighting device. A plurality of light emitting colors are simultaneously emitted by a plurality of light emitting materials to obtain white light emission by color mixing. The combination of a plurality of emission colors may include three emission maximum wavelengths of three primary colors of blue, green, and blue, or two using a complementary color relationship such as blue and yellow, blue green and orange, etc. The thing containing the light emission maximum wavelength may be used.

  In addition, a combination of light emitting materials for obtaining a plurality of emission colors includes a combination of a plurality of phosphorescent or fluorescent materials (light emitting dopants), a light emitting material that emits fluorescent or phosphorescent light, and the light emission. Any combination of a dye material that emits light from the material as excitation light may be used, but in the white organic electroluminescence device according to the present invention, a method of combining a plurality of light-emitting dopants is preferable.

  As a layer structure of an organic electroluminescence device for obtaining a plurality of emission colors, a method of having a plurality of emission dopants in one emission layer, a plurality of emission layers, and an emission wavelength in each emission layer And a method of forming minute pixels emitting light having different wavelengths in a matrix.

  In the white organic electroluminescence device according to the present invention, patterning may be performed by a metal mask, an ink jet printing method, or the like at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  The light emitting material used for the light emitting layer is not particularly limited. For example, in the case of a backlight in a liquid crystal display element, the platinum complex according to the present invention is known so as to be suitable for the wavelength range corresponding to the CF (color filter) characteristics. Any one of the light emitting materials may be selected and combined to be whitened.

  Thus, in addition to the display device and display, the white light-emitting organic EL element of the present invention can be used as various light sources, lighting devices, household lighting, interior lighting, and a kind of lamp such as an exposure light source. Further, it is also useful for display devices such as backlights for liquid crystal display devices.

  Others such as backlights for watches, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. There are a wide range of uses such as household appliances.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. The structural formulas of the compounds used in the examples are shown below.

Example 1
<< Preparation of organic EL element 1-1G >>
After patterning on a substrate (made by NH Techno Glass Co., Ltd .: NA-45) with a 150 nm ITO film on glass as the anode, the transparent support substrate provided with this ITO transparent electrode was ultrasonically cleaned with iso-propyl alcohol And dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus. On the other hand, α-NPD, CBP, Ir-1, BC, and Alq ₃ are placed in five molybdenum resistance heating boats, respectively. Installed.

Next, after the vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, α-NPD was deposited on the transparent support substrate to a thickness of 20 nm to provide a hole injection / transport layer. Further, the heating boat containing CBP and the boat containing Ir-1 were energized independently to adjust the deposition rate of CBP and Ir-1 to 100: 4, so that the film thickness was 30 nm. The light emitting layer was provided by vapor deposition.

Next, BC was vapor-deposited to provide a 10 nm thick hole blocking layer. Furthermore, Alq ₃ was deposited to provide an electron transport layer having a thickness of 40 nm.

Next, the vacuum chamber is opened, a rectangular hole mask made of stainless steel is placed on the electron injection layer, and then the vacuum chamber is decompressed to 4 × 10 ⁻⁴ Pa, lithium fluoride 0.5 nm and aluminum 110 nm. The organic EL element 1-1G was produced by forming a cathode by vapor deposition.

<< Production of Organic EL Elements 1-2G to 1-8G >>
In the production of the organic EL device 1-1G, the organic EL device 1-1G was prepared in the same manner as the organic EL device 1-1G except that BC used in the hole blocking layer was changed to the compounds shown in Table 1. 2G to 1-8G were produced.

<< Structure sealing of organic EL elements 1-1G to 1-8G >>
The produced organic EL elements 1-1G to 1-8G were transferred to a glove box under nitrogen atmosphere (a glove box substituted with high-purity nitrogen gas with a purity of 99.999% or more) without being brought into contact with the air. The sealing structure as shown in (a) and (b) was adopted. In addition, barium oxide 25 which is a water catching agent is a glass sealing can 24 made of high-purity barium oxide powder manufactured by Aldrich with a fluororesin semi-permeable membrane (Microtex S-NTF8031Q manufactured by Nitto Denko) with an adhesive. The material pasted on was prepared and used in advance. An ultraviolet curable adhesive 27 was used for adhering the sealing can and the organic EL element, and an element having a sealing structure was produced by adhering and sealing both by irradiating an ultraviolet lamp. In the figure, 21 is a glass substrate provided with a transparent electrode, 22 is an organic EL layer comprising the hole injection / transport layer, light emitting layer, hole blocking layer, electron transport layer, cathode buffer layer and the like, and 23 is a cathode.

  The following evaluation was performed about each of obtained organic EL element 1-1G-1-8G.

<Emission brightness>
The produced organic EL device was measured for light emission luminance (L) [cd / m ² ] when a current of ^2.5 mA / cm ² was supplied in a dry nitrogen gas atmosphere at a temperature of 23 degrees. Here, CS-1000 (manufactured by Minolta) was used for measurement of light emission luminance and the like.

《External extraction quantum efficiency》
About the produced organic EL element, the external extraction quantum efficiency (%) when a ^2.5 mA / cm ² constant current was applied in a dry nitrogen gas atmosphere at 23 ° C. was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used in the same manner.

《Half life》
When driving at a constant current of ^2.5 mA / cm ^{2 in} a dry nitrogen gas atmosphere at 23 ° C., the time required for the luminance to drop to half of the luminance immediately after the start of light emission (initial luminance) was measured. Was used as an index of life as half-life time (τ0.5). For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used.

  In describing the evaluation results, the light emission luminance, the external extraction quantum efficiency, and the light emission lifetime are expressed as relative values when each characteristic value of the organic EL element 1-1G is 100. The obtained results are shown in Table 1.

  From Table 1, it is clear that the organic EL device of the present invention is superior in both the external extraction quantum efficiency and the emission lifetime as compared with the comparison.

Example 2
In the production of the organic EL element 1-1G described in Example 1, the organic EL elements 2-3B to 2-8B in which the dopant Ir-1 used in the light emitting layer was replaced with Ir-12, and Ir-1 as Ir- Also in the organic EL elements 2-3R to 2-8R replaced with 9, the organic EL element of the present invention was found to exhibit the same effect.

Example 3
<Production of full-color display device>
(Green light-emitting organic EL device)
The organic EL element 1-3G produced in Example 1 was used.

(Blue light emitting organic EL device)
The organic EL element 2-4B produced in Example 2 was used.

(Red light emitting organic EL device)
The organic EL element 2-5R produced in Example 2 was used.

  The red, green and blue light-emitting organic EL elements are juxtaposed on the same substrate to produce an active matrix type full-color display device having the form shown in FIG. 1, and FIG. 2 shows the display of the produced display device. Only the schematic diagram of part A is shown. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. In this manner, a full color display device was produced by appropriately juxtaposing the red, green, and blue pixels.

  It was confirmed that by driving the full-color display device, a full-color moving image display having a high light emission efficiency and a long light emission life can be obtained.

Example 6: Illumination device (using white organic EL element)
In the organic EL element 2-9 produced in Example 2, it is the same as the organic EL element 1-9 except that Ir-1 used for the light emitting layer was changed to a mixture of Ir-1, Ir-9, and Ir-12 The organic EL device 2-9W produced by the method was used. The non-light emitting surface of the organic EL element 2-9W was covered with a glass case to obtain a lighting device. The illuminating device could be used as a thin illuminating device that emits white light with high luminous efficiency and long emission life. FIG. 5 is a schematic view of the lighting device, and FIG. 6 is a cross-sectional view of the lighting device. The organic EL element 101 is covered with a glass cover 102 and connected with a power line (anode) 103 and a power line (cathode) 104. 105 is a cathode and 106 is an organic EL layer. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full-color display device. It is a schematic diagram of the organic EL element which has a sealing structure. It is the schematic of an illuminating device. It is sectional drawing of an illuminating device. It is the schematic diagram which showed an example of the energy ranking diagram of an organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10, 101 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part 21, 107 Glass substrate 22 with transparent electrode 22, 106 Organic EL layer 23, 105 Cathode 24 Glass sealing can 25, 109 Water catching agent 27 UV curable adhesive 102 Glass cover 103 Power line (anode)
104 Power line (cathode)
108 Nitrogen gas 109 Water catching agent

Claims (8)

It has a constitutional layer including at least a phosphorescent light emitting layer and a hole blocking layer between a pair of electrodes, and the hole blocking layer contains at least one compound represented by the following general formula (1). An organic electroluminescence element.

[Wherein, A ₁ represents a substituent. Z ₁ and Z ₂ each represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₁ and R ₂ each represent a substituent, and when there are a plurality of R ₁ and R ₂ , they may be different or the same. n1 represents an integer of 0 to 3, and n2 represents an integer of 1 to 3. At least one of R ₂ represents a substituent having σp of −0.20 or less. ] It has a constituent layer including at least a phosphorescent light emitting layer and a hole blocking layer between a pair of electrodes, and the hole blocking layer contains at least one compound represented by the following general formula (2). An organic electroluminescence element.

[Wherein A ₂ represents a substituent. Z ₃ represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₃ and R ₄ each represent a substituent, and when there are a plurality of R ₃ and R ₄ , they may be different or the same. n3 represents an integer of 0 to 3, and n4 represents an integer of 1 to 4. At least one of R ₄ represents a substituent having σp of −0.20 or less. ] The organic electroluminescent element according to claim 2, wherein the compound represented by the general formula (2) is represented by the following general formula (3).

[Wherein A ₃ represents a substituent. Z ₃ represents an atomic group necessary for forming a 6-membered aromatic heterocyclic ring containing at least one nitrogen atom as a constituent atom. R ₅ and R ₆ each represent a substituent, and when there are a plurality of R ₅ and R ₆ , they may be different or the same. n5 represents an integer of 0 to 3, and n6 represents an integer of 0 to 2. R ₇ and R ₈ represent a hydrogen atom or a substituent, and at least one of R ₇ and R ₈ represents a substitution with σp of −0.20 or less. ] The organic light-emitting device according to claim 1, wherein the phosphorescent light-emitting layer contains osmium, iridium, rhodium, or a platinum complex compound. The organic electroluminescence element according to any one of claims 1 to 4, wherein the organic electroluminescence element emits white light. A display device comprising the organic electroluminescence element according to claim 1. An illuminating device comprising the organic electroluminescence element according to claim 1. A display device comprising: the lighting device according to claim 7; and a liquid crystal element as a display unit.

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