JP4552436B2 - Organic electroluminescence element, display device and lighting device - Google Patents

Description

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

  In conventional organic electroluminescence elements (hereinafter also referred to as organic EL elements), a carbazole derivative typified by CBP (4,4′-Bis (9-carbazolyl) -biphenyl) is used as a light emitting material of the organic electroluminescence element. There is a technique (for example, see Patent Document 1), and it is also known to use a carbazole derivative together with a phosphorescent dopant as a light-emitting host (for example, see Patent Document 2 and Patent Document 3).

  However, when a blue to blue-green phosphorescent compound is used as a light-emitting dopant, even if the CBP or carbazole derivative is used as a host compound, the external extraction quantum efficiency is low, which is an insufficient result (for example, Non-patent document 1)), further improvement is desired.

  In addition, with regard to extending the lifetime of an element, there is a technology that achieves a long lifetime by using a phosphorescent compound as a dopant and using a specific five-coordinate metal complex for a hole blocking layer in addition to a carbazole derivative ( For example, see Patent Document 2.) Furthermore, a host in which a fluorine or cyano group is substituted with a carbazole derivative is known (see Patent Documents 3 and 4).

However, the carbazole derivative described in the above cited document has insufficient luminous efficiency in a high luminance region (high current density region), and there is room for further improvement in the lifetime, and it is still capable of withstanding practical use. It has not yet reached efficiency and lifetime. For future practical use, it is desired to develop an organic EL element that emits light efficiently and with high luminance with low power consumption.
JP 2000-21572 A Japanese Patent Laid-Open No. 2002-8860 JP 2001-313179 A International Publication No. 03-077609 Pamphlet 62nd Japan Society of Applied Physics Academic Lecture Proceedings 12-a-M8

  An object of the present invention is to provide an organic electroluminescence element having a high light emission efficiency and a long light emission lifetime, and a display device and a lighting device having the element.

The above object of the present invention has been achieved by the following constitutions 1 to 5 .

1. The organic electroluminescent device characterized by containing the represented Ru of compounds with the following general formula (A).

〔式中、Ｒ_８は、アルキル基またはアリール基を表し、ｐは１〜５の整数を表す。〕 [Wherein, Z ₁ and Z ₂ each represents an atomic group necessary for forming a benzene ring or a pyridine ring, and R ₁ and R ₂ are groups represented by the following general formula (2), respectively. R ₅ represents a group represented by the following general formula (5), and n1 and m1 each represents an integer of 0 to 4. However, 1 ≦ n1 + m1 ≦ 8 is satisfied. ]
General formula (2)
-L ₁ -R ₃
Wherein, L ₁ is an alkylene group, an oxygen atom, or a sulfur atom, R ₃ is trifluoromethyl, fluoro, cyano Motoma other represents a cyanomethyl group. ]

Wherein, R ₈ represents an alkyl group or an aryl group, p is an integer of 1-5. ]

2. 2. The organic electroluminescence device as described in 1 above, wherein a phosphorescent dopant is contained in the light emitting layer.

3. 3. The organic electroluminescence device as described in 1 or 2 above, which emits white light.

4). 4. A display device comprising the organic electroluminescence element according to any one of 1 to 3 above .

5. 4. An illuminating device comprising the organic electroluminescent element according to any one of 1 to 3 above .

  According to the present invention, it is possible to provide an organic electroluminescence element having a high light emission efficiency and a long light emission lifetime, and a display device and a lighting device having the element.

  In the organic electroluminescence device of the present invention, an organic electroluminescence device having a high luminous efficiency and a long light emission lifetime can be obtained by adopting the constitution defined in any one of claims 1 to 9. . Furthermore, a high-luminance and long-life display device and lighting device could be obtained using an organic EL element exhibiting the above characteristics.

  Details of the constituent elements according to the present invention will be described below.

  As a result of intensive studies on the host material for phosphorescence emission, the present inventors have found that a compound composed of a specific carbazole derivative containing a weak electron-withdrawing group as a substituent is photochemically or electrochemically. When the organic EL device is produced using the compound having the partial structure according to the present invention, it is found that the organic EL device is excellent in stability and heat resistance and exhibits phosphorescence emission at a relatively short wavelength. The present inventors have found that the luminance and lifetime are improved, and have reached the present invention.

  In particular, the present inventors have found that it is possible to provide an organic EL element that achieves both improvement in light emission luminance, light emission efficiency, and durability in blue light emission, and a display device having high light emission luminance and good durability using the organic EL element.

  CBP, which is a conventionally known light-emitting host, has a carbazole ring as a partial structure, but since the carbazole ring has no substituent, the carbazole ring is in an electron-rich electronic state. As a whole, the polarization is estimated to be large.

  Further, a compound that does not have a substituent on the carbazole ring that constitutes CBP or has an electron donating group such as a methyl group as a substituent is a luminescent host. The transport balance between holes and electrons is considered to be slightly inferior.

  Therefore, as an improvement means to further enhance the EL device characteristics of these compounds, we maintain the electron-balance of holes and electrons in these materials, and control the electronic parameters of the substituents as much as possible in the intramolecular polarization. We thought that molecular design to suppress was necessary.

  Therefore, in order to suppress the polarization of the carbazole ring as an electron donor, an electron-withdrawing group in a specific range is effective as a substituent. As a result of intensive studies, the above general formulas (1) and (4) The present inventors have found that a compound having a substituent having a partial structure as defined in (6) or (7) as a partial structure is most effective from the viewpoint of suppressing polarization in the molecule.

  As a result, in the case of a compound having a nitrogen atom in the ring and an electron-rich ring structure (eg, a carbazole ring, a pyrrole ring, an indole ring, etc.) By imparting to the structure, it is intended to suppress intramolecular polarization.

<< Compound having a partial structure represented by the general formula (1) >>
The compound having a partial structure represented by the general formula (1) according to the present invention will be described.

In the general formula (1), the aromatic hydrocarbon rings represented by Z ₁ and Z ₂ are benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring. , Triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring , Pyrene ring, pyranthrene ring, anthraanthrene ring and the like. Furthermore, the aromatic hydrocarbon ring may have a substituent that R ₃ described later may further have.

In the general formula (1), the aromatic heterocycles represented by Z ₁ and Z ₂ include furan ring, thiophene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadi Consists of azole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, carboline ring Examples include a ring in which the carbon atom of the hydrocarbon ring is further substituted with a nitrogen atom. Furthermore, the aromatic heterocyclic group can have a substituent which R ₃ described later may further have.

In the present invention, in the general formula (1), Z ₁ and Z ₂ are preferably aromatic hydrocarbon rings, and it is particularly preferable to use a benzene ring among the above aromatic hydrocarbon rings.

(Group represented by general formula (2))
In the group represented by the general formula (2) represented by R ₁ and R ₂ in the general formula (1), examples of the alkylene group represented by L ₁ include a methylene group (also referred to as a monomethylene group). ), Ethylene group (also referred to as dimethylene group), trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group, 2,2,4-trimethylhexamethylene group, heptamethylene group, octamethylene Group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, cyclohexylene group (for example, 1,6-cyclohexanediyl group, etc.), cyclopentylene group (for example, 1,5-cyclopentanediyl group, etc.) Etc. Furthermore, the alkylene group may have a substituent that R ₃ described later may further have.

In the group represented by the general formula (2) represented by R ₁ and R ₂ in the general formula (1), the Hammett σp value represented by R ₃ is 0.01 ≦ σp <0.80. Specific examples of the group include polyhaloalkyl groups such as a cyano group (0.66), a nitro group (0.78), and a trifluoromethyl group (0.54), and a pentachlorophenyl group (0.24). Such as polyhaloaryl group, formyl group (0.42), alkyl or arylcarbonyl group, carbamoyl group (0.36), alkylsulfinyl group (for example, methylsulfinyl group (0.49)), arylsulfinyl group, An alkylsulfonyl group (for example, a methylsulfonyl group (0.72)), an arylsulfonyl group, an alkyl or arylsulfonyloxy group, a sulfamoyl group (0.57), Phenolate group, phosphine oxide group, phosphonic ester group, phosphonic acid amido group, an arylazo group, and the like as examples. Further, these groups may be substituted with a substituent which R ₃ described later may further have.

<< Consideration of electronic properties of the group represented by the general formula (2) >>
Groups represented by general formula (2), R ₃ of -L ₁ -R ₃ are, .sigma.p value of Hammett's used is based on the range of 0.01 ≦ σp <0.80, 0.80 max Close group (for example, cyano group (0.66), trifluoromethyl group (0.54), nitro group (0.78), sulfamoyl group (0.57), methylsulfonyl group (0.72), etc.) Although the electron withdrawing property is considerably strong, in the present invention, the electron withdrawing property of the group itself represented by the general formula (2) is reduced to a weak electron in the range of 0.01 to 0.15 through -L _1-. Adjustment to be attractive and substitution with the aromatic hydrocarbon ring or aromatic heterocycle can reduce the polarization of the partial structure containing a nitrogen atom, and can be neutralized electronically. I found out.

Incidentally, the difference between the σp value of the electron-withdrawing group R _{3 and} the σp value of -L ₁ -R ₃ is shown by a specific example.

Substituent σp value −CF ₃ 0.54
—CH ₂ —CF ₃ 0.09 (with alkylene group)
-CN 0.66
—CH ₂ —CN 0.01 (with alkylene group)
-F 0.06
—CH ₂ —F 0.11 (with alkylene group)
In addition, the reason is not clear at present through the above -L _1- rather than directly substituting the weak electron-withdrawing substituent into the aromatic hydrocarbon ring or the aromatic heterocycle. The present inventors have also found that the effects described in the present invention, that is, an organic EL device having high emission efficiency and a long emission lifetime can be obtained.

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.

<< Examples of Substituents that R ₃ may additionally have >>
R _{3 in the} general formula (2) may further have a substituent, for example, an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a (t) butyl group, a pentyl group, a hexyl group). Octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg, vinyl group, allyl group etc.), alkynyl group (eg, Propargyl group etc.), aryl group (eg phenyl group, tolyl group, xylyl group, naphthyl group, biphenylyl group, anthryl group, phenanthryl group etc.), heterocyclic group (eg pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group) , Furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazo Group, sulfolanyl group, piperidinyl group, pyrazolyl group, tetrazolyl group, etc.), alkoxyl group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), Cycloalkoxyl group (for example, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (for example, phenoxy group, naphthyloxy group, etc.), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio 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, meso Tiloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, Aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido) Octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octyl group) Carbonyl 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, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, Aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group Naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfinyl group (for example, methylsulfinyl group, ethyl) Rusulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group or arylsulfonyl group (for example, methylsulfonyl Group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl 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-pyridine Arylamino group), a nitro group, a cyano group, a silyl group (trimethylsilyl group, t- butyl dimethyl silyl group, dimethylphenyl silyl group, and a triphenylsilyl group, etc.) and the like.

(Group represented by general formula (3))
In the general formula (1), in the groups represented by the general formula (3) represented by R ₁ and R ₂ , as the arylene group represented by Ar ₁ , a phenylene group, a naphthylene group, and the above Z ₁ And divalent groups derived from an aromatic hydrocarbon ring represented by Z ₂ .

In the group represented by the general formula (3) represented by R ₁ and R ₂ in the general formula (1), the divalent group having an aromatic heterocyclic ring represented by Ar ₁ is 2 , 5-thiophenediyl group, 2,5-pyridinediyl group, and divalent groups derived from the aromatic heterocycles represented by Z ₁ and Z ₂ above.

In the general formula (1), R ₄ is σp value of Hammett general formula (3), each represented by R _1, R ₂ are, in the general formula (1), represented by each of R _1, R ₂ In the group represented by the general formula (2), it is synonymous with Hammett's σp represented by R ₃ , but the range of σp value is 0.08 <σp <0.80, and is represented by R ₃ . Among the specific examples of the groups to be selected, those within the above range are selected.

In the general formula (1), the divalent group having an aromatic carbocycle or an aromatic heterocycle represented by Ar ₁ may have a substituent that R ₃ may further have. Good.

<< Compound having a partial structure represented by the general formula (4) >>
The compound having a partial structure represented by the general formula (4) according to the present invention will be described.

In the general formula (4), the aromatic hydrocarbon ring and aromatic heterocycle formed by Z ₃ and Z ₄ are the aromatic hydrocarbon rings represented by Z ₁ and Z ₂ in the general formula (1), Each is synonymous with an aromatic heterocycle.

In the general formula (4), the substituent represented by R ₅ has the same meaning as the substituent that R _{3 in the} general formula (1) may further have, preferably the general formula (5) It is group represented by these.

Here, in the said General formula (5), the substituent represented by R < ₈ > is synonymous with the substituent which R < ₃ > of General formula (1) may have further.

<< Compound having a partial structure represented by the general formula (6) >>
The compound represented by the general formula (6) according to the present invention will be described.

In the general formula (6), the groups represented by R ₉ and R ₁₀ are respectively synonymous with the groups represented by the general formula (2) or the general formula (3).

<< Compound having a partial structure represented by the general formula (7) >>
The compound having the partial structure represented by the general formula (7) according to the present invention will be described.

In general formula (7), the aromatic hydrocarbon ring and aromatic heterocycle formed by Z ₅ are the aromatic hydrocarbon ring and aromatic heterocycle represented by Z ₁ and Z ₂ in general formula (1). Each is synonymous with a ring.

In the general formula (7), the groups represented by R ₁₁ and R ₁₂ have the same meanings as the groups represented by the general formula (2) or the general formula (3).

  Hereinafter, although the specific example of the compound which has the partial structure as described in General formula (1), (4), (6) or (7) based on this invention is shown, this invention is not limited to these.

  The compound having the partial structure described in the general formula (1), (4), (6) or (7) according to the present invention can be synthesized with reference to a conventionally known method for synthesizing a heterocyclic compound. . Here, among the above specific examples, the synthesis method of Compound 1 is shown.

<< Synthesis Example: Synthesis of Exemplary Compound 1 >>
The synthesis scheme and synthesis method of Exemplary Compound 1 are shown below.

  5 g of 3,6-dibromocarbazole (a) was dissolved in 100 ml of dehydrated tetrahydrofuran and kept at -70 degrees with dry ice. 30 ml of butyllithium-n-hexane solution was added and stirred for 1 hour, and then 6.5 g of trifluoroacetic anhydride was dissolved in 20 ml of dehydrated tetrahydrofuran and added, and stirred overnight at room temperature. Thereafter, the organic layer of the reaction solution was extracted and purified by column chromatography to obtain 3.4 g of compound (b).

  Next, 3.4 g of the compound (b) was dissolved in 100 ml of bis (2-hydroxyethyl) ether, 0.7 g of hydrazine monohydrate was added, and the mixture was heated and stirred for 10 hours. Thereafter, the organic layer of the reaction solution was extracted and purified by column chromatography to obtain 2.1 g of compound (c).

  Further, 2.0 g of compound (c) and 4,4-diiodobiphenyl were heated for 8 hours using palladium acetate and tri-tert-butylphosphine as catalysts in xylene solvent and sodium-tert-butoxide as a base. Stir.

  After completion of the reaction, the organic layer was extracted, dried over magnesium sulfate, the solvent was distilled off under reduced pressure, the residue was purified by column chromatography, and recrystallized from toluene to obtain 2.7 g of Compound (1).

The obtained exemplary compound 1 was identified by ¹ H-NMR, ¹³ C-NMR and the like.

  Next, a configuration of a typical organic EL element will be described.

<< Constituent layers of organic EL elements >>
The constituent layers of the organic EL element of the present invention will be described.

In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.
(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) 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 will be described.

  The light emitting layer according to the present invention contains a phosphorescent compound, and is a layer that emits light by recombination of electrons and holes injected from the electrode or the electron transport layer and the hole transport layer. It may be in the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

  In the light emitting layer according to the present invention, at least one portion selected from the partial structure group consisting of the group of the general formula (1), the general formula (4), the general formula (6), and the general formula (7). A compound having a structure is preferably contained as a host compound (light-emitting host).

  In addition, by using the phosphorescent dopant in the light emitting layer according to the present invention, it is possible to obtain an organic EL element with higher light emission efficiency and longer life.

  As the phosphorescent compound, the aforementioned phosphorescent compound can be used.

  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.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited. In principle, the phosphorescent compound can be obtained by selecting a central metal, a ligand, a ligand substituent, and the like. However, it is preferable that the phosphorescent compound has a maximum phosphorescence emission wavelength of 380 nm to 480 nm.

  Examples of such phosphorescent emission wavelengths include organic EL elements that emit blue light and organic EL elements that emit white light. These elements should be operated with lower emission voltage and lower power consumption. Can do.

  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 illumination and backlight.

  The light emitting layer may contain a host compound in addition to the phosphorescent compound.

  In the present invention, the host compound means 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.

  In the light emitting layer according to the present invention, at least one portion selected from the partial structure group consisting of the group of the general formula (1), the general formula (4), the general formula (6), and the general formula (7). A compound having a structure is preferably used as the host compound, but 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 2001-257076 A, JP 2002-308855 A, JP 2001-313179 A, 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.

  Moreover, the light emitting layer may contain the host compound which has a fluorescence maximum wavelength further as a host compound. In this case, the energy transfer from the other host compound and the phosphorescent compound to the fluorescent compound allows electroluminescence as an organic EL element to be emitted from the other host compound having a fluorescence maximum wavelength. A host compound having a fluorescence maximum wavelength is preferably a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific host compounds having a maximum fluorescence wavelength include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and 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. 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.

<< Dopant (Fluorescence, Phosphorescence) >>
The light emitting layer according to the present invention preferably contains a dopant, and further preferably contains a phosphorescent dopant. As a result, higher luminous efficiency can be obtained.

  A dopant (also referred to as a light-emitting dopant) that can be used in combination with the host compound according to the present invention will be described.

  The dopant is roughly classified into two types: a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

  Representative examples of the former (fluorescent dopant) include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, Examples include perylene dyes, stilbene dyes, polythiophene dyes, rare earth complex phosphors, and other known fluorescent compounds.

  The phosphorescent compound contained in the light emitting layer according to the present invention can be appropriately selected from known materials used for the light emitting layer of the organic EL device. For example, an iridium complex described in JP-A No. 2001-247859, or a formula represented by International Publication No. 00 / 70,655, pages 16 to 18, for example, tris (2-phenylpyridine) A platinum complex such as iridium or the like or an osmium complex, or 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin platinum complex may be used as the dopant. By using such a phosphorescent compound as a dopant, a light-emitting organic EL device with high internal quantum efficiency can be realized.

  The phosphorescent compound used in the present invention is preferably a complex compound containing any one metal belonging to Group 8, Group 10, or Group 10 in the periodic table, more preferably an iridium compound, An osmium compound, a platinum compound (platinum complex compound), or a rare earth complex, and most preferably an iridium compound.

  Although the specific example of the phosphorescent dopant which concerns on this invention is shown below, it is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In addition, for example, J. et al. Am. Chem. Soc. 123, 4304-4312 (2001), International Publication No. 00/70655 pamphlet, No. 02/15645 pamphlet, JP-A No. 2001-247859, No. 2001-345183, No. 2002-117978, 2002-170684, 2002-203678, 2002-235076, 2002-302671, 2002-324679, 2002-332291, 2002-332292, Examples include iridium complexes represented by the general formula described in JP 2002-338588 A, etc., iridium complexes exemplified as specific examples, iridium complexes represented by formula (IV) described in JP 2002-8860 A, and the like. It is done.

  The phosphorescent compound according to 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, and particularly 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 the 4th edition, Experimental Chemistry Course 7.

<< Blocking Layer >>: Hole Blocking Layer, Electron Blocking Layer The hole blocking layer is an electron transporting layer in a broad sense, and is provided adjacent to the light emitting layer. The hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and the probability of recombination of electrons and holes by blocking holes while transporting electrons. 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. Use of at least one of styryl compounds, triazole derivatives, phenanthroline derivatives, oxadiazole derivatives, and boron derivatives as the hole blocking material is also effective in obtaining the effects of the present invention.

  Examples of other compounds include exemplified compounds described in JP-A Nos. 2003-31367, 2003-31368, and Japanese Patent No. 2721441.

  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.

  The hole blocking layer and the electron blocking layer can be formed by thinning the above 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. .

《Hole transport layer》
The hole transport layer is made of a hole transport 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 can be provided as a single layer or a plurality of layers.

  The hole transport material has any 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, Conventionally known materials such as stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers, may be used.

  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-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which three triphenylamine units described in No. 88 are linked in a starburst type ) And the like.

  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.

  The 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, a printing method including an ink jet method, or an LB method. it can. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. This hole transport layer may have a single layer structure composed of one or more of the above materials.

《Electron transport layer》
The electron transport layer according to the present invention is only required to have a function of transmitting electrons injected from the cathode to the light emitting layer, and as the material thereof, any one of conventionally known compounds can be selected and used. Can do.

  Examples of materials used for this electron transport layer (hereinafter referred to as electron transport materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, carbodiimides, Examples include fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, in the 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. .

  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.

  Or metal complexes of 8-quinolinol derivatives, such as tris (8-quinolinol) aluminum (Alq3), 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 , Ca, Sn, Ga, or Pb can also be used as an electron transport material.

  In addition, metal-free or metal phthalocyanine, and those having the terminal substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transporting material. Alternatively, the distyrylpyrazine derivative exemplified as the material for the light-emitting layer can also be used as an electron transport material, and, like 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.

  The electron transport layer can be formed by forming the above compound by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method.

(Film thickness of electron transport layer)
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, a printing method including 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, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The electron 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. Further, IDIXO ^- it may be used (In ₂ O ₃ ZnO) spruce amorphous in can prepare a transparent conductive film material. 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, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred.

  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 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

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

<< Buffer layer >>: Anode buffer layer, cathode buffer layer An injection layer is provided as necessary, and includes a cathode buffer layer (electron injection layer) and an anode buffer layer (hole injection layer). You may exist between a positive hole transport layer and between a cathode and a light emitting layer or an electron carrying layer.

  The buffer layer is a layer that is provided between the electrode and the organic layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and the forefront of its industrialization (November 30, 1998, issued by NTT Corporation) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes an anode buffer layer and a cathode buffer layer.

  The details of the anode buffer layer (hole injection layer) are described in JP-A Nos. 9-45479, 9-260062, and 8-288069. Specific examples thereof include copper phthalocyanine. Examples thereof include a phthalocyanine buffer layer, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  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. Specifically, strontium, aluminum, etc. A metal buffer layer typified by lithium fluoride, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, an oxide buffer layer typified by aluminum oxide, etc. . The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The organic EL device of the present invention is preferably formed on a substrate.

  The substrate of the organic EL device of the present invention is not particularly limited to the type of glass, plastic, etc., and is not particularly limited as long as it is transparent. Examples of substrates that are preferably used include glass, quartz, A light transmissive resin film can be mentioned. 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 triacetate. Examples thereof include films having (TAC), cellulose acetate propionate (CAP) and the like. In addition, an inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film.

  The external extraction efficiency at room temperature for light emission of the organic electroluminescence device of the present invention is preferably 1% or more, more preferably 5% 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.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor may be used in combination. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

<< 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 / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode. explain.

  First, a thin film 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, thereby producing an anode. To do. Next, an organic compound thin film of an anode buffer layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and a cathode buffer layer, which are organic EL element materials, is formed thereon.

As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are 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 / second to 50 nm / second, a substrate temperature of −50 ° C. to 300 ° C., and a film thickness of 0.1 nm to 5 μm, preferably 5 nm to 200 nm.

  After forming 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 film thickness of 1 μm or less, preferably in the range of 50 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.

  The multicolor display device of the present invention is provided with a shadow mask only when the light emitting layer is formed, and the other layers are common, so that patterning of the shadow mask or the like is unnecessary, and the evaporation method, the casting method, the spin coating method, the ink jet method on one side. A film can be formed by a method or a printing method.

  When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.

  In addition, it is also possible to reverse the production order to produce a cathode, a cathode buffer layer, an electron transport layer, a hole transport layer, a light emitting layer, a hole transport layer, an anode buffer layer, and an anode in this order. When a DC voltage is applied to the multicolor 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. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

  The display device of the present invention can be used as a display device, a display, and various light emission sources. In a display device or a 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 includes home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light sensors Although a light source etc. are mentioned, it is not limited to this.

  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.

<Display device>
The organic EL element of the present invention may be used as one kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a 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 a single color emission color, for example, white emission, into BGR using a color filter to achieve full color. Further, 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 having the organic EL element of the present invention as a configuration will be described 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 shows 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 an organic EL element emits light according to a data signal only when a 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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example 1
<< Production of Organic EL Element OLED1-1 >>
After patterning on a glass substrate (NH Techno Glass Co., Ltd .: NA-45) having a 150 nm ITO film formed on glass as an anode, the glass substrate provided with this ITO transparent electrode was ultrasonically cleaned with iso-propyl alcohol. Then, it was dried with dry nitrogen gas, and UV ozone cleaning was performed for 5 minutes.

This glass substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while α-NPD, CBP, Ir-1, BCP, and Alq ₃ are placed in five tantalum resistance heating boats, respectively. The first vacuum chamber was attached.

  Further, lithium fluoride was placed in a tantalum resistance heating boat, and aluminum was placed in a tungsten resistance heating boat, and the tantalum resistance heating boat was attached to the second vacuum chamber of the vacuum evaporation apparatus.

First, the first vacuum chamber is depressurized to 4 × 10 ⁻⁴ Pa, and then heated by energizing the heating boat containing α-NPD, and the transparent support substrate is deposited at a deposition rate of 0.1 nm to 0.2 nm / sec. The film was deposited to a thickness of 25 nm to provide a hole injection / transport layer.

  Further, the heating boat containing CBP and the boat containing Ir-1 are energized independently to adjust the deposition rate of CBP as a light emitting host and Ir-1 as a light emitting dopant to 100: 7. A light emitting layer was provided by vapor deposition so as to have a thickness of 30 nm.

Subsequently, the heating boat containing BCP was heated by applying electricity, and an electron transport layer having a thickness of 10 nm was provided at a deposition rate of 0.1 to 0.2 nm / second. Further, the heating boat containing Alq ₃ was heated by energization to provide an electron injection layer having a film thickness of 40 nm at a deposition rate of 0.1 nm / second to 0.2 nm / second.

  Next, after the element formed up to the electron injection layer as described above is transferred to the second vacuum chamber in a vacuum state, a stainless steel rectangular perforated mask is disposed on the electron injection layer from the outside of the apparatus. Installed with remote control.

After reducing the pressure in the second vacuum chamber to 2 × 10 ⁻⁴ Pa, a cathode buffer layer having a film thickness of 0.5 nm was formed at a deposition rate of 0.01 nm / second to 0.02 nm / second by energizing a boat containing lithium fluoride. Then, a boat containing aluminum was energized to attach a cathode having a film thickness of 150 nm at a deposition rate of 1 to 2 nm / second.

  Further, this organic EL element was 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 atmosphere, and the results are shown in FIGS. 5 (a) and 5 (b). An OLED 1-1 was fabricated with the sealing structure as shown.

  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.

<< Production of Organic EL Elements OLED1-2 to 1-19 >>
In the production of the organic EL element OLED1-1, organic EL elements OLED1-2 to 1-19 were produced in the same manner except that the light-emitting host was changed to the compounds shown in Table 1.

  The following evaluation was performed about each of obtained organic EL element OLED1-1-OLED1-19.

《Luminescence lifetime, external extraction quantum efficiency》
Each of the organic EL elements OLED1-1 to 1-19 is continuously lit under a low current condition of ^2.5 mA / cm ^{2 at} a temperature of 23 ° C. and in a dry nitrogen gas atmosphere. ) External extraction quantum efficiency (η) was measured to see [cd / m ² ] and luminous efficiency. Here, the light emission luminance [cd / m ² ] was measured using Minolta CS-1000. Also,
External extraction quantum efficiency (%) = number of photons emitted to the outside of the organic EL element / number of electrons sent to the organic EL element × 100
The method for measuring the external extraction efficiency is to obtain the number of photons from 380 nm to 780 nm from the photon energy of each wavelength from the emission spectrum measured by the spectral radiance meter CS-1000, and further from the light emitting surface based on the Lambertian assumption. The number of photons emitted was determined. In addition, the number of electrons was determined from the amount of current.

As for the light emission lifetime, the initial luminance is halved when each of the elements of OLEDs 1-1 to 1-19 is continuously lit under a low current condition of a temperature of 23 ° C. and ^2.5 mA / m ² . The time required for (τ1 / 2) was measured.

  Further, the external extraction quantum efficiency (luminous efficiency) and the light emission lifetime are expressed as relative values when the organic EL element OLED1-1 is 100. The obtained results are shown in Table 1. The emission color was green in all the elements.

  From Table 1, it can be seen that when the compound according to the present invention is used as a host compound, the luminous efficiency is high and the luminous lifetime is also long.

Example 2
<< Production of Organic EL Element OLED2-1 >>
The α-NPD of the hole injection / transport layer of the OLED 1-1 of Example 1 was changed to m-MTDATXA, the CBP used for the production of the light emitting layer was left as it was, and the light emitting dopant (Ir-1) was Ir-12. Except having changed into, it carried out similarly and obtained organic EL element OLED2-1.

<< Production of Organic EL Elements OLED2-2 to 2-20 >>
The comparative compound CBP used for the light emitting layer of the organic EL element OLED2-1 was changed to the compounds shown in Table 2, and organic EL elements OLED2-2 to 2-20 were produced.

  The following evaluation was performed about each of obtained organic EL element OLED2-1 to 2-20.

<Luminescent life>
Each of the obtained organic EL elements OLED2-1 to 2-20 is continuously lit under a low current condition of a temperature of 23 ° C. and ^2.5 mA / m ² to obtain half the initial luminance. The time required (τ1 / 2) was measured. In addition, light emission luminance (L) [cd / m ² ] and external extraction quantum efficiency (η) immediately after the start of lighting were measured. Minolta CS-1000 was used for luminance measurement, and the external extraction quantum efficiency (η) was evaluated in the same manner as described above.

  The light emission lifetime and the external extraction quantum efficiency (η) (light emission efficiency) are expressed as relative values when the organic EL element OLED2-1 is set to 100, and the results obtained are shown in Table 2. The emission color was blue.

  From Table 2, it can be seen that even in a system in which the luminescent dopant is changed, when the compound according to the present invention is used as a host compound, the luminous efficiency is high and the luminescent lifetime is long.

Example 3
<Production of full-color display device>
<Blue light emitting element>
The OLED 2-10 was used as a blue light emitting element.

<Green light emitting element>
The OLED 1-7 was used as a green light emitting element.

<Red light emitting element>
A red light emitting device was produced in the same manner as in the production of the green light emitting device OLED1-7, except that the light emitting dopant was changed from Ir-1 to Ir-9.

  Each of the red, green and blue light emitting organic EL elements produced above was juxtaposed on the same substrate to produce an active matrix type full color display device having the form as shown in FIG. In FIG. 2, only the schematic diagram of the display part A of the produced display device 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 orthogonal positions. (Details 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 way, full-color display is possible by appropriately juxtaposing the red, green, and blue pixels.

  It has been found that by driving the full-color display device, a clear full-color moving image display having high luminance, high durability, and clearness can be obtained.

Example 4 (Example of lighting device, using white organic EL element)
In the organic EL element 1-7 produced in Example 1, the same as the organic EL element 1-7 except that Ir-1 used in the light emitting layer was changed to a mixture of Ir-1, Ir-9, and Ir-12. The organic EL device 1-7W (white) produced by the above method was used. The non-light emitting surface of the organic EL element 1-7W (white) 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. 6 is a schematic view of the lighting device, and FIG. 7 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.

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

Claims (5)

The organic electroluminescent element characterized by containing the compound represented by the following general formula (A).

[Wherein, Z ₁ and Z ₂ each represents an atomic group necessary for forming a benzene ring or a pyridine ring, and R ₁ and R ₂ are groups represented by the following general formula (2), respectively. R ₅ represents a group represented by the following general formula (5), and n1 and m1 each represents an integer of 0 to 4. However, 1 ≦ n1 + m1 ≦ 8 is satisfied. ]
General formula (2)
-L ₁ -R ₃
Wherein, L ₁ is an alkylene group, an oxygen atom, or a sulfur atom, R ₃ is trifluoromethyl, fluoro, cyano Motoma other represents a cyanomethyl group. ]

Wherein, R ₈ represents an alkyl group or an aryl group, p is an integer of 1-5. ] 2. The organic electroluminescence device according to claim 1, wherein a phosphorescent dopant is contained in the light emitting layer. The organic electroluminescence device according to claim 1, which emits white light. A display device comprising the organic electroluminescence element according to claim 1. An illuminating device comprising the organic electroluminescent element according to claim 1.

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