JPH1017860A - Electroluminescent element characterized in using cyclopentadiene derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an org. electroluminescent element which is excellent in electron transport properties and emits light with a high luminance at a low voltage by using a specific germacyclopentadiene deriv. SOLUTION: A germacyclopentadiene deriv. used is represented by the formula [wherein X and Y are each a 1-6C (un)satd. hydrocarbon group, alkoxy, alkenyloxy, alkynyloxy, OH, (substd.) aryl, a (subtd.) hetero ring, or an (un)satd. ring formed by combining both; and R1 to R4 are each H, halogen, (substd.) 1-6C alkyl, alkoxy, aryloxy, perfluoroalkyl, perfluoroalkoxy, amino, alkyl-, aryl-, alkoxy-, or aryloxycarbonyl, azo, alkyl-, aryl-, alkoxy-, or aryloxycarbonyloxy, sulfinyl, sulfonyl, sulfanyl, silyl, carbamoyl, heterocyclic, alkenyl, alkynyl, NO2 , formyl, NO, formyloxy, isocyano, etc.].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electroluminescence (ELECTR)
OLUMINESCENCE, hereinafter abbreviated as EL. ) Regarding the element,
More specifically, the present invention relates to an organic EL device using a cyclopentadiene derivative.

[0002]

2. Description of the Related Art In recent years, an organic EL element has been attracting attention as a candidate for an unprecedented high-luminance flat display, and research and development thereof have been actively conducted. The organic EL element has a structure in which an organic light emitting layer is sandwiched between two electrodes, and holes injected from an anode and electrons injected from a cathode are recombined in the light emitting layer to emit light. The organic material used includes a low molecular weight material and a high molecular weight material, and both are known to provide a high-luminance organic EL device.

[0003] There are two types of such organic EL elements. One is the addition of a fluorescent dye described by CWTang et al. In the charge transport layer (Journal of Applied Physics (J. Appl.
s.), 65, 3610 (1989)), and the other uses a fluorescent dye alone (for example, Japanese Journal of Applied Physics (Jpn. J. Appl. Phy.
s.), 27, L269 (1988). ).
In the latter device, the luminous efficiency is improved when the fluorescent dye is laminated with a hole transport layer that transports only holes, which are one of the charges, and / or an electron transport layer that transports only electrons. It is shown.

[0004] Regarding hole transporting materials used in organic EL devices, although a wide variety of materials centering on triphenylamine derivatives are known, few are known as electron transporting materials. . In addition, the existing electron transporting material is an existing hole transporting material, for example, N, N ′.
-Diphenyl-N, N'-di (3-methylphenyl)-
As compared with 4,4'-diaminobiphenyl (hereinafter abbreviated as TPD), the charge transporting ability is low, and when used in an organic EL device, the performance is limited by the electron transporting material used and the device can bring out sufficient device characteristics. Could not.

As specific examples of conventional electron transporting materials, metal complexes of oxine derivatives (those described in JP-A-59-194393, etc.), 2- (4-biphenylyl) -5-
(4-tert-butylphenyl) -1,3,4-oxadiazole (hereinafter abbreviated as PBD) and the like are known. The former can drive the organic EL element at a relatively low voltage, but is not yet sufficient, and is not practical for full color display because its own light emission is green. As an example of using the latter as an electron transport layer, an organic EL described in Japanese Journal of Diapride Physics (Jpn. J. Appl. Phys.), 27, L269 (1988)
It has been pointed out that although the device can be used, the stability of the thin film is poor, for example, crystallization is likely to occur.

In order to solve this problem, a compound having a plurality of oxadiazole rings (Journal of the Chemical Society of Japan, 11, 1540 (1991),
JP-A-6-145658, JP-A-6-92947, JP-A-5-152072, JP-A-5-202011 and JP-A-6-136359. ) Were developed, but also did not have practically sufficient properties such as a high driving voltage. It has been reported that dimerization of a quinoxaline derivative (JP-A-6-207169) can increase the molecular weight and improve the stability of a thin film, but the driving voltage is still high and is not sufficient for practical use.

Cyclopentadiene derivatives (Applied
Physics Letter (Appl. Phys. Lett.), 56 , 799 (199)
0), 1,2,3,4,5-pentacyclopentadiene), but an element with high efficiency and high light emission has not been obtained.

As described above, the electron transporting material used in the conventional organic EL device is inferior in electron transporting ability and insufficient in full color display, thin film stability, driving voltage, luminous efficiency and the like. Organic E by using excellent materials
It is considered that it is necessary to increase the efficiency of the L element, and first of all, it is necessary to have an excellent electron transport ability.

[0009]

An object of the present invention is to provide an organic EL device having a low voltage and a high luminous efficiency.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems of the conventional organic EL device, and have found that a stanacyclopentadiene ring or a germanacyclopentadiene ring derivative is used. As a result, they found that the voltage was low and the luminous efficiency was high, and completed the present invention.

The present inventors have conducted various studies on the reason why the stanacyclopentadiene ring or the germanacyclopentadiene ring is suitable as an organic EL device. As a result, as compared with the corresponding cyclopentadiene ring, thiophene ring, pyrrole ring or furan ring, The lowest unoccupied molecular orbitals are low,
The semi-empirical molecular orbital calculation revealed that the structure was easy to accept electrons. However, besides,
It is considered that the structure of the stannacyclopentadiene ring or the germanic cyclopentadiene ring has an effect on the electron transporting property.

The present invention provides the following (1), (2), (3),
Or (4). (1) An electroluminescent device using a cyclopentadiene derivative represented by the following formula (3).

[0013]

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Wherein A is Ge or Sn, X
And Y each independently represent a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group, an alkenyloxy group, an alkynyloxy group, a hydroxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted group. A heterocyclic ring or a structure in which X and Y are combined to form a saturated or unsaturated ring, and R _{1 to} R ₄ are each independently hydrogen, halogen, substituted or unsubstituted alkyl having 1 to 6 carbon atoms. Group, alkoxy group, aryloxy group, perfluoroalkyl group, perfluoroalkoxy group, amino group,
Alkylcarbonyl group, arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, sulfinyl group, sulfonyl group, sulfanyl group, Silyl group, carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group,
Nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group,
It has a structure in which a thiocyanate group, an isothiocyanate group or a cyano group or, when adjacent, a substituted or unsubstituted ring is fused. ]

(2) An electroluminescent device using at least one of the cyclopentadiene derivatives described in (1) above as a component of a charge transport layer. (3) An electroluminescent device using at least one of the cyclopentadiene derivatives described in the above (1) as a component of a light emitting layer. (4) An electroluminescent device, wherein at least one of the cyclopentadiene derivatives according to the above (1) is used as a component of a hole blocking layer.

The present invention will be described in detail below. The cyclopentadiene derivative used in the present invention can be obtained, for example, by the following production method. That is,

[0017]

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Wherein R ₁ and R ₂ each independently represent hydrogen, halogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkoxy group, an aryloxy group, a perfluoroalkyl group, a perfluoroalkyl group; Alkoxy group, amino group, alkylcarbonyl group, arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group,
Aryloxycarbonyloxy group, sulfinyl group,
Sulfonyl group, sulfanyl group, silyl group, carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, It has a structure in which an isothiocyanate group or a cyano group or, when adjacent, a substituted or unsubstituted ring is fused. With an alkali metal or a complex thereof, followed by the general formula 5

[0019]

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In the formula, A represents germanium or tin, and X and Y each independently represent a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group, an alkenyloxy group, an alkynyloxy group. Or a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocycle, or X and Y are combined to form a saturated or unsaturated ring. ], The desired cyclopentadiene derivative can be obtained.

The acetylene derivative used here includes:
Those having, as a substituent, a substance which does not easily inhibit the reaction between the alkali metal or its complex and acetylene can be suitably used. Particularly preferably, the substituent is inert to an alkali metal or a complex thereof.
Examples of the alkali metal or a complex thereof used include lithium, sodium, potassium, lithium naphthalenide, sodium naphthalenide, potassium naphthalenide, lithium 4,4′-ditert-butyl-2,
2'-biphenylide or lithium (N, N-dimethylamino) naphthalenide. The solvent to be used is not particularly limited as long as it is inert to an alkali metal or an alkali metal complex, and usually an ether solvent such as ether or tetrahydrofuran is used. This series of reactions is preferably performed in an inert gas stream, and nitrogen or argon gas is used. The reaction may be followed by a general analytical means such as NMR or chromatography, and the end point of the reaction may be determined.

When a benzene ring is condensed with a cyclopentadiene ring in the compound used in the present invention, a method different from the above-mentioned production method is used. Known methods known so far can be used, and for example, the following methods can be exemplified. That is,

[0023]

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[Wherein, X represents chlorine, bromine or iodine, and R ₁ to R ₈ each independently represent a carbon number of 1 to 6;
Saturated or unsaturated hydrocarbon group, alkoxy group, alkenyloxy group, alkynyloxy group, fluorine, hydrogen, substituted or unsubstituted aryl group, substituted or unsubstituted heterocycle, cyano group, when adjacent Has a saturated or unsaturated ring. With an alkali metal, an alkaline earth metal or an alkali metal complex on the 2,2′-dihalogenobiphenyl derivative represented by the following formula:

[0025]

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Wherein A represents germanium or tin, and X and Y each independently represent a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group, an alkenyloxy group, or an alkynyloxy group. Or a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic ring, or X and Y are combined to form a saturated or unsaturated ring. The cyclopentadiene derivative used in the present invention can be obtained by reacting a dichlorogermanium derivative or a dichlorostannane derivative represented by the following formula: Examples of the metal used here include lithium, sodium, magnesium, and potassium, and examples of the metal complex include normal butyl lithium, tertiary butyl lithium, and phenyl lithium. The substituent of the 2,2'-dihalogenobiphenyl derivative to be used is not particularly limited as long as it is inert to the alkali metal, alkaline earth metal or alkali metal complex under the reaction conditions. There is no particular limitation on the reaction temperature when the alkali metal, alkaline earth metal or alkali metal complex is allowed to act, and usually,
Performed at 0 ° C. or lower. However, when a substituent such as a highly reactive cyano group is present, a lower temperature is preferable,
Usually, it is carried out at -70 ° C or lower. The reaction solvent to be used is not particularly limited as long as it is inert to an alkali metal, an alkaline earth metal or an alkali metal complex, and usually an ether solvent such as ether or tetrahydrofuran is used.

The substituent attached to the hetero element of the cyclopentadiene derivative used in the present invention thus obtained may be a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a cyclopentyl group or a tertiary butyl group. Alkyl groups such as alkyl group, vinyl group, allyl group, butenyl group or styryl group, ethynyl group, alkynyl group such as propargyl group or phenylacetylinyl group, methoxy group, ethoxy group,
Alkoxy groups such as isopropoxy or tertiary butoxy, alkenyloxy such as vinyloxy or allyloxy, alkynyloxy such as ethynyloxy or phenylacetyloxy, phenyl, naphthyl, anthracenyl, biphenyl, Aryl group such as toluyl group, pyrenyl group, perylenyl group, anisyl group, terphenyl group or phenanthrenyl group, hydrofuryl group, hydropyrenyl group,
Dioxanyl group, thienyl group, furyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, quinolyl group, quinoxaloyl group, phenanthrolyl group, benzothienyl group, benzothiazolyl group, indolyl group, germanacyclopentadienyl group or Examples include a heterocyclic ring such as a pyridyl group.
Further, these substituents may be bonded to each other at an arbitrary position to form a spiro ring.

Examples of the substituent attached to the carbon of the cyclopentadiene ring include halogen such as hydrogen, fluorine or chlorine,
Methyl group, ethyl group, normal propyl group, isopropyl group, cyclopentyl group, or alkyl group such as tertiary butyl group, vinyl group, allyl group, alkenyl group such as butenyl group or styryl group, ethynyl group,
Alkynyl group such as propargyl group or phenylacetylinyl group, methoxy group, ethoxy group, alkoxy group such as isopropoxy group or tertiary butoxy group,
Alkenyloxy group such as vinyloxy group or allyloxy group, alkynyloxy group such as ethynyloxy group or phenylacetyloxy group, phenoxy group,
Naphthoxy group, aryloxy group such as biphenyloxy group or pyrenyloxy group, trifluoromethyl group, perfluoro group such as trifluoromethoxy group or pentafluoroethoxy group, dimethylamino group, amino group such as diethylamino group or diphenylamino group, Ketones such as acetyl group or benzoyl group,
An ester group such as an acetoxy group or a benzoyloxy group, an ester group such as a methoxycarbonyl group, an ethoxycarbonyl group or a phenoxycarbonyl group, a sulfinyl group such as a methylsulfinyl group or a phenylsulfinyl group, a trimethylsilyl group, a dimethyltertiarybutylsilyl group, A silyl group such as a methoxysilyl group or a triphenylsilyl group, a phenyl group,
Biphenyl group, terphenyl group, naphthyl group, anthracenyl group, pyrenyl group, toluyl group, anisyl group, fluorophenyl group, diphenylaminophenyl group, dimethylaminophenyl group, aryl group such as diethylaminophenyl group or phenanthrenyl group, thienyl group,
Furyl group, germanacyclopentadienyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, quinolyl group, quinoxaloyl group, phenanthrolyl group, benzothienyl group, benzothiazolyl group, indolyl group, carbazolyl group, pyridyl group, Hetero ring such as pyrrolyl group, benzoxazolyl group, pyrimidyl group or imidazolyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, isothiocyanate group or cyano group And the like. Further, these substituents may be bonded to each other at any position to form a ring. These substituents may be introduced before the formation of the cyclopentadiene ring or after the formation of the cyclopentadiene ring.

Examples of the cyclopentadiene derivative used in the present invention include the following. 1,1-dimethyl-2,3,4,5-tetraphenylgermacyclopentadiene 1,1-diethyl-2,3,4,5-tetrakis (2-methylphenyl) germacyclopentadiene 1,1-diisopropyl-2,3,4,5-tetrakis (3-methylphenyl) germacyclopentadiene 1-ethyl-1-methyl-2,3,4,5-tetrakis (4-methylphenyl) germacyclopentadiene 1,1 di-tert-butyl-2,3,4,5-tetrakis (2-ethylphenyl) germacyclo Pentadiene 1,1-diphenyl-2,3,4,5-tetrakis (3
-Ethylphenyl) germacyclopentadiene 1-methyl-1-phenyl-2,3,4,5-tetrakis (4-ethylphenyl) germacyclopentadiene

1-phenyl-1-tert-butyl-2,3,4,5-tetrakis (3-tert-butylphenyl) germacyclopentadiene 1,1-dimethyl-2,5-bis (3-methylphenyl) -3,4-diphenylgerma Cyclopentadiene 1,1-di (4-toluyl) -2,5-bis (4-methylphenyl) -3,4-diphenylgermacyclopentadiene 1-germacyclohexane-1-spirol 2 ′, 5′di (2-biphenyl)- 3 ', 4'diphenyl-1'
-Germacyclopentadiene 1-Germacyclopentane-1-spiro 2 ', 5'-di (3-biphenyl) -3', 4'-diphenyl-1 '
-Germacyclopentadiene 9-germafluorene-9-spiro-2 ', 5'-di (4-biphenyl) -3', 4'-diphenyl-1'-
Germacyclopentadiene 1,1-dimethyl-2,5-bis (2-trifluoromethylphenyl) -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (3-fluorophenyl) -3,4-diphenylgermacyclo Pentadiene

1,2-bis (1-methyl-2,5-bis (3-methoxyphenyl) -3,4-diphenylgermacyclopentadienyl) ethane 1,1-dimethyl-2,5-bis (4-cyanophenyl) -3,4- Diphenyl stanacyclopentadiene 1,1-dimethyl-2,5-bis {2- (2-benzoxazolyl) phenyl} -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis {3- (2-benzothienyl) phenyl 3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis {4- (2-benzofuryl) phenyl} -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis {2- (2- Benzothiazolyl) phenyl-3,4-diphenyl gel Pentadiene 1,1-dimethyl-2,5-bis {3- (2-benzimidazolyl) phenyl} -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis {4- (2-indolyl) phenyl} -3,4- Diphenylgermacyclopentadiene

1,1-dimethyl-2,5-bis {3- (5-methoxy-2-benzothiazolyl) phenyl} -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-di (1-naphthyl) -3 ,
4-Diphenylgermacyclopentadiene 1,1-dimethyl-2,5-di (2-methyl-1-naphthyl) -3,4-diphenylstanacyclopentadiene 1,1-dimethoxy-2,5-di (2naphthyl) -3,4-diphenylgerma Cyclopentadiene 1,1-dimethyl-2,5-di (2-benzothienyl)
-3,4-Diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (3-methyl-2-benzothienyl) -3,4-diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (3-phenyl-2-benzothienyl) -3,4 Diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (2-methyl-3-benzothienyl) -3,4 diphenylgermacyclopentadiene 1,1-dimethyl-2,5-di (2-benzothiazolyl) -3,4- Diphenylgermacyclopentadiene 1,1-dimethyl-2,5-di (2-benzoxazolyl) -3,4-diphenylgermacyclopentadiene

1,1-dimethyl-2,5-bis (5-methyl-2-benzooxazolyl) -3,4-diphenylstanacyclopentadiene 1,1-dimethyl-2,5-bis (5-phenyl-2-benzothiadiazolyl) -3 1,4-Diphenylgermacyclopentadiene 1,1-dimethyl-2,5-di (3-benzofuranyl)
-3,4 diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (3,4difluorophenyl) -3,4diphenylgermacyclopentadiene 1,1-dimethyl-2,5-bis (3,4,5-tri Fluorophenyl) -3,4-diphenyl stanacyclopentadiene 1,1-dimethyl-2,5-bis (2,3,4,5,6
-Pentafluorophenyl) -3,4-diphenylgermacyclopentadiene 5,5'-dibromo-1,1,1 ', 1'-tetraethyl-3,3', 4,4'-tetraphenyl-2,2 ' −
Bigermol 5,5'-dimethyl-1,1,1 ', 1'-tetraethyl-3,3', 4,4'-tetraphenyl-2,2'-
Vistanol 5,5 '''-dibromo-1,1,1', 1 ',
1 '', 1 '', 1 ''',1'''-octaethyl-
3,3 ', 3'',3''', 4,4 ', 4'',
4 ″ ′-octaphenyl-2,2 ′: 5 ′, 2 ″:
5 ″, 2 ′ ″-quartergermol 9,9′-germaspyrobifluorene 9,9′-stanaspyrobifluorene 9,9-diphenyl-9-stannafluorene 9,9-dinaphthyl-9-germafluorene

The EL device of the present invention has various configurations. Basically, the configuration is such that the cyclopentadiene derivative is sandwiched between a pair of electrodes (anode and cathode). , A hole-transporting material, a light-emitting material, and an electron-transporting material, or may be stacked as separate layers.

As specific examples, anode / cyclopentadiene derivative layer / cathode, anode / hole transport layer / cyclopentadiene derivative layer / cathode, anode / hole transport layer / light emitting layer / cyclopentadiene derivative layer / cathode, anode / Hole transport material +
Light-emitting material + cyclopentadiene derivative layer / cathode. Another special use of cyclopentadiene derivatives is in application to hole blocking materials. The hole blocking material is a material that transports only electrons among two charges of electrons and holes, and does not transmit or hardly transmits holes. Since the cyclopentadiene derivative used in the present invention transports electrons preferentially or selectively, another specific example of the organic EL device of the present invention is an anode / hole transport layer / cyclopentadiene derivative layer / electron transport layer. / Cathode and the like. In this case, light is emitted from the hole transport layer or the cyclopentadiene derivative layer. In particular, as the cyclopentadiene derivative which exerts such a hole blocking effect, one having a short emission wavelength can be mentioned. For example,
9,9'-germaspyrobifluorene and the like.
In a device using 9,9'-germaspirobifluorene as a hole blocking layer, TPD as a hole transporting layer, and 8-hydroxyquinoline aluminum (hereinafter abbreviated as Alq) as an electron transporting layer, Light emission is only purple, which is derived from TPD light emission, and has very excellent hole blocking ability. Such a device that emits light from a TPD is described in Kido et al. (Kido, et. Al. Science, 267, 1332 (1995)).
There was a device using a triazole derivative according to the above, but it was not perfect. As a more specific example, the cyclopentadiene derivative layer used in the present invention can be used as a light emitting layer or an electron transporting light emitting layer. In this case, the structure of the device is as follows: anode / hole transport layer / (cyclopentadiene derivative +
Electron transport material) layer / cathode.

The device of the present invention is preferably supported on a substrate, and there is no particular limitation on the substrate, and those conventionally used in EL devices, for example, glass, transparent plastic, and conductive materials A material made of a polymer, quartz, or the like can be used.

Each layer used in the present invention can be formed by thinning by a known method such as a vapor deposition method and a coating method. The thickness of the thin film of each layer thus formed is not particularly limited and can be appropriately selected depending on the situation.
It is selected in the range of nm.

As the anode in the EL device of the present invention, a material having a large work function (4 eV or more), a metal, an alloy, an electrically conductive compound and a mixture thereof as an electrode material is preferably used. Specific examples of such an electrode material include metals such as Au, CuI, SnO ₂ , ZnO, and ITO.
(Indium oxide) and the like. The anode can be manufactured by forming a thin film from these electrode substances by a method such as evaporation or sputtering. When light is extracted from this electrode, the transmittance is desirably greater than 10%, and the sheet resistance of the electrode is preferably several hundred Ω / square or less. The thickness depends on the material, but is preferably in the range of 10 nm to 1 μm, more preferably 10 to 200 nm.

The cathode has a small work function (4.3).
eV or less) A metal, an alloy, an electrically conductive compound, and a mixture thereof are used as an electrode material. Specific examples of such an electrode material include calcium, magnesium, lithium, aluminum, a magnesium alloy, a lithium alloy, an aluminum alloy, an aluminum / lithium mixture, a magnesium / silver mixture, and indium. The cathode can be manufactured by forming a thin film from these electrode substances by a method such as evaporation or sputtering. The sheet resistance as an electrode is preferably several hundreds Ω / square or less, and more preferably 10
nm to 1 μm, more preferably 50 to 200 nm.

The configuration of the organic EL device of the present invention has various modes as described above, but the luminous efficiency is improved by providing a hole transport layer. As a hole transporting material used for the hole transporting layer, when a hole is injected from an anode placed between two electrodes to which an electric field is applied, the hole can be appropriately transmitted to the light emitting layer. A compound, for example, 10 ⁴ to 10 ⁶ V
/ Cm when applying an electric field of at least 10 ⁻⁶ cm ² / V ·
Those having a hole mobility of seconds or more are preferred. The material used as the hole transporting material is not particularly limited as long as it has such properties. Conventionally, a photoconductive material commonly used as a hole charge transporting material or a hole transporting layer of an EL element is used. Any known ones can be selected from known ones to be used.

Examples of the hole transporting material include carbazole derivatives (N-phenylcarbazole, polyvinylcarbazole, etc.) and triarylamine derivatives (TP
D, a polymer having an aromatic tertiary amine in the main chain or side chain, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N ′
-Dinaphthyl-4,4'-diaminobiphenyl and the like. ), Phthalocyanine derivatives (metal-free, copper phthalocyanine, etc.), polysilanes and the like. When a plurality of electron transporting materials are used in the electron transporting layer in the organic EL device of the present invention, not only the germanocyclopentadiene derivative but also other electron transporting materials may be used. There is no particular limitation on such an electron transporting material, and any one of conventionally known compounds can be selected and used. Preferred examples of the electron transport material include:
Following 7

Or a diphenylquinone derivative such as that described in the journal of the Institute of Electrophotography, 30,3 (1991), or the following:

[0042]

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[0043]

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Compounds such as (Journal Applied
Physics (J. Apply. Phys.), 27, 269 (1988). ) And oxadiazole derivatives (Japanese Journal of Applied Physics (Jpn.
J. Appl. Phys.), 27, L713 (1988), Applied Physics Letter (Appl. Phys. Lett.), 55, 1489 (1989)), thiophene derivatives (JP-A-4-212286, etc.) ), Triazole derivatives (those described in Japanese Journal of Applied Physics (Jpn. J. Appl. Phys.), 32, L917 (1993), etc.), thiadiazole derivatives (the 43rd Annual Meeting of the Society of Polymer Science, Japan) , IIIP1a007, etc.), metal complexes of oxine derivatives (IEICE Technical Report,
92 (311), 43 (1992)), polymers of quinoxaline derivatives (Japanese Journal of Applied Physics (Jpn. J. Appl. Phys.), 33, L250
(1994). ), Phenanthroline derivatives (those described in the 43rd Polymer Symposium Proceedings, 14J07 and the like).

The luminescent materials used in the present invention include Polymer Functional Materials Series “Optical Functional Materials” edited by the Society of Polymer Science, Kyoritsu Shuppan
(1991), known light-emitting materials such as daylight fluorescent materials, fluorescent brighteners, laser dyes, organic scintillators, and various fluorescent analysis reagents as described in P236 can be used. Polycyclic condensed compounds such as anthracene, anthracene, phenanthrene, pyrene, chrysene, perylene, coronene, rubrene, and quinacridone; oligophenylene-based compounds such as quarterphenyl; 1,4-bis (2-methylstyryl) benzene; 1,4-bis (4-methylstyryl) benzene, 1,4-bis (4-methyl-5-phenyl-2-oxazolyl) benzene, 1,4-bis (5
-Phenyl-2-oxazolyl) benzene, 2,5-bis (5-tert-butyl-2-benzoxazolyl) thiophene, 1,4-diphenyl-1,3-butadiene, 1,6-diphenyl-1, Liquid scintillators such as 3,5-hexatriene and 1,1,4,4-tetraphenyl-1,3, -butadiene; metal complexes of oxine derivatives described in JP-A-63-264692; coumarin dyes; Dicyanomethylenepyran dye, dicyanomethylenethiopyran dye, polymethine dye, oxobenzanthracene dye, xanthene dye, carbostyril dye and perylene dye, oxazine compounds described in German Patent 2534713, the 40th Joint Lecture on Applied Physics Stilbene derivatives described in Proceedings of the Conference, 1146 (1993) and JP-A-4-363891 Preferably the oxadiazole compound. Further, the cyclopentadiene derivative of the present invention may be used.

The organic EL device of the present invention can be manufactured by a conventional method. The following is an example of a method suitable for the present invention.

An EL device comprising the anode / the cyclopentadiene derivative layer / cathode can be manufactured as follows. First, a thin film made of a desired electrode material, for example, a material for an anode, is formed on an appropriate substrate at a thickness of 1 μm or less,
An anode is formed so as to have a thickness in the range of 0 to 200 nm by a method such as vapor deposition or sputtering, and then a thin film of a cyclopentadiene derivative is formed thereon. As a method of thinning, for example, dip coating method,
There are a spin coating method, a casting method, a vapor deposition method, and the like, but a vapor deposition method is more preferable because a more uniform film is easily obtained, impurities are hardly mixed, and pinholes are hardly generated.

Next, after forming this cyclopentadiene derivative layer, a thin film made of a cathode material is formed thereon by a method of 1 μm or less, for example, by vapor deposition or sputtering, and a desired cathode is provided by providing a cathode. An element can be obtained. In the production of this organic EL device, the production order can be reversed, and the cathode, the cyclopentadiene derivative layer, and the anode can be produced in this order. When a DC voltage is applied to the thus obtained EL device, light emission can be observed from the transparent or translucent electrode side.
Furthermore, light is emitted by applying an AC voltage.
The waveform of the applied alternating current may be arbitrary.

[0049]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 An IT was placed on a glass substrate of 25 mm × 75 mm × 1.1 mm.
A film obtained by forming O to a thickness of 50 nm by a vapor deposition method (manufactured by Tokyo Sanyo Vacuum Co., Ltd.) was used as a transparent support substrate. This transparent support substrate was fixed to a substrate holder of a commercially available vapor deposition apparatus (manufactured by Vacuum Kiko Co., Ltd.), TPD was placed in a quartz crucible, and 1,1-dimethyl-2,3,4,4 was placed in another crucible. 5-Tetraphenylgermacyclopentadiene (hereinafter abbreviated as TPG) was charged, and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. Thereafter, the crucible containing TPD is heated to a thickness of 50 mm.
After vapor deposition of TPD to a thickness of 50 nm, a crucible containing TPG was further heated thereon to vapor-deposit TPG to a thickness of 50 nm. The deposition rate is 0.1-0.2
nm / sec. Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, and then, using a graphite crucible, magnesium was deposited at a deposition rate of 1.2 to 2.4 nm / sec. An element was formed by vapor deposition at a vapor deposition rate of 0.2 nm / sec, which was used as a counter electrode of a mixed metal electrode of magnesium and silver on the light emitting layer. When a direct current voltage was applied to the obtained device using the ITO electrode as an anode and the mixed electrode of magnesium and silver as a cathode, current flowed and green light was emitted.

Example 2 A device was prepared in the same manner as in Example 1, except that TPG was replaced with 9,9'-stanaspyrobifluorene. When a DC voltage was applied to the obtained device, a current flowed and blue-violet light emission was obtained.

Example 3 A device was prepared in the same manner as in Example 1 except that TPG was replaced with 9,9'-germaspirobifluorene. When a DC voltage of 17 V is applied to the obtained device, about 50 mA / c
m ² flowed, and blue light emission of about 100 cd / m ² was obtained.

Example 4 A device was prepared in the same manner as in Example 1 except that TPG was replaced with 1,1-diethyl-2,3,4,5-tetraphenylstanacyclopentadiene. When a DC voltage was applied to the obtained device, a current flowed and green light was emitted.

Example 5 The transparent support substrate used in Example 1 was fixed to a substrate holder of a vapor deposition apparatus, and TPD was placed in a crucible made of quartz, 9,9′-germaspyrobifluorene in another crucible, and further another crucible. Was charged with 4,4′-bis (2,2-diphenylvinyl) biphenyl (hereinafter abbreviated as DPVBi), and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. First, a crucible containing TPD was heated to deposit TPD so as to have a thickness of 50 nm. On this, a crucible containing DPVBi is heated to deposit DPVBi to a thickness of 20 nm, and a crucible containing 9,9′-spirobigermafluorene is further heated thereon to a thickness of 30 nm. Was deposited as follows. The deposition rate was 0.1-0.2 nm / sec. Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, and then magnesium was deposited from the graphite crucible at a deposition rate of 1.2 to 2.4 nm / sec.
An element was formed by vapor deposition at a vapor deposition rate of 0.2 nm / sec, and laminating 200 nm of a mixed metal electrode of magnesium and silver on the light-emitting layer as a counter electrode. When a direct current voltage was applied to the obtained device using the ITO electrode as an anode and the mixed electrode of magnesium and silver as a cathode, current flowed and blue light was emitted. The emission spectrum coincided with the fluorescence spectrum of the deposited film of DPVBi.

Example 6 An element was prepared in the same manner as in Example 5, except that DPVBi was changed to Alq. When a DC voltage was applied to the obtained device, a current flowed and green light was emitted.

Example 7 The transparent support substrate used in Example 1 was fixed to a substrate holder of a vapor deposition device, and TPD was placed in a quartz crucible and T was placed in another crucible.
Nile red was added to PG and another crucible, and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. The crucible containing TPD was heated, and TPD was deposited to a thickness of 50 nm. On this, TPG and a Nile Red crucible were both heated and vapor-deposited to a film thickness of 50 nm. The deposition rate of TPG was 0.1-0.2 nm / sec, and that of Nile Red was 1/100 of TPG. Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, and then magnesium was deposited from the graphite crucible at a deposition rate of 1.2 to 2.4 nm / sec.
Vapor deposition was performed at a vapor deposition rate of about 0.2 nm / sec, and a mixed metal electrode of magnesium and silver was laminated and vapor-deposited to a thickness of 200 nm on the light-emitting layer to prepare a device as a counter electrode. Anode for ITO electrode,
When a DC voltage was applied to the obtained device using a mixed electrode of magnesium and silver as a cathode, current flowed and red-orange light emission was obtained.

Example 8 The transparent support substrate used in Example 1 was fixed on a commercially available spinner (manufactured by Kyoei Semiconductor Co., Ltd.), and 50 parts by weight of polyvinyl carbazole and 50 parts by weight of 9,9′-gelmaspyrobifluorene were used. Was dissolved in 1,2-dichloroethane and applied at 5000 rpm. Thereafter, the substrate was dried at 50 ° C. under a reduced pressure of 10 ⁻¹ Pa, and then fixed to a substrate holder of a vapor deposition apparatus. Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, and then magnesium was evaporated from the graphite crucible at a deposition rate of 1.2 to 2.4 nm / sec. An evaporation was performed at a deposition rate of 0.2 nm / sec, and a mixed metal electrode of magnesium and silver was deposited to a thickness of 200 nm on the light emitting layer to form a counter electrode, thereby forming an element. When a DC voltage was applied to the obtained device using the ITO electrode as an anode and the mixed electrode of magnesium and silver as a cathode, a current flowed and purple light was emitted.

Example 9 Instead of a solution of 50 parts by weight of polyvinyl carbazole and 50 parts by weight of 9,9'-germaspirobifluorene in 1,2-dichloroethane, 50 parts by weight of polyvinyl carbazole was used.
A device was prepared in the same manner as in Example 8, except that a 1,2-dichloroethane solution containing 50 parts by weight of 9,9′-germaspirobifluorene and 1 part by weight of coumarin 6 (manufactured by KODAK) was used. When a DC voltage was applied to the obtained device, a current flowed and green light was emitted.

Example 10 A device was prepared in the same manner as in Example 9 except that coumarin 6 was replaced with perylene. When a DC voltage was applied to the obtained device, a current flowed and blue light was emitted.

Example 11 A device was prepared in the same manner as in Example 9 except that Nile Red was used instead of Coumarin 6. When a DC voltage was applied to the obtained device, current flowed and orange light emission was obtained.

Example 12 DPVBi was converted to 9,9'-germaspirobifluorene.
A device was prepared in the same manner as in Example 14 except that Alq was used instead of 9,9'-germaspyrobifluorene. When a DC voltage of 10 V is applied to the obtained device, about 300 mA is applied.
/ Cm ² , and purple light emission of about 1700 cd / m ² was obtained. The emission spectrum almost coincided with the fluorescence spectrum of the TPD deposited film, and the emission wavelength was 405 nm.

Example 13 The transparent support substrate used in Example 1 was fixed to a substrate holder of a vapor deposition device, and 40 parts by weight of TPD, 9, and 9 were placed in a crucible made of quartz.
60 parts by weight of 9′-germaspyrobifluorene and 1 part by weight of coumarin 6 were put therein, and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. The crucible was heated and deposited so as to have a thickness of 100 nm. The deposition rate was 1-1.2 nm / sec.
Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, and then magnesium was added to the graphite crucible in an amount of 1.2 to 2.
At a deposition rate of 4 nm / sec, silver was simultaneously deposited from the other crucible at a deposition rate of 0.1 to 0.2 nm / sec, and a mixed metal electrode of magnesium and silver was deposited on the light emitting layer by 200 nm.
An element was formed by stacking and vapor-depositing the resultant to form a counter electrode. Using the ITO electrode as the anode and the mixed electrode of magnesium and silver as the cathode,
When a DC voltage was applied to the obtained device, a current flowed and green light was emitted.

[0063]

The organic electroluminescent device using the cyclopentadiene derivative of the present invention as an electron transporting material has a better electron transporting property than a device using a conventional electron transporting material, and emits light with high luminance at a low voltage. Can be. By using these, a light-emitting element such as a full-color flat panel display can be manufactured.

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Claims (8)

[Claims] 1. An organic electroluminescent device using a germanocyclopentadiene derivative represented by the following formula 1. Embedded image [Wherein, X and Y each independently represent a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group,
Alkenyloxy group, alkynyloxy group, hydroxy group, a substituted or unsubstituted aryl group, to form a saturated or unsaturated ring substituted or unsubstituted hetero ring, or X and Y are bonded to the structure, R ₁ ~ R ₄ is each independently hydrogen, halogen, substituted or unsubstituted carbon atoms having 1 to 6 carbon atoms.
Alkyl group, alkoxy group, aryloxy group,
Perfluoroalkyl group, perfluoroalkoxy group,
Amino group, alkylcarbonyl group, arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group,
Aryloxycarbonyloxy group, sulfinyl group,
Sulfonyl group, sulfanyl group, silyl group, carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, It has a structure in which an isothiocyanate group or a cyano group or, when adjacent, a substituted or unsubstituted ring is fused. ] 2. An electroluminescent device using a stanacyclopentadiene derivative represented by the following formula (2). Embedded image [Wherein, X and Y each independently represent a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms, an alkoxy group,
Alkenyloxy group, alkynyloxy group, hydroxy group, a substituted or unsubstituted aryl group, to form a saturated or unsaturated ring substituted or unsubstituted hetero ring, or X and Y are bonded to the structure, R ₁ ~ R ₄ is each independently hydrogen, halogen, substituted or unsubstituted carbon atoms having 1 to 6 carbon atoms.
Alkyl group, alkoxy group, aryloxy group,
Perfluoroalkyl group, perfluoroalkoxy group,
Amino group, alkylcarbonyl group, arylcarbonyl group, alkoxycarbonyl group, aryloxycarbonyl group, azo group, alkylcarbonyloxy group, arylcarbonyloxy group, alkoxycarbonyloxy group,
Aryloxycarbonyloxy group, sulfinyl group,
Sulfonyl group, sulfanyl group, silyl group, carbamoyl group, aryl group, heterocyclic group, alkenyl group, alkynyl group, nitro group, formyl group, nitroso group, formyloxy group, isocyano group, cyanate group, isocyanate group, thiocyanate group, It has a structure in which an isothiocyanate group or a cyano group or, when adjacent, a substituted or unsubstituted ring is fused. ] 3. An electroluminescent device using at least one of the germanocyclopentadiene derivatives according to claim 1 as a component of a charge transport layer. 4. An electroluminescent device using at least one of the germanocyclopentadiene derivatives according to claim 1 as a component of a light emitting layer. 5. An electroluminescent device using at least one of the germanocyclopentadiene derivatives according to claim 1 as a component of a hole blocking layer. 6. An electroluminescent device using at least one of the stanacyclopentadiene derivatives according to claim 2 as a component of a charge transport layer. 7. An electroluminescent device using at least one of the stanacyclopentadiene derivatives according to claim 2 as a component of a light emitting layer. 8. An electroluminescent device using at least one of the stanacyclopentadiene derivatives according to claim 2 as a component of a hole blocking layer.