Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2000-09-29
2002-12-03
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S917000, C313S504000, C313S506000, C252S301160
Reexamination Certificate
active
06489046
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an organic electroluminescence device which is used as a light source such as a planar light emitting member of televisions and a back light of displays, exhibits an excellent purity of color and a high efficiency of light emission, has a long life and emits reddish light and to a novel compound having these characteristics.
BACKGROUND ART
Electroluminescence (referred to as EL, hereinafter) devices using organic compounds are expected to be used for inexpensive full color display devices of the solid light emission type which can display a large area and development thereof has been actively conducted. In general, an EL device is constituted with a light emitting layer and a pair of electrodes faced to each other at both sides of the light emitting layer. When a voltage is applied between the electrodes, electrons are injected at the side of the cathode and holes are injected at the side of the anode. The electrons are combined with the holes in the light emitting layer and an excited state is formed. When the excited state returns to the ground state, the energy is emitted as light.
Although the practical application of organic EL devices has started recently, devices for full color displays are still under development. In particular, a material for organic EL devices which exhibits an excellent purity of color and a high efficiency of light emission, has a long life and emits reddish light has been desired.
In an attempt to satisfy the above desire, a device emitting red light in which a derivative of naphthacene or pentacene is added to a light emitting layer is disclosed in Japanese Patent Application Laid-Open No. Heisei 8(1996)-311442. Although this device exhibits an excellent purity of red light, the device exhibits an efficiency of light emission as low as 0.7 lm/W and has an insufficient average life which is shorter than 150 hours. An average life of at least several thousand hours is necessary for practical applications. A device in which a compound derived from dicyanomethylene (DCM) is added to a light emitting layer is disclosed in Japanese Patent Application Laid-Open No. Heisei 3(1991)-162481. However, this device exhibits an insufficient purity of red light.
DISCLOSURE OF THE INVENTION
The present invention has been made to overcome the above problems and has an object of providing an organic EL device which exhibits an excellent purity of color and a high efficiency of light emission, has a long life and emits reddish light and a novel compound having these characteristics.
As the result of extensive studies by the present inventors to develop the organic EL device having the above advantageous properties, it was found that the object can be achieved by using a compound represented by the following general formula [1], [2] or [2′] as the light emitting material.
The organic EL device of the present invention comprises an organic layer disposed between at least one pair of electrodes, wherein the organic layer comprises a compound represented by general formula [1]:
wherein R
1
to R
14
each independently represent hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylamino group having 6 to 30 carbon atoms, an alkylamino group having 2 to 20 carbon atoms or an arylalkylamino group having 6 to 30 carbon atoms, the groups being substituted or unsubstituted; and at least one pair of R among R
1
to R
14
which are adjacent to each other do not represent hydrogen atom but represent groups which form a cyclic structure in combination.
The organic EL device of the present invention may also comprise an organic layer disposed between at least one pair of electrodes, wherein the organic layer comprises a compound represented by general formula [2]:
wherein R
15
to R
26
each independently represent hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylamino group having 6 to 30 carbon atoms, an alkylamino group having 2 to 20 carbon atoms or an arylalkylamino group having 6 to 30 carbon atoms, the groups being substituted or unsubstituted; at least one pair of R among R
15
to R
26
which are adjacent to each other do not represent hydrogen atom but represent groups which form a cyclic structure in combination; and Ar
1
and Ar
2
represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heterocyclic group having 5 to 30 carbon atoms.
The novel organic compound emitting red light which is useful for the organic EL device of the present invention is represented by general formula [2′]:
wherein R
15
to R
26
and Ar
1
and Ar
2
are as defined above in general formula [2], excluding the case in which Ar
1
and Ar
2
both represent phenyl group.
THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION
In the organic EL device of the present invention, an organic layer is disposed between at least one pair of electrodes and the organic layer comprises at least one of the compounds represented by general formula [1] and general formula [2] shown above.
R
1
to R
14
in general formula [1] shown above each independently represent hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylamino group having 6 to 30 carbon atoms, an alkylamino group having 2 to 20 carbon atoms or an arylalkylamino group having 6 to 30 carbon atoms. These groups may be substituted. At least one pair of R among R
1
to R
14
which are adjacent to each other do not represent hydrogen atom but represent groups which form a cyclic structure in combination.
It is preferable that R
1
to R
14
, except the pair of R which are adjacent to each other and represent groups forming a cyclic structure in combination, represent an alkyl group, an aryloxy group, an arylalkyl group, an aryl group, an arylamino group, an alkylamino group or an arylalkylamino group having 6 to 30 carbon atoms.
R
15
to R
26
in general formula [2] shown above each independently represent hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an arylalkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylamino group having 6 to 30 carbon atoms, an alkylamino group having 2 to 20 carbon atoms or an arylalkylamino group having 6 to 30 carbon atoms. These groups may be substituted. At least one pair of R among R
15
to R
26
which are adjacent to each other do not represent hydrogen atom but represent groups which form a cyclic structure in combination. Ar
1
and Ar
2
represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms or a substituted or unsubstituted heterocyclic group having 5 to 30 carbon atoms.
The novel organic compound emitting red light which is useful for the organic EL device of the present invention is represented by general formula [2′] shown above.
In general formula [2′], R
15
to R
26
, Ar
1
and Ar
2
are as defined above in general formula [2], excluding the case in which Ar
1
and Ar
2
both represent phenyl group.
The above organic layer comprises a light emitting layer which comprises at least one of the compounds represented by general formula [1] and general formula [2] shown above.
It is preferable that the light emitting layer comprises 0.1 to 20% by mole and more preferably 1 to 5% by mole of at least one of the compounds represented by general formula [1] and general formula [2].
The light emitting layer may be a light emitting layer having an elect
Ikeda Hidetsugu
Koga Hidetoshi
Tagami Sanae
Yanagisawa Yoshinori
Idemitsu Kosan Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Yamnitzky Marie
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