Compositions – Light transmission modifying compositions – Modification caused by energy other than light
Patent
1996-03-27
1998-11-17
Tucker, Philip
Compositions
Light transmission modifying compositions
Modification caused by energy other than light
25230116, 428917, 564307, 564434, G02F 100, C09K 1106, C07C21100
Patent
active
058371664
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP94/01585 filed Sep. 28, 1994.
TECHNICAL FIELD
The present invention relates to electroluminescence devices (hereinafter, referred to as organic EL devices) and novel arylenediamine derivatives. More particularly, the present invention relates to organic EL devices having a remarkably improved life of light emission by using an arylenediamine derivative as a component thereof, particularly as a material of a hole transporting layer thereof, and novel p-phenylenediamine derivatives and 4,4'-biphenylenediamine derivatives which can remarkably improve the life of light emission of organic EL devices.
BACKGROUND ART
As for the construction of organic EL devices, various types have heretofore been known. It has been disclosed that an aromatic tertiary amine is used as the material of a hole transporting layer in an organic EL device having the construction of ITO (Indium Tin Oxide)/a hole transporting layer/a light emitting layer/a cathode (Japanese Patent Application Laid-Open No. Showa 63(1988)-295695), and a high luminance of several hundred cd/m.sup.2 with an applied voltage of 20 V or more has been enabled by the device having this construction. Furthermore, it has been disclosed that, by using TPD aromatic tertiary amine, a luminance of 100 cd/m.sup.2 can be obtained with an applied voltage of 8 V even in the case of blue light emission (Japanese Patent Application Laid-Open No. Heisei 3(1991)-231970). However, the above-disclosed diamine derivative has a drawback in that contribution of canonical forms is weak because the two amino groups are located at positions separate from each other, and the diamine derivative has a high ionization potential. Therefore, the driving voltage of the EL device cannot be sufficiently decreased, and the device furthermore has a half-life period of several ten hours. Thus, the device described above does not have a sufficient property for practical application.
A compound derived by using m-phenylenediamine as the diamine has been disclosed (Japanese Patent Application Laid-Open No. Heisei 5(1993)-105647). A sufficient electron-donating property can be expected from this compound because only a phenylene group is present between the two amino groups. However, this compound has a drawback in that this compound has a still higher ionization potential than those of the diamine derivatives described above because the m-phenylenediamine skeleton in this compound cannot have canonical forms, the driving voltage of the EL device therefore cannot be sufficiently decreased, and the life of light emission is short.
When application of an EL device to a flat panel display or the like is considered, it is necessary that the life of light emission be improved. It has been disclosed in Japanese Patent Application Laid-Open No. Heisei 5(1993)-107758 that a triamine compound can be used as a material of charge transport in an EL device. However, this compound cannot sufficiently satisfy the requirements described above.
DISCLOSURE OF THE INVENTION
Under the situation described above, the present invention has an object of providing an organic EL device having a decreased driving voltage or an organic EL device having a remarkably improved life of light emission.
As the result of extensive studies undertaken by the present inventors to develop the organic EL device having the desirable properties described above, it has been discovered that an organic EL device having a long life of light emission can be obtained by using an arylenediamine derivative having a specific structure as a component of an organic EL device, particularly as a material of a hole transporting layer.
It has also been discovered by the present inventors that, among the arylenediamine derivatives described above, compounds having some types of structure, p-phenylenediamine derivatives having specific structures, and 4,4'-biphenylenediamine having specific structures are novel compounds which are not described in literature, and that an organic EL device having a remarkably imp
Hosokawa Chishio
Kawamura Hisayuki
Kusumoto Tadashi
Nakamura Hiroaki
Idemitsu Kosan Co. Ltd.
Tucker Philip
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