An organic luminescence device is a device where a thin film including a fluorescent organic compound or a phosphorescent organic compound is sandwiched between an anode and a cathode, an electron and a hole are injected from the respective electrodes to generate an exciton of the fluorescent compound or the phosphorescent compound, and light which is emitted when the exciton returns to the ground state is utilized.
According to the study of Kodak company in 1987 (Appl. Phys. Lett. 51, 913 (1987)), there has been reported a luminescence with approximately 1000 cd/m2 at an applied voltage of approximately 10 V in a device having a separated-function type two-layer configuration using ITO as an anode, a magnesium-silver alloy as a cathode, an aluminum quinolinol complex as an electron-transporting material and a luminescent material, and a triphenyl amine derivative as a hole-transporting material. The related patents include U.S. Pat. Nos. 4,539,507, 4,720,432, 4,885,211, and so on.
In addition, it is possible to generate luminescence in the range of ultraviolet to infrared lights by changing the type of the fluorescent organic compound, and in recent years various types of compounds have been studied actively. For instance, it is described in U.S. Pat. Nos. 5,151,629, 5,409,783, 5,382,477, Japanese Patent Application Laid-Open Nos. 2-247278, 3-255190, 5-202356, 9-202878, 9-227576, and so on.
In recent years, many studies have been conducted using phosphorescent compounds as luminescent materials and using energies in triplet excitation states. A high luminescence efficiency shown by an organic luminescence device using an iridium complex as a luminescent material has been reported by a group of the Princeton University (Nature 395, 151 (1998)).
Furthermore, in addition to the organic luminescence device using the low molecular weight material as mentioned above, an organic luminescence device using a conjugate polymer has been reported by a group of the Cambridge University (Nature, 347, 539 (1990)). In this report, luminescence from a single layer is confirmed by the film formation of polyphenylene vinylene (PPV) using a coating system.
The related patents of the organic luminescence device using the conjugate polymer include U.S. Pat. Nos. 5,247,190, 5,514,878, 5,672,678, Japanese Patent Application Laid-Open Nos. 4-145192, 5-247460, and so on.
In this way, the recent progress in the organic luminescence device is remarkable, and the characteristics thereof suggest the possibility of applications for various purposes, which enable the luminescence device with a high luminance, a high-speed response, and a thin and lightweight form.
However, an optical output of higher luminance or higher conversion efficiency is required under the present conditions. In addition, many problems still remain to be solved regarding the durability with respect to a change with time due to a long-term usage, deterioration caused by an atmospheric gas including oxygen, moisture, or the like, and so on. Besides, it is not still insufficient for solving problems related to the needs for luminescences of blue, green, and red having good color purity in the case of considering the applications to a full color display and so on.
On the other hand, a spiro compound having a specific steric configuration has been attracting attention as an organic functional material in terms of the specific physical properties of the material (J. Am. Chem. Soc., vol. 110, page 5687, 1988). As an example of using a spiro compound as an organic luminescence device, Japanese Patent Application Laid-Open No. 7-278537 or the like can be given, but the characteristics thereof in being used as a luminescent material or an electron-transporting material are not sufficient.