ABSTRACT
I. INTRODUCTION Although development of light-emitting devices and lasers using inorganic com pound semiconductors has progressed substantially, problems in these devices, es pecially electroluminescent (EL) diodes emitting blue light, still exist. On the other hand, electroluminescence in organic semiconductors has been known for some time [1-3]. Since Tang et al. reported their findings on the multilayered organic EL diode [4], the EL devices based on organic thin layers have attracted much attention [5-24] because of their possible application as the most promising nextgeneration flat-panel display systems and their fascinating potential to produce emissions of all colors ranging from blue to red, particularly in the blue band, in EL displays with the aid of the molecular design of organic materials possessing high fluorescent efficiency and semiconducting properties, which are difficult when using inorganic light-emitting diodes only, despite substantial progress achieved in inorganic EL diodes development.
