Takahiro NAKAYAMA, Yuzo ITOH and Atsushi KAKUTA

Hitachi Research Laboratory, Hitachi Ltd., 7-1-1, Ohmika-cho, Hitachi, Ibaraki, 319-12 Japan

(Received September 12, 1994; Accepted November 17, 1994)

The luminescent characteristics of organic thin films sandwiched between two mirrors were measured. The optical length between the two mirrors was set according to the scale of the luminescent wavelength in order to compose a microcavity structure. Photoluminescence (PL) and electroluminescence (EL) from tris(8-hydroxyquinoline)aluminum (ALQ) were enhanced at distinct resonating wavelengths, and suppressed in other regions. Then, narrow and enhanced luminescent peaks were observed from the devices with the microcavity structure. Based on their injection current dependence, the primary cause of these spectra was speculated to be spontaneous emission. An EL sample with the microcavity structure for multicolor emissions was fabricated.

Key words : electroluminescence, photoluminescence, organic thin film, microcavity, multicolor display