CHEMICAL AND MORPHOLOGICAL STABILITY OF ALUMINUM TRIS(8-HYDROXYQUINOLINE) (ALQ(3)) - EFFECTS IN LIGHT-EMITTING DEVICES

Aluminum tris(8-hydroxyquinoline) (Alq(3)) is presently considered one of the most reliable electron transporting and emitting materials for molecular-based organic light-emitting diodes (OLED's), This paper su mmarizes the investigations that our group, over the past three years, have conducted into the physical and chemical response of Alq(3) in t he presence of small amounts of moisture. The characteristic evolution of 8-hydroxyquinoline (8-Hq), a volatile byproduct of the hydrolysis of Alq(3), was quantified using thermogravimetric and gas chromatograp hy/mass spectroscopy (GC/MS) analysis as a function of sample morpholo gy, Annealed (more crystalline) samples exhibited greater stability to hydrolysis than freshly sublimed films, at the expense of photolumine scence (PL) efficiency, These phenomena are discussed with respect to failure mechanisms observed in Alq(3)-based OLED's.