THERMAL AND MORPHOLOGICAL EFFECTS ON THE HYDROLYTIC STABILITY OF ALUMINUM TRIS(8-HYDROXYQUINOLINE) (ALQ(3))

An investigation into the physical and chemical characteristics of alu minum tris(8-hydroxyquinoline) (Alq(3)), a reliable electron-transport ing and emitting material for low molecular weight based organic light -emitting diodes (OLEDs), was performed. In the presence of atmospheri c moisture, the thermal stability of Alq(3) was studied by monitoring the evolution of its volatile byproduct, 8-hydroxyquinoline (8-Hq), us ing thermogravimetric analysis and gas chromatography/mass spectroscop y (GC/MS). Sample morphology was shown to be an important parameter in the stability of Alq(3). Annealed (more crystalline) samples exhibite d greater stability to hydrolysis than freshly sublimed films, at the expense of photoluminescence efficiency. The possible implications of these phenomena are discussed with respect to failure mechanisms of Al q(3)-based OLEDs.