摘要
The emission lifetime of tris-(8-hydroxyquinoline) aluminium (AIQ3) as a powder or a thin film from vaporization is measured at excitation wavelength ∼400 nm. According to decay curves recorded with time-correlated single photon counting, the lifetimes are 17 and 12 ns for powder and film, respectively. Because films formed by sublimation contain microcrystals (C. W. Tang, S. A. Van Slyke and C. H. Chen, J. Appl. Phys. 65, 3610 (1989)), the measured lifetime reflects the structure and quality of the film. Decay curves of electronically excited AIQ3 dissolved in methanol, ethanol, acetonitrile, trichloromethane and benzene are measured; the lifetimes are 9.3, 11, 9.9, 18 and 20 ns, respectively. The lifetime of excited AIQ3 decreases with increasing solvent polarity; this trend is attributed to a dipole-dipole interaction associated with relaxation of AIQ3. The quantum yield of fluorescence of AlQ3 in ethanol is measured to be 9.4 %.