Non-stoichiometry of tris(8-hydroxyquinoline) aluminium: is it possible?

Abstract

The dependence of the 8-hydroxyquinoline (8-Hq) vapor pressure on temperature, log P_8-Hq [Torr] = 8.4249 − 2963.5/T, was experimentally determined in the 386–482 K temperature range using the Bourdon manometer technique. Tris(8-hydroxyquinoline) aluminum (α-Alq₃) crystals were synthesized under the 8-Hq controlled partial pressure of 0.1–11.30 Torr. The influence of 8-Hq vapor pressure on the structural and luminescence characteristics of crystalline Alq₃ was examined. It was found out that the P_8-Hq increase resulted in the changes in the photoluminescence spectra maximum, decay kinetics, and structural characteristics. The unit cell volume of the α-Alq₃ crystals decreased from 1141.1 to 1138.7 ų upon P_8-Hq increase.