The elecero-transpore nature of tris-8-hydroxyquinolate-aluminum (Alq3) and its derivatives have been studied by the density functional theory (DFT) with B3LYP functional. The frontier molecular orbital characteristics and energy level of Alq3 and its derivatives have been analyzed systematically. The results indicate that the emissions of Alq3 and its derivatives originate from the electron π → π* transitions between different ligands, the difluoro-substituted groups make HOMO-LUMO gaps, ionization potentials and electron affinities are conducive to improve the electron injection and charge transfer properties. The change in difluoro-substituted position on 8-hydroxyquinoline ligand is a powerful approach for tuning the ability of electron injection.

tris-8-hydroxyquinolate-aluminum; difluoro-; electron transition; reorganization energy; (DFT) B3LYP/6-31G