Characterization of electronic structure of aluminum (III) bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq) for phosphorescent organic light emitting devices

The structure of the triplet host material, aluminum (III) bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq), has been optimized by density functional theory (DFT) with B3LYP methods to study the electronic distribution of its HOMO and LUMO energy states. Calculated triplet bandgap energy of BAlq is shown to be consistent with the experimental data. By analyzing the partial density states (PDOS) of these ligands contributing to the total density of states (TDOS), it is concluded that the HOMO and LUMO orbitals of BAlq are mainly localized on the 4-phenylphenol and 2-methyl-8-hydroxyquinoline ligands, respectively.