Electronic structure of Alq3 and Liq using soft X-ray spectroscopy and density functional theory calculation

The electronic structure of aluminum tris-8-hydroxyquinoline (Alq₃) and 8-hydroquinolatolithium (Liq) was investigated using a combination of X-ray emission spectroscopy (XES), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and spectral simulation with density functional theory. The chemical bonding states of Alq₃ and Liq were analyzed using XPS core-level spectra. The band gaps of Alq₃ and Liq were measured by combining the XAS and XES results. Additionally, resonant and non-resonant XES were used to measure the density of states for O sites in the molecules.