Effect of Film Thickness on the Electrical Resistivity and Optical Functions Distribution of Iron Tris(8-hydroxyquinoline) Thin Films

Iron tris(8-hydroxyquinoline) (Feq₃) was synthesized and investigated by X-ray photoemission spectroscopy. It crystalizes in triclinic polycrystalline structure in powder form, whereas the Feq₃ films, with different thickness values (12, 20, 35, and 42 nm), have an amorphous structure. The influence of film thickness on the electrical resistivity and the optical properties is reported. The morphology of Feq₃ was investigated in terms of field-emission scanning electron microscope. Electrical resistivity measurements indicate an inverse proportionality to the film thickness. The optical properties of Feq₃ films were investigated in terms of photoluminescence spectra and spectrophotometric measurements of transmittance and reflectance. The optical functions such as absorption coefficient and refractive index of the films were calculated. The dependence of the Feq₃ film thickness on the optical energy band gap and dispersion parameters was studied. The outcomes indicate that the Feq₃ films are of great importance for applications in organic solar cells and light emitting diodes.