Synthesis, Characterization, DFT Studies, and Photodiode Application of Azo-azomethine-Based Ligand and Its Transition-Metal Complexes

An azo-azomethine-based ligand (H 2 L) and its transition-metal complexes were prepared, and the electronic structure of the synthesized compounds obtained computationally using density functional theory at B3LYP/6-31G (d,p) level. Furthermore, organic–inorganic heterojunctions were fabricated by forming thin films of complexes of H 2 L and Co(II), Ni(II), and Pd(II) metal on n -Si substrate. The fundamental electrical parameters of the rectifying heterojunctions were identified based on current–voltage data obtained in the dark at room temperature. The photosensing properties of the devices were investigated under illumination at various intensities from 40 mW/cm 2 to 100 mW/cm 2 . The results showed that the photoelectrical characteristics of the devices could be modified by the thin film of metal complex, with the best photosensing properties being obtained for the heterojunction based on compound 1.