Thin films of cyclotriphosphazenes containing 1,3,4-oxadiazoles as fluorophores

In this work, hexa-substituted cyclotriphosphazenes bearing 1,3,4-oxadiazole groups as fluorophores were employed in the formation of thin films. The cyclotriphosphazenes compounds as well as the films exhibited photoluminescence with emission in the UV-blue region. Fluorescence quantum yields of cyclotriphosphazenes range between 0.04 and 0.10. The bandgap of cyclotriphosphazenes was 4 eV showing properties of wide bandgap semiconductors. The morphological characterization of the films by SEM and AFM showed homogeneous surfaces without defects. The optical properties of cyclotriphosphazenes are different when they are in solution and thin films because of favorable binding supramolecular interactions. In thin films, the supramolecular interaction enhances the optical properties of these materials.