Tunable Emission of a Samarium Macrocyclic Complex in Poly(vinylidene difluoride)/Poly(methyl Methacrylate) Thin Films with Controlled Microstructure

Transparent and flexible thin films were obtained from poly(vinylidene difluoride)/poly(methyl methacrylate) (PVDF/PMMA) blends in the electroactive β and γ phases doped with a Schiff base macrocyclic Samarium(III) complex, Sm L, and were investigated for the potential use in optoelectronics. Sm L has a double emission in either solution or as a powder, pointing to an incomplete energy transfer from the ligand to the Sm(III) center. The microstructure of the PVDF/PMMA blends and their interaction with Sm L were investigated by infrared spectroscopy, X-ray diffraction, and electronic and optical microscopy. The photophysical properties of Sm L in the composite films were studied by steady-state and time-resolved fluorescence measurements. The emission lines specific to Sm(III) centers were absent in the PVDF/PMMA blends. The molecular fluorescence was highly tunable by varying the Sm L concentration, the PMMA content, and the excitation wavelength. The biexponential fluorescence decay of Sm L in powder form was observed only in the PVDF-rich blends and became a triexponential law for intermediate PVDF/PMMA compositions. Our results show that, on the basis of the fluorescence lifetime distribution and the emission wavelength variability, the macrocyclic Samarium(III) complex has great potential as a fluorescent probe in discriminating the microdomains in the blends.