Modulation of the fluorescent properties of rhodamine 6G by Zn²⁺-doped PVDF films

The photophysical properties of rhodamine 6G (Rh6G) deposited on the surface of Zn²⁺-doped polyvinylidene difluoride (PVDF) are reported. The zinc ion induces an increased amount of the ferroelectric β-phase in the PVDF. The doping suppresses aggregation of the Rh6G, even for the thickest films, as indicated by the lack the low energy signature in the absorption spectra. This effect has not been previously observed. The absorption spectra also show an unusual increase in intensity as the amount of Zn²⁺ is increased in the substrate while the Rh6G thickness is kept constant. The excitation spectra match the absorption spectra. As the Zn²⁺ ion concentration increases in the PVDF the emission spectra maxima shift to lower energy and the intensity of the emission increases. The excited states are assigned to monomers, excimers, and excitons. The coupling between the dimeric species is modulated by the electric field created by the ionic dopant and the ferroelectric phase.