Luminescent self-assembled thin films based on rare earth-heteropolytungstate

Rare earth (Eu³⁺, Dy³⁺)-heteropolytungstate thin films were fabricated by self-assembly method successfully. The thin films give off strong fluorescence, which can be observed by eyes upon UV irradiation. The characteristic emission behaviors of the rare earth ions in self-assembled thin film were investigated compared with those of the corresponding solids. It is noticed that the intensity ratio between ⁵D₀→⁷F₂ and ⁵D₀→⁷F₁ of Eu³⁺ and the intensity ratio between ⁴F_9/2→⁶H_13/2 and ⁴F_9/2→⁶H_15/2 of Dy³⁺ in the self-assembled films are different from those of the corresponding solids. Furthermore, the self-assembled films present shorter fluorescence lifetimes than the corresponding solids. The reasons for these results have been discussed.