Luminescence Properties and Energy Transfer of Eu3+, Bi3+ Co-Doped LuVO4 Films Modified with Pluronic F-127 Obtained by Sol–Gel

Nowadays, orthovanadates are studied because of their unique properties for optoelectronic applications. In this work, the LuVO4:Eu3+, Bi3+ films were prepared by the sol–gel method, using a new simple route, and deposited by the dip-coating technique. The obtained films are transparent, fracture-free, and homogenous. The sol–gel process was monitored by Fourier-transform infrared spectroscopy (FTIR), and according to X-ray diffraction (XRD) results, the crystal structure was tetragonal, and films that were highly oriented along the (200) low-energy direction were obtained. The morphological studies by scanning electron microscopy (SEM) showed uniformly distributed circular agglomerations of rice-like particles with nanometric sizes. The luminescence properties of the films were analyzed using a fixed concentration of 2.5 at. % Eu3+ and different concentrations of Bi3+ (0.5, 1.0, and 1.5 at. %); all the samples emit in red, and it has been observed that the light yield of Eu3+ is enhanced as the Bi3+ content increases when the films are excited at 350 nm, which corresponds to the 1S0→3P1 transition of Bi3+. Therefore, a highly efficient energy transfer mechanism between Bi3+ and Eu3+ has been observed, reaching up to 71%. Finally, it was established that this energy transfer process occurs via a quadrupole–quadrupole interaction.