Luminescence Properties and Energy Transfer of Eu 3+ , Bi 3+ Co-Doped LuVO 4 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 LuVO :Eu , Bi 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. % Eu and different concentrations of Bi (0.5, 1.0, and 1.5 at. %); all the samples emit in red, and it has been observed that the light yield of Eu is enhanced as the Bi content increases when the films are excited at 350 nm, which corresponds to the S → P transition of Bi . Therefore, a highly efficient energy transfer mechanism between Bi and Eu has been observed, reaching up to 71%. Finally, it was established that this energy transfer process occurs via a quadrupole-quadrupole interaction.