A novel strategy to enhance the luminescence performance of NaGdF4:Ln(3+) nanocrystals.

Promoting excitation efficiency is a direct route to enhance the luminescence properties of lanthanide doped materials. Here, we describe a novel strategy to enhance the luminescence performance of NaGdF4:Ln(3+) (Ln = Tb, Eu, Dy) nanoparticles by surface modification with benzoate (BA) and 1,10-phenanthroline (Phen) ligands via the sensitization of surface dopants. It was found that the surface ligands provide a new path for energy transfer to the activators due to the matching in energy levels between the two. Moreover, the overlap in excitation peaks for both Gd(3+) ions and ligands ensures the simultaneous energy transfer of Gd(3+)→ Ln(3+) and ligands → Ln(3+) under a single wavelength excitation. The obtained NaGdF4 nanocomposite was characterized in detail using XRD, FT-IR, TGA, SEM, and EDS. The luminescence performance of the surface modified NaGdF4:Ln(3+) nanoparticles was also optimized by tuning the loading amount of modified ligands. In addition, luminescence thermometry was realized by monitoring emission intensity at different temperatures.