Controlled synthesis and luminescence of lanthanide doped NaYF4 nanocrystals

A range of nearly monodispersed NaYF4 single-crystal nanorods, hexagonal nanoplates, and nanoparticles have been successfully prepared via a facile wet chemical technology. Varying the dopants leads to different luminescence. These as-prepared nanocrystals not only present novel room-temperature downconversion (DC) and upconversion (UC) fluorescence but can also be transparently dispersed in cyclohexane. The effects of reaction temperature and time, doped ion concentration, ratio of NaF to Ln(NO3)(3), and the reactant content on the shape, size, and crystal phase purity of the as-prepared nanocrystals have been investigated in detail. The fluorescence photos, spectra, luminescence mechanism, and the formation mechanism of the nanorods have also been demonstrated. For the next biolabel applications, the colloidal nanoparticles dispersed in cyclohexane have also been transferred into water by surface silane modification. For their unique DC and UC luminescence and high processability, these nanocrystals will open new avenues in biolabels, light-emitting diodes (LEDs), color displays, anti-counterfeiting, and solid-state lasers.