A general synthesis method for small-size and water-soluble NaYF4:Yb, Ln upconversion nanoparticles at high temperature

In this work, we have developed a general synthesis method for the small size (<50 nm) and water-soluble lanthanide ions doped NaYF 4 upconversion nanoparticles using triethylene glycol as a higher temperature solvent and diacid as surfactant.