Controlled Synthesis of Water-Soluble NaYF4:Yb3+, Er3+ Nanoparticles with Surfactant Dependent Properties

Abstract EN

Water-soluble NaYF4:Yb3+, Er3+ nanoparticles (NPs) are successfully prepared by a solvothermal reaction using branched polyethylenimine (PEI) with different chain lengths as the surfactants in a water/diethylene glycol (DEG) mixed solution.

It is shown that the size of NaYF4 NPs prepared with high molecular weight PEI (HPEI) is smaller than that of the NPs prepared with low molecular weight (LPEI), while small-sized NPs exhibit more intense upconversion luminescence intensities than large-sized NPs in the same excitation power of 980 nm.

It is found that HPEI is conducive to the formation of smaller NP with high crystallinity.

Small-sized NaYF4:Yb3+, Er3+ NPs with intense upconversion luminescence and improved crystallinity were related to their growth process.

A possible growth mechanism of the samples is proposed.

The results of this study can provide new insights into the controlled synthesis of novel NPs.