Size and morphology controllable synthesis of oil-dispersible LaF3:Yb,Er upconversion fluorescent nanocrystals via a solid–liquid two-phase approach

Oil-dispersible Yb–Er co-doped LaF3 upconversion (UC) fluorescent nanocrystals (NCs) were synthesized via a liquid–solid two-phase approach. The nucleation and growth of the NCs only occurred in the interface of the two phases, which made the process very slow, and thus well-crystallized and regular-shaped LaF3:Yb,Er NCs were obtained. The size, morphology and UC fluorescence of the NCs can be controlled by varying the solvent, temperature and reaction time.