A facile synthesis and photoluminescence properties of water-dispersible Re3+ doped CeF3nanocrystals and solid nanocomposites with polymers

Abstract

Water-dispersible Re³⁺ doped CeF₃ colloidal nanocrystals with well controllable morphology and high crystallinity have been successfully synthesized through a solvothermal process. The TEM images illustrate that the Re³⁺ doped CeF₃ nanocrystals are rectangular (or cubic) with a mean diameter of ∼10 nm. The excellent dispersibility in some of the polar solvents including water is achieved by using polyethyleneimine as the capping agent. The amine groups of the polymer chains on one hand bind to the nanocrystal surface; on the other hand the free ones could link to functional materials including bio-molecules. The CeF₃ nanocrystals doped with Tb³⁺ and Dy³⁺ ions show the characteristic emission of Tb^{3+ 5}D₄–⁷F_J (J = 6–3, with ⁵D₄–⁷F₅ green emission at 542 nm as the strongest one) and Dy^{3+ 4}F_9/2–⁶H_15/2 (blue-green color at 478 nm) and ⁴F_9/2–⁶H_13/2 (yellow color at 571 nm) transitions, respectively. The energy transfer from Ce³⁺ to Tb³⁺ and Dy³⁺ was also investigated in detail. In vitro studies of Re³⁺ doped CeF₃ colloidal nanocrystals on HepG2 cells confirm their excellent biological compatibility. The obtained solid CeF₃ : Tb³⁺/PDMS nanocomposites are very stable and flexible and exhibit strong green photoluminescence upon UV excitation.