Tuning the Energy Transfer Efficiency between Ce3+and Ln3+Ions (Ln=Tm, Sm, Tb, Dy) by Controlling the Crystal Phase of NaYF4Nanocrystals

Ligand-Sensitised LaF3 :Eu3+ and SrF2 :Eu3+ Nanoparticles and in Vitro Haemocompatiblity Studies

Luminescent Ln³⁺ -doped nanoparticles (NPs) functionalised with the desired organic ligand molecules for haemocompatibility studies were obtained in a one-pot synthesis. Chelated aromatic organic ligands such as isophthalic acid, terephthalic acid, ibuprofen, aspirin, 1,2,4,5-benzenetetracarboxylic acid, 2,6-pyridine dicarboxylic acid and adenosine were applied for surface functionalisation. The modification of the nanoparticles is based on the donor-acceptor character of the ligand-nanoparticle system, which is an alternative to covalent functionalisation by peptide bonding as presented in our recent report. The aromatic groups of selected ligands absorb UV light and transfer their excited-state energy to the dopant Eu³⁺ ions in LaF₃ and SrF₂ NPs. Herein, we discuss the structural and spectroscopic characterisation of the NPs and the results of haemocompatibility studies. Flow cytometry analysis of the nanoparticles' membrane-binding is also presented.

Novel sol–gel fabrication of Yb3+/Tm3+ co-doped β-NaYF4 thin films and investigation of their upconversion properties

An innovative sol–gel process, using a mixture of Na(hfa)·tetraglyme and RE(hfa)₃·diglyme (RE = Y, Yb, Tm) complexes, has been optimized to produce upconverting β-NaYF₄:Yb³⁺/Tm³⁺ thin films.

Ce3+ -Sensitized Tm3+ /Mn2+ -Doped NaYF4 Colloidal Nanocrystals: Intense Cool White Light from a Phosphor-Coated UV LED

Colloidal NaYF₄ :Ce³⁺ /Tm³⁺ /Mn²⁺ nanocrystals found to be an efficient single component phosphor to produce intense white light. The use of Mn²⁺ ions instead of green- and red-emitting Ln³⁺ ions is interesting as the later are expensive and less abundant. The single band blue emission of Tm³⁺ ions was combined with the broadband green-yellow emission of Mn²⁺ ions to produce strong white light emission using Ce³⁺ ions as excitation source. Interestingly, there is hardly any re-absorption of the blue emission by Mn²⁺ ions and the spectrum matches the commercial Ce³⁺ -doped yttrium aluminium garnet (YAG) phosphor coated over a blue LED. In addition, we have successfully incorporated the colloidal nanocrystals into a polymer matrix to make a nanocomposite as well as transparent films without altering the optical properties of the nanocrystals. The colloidal nanocomposite was coated over a UV LED to fabricate white LEDs. Finally, when the concentration of the dopant (Mn²⁺ ) ions was tuned the correlated color temperature (CCT) values varied between cool white light and daylight region.