Intense Ultraviolet Upconversion Luminescence from Sub-۱۰ nm SrF۲: ۲۰%Yb, ۰.۵% Tm Nanoparticles by Codoping with Bi³+ ions

Lanthanide-based upconverting nanoparticles (UCNPs) manifest marvelous privileges for bioimaging, photodynamic therapy and security technologies. However, they have not received broad approval due to their restrictively low efficiencies. Not very effective ۴f-۴f electronic transitions is a serious obstacle for both photon absorption strength and emission in UCNPs. Herein, an enhancement in the ultraviolet upconversion luminescence was realized in Yb,Tm-doped SrF۲ upconverting nanoparticles based on local structure distortion via the introduction of Bi³+ dopants. In this research, very small SrF۲: ۲۰%Yb, ۰.۵%Tm NPs were prosperously synthesized through a hydrothermal method. The UV upconversion luminescence enhancement in SrF۲: ۲۰% Yb, ۰.۵% Tm, x% Bi NPs was thoroughly studied. It was found that emission especially in the UV-blue range was conspicuously enhanced compared to the Bi³+-free sample. This improvement is mainly attributed to the new structural geometry in which luminescent centers are located. The results indicate that very small UCNPs with enhanced UV emission may have future prospects in biomedical fields, photocatalysis and anticounterfeiting.

کلیدواژه ها:

Upconversion nanoparticles ، Bi³+ dopants ، Lanthanides ، Synthesis ، Emission enhancement