Modulating upconversion luminescence through fluorescent dyes
In our work, we report an effective method to tune the upconversion emission of NaGdF{sub 4}:Yb{sup 3+},Er{sup 3+}@NaYF{sub 4} core/shell nanoparticles. The shell thickness-dependent upconversion luminescence of NaGdF{sub 4}:Yb{sup 3+},Er{sup 3+}@NaYF{sub 4} core/shell and the dye Rhodamine-B(RhB) composite were discussed in detail. It is found that the fluorescent dye RhB can remarkably improve the violet emission of the upconversion nanoparticles (UCNPs) and simultaneously generating the 605 nm yellow emission through energy transfer. Importantly, it is revealed that the effective energy transfer distance between upconversion nanoparticles and RhB is shorter than 18 nm in the media of NaYF{sub 4}. These results open a novel way for determining the energy transfer distance between the upconversion nanoparticles and the dyes and simultaneously tuning the emission brightness and the spectrum covering range of the upconversion nanoparticles for meeting the requirement in the application fields of light source, colorful display, biological imaging, and fluorescent probes. - Graphical abstract: TEM images of core/shell upconversion nanoparticles and the illustration of Energy transfer distance UCNPs and Rhodamine-B molecular. Display Omitted - Highlights: • The upconversion nanoparticles with controlled surface morphology and shell thickness were prepared by thermal decomposition method. The emission brightness and the spectrum covering range of the upconversion nanoparticles can be tuned. • The fluorescent dye RhB can remarkably improve the violet emission of the upconversion nanoparticles and simultaneously generating the 605 nm yellow emission through energy transfer. • It is the first reported that the effective energy transfer distance between upconversion nanoparticles and RhB is shorter than 18 nm in the media of NaYF{sub 4}.