Manipulating the Injected Energy Flux via Host-Sensitized Nanostructure for Improving Multiphoton Upconversion Luminescence of Tm³.

Abstract

Combating the concentration quenching effect by increasing the concentration of sensitized rare-earth ions in rational design upconversion nanostructure will make it easier to utilize injection energy flux and transfer it to emitters, resulting in improved upconversion luminescence (UCL). We proposed a host-sensitized nanostructure (active core@luminescent shell@inert shell) to improve multiphoton UCL of Tm³⁺ based on the LiLnF₄ host. Yb³⁺ ions were isolated in the core as energy absorbents, and Tm³⁺ was doped in the interior LiYbF₄ host shell. Compared with sandwich structured nanocrystals (Y@Y:Yb/Tm@Y), reverse structure (YbTm@Yb@Y), and fully doped structure (YbTm@YbTm@Y), the proposed structure achieved the highest efficiency of multiphoton UCL and favored a better FRET-based application performance as the Tm³⁺ located at an optimized spatial distribution. Furthermore, steady-state and dynamic analysis results demonstrate that by manipulating the spatial distribution of the active ions, excited energy can be tuned to enable multiphoton upconversion enhancement, overcoming the conventional limitations.