Suppression of inner energy dissipation in Yb-doped NaErF4 upconversion nanocrystals through an energy cycling strategy

Suppression of the inner energy dissipation, related to the lattice phonons and inner defects, in lanthanide doped upconversion luminescent materials remains a formidable challenge. Herein, we reveal an energy cycling strategy capable of suppressing the inner energy dissipation in lanthanide doped upconversion nanocrystals. Yb 3+ ions were introduced in Er 3+ heavily doped nanocrystals as an energy reservoir to compete with the inner energy dissipation. The detailed energy cycling processes between Er 3+ activator and Yb 3+ reservoir, responsible for the enhancement of Er 3+ upconversion intensity, are proposed and further verified on the basis of spectral observations. The energy cycling strategy, with unique merits like facile and cost-effective preparation as well as broad scope of application, is highly valuable in lanthanide luminescent nanomaterials. The energy cycling strategy can suppress the inner energy dissipation of upconversion nanocrystals and improve the luminescence intensity.