Negative thermal expansion effects boosting NIR-II luminescence in Yb2W3O12:Nd3+ film with silica shell

Abstract

Lanthanide ions doped near-infrared II(NIR-II) emitting luminescent materials have attracted widespread attention in temperature sensing and biological imaging. However, the NIR-II luminescence of crystals doped with lanthanide ions still faces the problem of fluorescence Thermal quenching (TQ). Negative thermal expansion (NTE) materials exhibit lattice contraction, leading to enhanced energy transfer between lanthanide ions and achieving thermal enhancement at high temperatures. Herein, the NTE Yb₂W₃O₁₂: Nd³⁺ films were prepared by sol-gel method. The thermal enhancement of Nd³⁺ doping Yb₂W₃O₁₂:Nd³⁺ NTE films under 808 nm excitation due to the lattice contraction of Yb₂W₃O₁₂, which leads to an increase in energy transfer from Nd³⁺ to Yb³⁺ ions, achieving 4.00 fold enhancement at 573 K. The Yb₂W₃O₁₂:Nd³⁺ film with SiO₂ shell to investigate the effect of hygroscopicity. The SiO₂ coating effectively suppressed the moisture absorption of Yb₂W₃O₁₂:Nd³⁺ film, maintaining absolute emission intensity of 15.00 fold at 573 K compared to room temperature. This work not only provides a feasible strategy for designing efficient and heat-resistant NIR-II luminescent materials, but also an effective new method for suppressing the moisture absorption of NTE materials.