Sandwich Nanoparticles Mediated by Ytterbium Sublattice for Advanced Photonic Applications

Upconversion nanoparticles (UCNPs) have been widely applied in temperature sensing and information security due to their temperature sensing capability and excellent optical properties. However, conventional thermometers based on thermally coupled energy levels have limited sensitivity and a narrow temperature detection range, which is insufficient for high-precision thermal measurements. To address this issue, we propose a sandwich-structured nanoparticle system mediated by a ytterbium sublattice, NaYF₄:10%Gd@NaYF₄:20%Yb, 2%Ho@NaYbF₄. This design can effectively excite emissions from nonthermally coupled energy levels over a wide temperature range (100-400 K), achieving a high relative sensitivity of up to 10.3% K^-1. Moreover, it supports the integration of applications such as noncontact temperature sensing and multilevel optical information encryption, demonstrating great potential for advanced photonic applications.