Unraveling the Excited-State Dynamics of Er 3+ in LiErF 4 -Based Upconversion Nanoparticles

作者：Shuo Zhang, Xiaoke Hu, Ping Huang, Xiaoying Shang, Yang Dengfeng, Zhiqing Shao, Xiaoyue Wang, Wei Zheng, Xueyuan Chen · 发表于：Nano Letters · 年份：2025 · DOI：10.1021/acs.nanolett.5c00884 · 被引用次数：30 · 研究领域：Luminescence Properties of Advanced Materials、Radiation Detection and Scintillator Technologies、Glass properties and applications

Lanthanide (Ln 3+ )-enriched upconversion nanoparticles (UCNPs) with high dopant concentrations have garnered significant attention due to their unique optical properties. However, their practical applications are hindered by the deleterious concentration quenching effect. Herein, through kinetic modeling of Er 3+ excited-state dynamics employing energy diffusion theories, we demonstrate that concentration quenching in LiErF 4 UCNPs predominantly originates from long-range energy migration through the 4 I 13/2 level toward surface and lattice defects, rather than the conventionally attributed cross-relaxation mechanism. Such migration-mediated energy dissipation can be effectively suppressed by the synergistic engineering strategies combining surface passivation, spatial confinement via a sandwiched LiYF 4 @LiErF 4 @LiYF 4 core–shell–shell architecture to restrict Er 3+ migration, and incorporation of Tm 3+ as energy trapping centers, boosting upconversion quantum yield from <0.01% to 2.29% (980 nm@70 W cm –2 ). The established mechanistic framework and material design principles provide critical insights for engineering heavily doped UCNPs, particularly advancing their application potential in single-particle spectroscopy and optoelectronic nanodevices.