Local structural engineering is an endogenous approach to modulate upconversion luminescence (UCL) from upstream to meet the needs of specific application scenarios. Herein, high pressure is utilized as a means to modulate the local structure, and the designed LiErF₄:0.5%Tm³⁺@LiYF₄ (Er:Tm@Y) nanoparticles with fast energy transfer rates, abundant cross-relaxation processes, and multiple near-infrared wavelengths (808, 980, 1530 nm) excitation properties are tailored as local structure-sensitive hosts. A unique excitation wavelength-dependent UCL enhancement of Er:Tm@Y upconversion nanoparticles is observed by pressure-induced local structure distortions. When the pressure of 6 GPa is applied, the UCL is enhanced by a factor of 2.6 at 980 nm excitation only. After pressure release, the luminescence diminishes and recovers. Density functional theory calculations show that the symmetry distortion of the LiErF4 crystal reaches a maximum at pressurization to 6 GPa, while a new Er-4f state emerges, greatly reducing the bandgap from 8.3 to 5.7 eV. Comparative experiments demonstrate that the local symmetry distortion caused by 0.5%Tm³⁺ doping and the different energy transfer patterns of Er³⁺ to Tm³⁺ at different excitations are responsible for this wavelength-dependent luminescence enhancement.

原文链接：https://doi.org/10.1002/adom.202202884