Spectroscopic characterization of UV-C and NIR emitting Tm³⁺/Pr³⁺ co-doped β-NaYF₄

Lanthanide-doped materials exhibit remarkable optical properties due to their robust multi-energy level structures, enabling various photon conversion processes such as Stokes photoluminescence (PL), quantum cutting (QC), and upconversion (UC). Among these, the simultaneous co-doping of Tm³⁺ and Pr³⁺ ions into β-NaYF₄ microcrystalline matrices has emerged as a promising strategy for achieving enhanced emissions in UV and NIR spectral regions. In this study, Tm³⁺/Pr³⁺ co-doped β-NaYF₄ microcrystalline powders were synthesized via solid-state method to take the advantage of the low phonon energy of the host matrix and avoid UV absorption losses. Energy transfer between Tm³⁺ and Pr³⁺ ions was analyzed through emission spectra and luminescence decay studies under varying laser power densities. Upon blue 466 nm pulsed laser excitation, which aligns with optical transitions in both Tm³⁺ and Pr³⁺ ions, the co-doped powders demonstrated the concurrent UV UC emission and NIR downshifting with significantly enhanced intensity compared to singly doped counterparts.