Emission color tuning through manipulating the energy transfer from VO₄^3- to Eu³⁺ in single-phased LuVO₄ : Eu³⁺ phosphors

Recently, rare earth (RE) ion doped single-phased phosphors, which can emit tunable colors upon single wavelength excitation, have received a great deal of attention, but most of them involve multiple dopants as luminescence centers. This work reports on single-phased LuVO₄:Eu³⁺ phosphors with tunable emission colors upon a single wavelength excitation while using Eu³⁺ as a single dopant ion. The tunable emission is realized through precisely manipulating the energy transfer efficiency from VO₄^3- to Eu³⁺ by controlling the Eu³⁺ doping content, which allows modulating the photoemission intensity ratio between VO₄^3- and Eu³⁺ upon excitation at 265 nm and therefore color tuning from blue (0.2204, 0.2194) to red (0.6703, 0.2986). Time-resolved photoluminescence (PL) spectroscopy measurements reveal that the energy transfer process occurs 4 μs after the excitation and becomes dominant 10 μs later with the disappearance of the VO₄^3- emission. The temperature-dependent PL spectra show that the energy transfer can be accelerated as the temperature increases, and it leads to abnormal enhancement of the Eu³⁺ emission at the earlier state. A similar scenario is not observed upon exciting the phosphors at the intrinsic absorption of Eu³⁺, which implies that the reversible energy transfer from Eu³⁺ to VO₄^3- is impossible. Our results demonstrate a feasible strategy for tuning the emission color of single-phased phosphors through controlling the energy transfer process from the host to the dopant, and it opens up new possibilities for designing tunable luminescent materials for future optoelectronics applications.