Tuning of Bi³⁺-related photoemission in the Sc₂O₃: Bi³⁺ phosphor

In this work, we report a kind of UV converted single-phased tunable Sc₂O₃:Bi³⁺ phosphor, which enables generating the color tuning from blue to green upon excitation at the wavelength range of 245–380 nm. The photoluminescence (PL) spectra reveal that the tunable colors are due to regular modulation of the photoemission intensity between three Bi³⁺-related luminescence centers (i.e., ~ 356 nm for Bi1, ~ 407 nm for Bi2, and ~ 489 nm for Bi3), leading to the color tuning forth and back between blue and green. Together with the structural analysis, our spectral results indicate that the three Bi³⁺-related centers come from three different Sc³⁺ sites and, more importantly, two of them [i.e., Bi3 and Bi2], which locate respectively at the same Sc³⁺ sites of the crystal lattice with the point symmetry C₂ and C_3i, feature controllable yet inefficiency energy transfer behavior. A possible mechanistic scheme, which bases on the PL observations, is constructed to illustrate the Bi³⁺-related color tuning more clearly.