Investigation of Pr3+ as a sensitizer in quantum-cutting fluoride phosphors

A quantum-cutting (QC) phosphor K2GdF5:Eu3+ shows poor optical absorption and a theoretical quantum efficiency (QE) of 107% in the ultraviolet (UV) and vacuum ultraviolet (VUV) excitation spectral ranges. Pr3+ was codoped as a sensitizer in K2GdF5:Eu3+, thus increasing the absorption in the UV and VUV spectral regions; the theoretical QE of K2GdF5:Eu3+,Pr3+ was increased to 138%. The spectra indicate that the possible mechanisms of QC and energy transfer differ from those of phosphors containing the Gd3+–Eu3+ couple. Temporally resolved measurements of fluorescence decay confirm the proposed QC mechanism for the phosphor containing the Gd3+–Eu3+,Pr3+ system.