Encaged-anion tunable luminescence of Ce³⁺-activated single host Ca₁₂Al₁₄O₃₂Cl₂ phosphor for UV pumped multi-color LEDs

A novel tunable-light-emitting single-host Ca₁₂Al₁₄O₃₂Cl₂:0.5%Ce³⁺ phosphor has been prepared in H₂ atmosphere by a solid-state reaction method. Upon 340 nm excitation, the phosphor shows an asymmetric broadband emission centered at 503 nm, assigned to the 5d-4f transitions of Ce³⁺. For Ce³⁺ doped Ca₁₂Al₁₄O₃₂Cl₂, a large red-shift (~69 nm) and an increased full width at half maximum from 66 to 115 nm can be observed in comparison with that of the Ce³⁺ doped Ca₁₂Al₁₄O₃₃ sample. In particular, the emission color of the Ca₁₂Al₁₄O₃₂Cl₂:0.5%Ce³⁺ phosphor can be tuned from blue to yellow by controlling anions in the nanocages, causing the different lattice deformations. Moreover, the CIE coordinates of the Ca₁₂Al₁₄O₃₂Cl₂:0.5%Ce³⁺ phosphor move from yellow to blue as the heating temperature increases from 293 to 623 K. Our results suggest that the encaged-anion modulation in combination with the heating is an effective strategy for realizing highly color tunable emission of Ce³⁺ doped in a single host, and furthermore, for designing novel phosphors for UV pumped multi-color LEDs and related devices.