Enhancement of white light emission of Dy³⁺:CaTiO₃ phosphor by Li⁺ co-doping

Abstract

A series of white-emitting CaTiO₃:Dy³⁺ and CaTiO₃:Dy³⁺, Li⁺ phosphors for light-emitting diode applications were prepared by conventional solid-state reactions. The phase of the as-prepared powders were measured by X-ray diffraction pattern. The emission and excitation spectra as well as the luminescence decays were investigated. The excited spectra indicated that they have intense excitation at 353 (⁶H1_5/2–⁶P_7/2), 366 (⁶H_15/2–⁴P_5/2), 388 (⁶H_15/2–⁴I_13/2) and 450 nm (⁶H_15/2–⁴I₁₅₂). Meanwhile, the emission of Dy³⁺ ions upon 353 nm excitation was observed at 480 nm (blue) due to the ⁴F_9/2–⁶H_15/2 transitions, 573 nm (yellow) due to ⁴F_9/2–⁶H_13/2 transitions and a weak 665 nm (red) due to ⁴F_9/2–⁶H_11/2 emissions, respectively. As a charge compensator, Li⁺ ions were incorporated into CaTiO₃:Dy³⁺, which enhanced the PL intensities depending on the doping concentration of Li⁺. Moreover, the chromaticity coordinates of CaTiO₃:Dy³⁺ and CaTiO₃:Dy³⁺, Li⁺ were very close to the ideal white light coordinates (0.33, 0.33). All the results demonstrated that CaTiO₃:Dy³⁺ and CaTiO₃:Dy³⁺, Li⁺ might be potential phosphors for NUV-based white light-emitting diodes.