Tricolor- and White Light–Emitting Ce3+/Tb3+/Mn2+-Coactivated Li2Ca4Si4O13 Phosphor via Energy Transfer

摘要

Single-component tunable Li2Ca4Si4O13:Ce³⁺,Tb³⁺,Mn²⁺ phosphors were successfully synthesized at 950 °C. Li2Ca4Si4O13:Ce³⁺,Tb³⁺ exhibits two luminescence peaking at 430 and 550 nm, which originated from the allowed 5d → 4f transition of the Ce³⁺ ion and the ⁵D4 → ⁷FJ (J = 6, 5, 4, 3) transition of the Tb³⁺ ion, respectively. Moreover, by codoping Ce³⁺ ions in the Li2Ca4Si4O13:Mn²⁺ system, yellow-red emission from the forbidden transition of Mn²⁺ could be enhanced. Under UV excitation, dual energy transfers (ETs), namely, Ce³⁺ → Mn²⁺ and Ce³⁺ → Tb³⁺, are present in the Li2Ca4Si₄O₁₃:Ce³⁺,Tb³⁺,Mn²⁺ system. The ET process was confirmed by the overlap of the excitation spectra, variations in the emission spectra, ET efficiency, and decay times of phosphors. In addition, quantum yields and CIE chromatic coordinates are presented. The emission color of these phosphors can be tuned precisely from blue to green via ET of Ce³⁺ → Tb³⁺ and from blue to yellow via ET of Ce³⁺ → Mn²⁺. White light can also be achieved upon excitation of UV light by properly tuning the relative composition of Tb³⁺/Mn²⁺. This result indicates that the developed phosphor may be regarded as a good tunable emitting phosphor for UV light-emitting diodes.