Color tuning via energy transfer in Sr3In(PO4)3:Ce3+/Tb3+/Mn2+ phosphors

Abstract

Sr₃In(PO₄)₃ (SIP):Ce³⁺/Tb³⁺/Mn²⁺ phosphors have been prepared via a solid state reaction process. Under UV excitation, there are three energy transfer (ET) pairs in the SIP host, i.e., Ce³⁺ → Tb³⁺, Ce³⁺ → Mn²⁺, and Tb³⁺ → Mn²⁺. Both of the ETs from Ce³⁺ to Tb³⁺ and from Ce³⁺ to Mn²⁺ in the SIP host have been demonstrated to be resonant type via a dipole–quadrupole mechanism, and the critical distance (R_C) calculated by the quenching concentration method and spectral overlap method, respectively, were investigated. By the ET of Ce³⁺ → Tb³⁺, Ce³⁺ → Mn²⁺, and Tb³⁺ → Mn²⁺ the emitting colors of the studied samples could be adjusted from blue to green, from blue to orange-red, and from green to green-yellow, respectively. More importantly, under low-voltage electron beam excitation, the CL spectra of the SIP:Ce³⁺, Mn²⁺ samples cover the whole visible light region, resulting in a white light emission. Additionally, the CL properties of SIP:Ce³⁺/Tb³⁺/Mn²⁺ phosphors have been investigated in detail. The results reveal that the as-prepared phosphors have good CL intensity and CIE coordinate stability under electron beam bombardment. Compared with the commercial green phosphor ZnO:Zn, SIP:7% Ce³⁺, the 10% Tb³⁺ sample has a higher CL brightness. In conclusion, tunable light with high quantum yield (68%) has been obtained in SIP:Ce³⁺/Tb³⁺/Mn²⁺ phosphors by utilizing the principle of energy transfer and properly selecting the activator contents under UV and electron beam excitation.