Photoluminescence properties and energy transfer of high thermal stable Na2GdPO4F2:RE (RE = Sm3+, Ce3+, Tb3+) phosphor for solid-state lighting

In this paper, a series of Na2GdPO4F2:Sm3+/Ce3+/Tb3+ phosphors had been synthesized via solid-state reactions and the luminescence properties of the phosphors had been investigated in detail. The Sm3+ ions in the host exhibited intense red emission under 402 nm irradiation and the mechanism for energy migration among Sm3+ ions was determined to be electronic dipole-dipole (d-d) interaction. For Ce3+ and Tb3+ codoped phosphors, the Ce3+→Tb3+ energy transfer took place, making the phosphor has intense green emission at 320 nm excitation. The mechanism for Ce3+→Tb3+ energy transfer had been verified as electronic dipole-quadrupole (d-q) interaction through the luminescence analysis using I–H model. The Na2GdPO4F2:Sm3+ and Na2GdPO4F2:Ce3+,Tb3+ phosphors both possessed pretty good thermal stability, and by coating them on the UV chips, red and green LED devices had been obtained, respectively. Moreover, utilizing the Tb3+ ions as bridges, Ce3+→Tb3+→Sm3+ energy transfer had been observed in NGPF:Ce3+,Tb3+,Sm3+ phosphor. The investigation results on the property of as-prepared samples indicated that Na2GdPO4F2 is a good host for rare earth ion doping and the Na2GdPO4F2:Sm3+ and Na2GdPO4F2:Ce3+,Tb3+ might be potential UV excited red and green phosphors for UV-WLEDs.