A series of novel red-emitting Sm³⁺-doped phosphors were synthesized by a conventional solid state reaction. The crystal structure and atomic coordinates of was characterized by Rietveld refinement. Luminesce properties of as-synthesized Sm³⁺-doped phosphors are carried out by PL/PLE, decay life time, thermal quenching as well as reflectance spectrometer and LED fabrications. The results indicate that composition-optimized phosphor exhibits orange-red emission peaks located on 564, 601, 608 and 648 nm attributed to the transitions of ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 →⁶H_7/2

and ⁴G^5/2 → ⁶H_9/2, respectively. The results of LED fabrication by combing 380 chip and blue/green phosphors are demonstrated in this study. Finally, from viewpoint of theoretical calculations, band structure and density of state for host and Sm³⁺-doped phosphor are studied by first principles calculations. All the results indicate that our phosphors could be a potential material for white light-emitting diodes.

FIG. 1 (a) Electroluminescence spectrum of BaMgAl₁₀O₁₇:Eu²⁺, Ba₂SiO₄:Eu²⁺ and as-synthesized red phosphor with 380 chip. Inset: photo image of LED device derived at 20 mA; (b) CIE coordinates of red phosphor excited at 365 nm. Inset: red phosphor image in UV box under 365 nm excitation.

References

[1] Irish Valerie B. Maggay, Kai-Yuan Yeh, Bingfu Lei, Mikhail G. Brik, Michal Piasecki and Wei-Ren Liu,* “Luminescence properties of Eu²⁺ - activated NaCaBeSi₂O₆F for white light-emitting diode applications,” Mater. Res. Bull., 100, 26-31 (2018).

[2]Chun-Ting Chen, Maxim S. Molokeev, Tzu-Jen Lin and ± “Synthesis, luminescent properties and theoretical calculations of a novel orange-red-emitting Ca₂Y₈(SiO₄)₆O₂:Sm³⁺ phosphors for white light-emitting diodes applications,” Dyes and Pigments, 150, 121-129 (2018).

[3] Jy-Chern Chang, Haikun Liu, Pin-Chun Lin, Libing Liao and Wei-Ren Liu,* “Intense broad-band absorption and efficient blue-emitting SrCa₂MgSi₂O₈:Eu²⁺ phosphor for high color-rendering white LED Applications,” J. Alloy and Compds., in press.