Tailoring the Luminescent Properties of SrS:Ce 3+ by Sr-Deficiency and Na + Doping.

Ce 3+ -doped SrS phosphors with a charge-compensating Na + addition were successfully synthesized via a solid-state reaction method, and the related X-ray diffraction patterns can be indexed to the rock-salt-like crystal structure of the Fm 3̅ m space group. SrS:(Ce 3+ ) x (0.005 ≤ x ≤ 0.05) and SrS:(Ce 3+ ) 0.01 ,(Na + ) y (0.005 ≤ y ≤ 0.030) phosphors were excited by 430 nm UV-Vis light, targeted to the 5d 1 → 4f 1 transition of Ce 3+ . The composition-optimized SrS:(Ce 3+ ) 0.01 , (Na + ) 0.015 phosphors showed an intense broad emission band at λ = 430-700 nm. The doping of Na + was probed by solid-state nuclear magnetic resonance. The 430 nm pumped white light-emitting diode structure fabricated with a combination of SrS:(Ce 3+ ) 0.01 ,(Na + ) 0.015 and Sr 2 Si 5 N 8 :Eu 2+ phosphors shows a color-rendering index ( R a ) of 89.7. The proposed strategy provides new avenues for the design and realization of novel high color quality solid-state LEDs.