Enhanced cyan emission via competitive site occupancy engineering in Sr2SiO4:Eu2+ phosphor for achieving full-spectrum LED lighting

Highly efficient containing cyan-emitting phosphors are used to bridge the cyan cavity for near ultraviolet (NUV) light-emitting diodes (LEDs) to obtain high-quality full-spectrum white lighting. In this work, a series of Sr2-xNaxSi1-xNbxO4:Eu2+ (x = 0–0.25) (SNSNO:Eu2+) solid solution phosphors were prepared by a solid-state reaction method. The bright SNSNO:Eu2+ phosphors were proceeded to fill the cyan gap. Such a cosubstitution of Na + -Nb5+ ion pair improves the cyan sub-band emission peaking at around 500 nm owing to the competitive site occupancy of Eu2+ on the Sr2+ site. Notably, codoping Na+-Nb5+ ion pairs into the host can realize a tuning of spectrum of SNSNO:Eu2+ from yellow-green to cyan-green region by crystallographic site engineering. Finally, employing mixture of SNSNO:Eu2+ and commercial BAM:Eu2+ and CaAlSiN3:Eu2+ coated on a 365 nm NUV chip, a full spectrum wLED package with remarkable color rendering index (Ra = 95.1) and low CCT = 3167 K was generated. The results indicate that the SNSNO:Eu2+ phosphor is very significative on closing the cyan gap for full-spectrum white lighting.