Highly Efficient Narrow-Band Green-Emitting Na3K5(Li3SiO4)8:Eu2+ Phosphor with Low Thermal Quenching

In the pursuit of high efficiency and wide color gamut in displays, there is still an urgent demand for high-performing narrow-band green-emitting phosphors. Inspired by a mineral UCr4C4-type structure with a highly condensed framework, a novel narrow-band green-emitting Na3K5(Li3SiO4)(8):Eu2+ (NKLSO:Eu2+) phosphor is designed. This phosphor exhibits a green emission peaking at 525 nm with a full width at half-maximum (fwhm) of 43 nm. The narrow-band emission is associated with the highly symmetric sites for Eu2+. Benefiting from its high structural rigidity, this NKLSO:Eu2+ phosphor shows a very low photoluminescence (PL) thermal quenching, maintaining 96%@150 degrees C integrated PL intensity of the original PL intensity. Moreover, by incorporating a small amount of Al3+ into the lattice, the internal quantum efficiency (QE) and external QE of this phosphor is enhanced from 70 to similar to 100% and 21 to 38%, respectively. The as-fabricated wLED-1 (InGaN chip@blue, NKLSO:1.25% Eu2+@green, KSiF6:Mn4+@red) shows a wide color gamut (106% NTSC), demonstrating vivid photographs when used in a projector. The as-fabricated wLED-4 (BaMgAl10O17:Eu2+@blue, NKLSO:1.25% Eu2+@green, CaAlSiN3:Eu2+@red) presents a low correlated color temperature of 5390 K and a high color rendering index (Ra) of 86.9. These results show that narrow-band green-emitting NKLSO:Eu2+ has potential applications in both backlight displays and solid-state lighting.