Phosphor materials with narrowband emission show great importance in the light-emitting diode (LED) industry due to its ability to produce wide color gamut displays and vivid colors in backlighting applications. The search for cheaper synthesis methods and highly efficient phosphors are of great importance nowadays. Here, we report a green-emitting narrowband alkali-lithosilicate phosphor with the composition of NaK2Li[Li3SiO4]4 doped with Eu2+ which has a full width at half maximum of ~43 nm and peak emission wavelength of 530 nm with external quantum efficiency reaching up to ~38% after post-treatment which is higher than the conventional green phosphor. The phosphor was synthesized by using solid-state metathesis reactions. The starting precursors were mixed and ground in an agate mortar until homogenous then put inside a tube furnace for sintering. The bulk powder phosphor was then characterized using X-ray powder diffraction pattern, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence and photoluminescence excitation, thermal properties, decay time and luminescence at different pressure and temperature were measured and analyzed. The phosphors were also subjected to LED package data. According to the results, the phosphor’s color gamut covers 100.9% of the standard National Television System Committee (NTSC).

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