A highly Mn2+-doped narrowband green phosphor toward wide color-gamut display applications

Abstract

Weak blue light absorption severely limits the application of Mn²⁺-activated narrowband green phosphors. Herein, a strategy to improve the absorption of Mn²⁺-activated phosphors is proposed by selecting a suitable host to achieve a high doping concentration of Mn²⁺. Specifically, a magnetoplumbite-type compound La_0.827Al_11.9O_19.09 with a unique layered structure is selected as the host to accommodate Mn²⁺ (La_0.827Al_11.9−xMn_xO_19.09,LAO:xMn²⁺) and a high doping concentration of x = 0.30 is obtained. Upon 450 nm excitation, the prepared phosphor LAO:0.30Mn²⁺ displays an intense narrowband green emission peaking at 517 nm with a full width at half-maximum (FWHM) of 28 nm, a color purity of 88% and an internal/external quantum yield of 90%/16%. Furthermore, it exhibits a low thermal quenching (6% at 423 K) and negligible color drifting (3.29‰ at 423 K). The LED device fabricated from the green phosphor LAO:0.30Mn²⁺, the commercial red phosphor K₂TiF₆:Mn⁴⁺ and a blue InGaN chip can emit bright white light with a corresponding correlated color temperature (CCT) of 5464 K and a color gamut value of 124% of the National Television Commission (NTSC) standard. These results indicate that the LAO:0.30Mn²⁺ phosphor has great potential for usage as a green component in wide-color gamut LCD backlight applications.