Narrow-Band SrMgAlO:Eu, Mn Green Phosphors for Wide-Color-Gamut Backlight for LCD Displays.

The strength of the photoluminescence excitation (PLE) spectrum of SrMgAlO:Eu, Mn (SAM:Eu, Mn) phosphor increased at deep blue (∼430 nm) and red-shifted from violet to deep blue with increasing concentrations of both Eu ions Mn ions. Eu-Mn energy transfer between Eu ions in Sr-O layer and Mn ions at Al-O tetrahedral sites was maximized, and the photoluminescence (PL) intensity of the narrow-band Mn emission was improved by optimizing the concentrations of Eu and Mn ions. The PL emission spectrum of the (SrEu)(MgMn)AlO (SAM:Eu, Mn) phosphor peaks was optimized at 518 nm at a full width at half-maximum (FWHM) of 26 nm under light-emitting diode (LED) excitation at 432 nm LED. The color gamut area of a color-filtered RGB triangle of down-converted white LEDs (DC-WLEDs) incorporated with optimum SAM:Eu, Mn green and KSiF:Mn (KSF:Mn) red phosphors is enlarged by 114% relative to that of the NTSC standard system in the CIE 1931 color space. The luminous efficacy of our DC-WLED was measured and found to be ∼92 lm/W at 20 mA. Increased energy transfers between dual activators and red-shifted band-edge and enhanced intensity of PLE spectrum indicate the possibility of developing dual-activated narrow-band green phosphors for wide-color gamut in an LCD backlighting system.