Abstract
The strength of the photoluminescence excitation (PLE) spectrum of SrMgAl(10)O(17):Eu(2+), Mn(2+) (SAM:Eu(2+), Mn(2+)) phosphor increased at deep blue (∼430 nm) and red-shifted from violet to deep blue with increasing concentrations of both Eu(2+) ions Mn(2+) ions. Eu(2+)-Mn(2+) energy transfer between Eu(2+) ions in Sr-O layer and Mn(2+) ions at Al-O tetrahedral sites was maximized, and the photoluminescence (PL) intensity of the narrow-band Mn(2+) emission was improved by optimizing the concentrations of Eu(2+) and Mn(2+) ions. The PL emission spectrum of the (Sr(0.6)Eu(0.4))(Mg(0.4)Mn(0.6))Al(10)O(17) (SAM:Eu(2+), Mn(2+)) 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(2+), Mn(2+) green and K(2)SiF(6):Mn(4+) (KSF:Mn(4+)) 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.