Effect of ionic couple substitution on the enhanced photoluminescence properties of (BaMg)1-x(KxAl10+x)O17:Eu2+ phosphor for white LEDs application

Compared with traditional incandescent and fluorescent lamps, phosphor-converted white light-emitting diodes (LEDs) have revolutionized the lighting industry. To improve the performance of white LEDs, phosphors having excellent luminescence properties are required. BaMgAl10O17 (BAM) doped with Eu2+ is a candidate phosphor with blue emission for white LEDs. However, it has the disadvantages of low thermal stability and chromaticity coordinate deviation. Here, based on ionic couple substitution strategy, the co-substitution of Ba2+-Mg2+ in BAM: Eu2+ by K+-Al3+ until fully converted to KAl11O17:Eu2+ (KAO:Eu2+) was successfully achieved. The co-substitution leads to an improvement of luminescence thermal stability as a result of the interaction between Eu2+ ion and crystal defects. Moreover, the synthesis temperature (∼1350 °C) of KAO:Eu2+ is lower than that of BAM:Eu2+ (>1600 °C) and it exhibits better color purity than that of BAM:Eu2+ and small chromaticity coordinate deviation. A white LED device, fabricated using the KAO:Eu2+ phosphor as a blue component, exhibits better performance, and, accordingly, KAO:Eu2+ is a good blue-emitting candidate for phosphor-converted white LEDs. This study provides a practical guideline for improving the luminescence properties in the known system and developing materials with unique optical features.