Synthesis and optical performance of a new red-emitting ZnTiF6·6H2O:Mn4+ phosphor for warm white-light-emitting diodes

Mn4+-activated fluoride compounds, emerging as highly efficient rare-earth-free red-emitting phosphors, have been regarded as excellent color converters for warm white-light-emitting diodes recently. In this paper, using a facile two-step co-precipitation approach, we report the synthesis and structure of a novel ZnTiF6·6H2O:Mn4+ red-emitting phosphor as well as its optical performance in detail. Particularly, the as-prepared yellowish ZnTiF6·6H2O:Mn4+ powders exhibit an intense narrow-band Mn4+2Eg → 4A2g red emission with internal quantum efficiency of 26.4% upon the excitation of blue light corresponding to 4A2g → 4T2g transitions of Mn4+. As a consequence, the warm white-light-emitting diodes with tunable correlated color temperature and color rendering index can be easily realized by combining ZnTiF6·6H2O:Mn4+ red phosphor with commercial YAG:Ce3+ yellow phosphor on the blue-InGaN chip.