Organic solvent-assisted co-precipitation synthesis of red-emitting K 2 TiF 6 :Mn phosphors with improved quantum efficiency and optimized morphology.

We report an organic solvent-assisted (OSA) co-precipitation strategy for the production of Mn 4+ -activated K 2 TiF 6 phosphor. The phosphor particle size was controlled through the selection of organic solvents with an alcohol functional group and different carbon chain lengths used in the synthesis. The synergistic effect of the organic solvent and hydrofluoric acid results in large smoothed hexagonal-shaped crystal sheets of particles that become larger as the carbon chain length of the organic solvent increases. The photoluminescence (PL) properties of K 2 TiF 6 :Mn powders strongly depend on the size and thickness of the particles. The addition of n -butanol during the synthesis increases the emission intensity of K 2 TiF 6 :Mn by 208%. The PL quantum efficiency of phosphors prepared using the n -butanol-assisted strategy is much higher (98.2%) than that of conventionally prepared phosphors (89.9%). Our findings demonstrate a way to prepare the K 2 TiF 6 :Mn phosphor with targeted morphology and very high quantum efficiency and also provide the route for the optimization of all Mn 4+ -activated fluoride phosphors used in white light-emitting diodes.