%0 Journal Article %T Ultrafast Self-Crystallization of High-External-Quantum-Efficient Fluoride Phosphors for Warm White Light-Emitting Diodes %J - %D 2018 %R https://doi.org/10.1021/acsami.8b03525 %X In this study, we used HF (as good solvent) to dissolve K2GeF6 and K2MnF6 and added ethanol (as poor solvent) to cause ultrafast self-crystallization of K2GeF6:Mn4+ crystals, which had an unprecedentedly high external quantum efficiency that reached 73%. By using the red phosphor, we achieved a high-quality warm white light-emitting diode with color-rendering index of Ra = 94, R9 = 95, luminous efficacy of 150 lm W¨C1, and correlated color temperature at 3652 K. Furthermore, the good¨Cpoor solvent strategy can be used to fast synthesize other fluorides %U https://pubs.acs.org/doi/10.1021/acsami.8b03525