Continuous production of K2SiF6:Mn4+ red phosphor by green route synthesis method for warm WLEDs application

The K2SiF6:Mn4+ red phosphor has caused widespread concern in warm white light-emitting diodes (WLEDs) due to its unique broadband blue light absorption and narrow-band red emission. However, commercial K2SiF6:Mn4+ red phosphor inevitably needs to use extremely corrosive HF as a raw material, which will cause great harm to the environment and human beings. In this work, the K2SiF6:Mn4+ phosphor with highly uniform particle shape and size was successfully synthesized without using HF solution through microfluidic technology. The structure, morphology and photoluminescence properties of the K2SiF6:Mn4+ phosphors prepared in this work were systematically investigated and analyzed. The K2SiF6:Mn4+ phosphors synthesized by microfluidic technology are all cubic particles. The sample was the most uniform with a particle size of about 4.14 μm when the pipe diameter was 4 mm and the injection speed was 1000 μL/min, and the number of active Mn4+ in this sample is the largest according to the calculation results, resulting in its maximum luminous intensity. Finally, a warm WLED with low CCT (3379 K) and high CRI (Ra = 89.7) was fabricated by combining the as-prepared red K2SiF6:Mn4+ phosphor with yellow phosphor YAG:Ce3+ and blue LED chip. The results indicate that the K2SiF6:Mn4+ phosphor prepared by the proposed green continuous route is suitable for WLEDs.