Acetate-triggered morphology evolution and improved photoluminescence performance of K2NaInF6:Mn4+ crystals for wide applications

Mn4+-doped red fluoride phosphors generally exhibit irregular bulks, thus, it is promising and challenging to regulate the morphology via a facile green synthesis approach for their desired application. In this study, the morphology evolution of a phosphor K2NaInF6:Mn4+ (KNIF:Mn) from irregular polyhedrons to uniformly micro-cubic crystals about 2–3 μm has been achieved via acetate (CH3CH2COO-, Ac-)-triggered strategy while maintaining the high phase purity and photoluminescence (PL) efficiency. The modified KNIF:Mn micro-cubic crystals demonstrate higher moisture resistance and thermal stability compared to the unmodified counterpart. The obtained KNIF:Mn particles with regular morphology show superior performance in latent fingerprint visualization (LFV) as well as “warm” white light-emitting diodes (WLEDs). The phosphor mass required for fabrication of WLEDs with a correlated color temperature (CCT) of about 3900 K is deceased to half due to the optimized morphology, which indicates the potential on large-scale commercial applications.