Deep red fluoride dots-in-nanoparticles for high color quality micro white light-emitting diodes.

In this study, a novel nanostructure of fluoride red emitting phosphor is synthesized via soft templates. K2SiF6:Mn4+ nanocrystals in the range of 3-5 nm diameter are found inside the porous K2SiF6:Mn4+ nanoparticle hosts, forming unique dots-in-nanoparticles (d-NPs) structures with controlled optical properties. The porous K2SiF6:Mn4+ d-NPs exhibit a sharp and deep red emission with an excellent quantum yield of ∼95.9%, and ultra-high color purity with the corresponding x and y in the CIE chromaticity coordinates are 0.7102 and 0.2870, respectively. Moreover, this nanophosphor possesses good thermal stability in range of 300 K-500 K, under light excitation of 455 nm. The K2SiF6:Mn4+ d-NPs are covered onto a surface of 100×100 µm2 blue-yellow InxGa1-xN nanowire light-emitting diode (LED) to make warm white LEDs (WLEDs). The fabricated WLEDs present an excellent color rendering index of ∼95.4 and a low correlated color temperature of ∼3649 K. Porous K2SiF6:Mn4+ d-NPs are suggested as a potential red component for high color quality micro WLED applications.