The formation mechanism, improved photoluminescence and LED applications of red phosphor K2SiF6:Mn4+

Abstract

A red phosphor K₂SiF₆:Mn⁴⁺ has been prepared by etching of SiO₂ in HF solution at a KMnO₄ concentration as low as 0.08 mol L⁻¹. The luminescence properties of the phosphor have been improved obviously by using KF and H₂O₂. The structure, morphology and thermal stability of the phosphor have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetry and differential scanning calorimetry (TG-DSC), respectively. The formation mechanism of the red phosphor K₂SiF₆:Mn⁴⁺ is discussed in detail. Digital images and diffuse reflection spectra show that the phosphor is white under visible room light. An intense absorption band in the blue and a bright emission in red make the phosphor K₂SiF₆:Mn⁴⁺ a candidate for applications in InGaN–YAG:Ce type LEDs for high color rendering. A “warm” white light LED with an efficiency of 116 lm W⁻¹ and a color rendering index of 89.9 at a color temperature of 3900 K has been obtained by fabricating YAG:Ce with K₂SiF₆:Mn⁴⁺ on an InGaN chip.