Water resistance, thermal stability, luminescence enhancement of core-double shell structure K2TiF6:Mn4+ phosphor

Be2+‐Induced Red Emission Enhancement in CaAl12O19:Mn4+ for Wide Color Gamut Display: Suppressing Self‐Reduction of Mn4+ to Mn2+

“…Phosphor-converted light emitting diodes (Pc-LEDs) have shown great benefits in daily lighting, plant growth, phototherapy, and nondestructive testing due to their easy portability and high energy efficiency. [1][2][3][4][5][6] Pc-LEDs also show attractive application prospects in high-color gamut display that needs narrow-emitting phosphors. [5][6][7] Mn 4+ is often selected for red narrow-emitting phosphor due to its 2 E g → 4 A 2g transition, such as the commercial K 2 SiF 6 : Mn 4+ (KSF) red phosphor.…”

Highly Moisture-Stable and Enhanced Luminescence-Efficient Mn4+-Activated Red-Emitting Fluoride Phosphors via a Bi-hydrogen-Bond Organic Coating

“…Various strategies have been reported to improve the moisture resistance of Mn 4+ -activated fluoride phosphors and can be roughly classified into organic coating, inorganic heterogeneous/homogeneous coating, surface deactivation and cation substitution, etc. ,, Various inorganic compounds, such as TiO 2 , Al 2 O 3 , , CaF 2 , , and SrF 2 have been used to form a heterogeneous protective layer to improve moisture resistance for fluoride phosphors but at the expense of sacrificing the luminescence efficiency generally due to surface defects and nonradiative decay probability induced by the differences of physicochemical properties between inner phosphors and the coating layer . Moreover, an inorganic coating generally needs a gas-phase deposition technique or highly toxic HF as solvent to form an inorganic layer on the surface of phosphors, and synthesis processes are complex, polluting, and unsafe. , An inorganic homogeneous coating and surface deactivation were developed to construct a Mn 4+ -free or Mn 4+ -rare A 2 XF 6 fluoride matrix shell on the surface of phosphors to isolate the [MnF 6 ] 2– clusters from water and enhance the moisture resistance. − Due to the same physicochemical properties between inner phosphors and protective layers, a homogeneous coating and surface deactivation would not scarify the luminescence efficiency . Being similar to inorganic heterogeneous coatings, an inorganic homogeneous coating also generally leads to extra consumption of HF solution to synthesize an A 2 XF 6 shell, , while surface deactivation would lower the absorption efficiency due to the Mn 4+ reduction .…”