A green synthetic route to the highly efficient K₂SiF₆:Mn⁴⁺narrow-band red phosphor for warm white light-emitting diodes

Abstract

A green synthetic route to the highly efficient K2SiF6:Mn4+narrow-band red phosphor for warm white light-emitting diodes.

A universal HF‐free synthetic method to highly efficient narrow‐band red‐emitting A2XF6:Mn4+ (A = K, Na, Rb, Cs; X = Si, Ge, Ti) phosphors

“…At 150°C, the PL intensity of KSFM and RSFM is not changed yet, but that of KTFM, KGFM, NSFM, and CSFM is decreased by 70%, 20%, 25%, and 25%, respectively. The high thermal stability of KSFM, KGFM, and RSFM phosphors can be attributed to the vibronic emission mechanism of Mn 4+ ions …”

“…45 The authors proposed a green method to synthesize highly efficient K 2 SiF 6 :Mn 4+ by replacing HF with NH 4 F/HCl combination. 46 The prepared K 2 SiF 6 : Mn 4+ phosphor exhibited a high QE (IQE = 92%), indicating the feasibility of the proposed HF-free routine. Inspired by the universal wet chemical etching method that can be used to synthesize a series of fluoride phosphors A 2 XF 6 :Mn 4+ (A = K, Na, Rb, Cs; X = Si, Ge, Ti) by etching Si, Ti, or Ge crystals, 42,47,48 we attempt to apply our proposed approach to other compositions.…”

“…The high thermal stability of KSFM, KGFM, and RSFM phosphors can be attributed to the vibronic emission mechanism of Mn 4+ ions. 28,46,51 To apply phosphors in LCD backlights, it is required that the temperature-dependent color shift of phosphors should be as small as possible. The normalized temperature-dependent PL spectra of KGFM (4.61 mol%) are given in Figure 5A.…”

“…Unfortunately, the internal quantum efficiency (IQE) of the as‐synthesized K 2 SiF 6 :Mn 4+ was only 28%, which is much lower than that required for commercial applications . The authors proposed a green method to synthesize highly efficient K 2 SiF 6 :Mn 4+ by replacing HF with NH 4 F/HCl combination . The prepared K 2 SiF 6 : Mn 4+ phosphor exhibited a high QE (IQE = 92%), indicating the feasibility of the proposed HF‐free routine.…”

Versatile Homoleptic Naphthyl‐Acetylide Heteronuclear [Pt2M4(CC‐Np)8] (M = Ag, Cu) Phosphors for Highly Efficient White and NIR Hybrid Light‐Emitting Diodes

“…For instance, the most far red emitting Ce 3+ doped phosphor (λ em = 625 nm) has recently been reported by Schnick and co‐workers . As alternative, the most successful orange‐red IPs are the commercial nitride CaAlSiN 3 :Eu 2+ and fluoride K 2 SiF 6 :Mn 4+ phosphors . However, the first one exhibits an emission reaching into the NIR region, which limits its luminous efficacy, and the second one presents chemical instability .…”