A Red-Emitting Phosphor Rb₂TaF₇:Mn⁴⁺ for White Light-Emitting Diodes

Herein, a new red phosphor Rb₂TaF₇:Mn⁴⁺ was prepared by the co-precipitation method. Under excitation of the blue light at 468 nm, this phosphor exhibits a series of red-emitting peaks, due to the ²E→⁴A₂ transitions of Mn⁴⁺. It is worth mentioning that an intense zero-phonon line (ZPL) of Mn⁴⁺ appears at 620 nm in this non-equivalent Mn⁴⁺ doping system. A white light-emitting diode (w-LED) based on the Rb₂TaF₇:Mn⁴⁺ (1.0 mol%) phosphor emits bright white light with a color temperature (T _c) of 4387 K and a color rendering index (Ra) of 88, showing its potential application in w-LEDs.