Mn4+-activated oxyfluoride K3TaOF6red phosphor with intense zero phonon line for warm white light-emitting diodes

Abstract

The intense zero phonon line (ZPL) of the Mn4+:2E→4A2transition can further promote the color rendering and luminous efficiency for high-quality white-emitting diodes (w-LEDs). In this article, a Mn4+-activated K3TaOF6oxyfluoride red phosphor was synthesizedviaa facile two-step method. Its phase and morphology were characterized by X-ray diffraction, SEM and TEM. The as-prepared K3TaOF6:Mn4+exhibits an intense absorption of blue light and a strong emission band peaking at 628 nm with a color purity as high as 96.4%. Attributed to the distorted octahedral coordination environment of Mn4+ions, an intense ZPL emission was detected at 620 nm. By theoretical calculation, Mn4+ions in the K3TaOF6host experience a strong crystal field. In addition, the temperature-dependent PL and thermoluminescence (TL) spectra suggest that thermal ionization dominates the thermal quenching phenomenon in this phosphor.