Quenching of the red Mn4+ luminescence in Mn4+-doped fluoride LED phosphors

作者：Tim Senden, Relinde J. A. van Dijk‐Moes, Andries Meijerink · 发表于：Light Science & Applications · 年份：2018 · DOI：10.1038/s41377-018-0013-1 · 被引用次数：500 · 研究领域：Luminescence Properties of Advanced Materials、Inorganic Fluorides and Related Compounds、Solid State Laser Technologies

Abstract Red-emitting Mn 4+ -doped fluorides are a promising class of materials to improve the color rendering and luminous efficacy of white light-emitting diodes (w-LEDs). For w-LEDs, the luminescence quenching temperature is very important, but surprisingly no systematic research has been conducted to understand the mechanism for thermal quenching in Mn 4+ -doped fluorides. Furthermore, concentration quenching of the Mn 4+ luminescence can be an issue but detailed investigations are lacking. In this work, we study thermal quenching and concentration quenching in Mn 4+ -doped fluorides by measuring luminescence spectra and decay curves of K 2 TiF 6 :Mn 4+ between 4 and 600 K and for Mn 4+ concentrations from 0.01% to 15.7%. Temperature-dependent measurements on K 2 TiF 6 :Mn 4+ and other Mn 4+ -doped phosphors show that quenching occurs through thermally activated crossover between the 4 T 2 excited state and 4 A 2 ground state. The quenching temperature can be optimized by designing host lattices in which Mn 4+ has a high 4 T 2 state energy. Concentration-dependent studies reveal that concentration quenching effects are limited in K 2 TiF 6 :Mn 4+ up to 5% Mn 4+ . This is important, as high Mn 4+ concentrations are required for sufficient absorption of blue LED light in the parity-forbidden Mn 4+ d – d transitions. At even higher Mn 4+ concentrations (>10%), the quantum efficiency decreases, mostly due to direct energy transfer to quenching sites (defects and impurity ions...