Green synthesis, luminescent properties and application for WLED of flower-like K2LiAlF6:Mn4+ phosphor

Abstract

Chrysanthemum-like K 2 LiAlF 6 :Mn 4+ phosphors were synthesized by simple co-precipitation method without using HF. The K 2 LiAlF 6 :Mn 4+ phosphor can be effectively excited through blue light at 465 nm, then produces sharp red-light emission near 634 nm. The luminescence quenching of Mn 4+ is caused by the d-d interaction between Mn 4+ ions. The effects of surfactant and lithium source on the luminescent properties of K 2 LiAlF 6 :Mn 4+ phosphors were discussed. Mn 4+ is located in a strong crystal field environment in the K 2 LiAlF 6 matrix and its emission mechanism is discussed. Warm white light emitting diode (WLED) device, which is fabricated by coating a certain proportion mixture of yellow YAG:Ce 3+ phosphor and red K 2 LiAlF 6 :5%Mn 4+ phosphor on the blue GaN chip, has low correlation color temperature (CCT = 3588 K), high color rendering index (R a = 90.8) and good electroluminescence stability under different currents. These properties illustrate that K 2 LiAlF 6 :5%Mn 4+ phosphor is a promising red light emitting material. • Chrysanthemum-like K 2 LiAlF 6 :Mn 4+ were prepared by using low-toxic NH 4 F and HCl instead of highly toxic HF. • The effects of reaction conditions on luminous characteristics of K 2 LiAlF 6 :Mn 4+ were discussed. • K 2 LiAlF 6 :Mn 4+ phosphors have excellent photoelectric performance for LED application.