Synthesis and study of luminescence properties of a deep red–emitting phosphor K2LiAlF6:Mn4+ for plant cultivation

Abstract Light is the most important component in plant growth and development. This study synthesised a novel Mn4+‐doped K2LiAlF6 red‐emitting phosphor using the coprecipitation method. We observed that on addition of dopant Mn4+ ions to the host K2LiAlF6, its phase changed from rhombohedral to cubic due to the change in the lattice position of the atoms. When the atoms are excited at 468 nm, the K2LiAlF6:Mn4+ phosphor exhibited a red emission band ranging from 630 to 700 nm, centred at 638 nm, which matched well with the absorption spectra of phytochrome PR. The critical quenching content of Mn4+ ions was ~3 mol%. The critical distance between Mn4+ ions was determined to be 19.724 Å, and non‐radiative energy transfer among the nearest‐neighbour Mn4+ ions was the mechanism used for the concentration quenching effect. The Commission International de l'Eclairage (CIE) chromaticity coordinates of the K2LiAlF6:0.03 Mn4+ sample were (x = 0.7162, y = 0.2837). The luminescence mean decay time was calculated to be 8.29 ms. These results demonstrated the promising prospect of K2LiAlF6:Mn4+ as a red‐emitting phosphor for application in red light‐emitting diodes for plant cultivation.