Synthesis, structure, and luminescence characteristics of far-red emitting Mn 4+ -activated LaScO 3 perovskite phosphors for plant growth.

Far-red emitting phosphors LaScO 3 :Mn 4+ were successfully synthesized via a high-temperature solid-state reaction method. The X-ray powder diffraction confirmed that the pure-phase LaScO 3 :Mn 4+ phosphors had formed. Under 398 nm excitation, the LaScO 3 :Mn 4+ phosphors emitted far red light within the range of 650-800 nm peaking at 703 nm (14 225 cm -1 ) due to the 2 E g → 4 A 2g transition, which was close to the spectral absorption center of phytochrome P FR located at around 730 nm. The optimal doping concentration and luminescence concentration quenching mechanism of LaScO 3 :Mn 4+ phosphors was found to be 0.001 and electric dipole-dipole interaction, respectively. And the CIE chromaticity coordinates of the LaScO 3 :0.001Mn 4+ phosphor were (0.7324, 0.2676). The decay lifetimes of the LaScO 3 :Mn 4+ phosphors gradually decreased from 0.149 to 0.126 ms when the Mn 4+ doping concentration increased from 0.05 to 0.9 mol%. Crystal field analysis showed that the Mn 4+ ions experienced a strong crystal field in the LaScO 3 host. The research conducted on the LaScO 3 :Mn 4+ phosphors illustrated their potential application in plant lighting to control or regulate plant growth.