A novel Cr3+-activated far-red titanate phosphor: synthesis, luminescence enhancement and application prospect

Plant factory, a new agricultural planting technology, has emerged and rapidly grown in recent years, with phosphor conversion light emitting diodes (pc-LEDs) considered as the first choice of source light for the plant factory. In this study, a new type of Cr3+-activated Li2MgTi3O8 phosphor (LMT: Cr3+) was synthesized by high temperature solid state method. X-Ray diffraction patterns showed that there was no detectable impurity in these samples. The photoluminescence spectra revealed that this phosphor can emit far-red light with the peak at 740 nm excited by ultraviolet and blue light, overlapped well with the PFR. After introducing Zn2+ ions (LMT: Cr3+, Zn2+), the luminescence intensity increases by 46% mainly due to the increase of lattice distortion, and internal quantum yield was improved from 25.4% to 41.3% under 365 nm excitation. Finally, the pc-LED devices, consisting of 470 nm chip coated with the optimal phosphor, exhibited good luminescence and overlapping with PFR. These results indicate that the LMT: Cr3+, Zn2+ phosphor has the potential application in modern agriculture.