A New Series of Long Wavelength Red Phosphors BaLaLiTe1-O6:xMn4+ for Plant Cultivation LED

Mn4+ doped phosphors have been attracted more and more attention because their emitting spectra can be absorbed by chlorophyll or phytochrome (P-r and P-fr) of plants. Herein, we prepared a new series of phosphors BaLaLiTe1-xO6:xMn(4+) (BLLT:xMn(4+), x = 0.002-0.014) by solid state reaction method. Their structure and phase purity were verified by X-ray diffraction (XRD) analysis. Under 336 nm exciting, BLLT:xMn(4+) can emit long wavelength red light at around 700 nm, which fits well with the P-fr spectra of plants. The Mn4+ concentration was optimized to be x = 0.01, and when it was exceeded, concentration quenching would occur. The internal (IQE) and external quantum efficiency (EQE) of BLLT:0.01Mn(4+) were measured to be 32% and 23% by direct method. Besides, the BLLT:0.01Mn(4+) possesses good thermostability, remaining 76% of the integrated intensity at 423 K of that at 298 K. Hence, we think BLLT:0.01Mn(4+) have potentially applications for plant growth LED.