Enhancing the Luminescence of La3Mg2NbO9:Mn4+ Phosphor through H3BO3 and Charge Compensator Co-Doping for Use in Plant Growth Lamps

Mn4+-doped red-light-emitting phosphors have become a research hotspot that can effectively enhance photosynthesis and promote morphogenesis in plants. Herein, the red phosphor La3Mg2NbO9:Mn4+ was synthesized through the solid-state reaction method. The effects of adding H3BO3 and a charge compensator R+ (R = Li, Na, K) on the crystal structure, morphology, quantum efficiency, and luminous performance of the La3Mg2NbO9:Mn4+ phosphor were systematically analyzed, respectively. The results showed that adding H3BO3 flux and a charge compensator improved the quantum efficiency and luminescence intensity. The emission intensity of the phosphor was enhanced about 5.9 times when Li+ was used as the charge compensator, while it was enhanced about 240% with the addition of H3BO3 flux. Remarkably, it was also found that the addition of H3BO3 flux and a charge compensator simultaneously improved the thermal stability at 423 K from 47.3% to 68.9%. The prototype red LED fabricated using the La3Mg2NbO9:Mn4+,H3BO3,Li+ phosphor exhibited a perfect overlap with the phytochrome absorption band for plant growth. All of these results indicate that the La3Mg2NbO9:Mn4+,H3BO3,Li+ phosphor has great potential for use in agricultural plant lighting.