Double perovskite Ba2LaNbO6:Mn4+,Yb3+ phosphors: Potential application to plant-cultivation LEDs

Phototropism and photomorphogenesis play important roles in plant growth. In this work, a series of novel Ba2LaNbO6 (BLN):Mn4+,Yb3+ phosphors for plant-cultivation light-emitting diodes (LEDs) were successfully synthesized through a high-temperature solid-state reaction. The emission peak of Me4+ centered at 677 nm matched the red light emission required for phototropism well, while that of Yb3+ centered at 998 nm matched the far-red light emission required for photomorphogenesis. SEM images of the BLN:Mn4+,Yb3+ phosphors developed in this study showed that the samples were composed of micron-sized particles that can be coated onto LED chips. The photoluminescence excitation spectra of the phosphors showed broad bands from 250 nm to 550 nm, matching those of LED chips well. The activation energy of Mn4+ in the BLN:Mn4+ phosphor was calculated to be approximately 0.462 eV, thus confirming the good thermal stability of the material. The CCT, CRI, and luminous efficiency of a developed LED were 4021 K, 76.8, and 38 Im/W, respectively. Analysis of fluorescence lifetimes proved the occurrence of energy transfer between Mn4+ and Yb3+, and the intensity ratio of far-red and near-infrared emissions could be controlled by adjusting the doping ratio of Mn4+ and Yb3+ to meet the requirements of different plants. Taken together, the results showed that BLN:Mn4+,Yb3+ is a phosphor that can potentially be applied to plant-cultivation LEDs.