High-Efficiency Ce³⁺ Activated Orthorhombic Lanthanide Silicate Blue Phosphors for Plant Growth Lighting

Plant growth can be controlled and freed from natural environmental interference through indoor plant cultivation. Artificial light sources with better quality are required to promote indoor plant growth. In this study, we used a simple high-temperature solid-state reaction to synthesize high-efficiency Ce³⁺-activated NaGdSiO₄ (NGSO) phosphors. X-ray diffraction and Rietveld refinement were performed to determine the detailed crystal structure of the NGSO:Ce³⁺ phosphors. The morphology of NGSO:Ce³⁺ and the elemental state of Ce³⁺ were measured and analyzed. Under near-ultraviolet (n-UV) light excitation, the Ce³⁺-activated NGSO phosphors exhibit a broad emission band from 375 to 500 nm, and their emission peaks are at approximately 401 nm. This asymmetrical blue emission band is caused by the spin-allowed 5d → 4f transition of Ce³⁺ and overlaps well with the blue absorption region of carotenoids and chlorophyll. The temperature-dependent luminescence spectra were utilized to assess the thermal stability of NGSO:Ce³⁺. The external quantum efficiency (EQE) was measured to be 60.91%, and the internal quantum efficiency (IQE) was measured to be 73.39%. A blue LED device assembled from the NGSO:Ce³⁺ phosphor has demonstrated the application potential in accelerating plant growth.