Unlocking dual Mn 3+ /Mn 4+ emissions in garnet phosphors for WLED and plant growth lighting applications

Garnet-based lattices (A₃B₅O₁₂) have emerged as promising hosts for Mn co-doping due to their wide band gap and robust mechanical properties. However, challenges in stabilizing Mn³⁺, balancing Mn³⁺/Mn⁴⁺ emissions, and optimizing synthesis for thermal stability and efficiency have limited practical applications. In this study, Gd₃Ga₅O₁₂ (GGG) garnet was synthesized with Mn³⁺ and Mn⁴⁺ co-doping via a simple solid-state reaction. The incorporation of Mn ions into octahedral [GaO₆] sites and optimizing the synthesis condition to enhance photoluminescence (PL) properties were investigated. The phosphor achieved 100% color purity, 0.32 eV activation energy, 20.0% internal quantum efficiency, and a 0.0408 ms lifetime. A prototype pc-LED was fabricated, demonstrating that the Mn³⁺/Mn⁴⁺-doped Garnet-based phosphor can be used as potential WLED and plant growth LED components. These results provide insights into stabilizing Mn³⁺, controlling Mn³⁺/Mn⁴⁺ balance, and improving thermal stability for advanced lighting applications.