How to Improve Phosphor Thermal Stability

Improving the thermal stability of phosphors is crucial for extending LED lifespan, primarily achieved through material modification and process optimization.

Regarding materials, employing a core-shell structure design, such as coating phosphor particles with SiO₂ or Al₂O₃, can effectively isolate them from high-temperature oxidation. Rare earth ion doping (e.g., Ce³⁺ doping in nitrides) can enhance lattice stability, allowing the luminophore to maintain over 90% efficiency even at 150℃.

In terms of process, optimizing sintering conditions is paramount. Using a gradient heating sintering method, controlling the heating rate at 5℃/min, avoids micro-cracks caused by rapid thermal expansion and contraction. For YAG phosphors, adding an appropriate flux (e.g., BaF₂) can lower the sintering temperature and reduce lattice defects. In the encapsulation stage, selecting high thermal conductivity silicone (thermal conductivity >1.5W/m·K) and adding nano-alumina thermal conductive fillers can reduce the working temperature of the phosphor by 30-50℃.

Novel nitride phosphors (such as β-sialon) inherently possess excellent thermal stability, exhibiting less than 5% luminous decay at high temperatures of 200℃, making them an ideal choice for high-power LED lighting. Through the synergistic optimization of materials and processes, modern phosphors can now operate stably for over 5000 hours in a 180℃ environment.