RESUMO
Laser-driven illumination has unique advantages in high-power applications. Taking advantage of the valuable experience of light-emitting diodes (LED) development, phosphor in silicone (PiS) is considered to be one of the most potential commercial phosphor converter solutions for laser-driven illumination. However, the thermal quenching of the PiS converter is a bottleneck problem. Herein, a boron nitride (BN)-coated copper foam strategy is introduced for the laser-driven illumination system. The phosphor/silicone is embedded in the designed BN/copper foam to form a phosphor in metal (PiM) converter. Copper foam serves as an internal connected heat transfer channel; the BN coating solves the light absorption problem of the copper foam effectively. Based on this PiM(BN/copper foam) design, the heat dissipation is effectively improved. Under high-power laser excitation (8.13 W), the PiS converter cannot reach thermal equilibrium, and therefore the temperature increases sharply up to 660 °C. In comparison, the thermal performance of an optimized PiM(BN/copper foam) converter is able to maintain excellent stability, where the maximum temperature is only 166.5 °C. The proposed PiM strategy has a maximum temperature that is 493.5 °C lower than that of the reference PiS solution. Due to the superior thermal management, the luminous efficiency of the illumination system is constantly stable at 254 lm/W, though with less phosphor mass; and the related color temperature is about 6000 K all the time. This provides a practical and feasible heat-dissipation solution for high-power laser-driven illumination.
RESUMO
Currently, laser-driven lighting based on phosphor-in-glass (PIG) has drawn much interest in solid state lighting due to its high electro-optical efficiency and high-power density. However, the fabrication of PIG requires expensive equipment, long sintering time, and high cost. In this work, we utilized a simple, fast, and high temperature Joule heating process to make phosphor-in-glass bulk sintered in less than 20 s, which greatly improved the production efficiency. The PIG converters sintered under different sintering temperatures were investigated experimentally. The optimized PIG converter exhibited high and robust luminous efficacy (164.24 lm/W), a high radiant flux, and a small CCT deviation at 3.00 W. Moreover, the optimized sample also showed high temperature resistance at 3.00 W, robust temperature management during normal working. These results indicated that the optimized PIG converter sintered by the Joule heating process could offer great potential for the application in high-power laser-driven white lighting.
