Enhancement of the luminous efficiency of a ceramic phosphor plate by post-annealing for high-power LED applications

Abstract Currently, phosphor-converted white light-emitting diodes offer low energy consumption, good environmental stability, and a long lifetime. Hence, they are widely utilized in high-power light-emitting diode (LED) applications such as those in the automotive headlamp industries. However, obtaining high luminous efficiency of such diodes is challenging because of their internal structural properties such as micropores. Herein, we developed phosphor-in-glass (PiG) plates by mixing a blue LED chip and yellow phosphor to create high-power white LEDs (w-LEDs). In addition, the influence of post-annealing on the prepared PiG plates at different temperatures (350°C-550 °C) was investigated. Post-annealing, a treatment that facilitates the mobility of the ceramic matrix encapsulating the phosphor powder, decreases an LED's porosity, thereby enhancing its overall luminous efficiency. Results show that PiG plates post-annealed at 450 °C exhibit superior optical performance and effective color properties than PiG plates that were non-annealed or post-annealed at 350 °C, 400 °C, 500 °C, and 550 °C. Therefore, post-annealed PiG plates are more suitable potential materials for application in the high-power LED industry.