Challenges and Strategies to Design Phosphors for Future White Light Emitting Diodes

Abstract

Phosphor-converted white-light-emitting diodes (pc-WLEDs) are a commercially successful product for energy-efficient illumination. A large number of reported phosphors exhibit high photoluminescence efficiency but struggle in pc-WLED applications. So what kind of phosphors are required to upgrade the existing pc-WLED? An answer to this question is provided here. The industry is moving toward high-power pc-WLED. For that, issues of thermal instability (at ∼200 °C) and luminescence saturation of phosphors, along with the efficiency drop of the InGaN chip, need to be addressed. Another research direction is to reduce excessive blue light from the present commercial pc-WLED, by replacing the blue-emitting InGaN chip with an ultraviolet (UV)-violet chip. Designing phosphors for high-power pc-WLED with UV-violet chip still remains a challenge. This Perspective highlights the present challenges and provides insights to address them in the future.