Energy-saving chromium-activated garnet-structured phosphor-converted near-infrared light-emitting diodes

Phosphor-converted near-infrared light-emitting diodes (pc-NIR LEDs) are smart and energy-saving light sources compared with conventional tungsten halogen light bulbs and will enable upcoming modern devices to meet the requirements of various non-destructive security, military, medicine, and biomedicine applications due to their compactness, low cost, and versatility. NIR phosphors with garnet structures are being investigated because of their advantages of high internal efficiency, high thermal stability, and tunable spectral properties. In this paper, the garnet structure is exclusively reviewed to unravel its structure-property relationship and to understand the luminescence mechanism of Cr3+. This work provides a deep understanding of NIR luminescence in the garnet system and is expected to guide the design of next-generation garnet-based smart NIR light sources.