Three Birds with One Stone: K₂SiF₆:Mn⁴⁺ Single Crystal Phosphors for High‐Power and Laser‐Driven Lighting

Narrow‐band red‐emitting fluoride phosphors play a crucial role in lighting and backlight displays, whereas the stability issue is a major challenge. Here, highly stable K 2 SiF 6 :Mn 4+ (KSFM) single crystal phosphors with tunable sizes (20–1000 µ m) are grown by a facile saturated crystallization method. The small specific surface area together with the unique Mn 4+ ‐rare interface layer in KSFM single crystals enables the simultaneous fulfillment of high external quantum efficiency, excellent moisture, improved thermal quenching, and dissipation for high‐power and laser‐driven lighting applications. As a prototype, a warm white laser diode device with a high luminous flux of 202.7 lm and correlated color temperature of 3277 K, as well as a color rendering index of 87.9 is presented. This work provides new insights into the development of highly efficient and stable materials for advanced lighting applications.