A thermal-stable Mn4+-doped far-red-emitting phosphor-converted LED for indoor plant cultivation

Artificial light-emitting diode (LED) light source, regarded as a front-runner technology for the promoting of plant growth, has attracted much attention toward the burgeoning fertilizer-free indoor plant cultivation. It still remains a challenge that explore a far-red-emitting phosphor of high-thermal stability. Overall, we report a Mn4+ ion-doped ordered double perovskite tungstates prepared by high-temperature solid-state reaction method in air. The crystal structure, morphology, and fluorescence properties were investigated and discussed in detail. The far-red emission of the optimized CaSrMgWO6:1%Mn4+, covering the wavelength region of 630–780 nm, matches the absorption ranges of the chlorophyll a and phytochrome (Pfr). The value of Dq/B is estimated to be 2.81. Most notable is the excellent thermal quenching resistance of the Mn4+ emission, remaining 86.7% at 150 °C, thereby suitably fabricating a far-red LED device. The LED light-driven regulation of the physiological and biochemical changes enables a proof-of-concept garlic cultivation. The growth of weight, stem length, and root length of the garlic was significantly promoted with the extra supply of the far-red light. This work demonstrates that the as-obtained far-red-emitting phosphor holds a promising perspective for the phosphor-converted far-red LED light sources toward the flourishing fertilizer-free indoor plant cultivation.