Cr3+-doped far-red phosphors with zero thermal quenching and excellent spectral matching for plant lighting application

Far-red-emitting (700−740 nm) phosphors are essential for the fabrication of plant lighting phosphor-converted light-emitting diodes (pc-LEDs). However, the development of highly efficient, thermally stable, and spectrally matched far-red phosphors still remains a challenge. Herein, far-red GdAlO 3 :Cr 3+ (GAO:Cr 3+ ) phosphors were synthesized via solid-state reaction and investigated for plant lighting pc-LED applications. A low-temperature flux-assisted synthesis strategy was adopted to improve the crystalline quality, suppress the defect formation, and maintain the valence state of Cr 3+ in the phosphors, finally leading to significant luminescent enhancement (∼10 times). The GAO:Cr 3+ phosphors show the 2 E sharp-line emissions around 730 nm, which is highly matched with the far-red absorption band of plants. The optimized GAO:0.01Cr 3+ phosphor exhibits a high internal quantum efficiency of 98.3% and zero thermal quenching even up to 250°C. The fabricated pc-LED can generate an overall output power of 78.1 mW at 100 mA drive current, with a high energy conversion efficiency of 25.3%. The findings demonstrate the great potential of GAO:Cr 3+ as far-red-emitting phosphor materials for plant growth pc-LED applications.