Highly‐Efficiency Far‐Red Emission in Cr3+ Activated Ca1.8Mg1.2Al2Ge3O12 toward Plant Precise Lighting

Abstract Far‐red (FR) region (beyond 700 nm) lighting sources possess special potential for plant lighting. However, it remains a challenge to obtain high‐performance Cr 3+ ‐doped FR phosphors. This study developed a FR phosphor, Ca 1.8 Mg 1.2 Al 2 Ge 3 O 12 :Cr 3+ (CMAGG: Cr 3+ ), using the cation substitution strategy. Under 438 nm blue light excitation, the phosphors display FR emission centered at 720 nm with a full width at half maximum (FWHM) of 91 nm. Benefit from the favorable match with the FR phytochrome (P fr ), the phosphor is combined with InGaN blue light chips to create a FR phosphor‐converted light‐emitting diode (pc‐LED), which is used in Italian lettuce growth experiments and it results shown in a 15% increase in fresh weight and a 6.5% increase in dry weight. Notably, supplemental FR light modulated its growth morphology. The results of this study will be useful for further research on novel Cr 3+ ‐doped FR phosphors to meet the precise spectral requirements for plant growth.