Enhanced far-red luminescence in Ca14Al10Zn6O35:Mn4+, Mg2+phosphors via local structure modulation

Far-red light (700-800 nm) plays a vital role in promoting photosynthetic activity and regulating photomorphogenesis in controlled-environment agriculture. However, the development of efficient far-red phosphors remains a significant challenge. In this study, a high-performance far-red emitting (Ca,Mg)14Al10Zn6O35:Mn4+ (CMAZO:Mn4+) phosphor, was developed via a cationic substitution strategy. Upon blue light excitation, CMAZO:Mn4+ exhibits bright far-red emission centered at 720 nm, aligning well with the absorption spectrum of phytochromes. The partial substitution of Ca2+ by smaller Mg2+ ions in the Ca14Al10Zn6O35:Mn4+ (CAZO:Mn4+) lattice induces lattice shrinkage and enhances structural rigidity, thereby effectively suppressing nonradiative relaxation pathways. As a result, CMAZO:Mn4+ achieves an emission intensity 1.22 times greater than that of CAZO:Mn4+ and demonstrates enhanced thermal stability. At the optimal Mg2+ doping content, the phosphor reaches a quantum efficiency of 84.0 %. Notably, at 423 K, it maintains 86 % of its room temperature emission intensity. The pc-LED device, fabricated by integrating CMAZO:Mn4+C with an InGaN blue chip, demonstrates excellent photoelectric performance. These results suggest that CMAZO:Mn4+ is a promising far-red luminescent material for advanced indoor plant lighting applications.